Devices that operate as a result of the action of electric current, performing work that can manifest itself in the form of thermal, mechanical and other types of energy are called electrical appliances.

Electrical appliances include various kettles, coffee makers, meat grinders, steamers, multicookers, microwave ovens, hair dryers, irons, floor fans, humidifiers, etc. All electrical devices are certified by a technical control laboratory, as well as instructions or technical descriptions for their use.

Currently, electric heating devices are widely used. They allow you to maintain the desired temperature in any industrial or domestic premises. They usually have a simple design, small dimensions, and save energy. These include: electric fireplaces, electric heaters, radiators, reflective stoves, floor heaters, convectors, etc.

Electric fireplaces

Typically fireplaces are made in the form of a steel box with decorative finishing. The heating elements are spirals on ceramic rods that are mounted in the box. On the back panel of the box there are contact terminals to which the ends of the heating coils are connected. A decorative barrier grille is used as a front wall. A metal reflector located deep in the body creates a stream of directed heat rays.

They are portable, lightweight, not complicated to set up, and are very convenient for bedrooms or other small rooms, providing uniform heating. Power consumption ranges from 450 W to 1050 W, larger volumes range from 1.6 to 3.2 kW. Another type of fireplace is used to decorate the interior - decorative. They not only heat rooms, but also decorate them.

Heaters

These are household electrical appliances that can maintain a set temperature in a room from 17 to 27 o C, the accuracy of execution is +/- 2.5 o C. By warming up the air in the room, they also work as fans. Reliability in the operation of an electrical appliance is ensured at a relative air humidity of 40 to 75% and a temperature of 15 to 30 o C.

The heater device consists of the following parts: a 1050 W heating element, a thermostat that can block the switch, a fan with a compact motor, a signal light and a connecting cord.

All named units are placed in a steel box. The compact open-type electric motor has a squirrel-cage rotor and is easy to use. The thermostat control buttons are built into the handle and correspond to temperatures of 15 - 25 o C. Temperature adjustment is performed manually.

At the bottom of the box there is a blocking switch that is activated when the device is correctly installed on a flat horizontal surface.

The heater is turned on by smoothly turning the adjustment button in the direction of a special mark by which the air temperature in the room is set.

The heater must not be left unattended. According to fire safety rules, a specially equipped place must be allocated for it so that a fire does not occur.

Radiators

For additional heating of the room, radiators are used, which in 1.5 hours of operation raise the temperature by 4 - 5 o C, with a room volume of 25 m³. If the room has a volume of 11 m³, then the device, being the only heat source, will be able to maintain a temperature in the range of 15 - 18 o C, with an outside temperature of 0 o C.

The radiator consists of a metal body, a thermostat, a tubular heating element and a connecting cord. The metal housing is hermetically welded, coated with special heat-resistant paint and filled with transformer oil.

The fuel element is made of heat-resistant nichrome and is placed in a tubular electric heater. To prevent oxidation of the tube insulation, it is covered with pressed powder from melted magnesium oxide. The emergency switch and thermal relay are located in the steel box of the thermostat.

The temperature control button, signal light, and emergency switch handle are located on the wall of the thermostat. The signal light comes on when the radiator is connected to the electrical network. The thermal relay automatically maintains the set temperature on the radiator body, which can reach 100 o C.

Reflective furnaces

One of the simplest heating electrical appliances is a reflective stove, which consists of a heating element mounted on a hinge and a reflector in the form of a sphere. By rotating the reflector, users can change the direction of the heat flow that comes from the heating coil.

A wire fence blocks access to the heater, protecting users from accidental contact with high-temperature and therefore dangerous areas of the oven.

The thermal element heats up to a temperature of 850 - 950 o C, creating a heat flow that is noticeable at a distance of 3 - 5 meters. The thermal element is a cone with a groove cut along a spiral line. A spiral made of nichrome is placed in this groove and secured.

At the base of the housing there is a base, approximately the same as that of an electric light bulb, with its help the heating element is screwed into the reflector socket.

A floor electric heater is often used as an additional source of heat for heating rooms. A simple device: a metal case, a thermal element and a non-removable connecting cord makes it very accessible, since its cost is not high.

Stamped steel sides form a drawer with a curved top lid. A polyvinyl chloride tube fits around a metal handle, which is attached to the top cover. A welded wire frame mounted on the body allows you to dry small items on it. Inside the case there is a protective heat-resistant coating, outside the case and frame are protected from the external environment by heat-resistant paint.

Two steel stands are attached to two walls of the housing and hold the heater at a sufficient distance from the floor for safety reasons. The heating element of such a device consists of ceramic cylinders (2), on which a nichrome spiral is fixed.

At the bottom of the case there is a signal light, which lights up after connecting the device to the network. Electrical circuits devices of this type are simple and are available in the technical documentation accompanying each heater.

Convectors

These heating devices use the phenomenon of convection in their operation and serve as auxiliary heaters for any type of room. Due to natural active convection, the air is heated and mixed, increasing the temperature. The convector has an increased service life, since the heater has a reliable design that operates for a long period of time.

Safety of Electric Heating Appliances

When using household electrical appliances, you must follow basic fire safety rules. The safety of electrical appliances is a guarantee of preserving the life and health of users.

The safety of electrical appliances is possible subject to compliance with certain standards and regulations. Buy electric heating devices that have an automatic shut-off function. Pay attention to the place where the device will stand; there should be empty space next to it. At least 1 meter from flammable objects: bed linen, curtains, etc.

It is permissible to use only certified devices that have markings - this ensures the safety of electrical devices. The abundance in the market allows this to be done. Before leaving home, be sure to turn off your electrical heating equipment. You cannot overload the city electrical network with many electrical devices turned on at the same time.

Household electrical appliances

Water heating devices

The simplest device for heating water is a boiler. Boilers are produced in different sizes, different capacities, designed for different rated voltages, but the principle of operation is the same for all.

The main element of the device is a heating element - a tube with a diameter of 5-10 mm, the working part of which is twisted into a spiral with a diameter of 30 to 100 mm. The lining of the heating element is made of steel, copper, brass, and food-grade aluminum. To protect the electrical wire, there is a rubber or plastic stopper at the junction of the heating element and the wire. The design of the boiler is such that it can be hung from the edge of the dish.

All other household appliances designed for heating water are made with built-in heating elements. An electric kettle and an electric samovar also have a thermal switch that protects the device from overheating.

Heating elements are also used in electric water heaters designed to heat running water. The heating element is built into a metal tank covered with a plastic casing. The heaters also have a heating power regulator, a pressure regulator, and a thermostat.

Kitchen appliances

Devices for processing products can be divided into two large groups. The first includes devices for processing products, such as electric meat grinders, electric coffee grinders, electric potato peelers, electric juicers, and mixers.

The second group includes cooking appliances, such as electric stoves (electric stove), electric saucepans, electric frying pans, electric ovens, electric coffee makers, electric grills, electric kebabs, electric waffle irons. toasters, microwave ovens.

Food processing devices make work easier in the kitchen, allowing you to do less heavy mechanical work, thereby speeding up the process of preparing food and saving effort.

Electric meat grinders, which come in auger and cutter types, are designed for preparing minced meat or fish. Screw electric meat grinders have the same design as a manual meat grinder, with the exception that the rotation of the screw, which feeds parts of the product to the rotating knife, is carried out by an electric motor.

A meat grinder works on the same principle as a coffee grinder: at the bottom of the container in which the product is placed, there is a rotating knife that grinds the product into minced meat.

The design of both types of meat grinder is extremely simple and consists of an electric motor that rotates the auger or cutter knife axially. To protect the motor from overload, meat grinders are equipped with a mechanical protective device. The cutter meat grinder has a lock that makes it impossible to operate the device without a lid. The design of the meat grinder may include a time relay, a device for storing attachments, and a device for winding a cord. Attachments and replacement knives must be sold as a set.

Electric coffee grinders are available in two types. Impact coffee grinders are a small cutter that also has a locking mechanism that makes it impossible to operate without a lid. An electric motor drives a two-blade blade located at the bottom of the grinding container.

The design of an impact coffee grinder is even simpler than a cutter grinder. It does not have a time relay, mechanical protective device, or other devices. There is only a button on the case that closes the network.

A burr-type electric coffee grinder grinds coffee beans (as well as other bulk products) using discs, cylinders, cones and other elements that act as millstones. The most common design of this device has two disk millstones - movable and fixed. The grains are poured into the working mechanism through a special funnel. The ground product goes into a hopper, from where it can be removed by opening the lid.

This coffee grinder is more convenient, since at the same power as an impact coffee grinder it has a grinding degree regulator that sets the distance between the millstones, it can hold four times more product (125 g versus 30 g in an impact coffee grinder), it also has cord storage device.

The electric potato peeler is designed for preparing potato mass. This operation can be performed using a juicer, but in this case the mass will be heterogeneous. The potato grater is an electric motor on which a grating disk is attached. Potatoes are loaded into the hopper, while the grating disc crushes them, and the potato mass, passing through the holes of the cutting elements, comes out into the receiving container.

A juicer designed to extract juice from fruits and vegetables works on the same principle. The juicer also has a grating disc that grinds the product. After this, the crushed mass enters a centrifuge, during which rotation the juice is released. From time to time the centrifuge is cleaned by an ejector.

Potato grinders and juicers have a simple design that allows you to repair them yourself. As a rule, problems with these devices occur due to the fact that the gap between the grinding disk and the plastic parts of the body increases due to their wear. In this case, it is recommended to disassemble the device, replace worn parts, and then assemble and adjust the device.

Product processing devices also include a mixer. This device is an electric motor in a plastic case that rotates two axes onto which various attachments are placed. The mixer has step speed adjustment for processing different products.

If the device is made in a desktop version and has a device for squeezing juice from citrus fruits, a tilting mixer operating in a special container, as well as other additional devices, it is usually called a food processor.

Of all the cooking devices, the electric stove is one of the simplest household appliances for processing food. It is a metal stand on which there is a ceramic base with grooves into which the spiral is placed. The tile sometimes has a step heating control.

However, tiles with an open spiral can be found less and less often, as the open spiral is increasingly being replaced by heating element. This can be explained by the fact that during the cooking process the spiral can be damaged by spilling milk or water on it. Secondly, since the spiral is open, the possibility of an electric shock is likely.

PETN electric stoves are more reliable in this sense. The metal tube protects the heating element from harmful influences and also protects against electrical shock. Otherwise, the electric stove remains the same: it has a step-by-step heating power regulator with the corresponding designations in degrees Celsius.

An electric stove works on the same principle as a heating element electric stove, with the exception that it has an oven. On the front panel there are position switches for heating power, an oven lighting switch, and a thermostat signal lamp.

The heating elements can be folded back to clean the trays; the stove has a lock that prevents the oven and burners from being turned on at the same time. The stove has a lockable lid.

An electric pan is also available with heating element. It has an aluminum or steel body, a thermostat that allows you to regulate the water temperature within 65-95°C, and a thermal switch that turns off the device when the water boils away or is turned on without water.

The device is similar for an electric frying pan. Under the base it has a tubular heater that allows you to heat the work surface to 185°C in 6 minutes. As in other devices that use heating elements, the frying pan has a thermostat designed to regulate the heating of the working surface in the range from 100 to 275°C. Electric pans are produced for cooking under high blood pressure(pressure cookers) and for steaming food (steamers).

Electric ovens are designed for baking flour products, for preparing stews from meat, fish and vegetables. The heating element of an electric oven transfers heat evenly across the entire working surface. Some models have a viewing glass on top.

The body of the electric furnace is made of aluminum alloy; the heating element, which is a nichrome spiral with beads placed on it, is located in the lid. The heating element can also be tubular.

The maximum oven temperature is 240°C. The design of the oven allows it to be used as an oven, frying pan, fryer, or steamer. The lid is made in the form of a frying pan and can be used for cooking.

An electric coffee maker can be vacuum, compression, percolation, or filtration. In a vacuum coffee maker, coffee is prepared by passing hot water or steam under pressure through a layer of ground coffee. Due to the vacuum, the coffee flows into the water container.

In a compression coffee maker, coffee is prepared by passing water or steam under pressure through a layer of ground coffee. In a percolating coffee maker, water or steam passes repeatedly through a layer of ground coffee.

In a filter coffee maker, coffee is prepared by passing water or steam once through a layer of ground coffee located in the filter (doser mesh).

All coffee makers have a thermal limiter that turns off the appliance if it overheats. The coffee container is installed on a steam table, which heats the coffee to the desired temperature.

The coffee maker has a heating element. The steam generated as a result of heating the water exits through the tube and enters the dispenser, where the ground coffee is located, passes through the dispenser and is discharged into the drink container.

An electric grill is a household device for heating food using infrared radiation. A tubular heater or tungsten filament in a quartz glass tube is located under the arch. Devices for securing food are attached to the side walls. The drive that rotates the fasteners can be manual or automatic. The electric grill can be either open or closed.

Electric grills are equipped with thermostats that allow the device to be heated from 190 to 250°C. Some models have a front glass door, lighting, and a timer.

An electric barbecue maker is built on the same principle as an electric grill. Electric kebabs are available in two versions: vertical and horizontal. An electric motor rotates the skewers at a speed of 0.5-5 revolutions per minute. In electric grills and electric barbecue makers, a signal light is not installed, since the heating element glows during operation.

A heating element or tungsten filament in a quartz glass tube also acts as a heating element. In electric grills and electric barbecues, the emitter temperature is at least 700°C, the heating element heats up in 5 minutes, the tungsten filament in a quartz glass tube - in 1.5 minutes.

An electric waffle iron is a form whose working surfaces are heated by heating thermoelements located in special recesses.

Under the lower heating plate there is a bimetallic thermostat, which disconnects the device from the network at temperatures above 200°C. Also under the bottom plate there is a fuse designed to turn off the device in the event of failure of the bimetallic thermostat. Reusing the fuse is possible only after soldering it with a soldering iron.

Electric toasters are designed to toast slices of bread using an infrared emitter (tungsten filament in a quartz glass tube). Depending on the model, they may have an automatic switch with a timer or a manual shutoff.

Models differ in the number and size of frying chambers, in the time and uniformity of frying, in the ability to remove crumbs, and in power consumption.

In devices with manual shutdown, the slices of bread are placed in special niches, from where they are then removed manually. Frying can be done on one or both sides. In appliances with an automatic shut-off, the toasting is carried out for a certain time, the shut-off occurs automatically, and the slices of bread are pushed out by spring pushers.

An electric roaster, a household appliance designed for making sandwiches, is built on the same principle. Just like electric toasters, the heating element is a tungsten filament in a quartz glass tube. Switching off the device can be manual or automatic.

For uniform heating, the electric roaster has several heating elements on top and bottom. Using a step-by-step heating power regulator, you can turn on the heating elements selectively, i.e., upper or lower, or all at once.

An electric roaster (just like an electric toaster) has a timer with which you can set the heating time. Since the infrared emitter heats up very quickly (maximum 1.5 minutes), the time relay is designed for 6 minutes of operation.

Of all household cooking devices, the most complex is the ultra-high frequency oven (microwave oven). While other household appliances are fairly easy to repair, since most problems occur due to mechanical damage, the microwave oven has a more complex structure and is filled with electronics, and therefore it is best to carry out repairs in a workshop.

A microwave oven uses the property of an electromagnetic field to uniformly heat the entire volume of the chamber, regardless of the contact of the processed product with the coolant, or the thermal inertia of the heater. The microwave field is completely converted into heat, which allows for uniform and rapid heating of products.

Unlike methods where heating is produced by contact of the product with a coolant, microwave heating generates heat due to the displacement of charged particles when the product is exposed to an electromagnetic field. Heat is generated due to intermolecular friction.

Regardless of the model of this household appliance, it has the following devices: a power source that converts the mains voltage for the microwave generator (high-frequency voltage rectifier or transformer with voltage regulator); magnetron – an electric vacuum device that generates pulsed and continuous microwave oscillations (microwave generator); device for transmitting microwave energy to the heating chamber; a heating chamber with appropriate electrodynamic properties for distributing microwave energy throughout the entire volume; – sealing devices that prevent leakage of microwave energy.

The microwave oven must have a time relay to regulate the heating duration. As a rule, modern models of microwave ovens have a control panel with a touch drive.

The device has a frame made by cold stamping and welding. The furnace lining is made of cold-rolled steel, painted with enamel. Removable elements are attached to the frame with screws. At the front there is a chamber door that opens downwards or to the side; the door may have a transparent quartz glass window so that you can observe the process of preparing food. The housing has ventilation holes for cooling the magnetron and the working chamber.

Heating appliances

A house cannot be comfortable if it is cold. The recommended air temperature in the apartment should be 16-25°C. In living areas the air temperature should be 18-22°C, in bedrooms 14-17°C.

In everyday life, heating devices such as convectors, radiators, and infrared directed radiation heaters are used.

Convector-type heating devices use the convection movement of warm air. Cold air passing through the heating device is heated by a metal spiral and should not have a temperature of 85°C at the outlet.

In convector-type heating devices, adjustable resistances are installed so that the heating strength can be set, as well as bimetallic thermostats that turn off the device in case of overheating. The heating element in most cases is a spiral, sometimes located in a glass tube. The convector body is designed to reflect heat.

Radiator-type heating devices are designed so that heat transfer occurs from the working surface. They rarely install heating power regulators, as well as thermostats, since the electric radiator has insufficient power and is more often used as an additional means for heating the room.

Electric radiators are divided into dry (without an intermediate carrier), oil-filled, sectional and panel. According to their design, electric radiators can be wall-mounted or floor-mounted.

Directional infrared heaters are a reflector with a heater placed at the focal point. With the help of a reflector, directed heat transfer is formed. The body can be made of any material. Maximum heating temperature – 900°C, power – up to 2 kW.

Infrared heaters are distinguished by the type of heating element, which can be closed or open, as well as by the shape of the reflector, which can be spherical, parabolic, cylindrical.

Spirals in quartz tubes, bi-spirals on ceramic bases, and high-resistance wire wound on a ceramic rod are used as a heater. The spiral is necessarily covered with an oxide film, which prevents interturn short circuits.

To increase the heat transfer effect, the surface of an aluminum reflector is polished and anodized, while reflectors made of other metals are chrome-plated or nickel-plated.

Depending on the complexity of the design, the infrared heater may have a stepwise power switch,

As a rule, the reason for the breakdown of heating devices is trivial. This is either wear of the heating element, or wear of the insulation on the wire, or other mechanical damage. Knowing the principle of the thermal effect of electricity, it is easy to repair the heating device yourself.

Refrigerators and freezers

First of all, refrigerators are divided according to the methods of producing cold: compression, absorption, thermoelectric. They are also divided according to the volume and number of freezers, according to the design option: floor-mounted, wall-mounted, block-mounted, etc.

Compression-type refrigerators are a cabinet with a refrigeration unit, as well as elements of automation and electrical equipment. The refrigeration unit produces cold using a special substance called refrigerant.

A refrigerant is a substance that transforms into a vapor state at low temperatures. It must have moderate boiling pressure, high thermal conductivity, have the lowest possible solidification temperature and the highest possible critical temperature. In addition, it must be harmless to the body and not cause metal corrosion. That is why the most common refrigerants are freons and ammonia.

The refrigeration unit of a household refrigerator consists of a motor-compressor, an evaporator, a condenser, a piping system, and a filter-drier. Typically, the compressor is located at the bottom, the condenser is on the back wall, and the evaporator forms a small freezer compartment at the top of the chamber.

The compressor circulates the refrigerant in the system. The compressor is driven by an electric motor. The principle of operation of the compressor is as follows: an electric motor drives a piston, which moves the valve. This creates a vacuum and part of the refrigerant enters the suction chamber through the suction valve. With further movement of the valve, pressure is created, from which the suction valve closes, and the refrigerant leaves the suction chamber into the pipeline. This is a general principle of operation for any compressor, regardless of version.

The electric motor of the refrigerator operates cyclically, that is, it periodically turns on and off. The shorter the intervals, the lower the temperature of the freezers, the greater the energy consumption, and vice versa. The frequency of operation of the electric motor is ensured by a temperature sensor-relay, which maintains a certain temperature in the freezers.

The refrigerator condenser is a heat exchange device through which the refrigerant transfers heat to the environment. Cooling occurs due to air, and therefore the condenser coil is usually made with metal fins that enhance cooling. Capacitors are usually made of copper or aluminum, since these metals have high thermal conductivity. The refrigerant, cooling, turns into a liquid state and enters the evaporator.

In the evaporator, the refrigerant absorbs heat from the cooled chamber. As a rule, in the refrigerator it is located above the freezer. Evaporators have channels of various configurations and differ in the method of attachment to the freezer.

The supply of liquid refrigerant from the condenser to the evaporator is carried out by a capillary tube, which has low permeability and, connecting parts of the installation with high and low pressure, creates a pressure difference between the condenser and the evaporator, allowing a limited amount of liquid refrigerant to pass through.

The filter is located at the entrance to the capillary tube to prevent clogging by solid particles. It is a metal case filled with bronze balls with a diameter of 0.3 mm or having a brass mesh inside.

To clean the working environment from moisture and acids, various adsorbents are used, which are used to fill filter-driers. Synthetic zeolites and mineral adsorbents (silica gel, almulugel, etc.) are used as filter materials. Due to their crystalline structure, synthetic zeolites absorb moisture well and almost completely absorb refrigerant and engine oil.

A filter that adsorbs moisture that may freeze in the capillary tube is called a drying cartridge, which is installed in front of the entrance to the capillary tube, and therefore is often combined with a filter drier. The drying cartridge is also filled with synthetic zeolite. Sometimes methyl alcohol is used instead of a drying cartridge. In this case, moisture is not removed from the system, its freezing point simply decreases. The amount of methyl alcohol is 1-2% of the amount of refrigerant. However, methyl alcohol is not used if the condenser is made of aluminum, since the interaction of substances leads to the destruction of aluminum and leakage of refrigerant.

In general, the process of operation of a compression cooling unit is as follows. The refrigerant vapor is sucked out of the evaporator by a compressor, which cools the winding of the electric motor. The refrigerant vapor compressed in the compressor enters the condenser, where it cools and turns into a liquid state. Liquid refrigerant flows through the filter and capillary tube into the evaporator. There, under the influence of low pressure (98 kPa), it begins to boil, taking heat from the freezer. From the evaporator, the refrigerant vapors again enter the compressor. The electric motor is turned on and off by a start-up relay, which in turn is turned on by a sensor-relay that automatically maintains the temperature.

Another type of refrigerator is absorption. They are designed for short-term storage of perishable products and for producing edible ice. Cooling occurs due to the absorption process - the absorption of refrigerant vapors generated in the evaporator by a liquid or solid absorber. The refrigerant is ammonia, the absorbent is water double distillate, the inhibitor is sodium dichromate, and the gas is hydrogen.

The system is filled with ammonia-water solution and hydrogen. Hydrogen is inert and therefore does not react with ammonia. The ammonia-water solution is heated in the generator, resulting in the release of ammonia-water vapor, which rises through the rectifier. As a result of the water having a higher condensation temperature, pure ammonia vapor enters the condenser.

In this case, ammonia vapor displaces hydrogen and condenses under a pressure of 1500-2000 kPa, equal to the pressure inside the entire system. Cooling is carried out due to the design of the condenser, as well as the cold vapor-gas mixture leaving the evaporator.

In the evaporator, liquid ammonia evaporates, absorbing heat. Vapors are removed from the evaporator by circulating the refrigerant in a closed system. Ammonia vapor is absorbed in the absorber by an ammonia-water solution, from where it is then returned to the generator to continue its movement. The heater is a spiral of nichrome wire inserted into a metal sleeve with porcelain bushings strung on it; the free space is filled with quartz sand.

Absorption refrigeration units can be manual or automatic system temperature adjustment. In the first case, a manual step power regulator is used, in the second, a thermostat is used that turns off and turns on the heating element to maintain constant temperature.

The advantage of absorption refrigerators is their quiet operation, while compression refrigerators produce a specific sound due to the movement of the valve in the compressor. Also, the advantages of absorption plants include simplicity of design, the absence of valves and moving parts.

However, due to the fact that the heater in an absorption refrigerator must be constantly turned on, energy consumption is greater, and therefore using an absorption refrigerator is more expensive.

Among other things, both types of refrigerators often contain additional devices that perform various functions: to maintain a certain humidity in the freezers; cooling drinks and dispensing them without opening the door; operating mode signaling; automatic door closing; fixing a certain angle of opening the door, preventing it from hitting a wall or central heating radiator.

Unlike refrigerators, freezers are designed for deeper freezing at a temperature that prevents the formation of large ice crystals, as well as for storing food at a lower temperature. The freezer is a compression unit in which, unlike a conventional refrigerator, the compressor does not operate periodically, but constantly. Between the evaporator and the suction pipe of the compressor there is a refrigerant boiler (which has not had time to dissolve in the evaporator), which allows increasing efficiency. The zeolite desiccant is double-sided, which makes it possible to perform double-sided evacuation of the unit when it is filled with refrigerant.

Unlike a refrigerator, in which the evaporator is located so that it is more convenient to divide the internal space into a freezer and a food storage chamber, in a freezer the evaporator is located so that the entire chamber is cooled evenly, so it does not have a separate freezer, it only has several shelves for placing products.

Refrigerator repairs should be carried out in a workshop, since it is impossible to repair the refrigeration unit yourself; this requires special repair equipment. As a result of repairs, it is necessary to carry out diagnostics, removal of refrigerant, desoldering of joints, washing and drying of components, assembly, testing for leaks, evacuation and filling with refrigerant, and running-in. You understand that it is simply impossible to perform such complex work at home. All you can do yourself is to fix the door hook, replace the insulating strip on the door, change the light bulb.

In the event of a refrigerant leak, safety precautions must be taken as the refrigerant is flammable. You should be careful not to get it on your hands, face, or eyes.

Unlike compression and absorption type refrigeration units, thermoelectric refrigerators do not have a refrigerant; they operate only on electricity.

Thermoelectric cooling occurs as follows. An electric current passes through a thermopile made up of two types of semiconductor heating elements: some are cooled, others are heated.

As you already know, all materials can be divided into two groups: conductors of electric current and dielectrics. In addition, there are materials that occupy an intermediate position between conductors and dielectrics. Unlike metals (conductors), they have greater resistance to electric current, but less than that of dielectrics.

Any conductor heats up when electric current passes through it. This is also true for semiconductors, however, if when a conductor is heated its resistance increases, then when a semiconductor is heated the opposite happens: the more the semiconductor heats up, the less resistance it has. Also, current flows through a semiconductor in only one direction.

These properties of semiconductors (copper oxide, selenium, silicon, germanium, etc.) allow them to be used in thermoelectric cooling environments.

Some refrigerator thermoelements are made of an alloy of lead and tellurium, others are made of an alloy of tellurium and antimony. Thermoelements can also be made from bismuth and selenium alloys.

Semiconductors are connected to each other in series using metal plates. When electric current passes through them, some heat up a little, while others cool down. Heating semiconductors are located outside the cooling chamber, cooling ones are located inside. To achieve a lower temperature, the refrigerator also has a fan.

Thermoelectric refrigerators are rarely used in everyday life, as they are inferior in quality to compression and absorption refrigeration units. The refrigerator can be used as a car refrigerator, as it is designed for short-term cooling of food - no more than 48 hours. As a rule, its body is designed so that the device can be used as an armrest.

The refrigerator can work from both direct current 12 V, and from alternating current 127 and 220 V. Many models do not have an alternating current rectifier. This is due to the fact that the device has the most compact design so that it is convenient to use in a car. If you need to turn on the device via a network with a voltage of 127 or 220 V, you should use a charging-rectifier device connected to the cord plug.

Washing machines

Washing machines can be semi-automatic, in which the washing and spinning processes are controlled by the operator, as well as automatic, in which the processes are carried out in accordance with a given program.

A semi-automatic washing machine is a body made of sheet steel, which contains a washing tank and a centrifuge. The surface is covered with nitro-enamel or anodized, the tank and centrifuge have separate lids, the housing is closed with a removable lid. To facilitate operation, the body has handles and rollers. On the back wall there is a niche for storing rolled cord.

The washing tank is made of stainless steel sheet coated with vitreous enamel and has a cylindrical shape or is made in the shape of a cube with rounded edges, with a sloping bottom, at the bottom of which there is a drain.

The activator is installed in the wall of the washing tub or at the bottom. It is located in a recess, which prevents laundry from getting into the gap between the tank and the activator.

The activator is an electrically driven paddle disk. The tightness is created by rubber gaskets. The activator rotates at a speed of 475 to 750 rpm. Its operating time is regulated by a mechanical time relay.

The centrifuge is a basket made of aluminum, operating on an electric drive. The rotation speed during spinning is 2600-3270 rpm. To start the electric motor, there is a capacitor in the circuit, and a thermal relay is installed to protect the windings from burnout. Electric motors for the activator and centrifuge are installed separately; four types of insulation are used to protect against electric shock. The operating time of the centrifuge is also controlled by a mechanical time relay.

The solution is drained using a centrifugal pump, driven by the activator motor shaft. Capacity ranges from 18 to 30 liters per minute.

Automatic washing machines, also called drum-type or front-loading machines, carry out all operations according to a given program. Washing and spinning take place in the same drum, which allows the use of electronics that fully automate the washing process.

Filling and draining of water, dosed introduction of detergents, locking, washing in heated water, rinsing, spinning are performed automatically. The processes can also be adjusted taking into account the degree of soiling of the laundry, as well as its wear resistance.

The washing tank is mounted on springs that reduce vibration, and has a drum inside, which is driven by an electric motor with a belt drive and several speeds (for washing and spinning). Water is supplied from the cold water supply network - heated by a tubular heater. The water is drained by a pump. Commands are entered from the control panel.

Vacuum cleaners and floor polishers

Vacuum cleaners perform all work that involves thin air: cleaning carpets and floors, cleaning clothes, whitewashing. The operating principle of the vacuum cleaner is that air is sucked in by the unit through special filters.

Vacuum cleaners come in floor and hand-held types. Floor-standing vacuum cleaners have a stable design on running rollers. Handheld vacuum cleaners are portable and have a handle. Handheld vacuum cleaners can be either hose or car vacuum cleaners. Depending on the direction of the air flow, vacuum cleaners are either direct-flow or vortex.

The design of any vacuum cleaner must have a dust collector, which can be made in the form of a replaceable paper bag or a device for pressing dust. As a rule, the dust collector has snap locks to make it easy to remove the filter (dust collector).

Also, the vacuum cleaner must have an automatic shutdown device when the dust container is full or a filling signal. Filling the dust container creates an obstacle to the operation of the air suction unit, which may not withstand the load.

Since, unlike other devices, the vacuum cleaner has a longer cord, it must be equipped with a device for automatic cord winding.

The corrugated air hose in a stretchable nylon braid must have a length of at least 2 m for floor-standing vacuum cleaners and at least 1 m for hand-held vacuum cleaners. The extension tube is made of aluminum and must be 1 m long (for floor-standing vacuum cleaners).

The vacuum cleaner must be equipped with brush attachments, which are designed for cleaning various surfaces and are made of horsehair and ridge bristles. The body is made of polyethylene, polyvinyl chloride, polystyrene.

The most important part of a vacuum cleaner is the electric motor, which converts electrical energy into mechanical energy. An electric motor drives a bladed propeller, which creates a vacuum of air. The air suction unit can be designed in different ways, depending on the design of the vacuum cleaner (gearbox, clutch, belt, etc.)

The vacuum cleaner must have holes for air outlet and air inlet, to which a corrugated hose can be connected. Some vacuum cleaner models have a power regulator. Some vacuum cleaners have a special housing that reduces noise. For vacuum cleaners that do not have a noise-reducing housing, the noise level should not exceed 80 decibels.

Electric floor polishers designed for polishing floors can be of two types – with and without a vacuum cleaner. The floor polisher has a bar that rotates freely in a vertical plane, which is held in this position using a special clamp.

The ventilation device is located so that during operation air flows cool the working units. Replaceable paper bags are used as a dust collector. The floor polisher has three brushes, which are driven by an electric motor. In addition to brushes, the kit includes polishing washers. The brushes and ventilation device turn on simultaneously.

The design of the floor polisher is very simple and no special tools are required to repair it, so you can carry out repairs yourself.

Devices for improving microclimate

by the most simple device The fan that circulates air in a living space is a fan. Depending on its purpose, the fan can supply or exhaust air, as well as blow or mix. More complex are fan heaters, which are designed for heat transfer due to forced convection. Humidifiers create the necessary air humidity. Ionizers increase the number of negative ions in the air, the carrier of which is oxygen.

Air purifiers and air conditioners are the most complex and complex devices that perform several operations: ventilate the room, create the required level of humidity, heat and cool the air, and clean it from fine particles.

All these devices can be combined under the general name devices for improving the microclimate. The composition of the air in any room in the absence of normal ventilation deteriorates due to contamination with dust, aerosols, combustion products, and carcinogenic substances.

This leads to the need to use ventilation devices that would ensure good air circulation, the most affordable of which is a fan.

The fan is a bladed propeller driven by an electric motor. According to the design option, fans can be table, wall, floor, or ceiling. A fan can be universal if the design allows it to be installed in different ways.

Fans are also usually distinguished by the presence of protective devices. A fan without a protective guard has an open blade propeller. Such devices are usually available in desktop, wall and ceiling versions.

A fan with an open-type protective guard has a bladed propeller covered with a metal frame. This type of barrier is mainly used for floor fans (floor lamp type).

A fan with a closed type guard is a bladed propeller recessed into the fan housing and covered with a grille. This type of protective fence is used exclusively in exhaust devices. It is also generally accepted that exhaust fans operate on a tangential principle (turbine).

Table and floor fans typically have multiple speeds. Speed ​​control can be smooth or stepped. Two-speed fans have two buttons that turn on different speeds; multi-speed floor lamp fans have a panel with buttons for switching speeds.

Desktop and floor-standing fans must also have a device to direct the air flow. The vertical tilt of the blade propeller is done non-automatically using a special fixing screw (handle). The automatic circular change in air direction is carried out by a rotary mechanism, which can be stopped by pressing a button on the control panel or pressing a sleeve on the body.

Ceiling fans differ slightly in design. If all the fans discussed above are axial in principle, then the ceiling fan is centrifugal.

The fan is suspended from the ceiling using a rod, at the end of which there is an electric motor. The wings are attached to the electric motor with screws. Turning the fan on and off, as well as speed control, is carried out by a regulator located on the wall.

Deluxe fans may have the following additional devices: a mechanism for automatically cleaning the cord; height adjustment device; timer.

The design of almost all fans is very simple, designed for ease of use; it is possible to carry out independent repairs without the use of special tools.

Fan heaters, just like regular fans, can be floor-mounted, table-top, wall-mounted, or universal. Heating is produced by forced convection. The fan has heating elements, behind which the fan itself is located. The heating element is a tungsten filament in a quartz glass tube.

Almost all fan heaters have a closed type protective enclosure, required in accordance with fire safety requirements.

Fan heaters can be single-speed, two-speed or multi-speed. The adjustment can be smooth or stepped. In addition, there is a heating regulator. In most cases, it is a multi-channel switch for turning on all or some heating elements, although smooth adjustment of the heating power is also possible. To protect the device from overheating, a bimetallic thermal switch is installed. The warning light may not be used if it is possible to determine from the operation of the heating elements whether the heating is on or not.

Superior comfort fan heaters have a device for automatic cord winding, as well as a compartment for storing it, a signal lamp, and a handle for carrying the device.

Air humidifiers are used to create the desired level of humidity, as well as spray aromatic aqueous solutions and medications in the room. At the same time, the humidifier increases the number of negative ions in the air, resulting in the air being cleared of dust and smoke.

The device has a water tank, a centrifugal fan, and a mesh through which spraying occurs. During operation, water rises along the walls of the tank, entering the fan, which throws it onto the mesh; it enters the air in the form of fog or small splashes.

Humidifiers are available in wall-mounted, table-top and floor-mounted versions. The device may have a smooth or stepped water spray control or may be unregulated.

The design of the humidifier is simple; repairs do not require special tools, so repairs can be done independently. However, it should be remembered that the device works with water, as well as aqueous solutions, which are conductors of electricity, so you should pay special attention to insulation, and if necessary (for example, when checking the device), take the necessary safety measures.

Ionizers are designed to increase the amount of negative ions in the air. As already mentioned, the carrier of negative ions is oxygen. The feeling of fresh air depends precisely on the amount of negative ions. However, their lifetime is short, since they come into contact with fine particles (dust), thereby losing their polarity. The air becomes heavy and stuffy.

Household ionizers are based on various voltage multiplication circuits. The device has two contacts, between which a corona charge passes, which ionizes the air. Negatively charged electrons propagate at high speed due to a special reflective contact.

The ionizer should not be left on for a long time. According to the recommendation of experts, it should work at a distance of 1 m from a person for 15-30 minutes.

As a rule, the main source of air pollution is the kitchen, especially the gas stove. Combustion products and dust come into contact with negatively charged ions, and the air becomes heavy and contains a lot of foreign odors. That is why kitchens use devices for recirculating air purification from various contaminants.

The principle of operation of an air purifier is similar to the action of a gas mask, in which the air is purified from toxic substances through the work of the human lungs. Air purifiers are equipped with special supply and exhaust fans.

It is customary to install the air purifier above the gas stove at a distance of 60-90 cm, since it is the main source of air pollution by combustion products. Therefore, air purifiers are produced in standard sizes corresponding to the sizes of gas and electric stoves. Among other things, the device is equipped with a backlight in case of insufficient natural light.

The purifier works according to the following principle: behind the filter there is a fan that circulates air. Passing through the filter, the air is cleaned.

The design of the purifier allows you to replace the filter yourself. The filter is designed to clean the air from products of incomplete combustion of gas and is a replaceable cassette with a sorbent (for example, activated carbon or aluminosilicate ball catalysts). The filter must be changed every 6-12 months.

The purifier can also be designed to sterilize the air due to the operation of a bactericidal mercury-quartz lamp, which can operate all the time the device is operating. It is recommended to turn on the air purifier when you start cooking and turn it off when finished.

The fan has at least two operating modes: nominal and forced. The device is controlled from the front panel, which has all the necessary keys, as well as signal lights.

The fact that it is customary to install an air purifier in the kitchen above a gas stove does not mean that the air purifier cannot be used in other rooms where, for some reason, air pollution is possible.

In this case, instead of an air purifier, an air conditioner is installed, which, in addition to cleaning the air, also heats or cools it and ensures air circulation at the required level.

In principle, an air conditioner is a derivative of all the microclimate improvement devices described above. It has a fan that circulates air, heating elements and a cooling unit that maintain the desired temperature in the room; the air is purified using a filter similar to the one used in an air purifier. In addition, air conditioners have electronics that automate operations, as well as remote control for ease of use of this household device.

The air conditioner consists of two compartments, one of which is located outdoors, the other indoors. The compartments can be made in one housing, or they can be made separately and connected by a corrugated hose.

In most air conditioners, a compressor-type cooling unit is installed, as it is more reliable in operation and less energy-intensive than absorption. The difference lies only in the reduced size (compared to a refrigerator or freezer) of the unit, as well as its special location in the air conditioner housing, due to the design features of this device. The compressor, condenser and dryer are located in the outer compartment, since these parts of the installation require cooling. The evaporator is located in the internal compartment and cools the air.

The air conditioner can be equipped with an air heating function, for which heating elements made of tungsten filament in a quartz glass pipe are installed in the internal compartment. As a rule, air conditioners that have a common housing do not have the function of heating the air, since the cooling unit is difficult to combine with heating elements in the same housing.

Air filters, just like in air purifiers, are made in the form of replaceable cassettes filled with sorbent. However, it has to be changed more often, since the kitchen air purifier only works while cooking, and the air conditioner is designed to work around the clock.

The air conditioner fan is axial, having at least two operating modes: nominal and forced. The fan can operate when the cooling unit, heating elements are turned on, or can be turned on separately in ventilation mode.

The air conditioner is also equipped with bimetallic thermal switches that turn off the device if the appropriate temperature conditions are violated.

Separately, it should be said about the electronics that are used in air conditioners. Since the execution of some operations depends on the execution of others (for example, three ways to turn on the fan, as mentioned above), as well as the incompatibility of some operations (air heating and cooling), it is necessary to automate the control of the device, otherwise the control panel will be too cumbersome, in It will be difficult for her to understand. It would also be difficult to control an air conditioner using any mechanical means (switches, regulators), so over time, more and more air conditioners began to be equipped with special electronic control circuits to make the device easier to use.

Since the air conditioner is in most cases located in a window, in a ventilation shaft, and therefore it is inconvenient to locate the device control on the body, it is easier to use remote control.

From a remote control powered by AA batteries, you can perform all operations to control the device. In addition to simply turning on ventilation, heating and cooling, adjusting air circulation, using a remote control you can set a program that would constantly maintain the desired temperature in the room throughout the day; you can program the air conditioner to turn on and off at certain periods of time.

Personal devices

There are many personal appliances used in everyday life - electric shavers, hair dryers, massagers, etc. All of them are small in size, most of them are manual. These devices cannot be classified as converting electricity into thermal or mechanical energy, since the devices have different purposes and the only thing that can unite them is individual use.

First of all, it should be said about devices that produce “soft heat”, designed to heat the human body. A spiral of nichrome or constantine wire, woven into asbestos fabric and sewn into low-stretch fabric, is used as a heater. An elastic carbon-graphite cord is sometimes used as a heater. The maximum heating temperature does not exceed 70°C.

The device has a step-by-step heating power regulator, as well as an emergency thermal switch. The advantages of such heating devices include the fact that they are reliable, not afraid of bending, and have reinforced electrical insulation that can withstand a voltage of 375 V.

The most common household appliances for individual use can rightfully be considered a hair dryer and an electric razor, which are found in every home. The hair dryer is designed for drying, combing and styling hair.

This device can be called a manual fan heater. The maximum heating temperature is 60°C, moderate heating 50°C, low heating 40°C. Heating control can be stepped or smooth. The heating element is made of nichrome or constantine wire twisted into a spiral. The heating element also performs the function of reducing the network voltage. To protect the device from overheating, it is equipped with a thermal switch that turns off the device and turns it on after cooling.

The fan is driven by an electric motor running on DC current. The air passes through the slots in the housing and exits into the divider. To rectify alternating current, a diode rectifier is installed, the electric motor is located in a housing made of polystyrene, polyvinyl chloride or other dielectric material. The hairdryer comes with various attachments that are screwed onto the body.

Electric shavers operate from a network with a voltage of 127, 220 V, or from autonomous DC power sources with a voltage of up to 12 V. The razor can have a universal connection to the network and autonomous power sources. The movement of the knives in the razor is reciprocating or rotating. Almost all razors are equipped with a cutting unit. Magnetic vibrators and commutator motors are used as motors in razors.

The magnetic vibrator is used in razors with reciprocating blade movement, as well as in clippers. The principle of operation of a magnetic vibrator is as follows. The field winding magnetizes the rotor, as a result of which the stator and rotor cores turn out to have opposite poles facing each other. The rotor is attracted to the stator core. Alternating current has a frequency of 50 Hz per minute, and therefore there is a constant change in polarity, as a result of which the rotor oscillates at a speed of 6000 times per minute.

As already explained in the book, a commutator-type motor consists of a stator and a rotor with windings that rotate due to a magnetic vortex flux. The motor windings are designed for several phases, and therefore a collector-type switch is connected to the stator and rotor. This type of razor has a small DC motor that drives floating circular blades.

Individual use devices also include various massagers designed for sports and therapeutic muscle massage. Just like an electric razor with reciprocating blades, massagers use a motor with a magnetic vibrator.

The massager has a plastic body and comes with a set of attachments for various types of massage. For cosmetic massage, funnel-shaped, sponge, ball nozzles, and a rubber drummer are intended. The mushroom nozzle is designed to massage the ligaments and tendons. Instead of nozzles, a massager with a magnetic vibrator can have a massage belt. In this case, the principle of operation of the device does not change.

As mentioned above, the magnetic vibrator operates at a speed of 6000 vibrations per minute at a voltage of 220 V with a frequency of 50 Hz. This is a fairly high speed, which sometimes has to be adjusted, so most massagers are equipped with a step frequency regulator. The amplitude of the electric current is changed using a solenoid coil.

The massager can also be pneumovacuum. The compressor piston is driven by an electric motor. When the compressor operates, air pressure and rarefaction are alternately created in various vacuum nozzles, due to which the massage is performed. In addition to the electric current frequency regulator, the massager is also equipped with an air supply regulator.

The number of attachments for a pneumatic vacuum massager is smaller than for a massager operating on a magnetic vibrator: a funnel-shaped and ball attachment, a rubber drummer.

Power tools

Even if you are not very knowledgeable about electricity or technology, you still need to keep tools at home in case of repairs. Tools can be mechanical or electrical. Electric ones include a drill, hammer drill, sharpener, jigsaw, grinder, electric planer and others. Generally, electricity is used in tools to generate mechanical energy, however, there are also tools that generate thermal energy: a soldering iron, a heater.

The number one tool can rightfully be considered a drill, since not a single repair can be done without its participation. The drill is an electric motor that rotates a cam clamp into which drills for wood and metal, attachments for mixing solutions, and other attachments can be inserted.

There is a button on the handle of the drill that closes the circuit. The maximum speed is 1200 rpm. While this speed is suitable for drilling holes, it is completely unsuitable for using a drill as a screwdriver. Therefore, the drill has a smooth speed regulator, which is located on the button that closes the network, in the form of a small control ring.

The drill also has a switch that allows you to change the direction of rotation, as well as activate the impact mechanism. The drill must have mechanical overload protection for the motor.

A screwdriver can be considered a type of drill. It differs from a drill only in that the electric motor rotates at a lower speed required to tighten the screws. The screwdriver has a button that closes the network, a direction switch, and an impact mechanism, but does not have a connecting cord.

Since this device has to be used to sheathe the roof, as well as in cases where a power source is not available, the screwdriver runs on 9 and 12 V batteries. The battery is charged from a 220 V power source for several hours and has an electrical capacity allowing you to work for several hours. The battery is made in the form of a small attachment to the screwdriver handle, which is the most convenient technical solution: the battery, due to its weight, acts as a counterweight, so you can use a screwdriver to tighten very tight screws with virtually no effort by hand.

Similar to a drill or other device designed for drilling holes in concrete and stone walls. A hammer drill, like a drill, has an electric motor that rotates the clamp for various attachments. The same power regulator, rotation direction switch and impact mechanism. The difference from a drill is that the hammer drill is slightly larger in size; the electric motor rotates the cam clamp at a speed of 300-400 rpm. The clamp is slightly larger in size; a special drill for working on concrete and brick – a drill – is inserted into it. Some hammer drill models have a side handle that allows you to apply more force while drilling.

An electric sharpener is an electric motor, to the axis of which a carborundum disk is attached for sharpening the tool. The sharpener can be made in two versions - stationary and manual.

The stationary sharpener has an electric motor that simultaneously rotates two grinding wheels, protected by a metal visor that covers the discs from unwanted contact with the working surface, and also catches sparks, which can be a fire hazard.

A manual sharpener is an electric motor located vertically, on the axis of which a sharpening wheel is mounted. The circuit is closed using a button on the plastic case. The body has rubber feet that give the instrument stability and also dampen vibration. Some models have a compartment for the connecting cord.

The jigsaw is designed for working on wood and metal. The electric motor is located in a plastic housing mounted on a slide that slides along the surface being treated. The knife is attached perpendicular to the surface of the sled and passes through its horseshoe-shaped cutout.

The network is closed by pressing a button, which can be held with a finger or secured by moving it forward. An electric motor drives a crank mechanism, which transmits forward motion to the blade. By moving the tool on the slide along the drawn line, you can cut wood and metal very accurately. The tool kit must include wood blades for longitudinal and cross cutting, as well as metal blades.

A wood sander can have different designs. Sanding can be done by vibration generated by an electric motor or by the rotation of a ring of sandpaper driven by rotating cylinders.

A vibration-powered grinder is an electric motor mounted vertically, with an axis pointing downward, to which a mechanism is attached that transmits rotational motion to the base. The grinder has a plastic body with handles by which you should hold the tool while working.

Sandpaper is attached to the base, which has a rubber gasket, using two clamps. Some models of grinding machines (especially foreign ones) have a replaceable dust collector. In this case, the base and sandpaper have several holes with a diameter of 10 mm through which dust is collected. There is no fan in this type of grinding machine; dust is collected in the dust collector due to temperature differences and vortex flows during operation of the device.

The sanding machine may have two rotating cylinders at the base, onto which a ring of sandpaper of the appropriate width is placed. The rotating cylinders are mounted on shock absorbers, which reduce vibration and also allow the load to be applied to the surface being treated more smoothly.

The variants of grinding machines described above, just like a jigsaw, may have a power button that can be held or fixed by moving it forward. As a rule, grinding machines do not have speed regulators, nor do they have mechanical protective devices, since, unlike a drill, hammer drill and jigsaw, the operation of the electric motor does not create any serious mechanical obstacles.

Metal grinding is done by rotating the grinding wheel. The grinder (“grinder”) has a cone-shaped body, at the end of which there is a rotating disk, partially covered by a protective guard. The body has a side handle for holding the tool while working, a key-type switch, and the body is half made of polystyrene and metal (so that sparks do not burn through the polystyrene).

Almost any instrument can be made electric. An example would be an electric plane. Outwardly, it is an ordinary plane, only instead of a block into which the cutter is inserted, a drum is installed.

The drum has mounts for a replaceable cutter and is driven by an electric motor. The rotation speed is 2000 rpm, depending on how much the cutter protrudes, the electric planer can replace a sherhebel, a planer, or a jointer.

There are much fewer tools that convert electricity into thermal energy, the most common being a soldering iron. Heating can be continuous, forced or pulsed. The rod can be seminal or non-replaceable.

The most commonly used soldering iron is continuous heating. The soldering rod condenses heat, the heating temperature is sufficient to work with solder. A forced heating soldering iron has two heaters, one of which heats up and the other maintains the temperature. A pulse heating soldering iron has a small rod made in the shape of a loop, heated by induction.

Soldering iron rods are made of copper with additions of zinc, lithium, zirconium and can be straight or curved like the letter “G”. Some models of soldering irons have a thermostat.

Depending on the heating method, soldering irons can be wire or induction. In wire soldering irons, the heating element is wound around a rod in several layers and insulated with mica or mica plastic.

Induction heaters are connected to the gap in the short-circuited winding of the transformer located in the housing. Sometimes the heating element is located inside the rod, which allows for stronger heating.

Tools that use the thermal effect of electricity include a heater, or, more simply, a heat fan.

The heater is used for drying the room if the humidity level is high and does not allow for certain types of finishing work, as well as for drying certain areas of the room for faster work.

The principle of operation of a heat fan has already been explained above, so there is no point in describing the principle of operation of a heater. It should only be said that the heater has a single control device - a multi-channel switch, which allows you to selectively turn on the heating elements, as well as the fan.

Other household appliances

Unfortunately, it is impossible within the confines of one book to examine in detail all the variety of household appliances, so we did not consider some household appliances, limiting ourselves to only explaining the general principle by which they work.

They all have a relatively simple design and can be repaired yourself without the use of special tools.

We also did not consider some models of household appliances that can already be considered outdated. For example, a washing machine with manual spinning. These have not been on sale for a long time, although somewhere such washing machines probably still exist.

We also did not consider some of the features of imported equipment, which is distinguished by its exquisite design and many different necessary and not so necessary improvements. Foreign manufacturers of household appliances use the same technologies as domestic ones, and therefore attention was paid only to the basic principles of operation of household appliances, and if necessary, possible improvements were listed that could be applied.

When describing the design of certain household appliances, no more detailed attention was paid to the design features of some components and assemblies, since this information is needed more by a specialist than by a user, and therefore we did not delve into the specifics of the technical solutions of a particular device in order to remain understandable .

Modern coffee makers

The current level of development of production has made it possible to equip our homes with a completely new generation of home appliances. Electronic assistants such as vacuum cleaners, polishers, dishwashers and washing machines make household chores easier. With the help of certain models of household electric vacuum cleaners, it is not only possible to reduce the time spent on cleaning the apartment by 2.5-3 times, but also successfully whiten the ceiling, walls, and humidify the air in the room. And washing dishes using a dishwasher will save up to 12-15%
time, and also helps to use water and detergents more efficiently. In addition, washing dishes in a machine is more hygienic than manually, and physical phenomena development of dishwashing in a machine

Dishwashers

similar to washing clothes. Modern washing machines with the possibility of programming leave the housewives more free time, they allow automatic filling and draining of water, heating it to a given temperature, soaking clothes, introducing the required amount of detergent, washing, rinsing and wringing. But there are some difficulties with connecting machines of this type to the electronic and plumbing networks.

Modern refrigerators have become more capacious, they simply and quickly freeze food, they have special compartments for various types of goods. Refrigerators based on the principle of producing “cold” can be divided into two types: absorption and compression. Absorption refrigerators have exceptional consumer features: they are silent in operation, reliable in operation, and relatively easy to repair.

But their significant drawback is that during operation they consume 3 times more electricity than compression-type refrigerators. The mechanism of operation of absorption-type refrigerators is based on the fact that when a concentrated aqueous solution of refrigerant is heated, it evaporates, taking away heat from the

Side-by-side refrigerator Liebherr

refrigeration chamber. To ensure the operation of an absorption refrigerator throughout the year, up to 1400 kWh of electricity is needed. During the same time, a compression refrigerator consumes about 400 kWh.

The refrigeration unit of a compression refrigerator forms a closed system filled with refrigerant. The compressor sucks refrigerant vapor from the evaporator and thereby creates a low pressure in it. The refrigerant vapor in the compressor is compressed and supplied to the condenser, where, after cooling, it is converted into liquid, which again enters the evaporator and is converted into steam.

Kitchen equipment sets are increasingly being supplemented by microwave ovens, electronic coffee makers, mixers, juicers, meat grinders, etc. To prepare food, household electric heating devices such as floor (and tabletop) electric stoves, electric frying pans, electric kettles, electric saucepans, and electric kebabs are increasingly being used.

A huge variety of electric stoves

An electric stove is a more versatile device for cooking. This is a permanently installed device equipped with burners and an electric frying cabinet. Cooking is done on the burners in stove-top dishes, and in the electric frying oven - baking flour products, frying, stewing vegetables and meat. The electric stove burner functions as a heater. Electric stoves use 3 types of burners: cast iron, tubular, pyroceramic. The shape of the working surface of the burner is usually round, and the diameter can be 90, 100, 110, 145, 180 and 220 mm. The most common are burners with a diameter of 145 mm and 180 mm, and burners with a diameter of 90, 100 and 110 mm are intended for coffee pots. Based on the maximum power of the heating parts, the burners are divided into two groups: normal heating (heating time to operating temperature is 10-12 minutes for metal burners and 4-5 minutes for tubular burners), accelerated heating (heating time to operating temperature is 3-6 minutes for metal burners and 1-3 minutes for tubular burners).

Depending on the design, accelerated heating burners are divided into express and automatic burners. An express burner is a burner with accelerated heating to operating temperature due to additionally installed power. Express burners are usually made of metal. An automatic burner is an accelerated heating burner that provides automatic carrying out of various technological processes with an independent transition from the heating mode to a given thermal mode.

Electronic household stoves

The burners are equipped with devices that allow you to regulate either power consumption from 100-350 W (on a small installation), or the temperature of the working surface in the range of 100-500 °C. Cast iron burners have two or three spiral grooves into which filler and heating elements are placed. The filler for the burners is an electrical insulating mass prepared on the basis of talc or periclase. In terms of thermal and electrical insulating properties, the fillers are actually similar, but talc-based fillers have the lowest mechanical strength.

Tubular burners are made from one-, two-, or three-tubular heating parts (TEN), bent in the form of 1 or several turns of the Archimedes spiral. To improve the thermal contact of the cookware with the heating element, its working surface is made flat. To increase efficiency, a reflector made of stainless steel is installed under the heating element.

Pyroceramic burners are a heating element covered on top with a pyroceramic material: technical ceramic glass or other material. The oven of an electric stove allows you to make more use of the advantages of electric heating when preparing food.

The iron muffle is thermally insulated with fiberglass or mineral wool. The thermal insulation layer is covered with duralumin foil, which in this case acts as a reflector. The duralumin foil and the side walls of the electric stove are divided by an air gap. The muffle is attached to the front wall, forming a loading window, which is locked with a door. A viewing glass is built into the oven door, which allows you to monitor the progress of the technological process. Temperature control is carried out by a thermostat.

Microwave ovens are now widely used, in which a completely different method of heat treatment of goods is used than in gas or electric stoves. Microwave ovens use the energy of ultra-high frequency electrical oscillations, or microwave waves generated by a magnetron. Foods cooked in microwave ovens do not burn, completely retain vitamins, do not dehydrate and do not fry, and the process of making a dish is much faster than, for example, on a gas stove. At the same time, the microwave oven does not heat up, does not emit any combustion products, and the air in the kitchen remains fresh and unsullied. In addition, cooking food in a microwave oven can significantly reduce the use of fat, which is often an important condition for dietary nutrition.

microwaves

When using microwave ovens, precautions must be taken: it is not recommended to use sealed containers for making goods; plastic bags must be opened or pierced before making goods. Do not use iron utensils, foil, newsprint, or paper napkins containing synthetic materials. When preparing or heating watery dishes and foods, you need to stir them. Products with skins, such as potatoes or tomatoes, need to be pricked before cooking in the microwave.

Obviously, mastering the art of making delicious food in the microwave requires experience. Therefore, you need to approach your work creatively. When preparing dishes, a pan made of heat-resistant glass is used. Its capacity can be 0.5 -2.5 liters. This pan is produced specifically for use in the microwave oven. In addition, makitra (clay pot) and glass ceramic plates can be used for cooking in microwave ovens.

Infrared radiation is increasingly being used for heat treatment of goods. Its implementation reduces the duration of heat treatment processes, energy costs, and technological losses of the product. The essence of the infrared method of heating food products is that the energy imparted to the product by radiation is released in the form of heat not only in the surface layer of the product, but also inside it, as a result of which the processing time of the product is reduced by 40-50% for meat and 30% for fish, while the biovalue of the product is not affected. Special devices for making food that heat the product using infrared radiation include electric grills, electric kebabs, and electric toasters. The introduction of infrared radiation for heat treatment of a product makes it possible to reduce the duration of heat treatment of the product, to conduct the process without the use of fats, which is important for diet food, while obtaining a product with improved taste properties.

Philips deep fryer

Capacitive devices for heating liquids include electric juice cookers, electric steamers, electric deep fryers and electric pans for general purposes (express pots, rice cookers, slow cookers). Household electric pans have become widespread due to their ease of operation, efficiency and the highest quality of the prepared product.

Electric meat grinders, coffee mills or electric coffee grinders, electronic coffee makers, electric juicers, electric beaters and mixers are widely used for processing goods.

Electrical appliances for specifically heating water, both without storing it and for heating containers with water, have also become widespread in everyday life. In such devices, water is brought to a temperature of 60-100 °C. These are portable devices for heating and boiling small quantities of water, for example, electric kettles,

electric samovars, electric jugs, instantaneous electric water heaters and capacitive (non-flowing) electric water heaters.

In principle, all devices for this purpose are designed identically; the difference exists only in the design features and multifunctional purpose of each of them. Various kinds of electronic kettles, samovars, coffee pots have a container for heated water, in the lower part of which there is a heating element - a tubular electric heater of one shape or another. Tubular electric heaters are sealed, usually have a very high degree of protection, are reliable, and are not dangerous in operation. A tubular electric heater is a thin-walled iron tube in which a spiral of wire with very high resistivity is located. You should be especially careful about household devices that use tubular electric heaters, because a malfunction associated with the failure of this electric heater eliminates the possibility of repairing the entire device. First of all, you should not forget that devices designed for heating water can only be connected to the electrical network when they are filled with water to more than one third of their own volume, otherwise the heating element may burn out. You should not pour out all the water from the electric kettle until it has cooled down or while it is plugged in, and you should also not pour or add cool water into a heated kettle, because the spiral may fail due to this.

Heaters – Termica Comfortline Comfort

Electric heating devices for heating residential premises have become widespread relatively recently. They have certain advantages over other types of heating, because they are not dangerous to operate, small-sized and hygienic, and when using them, it is easy to automate the microclimate control of each room. Now in world practice there are three types of electric heating: full, additional and combined. With full heating, all heat losses of the building are compensated by electric heating devices; with combined heating, the main part of the heat losses is covered by centralized heating systems, and additional electric heating is a type of combined heating and is used in the off-season, when central heating does not work, or when the outside air temperature drops below the calculated one in addition to centralized.

With the development of technology, the problem of air purification becomes more and more acute. The solution to this problem includes three main areas: combating sources of pollution, ventilation and environmental improvement, and air purification using air conditioners.

Household above-slab electric air purifiers help prevent contamination of walls, ceilings, curtains, furniture with grease particles and soot that are formed during food preparation, and also reduce the amount of harmful products due to incomplete combustion of gas and the nasty smell of burnt food.

To create suitable conditions in residential premises, household air conditioners are used, which lower or increase the air temperature in the rooms, dry the air and clean it of dust. The air conditioner can automatically maintain a set temperature, ventilate the room, change the speed and direction of air flow, and also exchange air with the environment.

Electric irons and dryers became common. Modern irons are equipped with thermostats that automatically maintain the temperature required for ironing certain types of fabrics on the soleplate of the iron, as well as steam humidifiers that allow you to iron fabrics without preparatory moistening. In addition, the iron can be weighted and also have a sprinkler. It is recommended to clean the iron at least once every 1.5-2 years to remove thin fibers of fabric that get inside the iron through the cracks between the body and sole. These fibers can clog the thermostat contacts and burn on the soleplate, creating a burning smell. When disassembling the iron, it is recommended to tighten all the nuts inside the iron and clean the thermostat contacts, which can be done by stretching a small strip of fine sandpaper between them. Brown deposits, which often appear on the working surface of the iron, can be removed by wiping it with a dampened cloth sprinkled with baking soda, and you can protect the iron from contamination by treating its working surface with paraffin: grated paraffin is poured inside a double layer of material and ironed with a slightly heated iron.

And then there are special electrical appliances with a very comfortable name: “devices of gentle warmth.” Their purpose is to provide warmth to the human body. These are electric blankets, electric blankets, electric bandages, and heating pads. They all have the shape of ordinary household items, and flexible heating elements are located inside the devices. To prevent burns, the devices are equipped with thermal switches that limit the surface temperature of the product.

If we imagine our daily life without all electrical household appliances, then for many this situation will seem like a catastrophe on a universal scale.

The absence of a dishwasher, air conditioner, tape recorder or microwave oven will simply make life less comfortable; but the lack of an iron, washing machine or refrigerator will be a difficult ordeal for housewives; the absence of an electric soldering iron will deprive the radio amateur of an exciting hobby; without an electric drill it is impossible to carry out basic apartment repairs; etc.

The life of a modern person is unthinkable without household electrical appliances.

But, unfortunately, nothing lasts forever, and electrical appliances sooner or later fail. Can they be repaired? The answer in most cases is positive: it all depends on what kind of malfunction occurred and how complex the repair is so that it can be done at home.

In one book, it is, of course, impossible to tell about all electrical household appliances, about all the problems that happen to them. Therefore, here we talk about the most common technique, the most common breakdowns and available ways to fix them on your own.

electric iron

The most commonly used electrical appliance is the electric iron. After all, indeed, for example, a refrigerator with a stretch can be replaced by a cellar, a washing machine - by a washboard and hard-working hands; but today hardly anyone knows how to use a rubel and a rolling pin for ironing clothes, and it is dangerous to iron modern fabrics with a coal iron (even if someone inherited it).

First, about what types of irons the industry offers us. Their characteristics are contained in the markings of the irons. So, alphabetic characters are deciphered as follows:

UT – iron with thermostat;

UTP – iron with thermostat and steam humidifier;

UTPR – iron with thermostat, steam humidifier and sprayer;

UTU – iron with thermostat, weighted.

The meaning of digital characters is even easier to decipher: the first number following the alphabetic indicators indicates the power consumed by the iron (in W); The second number hides its mass (in kg). Example: the marking UTP1000–1.4 means “iron with a thermostat and a steam humidifier with a power of 1000 W (1 kW) and a weight of 1.4 kg.”

It is no coincidence that increased attention is paid to the mass of the iron, because the maximum heating time of the sole depends on it; There is a pattern here: for light irons, for example UT1000-1.2, the maximum heating time for the sole is 2.5 minutes; for heavier ones, such as, for example, UTU1000–2.5, up to 7.5 minutes.

On fig. 86 shows the design of an electric iron of the UT brand.

Rice . 86 . Design of an electric iron of the UT brand: 1 – sole; 2 – tubular electric heater (TEH); 3 – thermostat; 4 – heat-insulating gasket; 5 – cord; 6 – housing cover; 7 – handle; 8 – signal light; 9 – housing casing.

Structurally, the iron consists of an aluminum or cast iron sole into which a tubular electric heater (TEN) is pressed; a casing made of heat-resistant plastic, separated from the sole by a heat-insulating gasket; handles and covers (the casing, handle and cover form the body of the iron). Other additions - an automatic thermostat, a steam humidification system and a sprinkler (along with a water tank) - are also mounted under the cover of the iron body. To connect the iron to the electrical network, a connecting cord with a movable input is provided.

The condition of the heating element is monitored visually using a signal light: when the heating element is turned off, the light goes out - this means that it has heated up to the temperature set by the thermostat. The 3.5 V signal light is powered by a voltage drop across a small section of a nichrome spiral connected in series with the heating element.

The thermostat is based on a bimetallic plate that controls a high-speed switch. The thermostat operates as follows: the bimetallic plate is heated by the sole of the iron; due to the difference in the coefficient of thermal expansion of the two metals, it bends and presses the contact plate; As a result, the circuit opens, the heating element turns off and begins to cool. But, as soon as the bimetallic plate cools down to a certain temperature, its bend straightens out, releases the contact plate, and the heating element turns on again.

A common problem is a malfunction of the iron's power cord. A break in the cores of the power cord, as a rule, occurs at the point of its entry into the handle of the iron. Since the lead is movable, the cord is constantly subjected to bending during ironing. Such a breakdown does not at all require a complete replacement of the cord, the repair consists in restoring its integrity: the cord is cut off at the break point, the screw clamp is freed from pieces of cores, the end of the cord of the required length is re-stripped and re-embedded in the terminal block.

An iron whose tubular electric heater has failed (burned out) cannot be repaired, since the heating element is pressed into the sole of the iron.

One of the problems with the thermostat is its misaligned setting, which leads to insufficient heating or overheating of the iron. It is quite possible for a home electrician to restore the setting. To do this, you need to turn the thermostat knob counterclockwise until it stops (that is, set it to the minimum temperature), disassemble the iron and separate the body casing from the soleplate with the thermostat. Then, with your finger, slightly raise and lower the end of the movable contact plate at the point where it touches the bimetallic plate: when you turn the contacts on and off, you will hear clicks that can even be felt tactilely.

Next, you will have to work with two hands: with one continue to click the contacts, and with a screwdriver held in the other hand, rotate the adjusting screw clockwise until the clicks stop, then turn the adjusting screw back (counterclockwise) half a turn - The clicking should resume. This position of the thermostat will correspond to the setting for the minimum heating temperature of the sole. The repair is completed by assembling the iron.

The terminals of all electrical elements of the iron - heating element, coil, signal lamp socket and power cord - are located on the block at the back of the iron and are covered with a removable cover. When disassembling the iron, you first need to unscrew the bolts holding the cover, remove the cover itself and free the contact block from the wires connected to it, and then unscrew the screws securing the body to the soleplate.

When disassembling the iron to troubleshoot problems, you can perform a preventative tightening of all fasteners (bolts, screws, nuts) that are inside the case. It is recommended to simultaneously clean the thermostat contacts by passing a small strip of fine-grained sandpaper between them several times.

The body of the iron is not connected to the entire plane of the sole, but is in contact with it only at a few points, which reduces its heating from the sole; therefore, there is a gap between the body casing and the sole, into which fabric fibers fall during operation of the iron. If you do not regularly clean this gap, the fibers clog the contacts of the thermostat and it may fail (in addition, the fibers burn on the sole, spreading a burning smell). As a preventive measure to prevent problems of this nature, it is recommended to clean the iron once every 1.5–2 years.

The sole of the iron also needs care:

– a brown coating that often appears on the working surface of the iron from woolen and synthetic fabrics can be removed by wiping it with a damp cloth sprinkled with baking soda. But this should not be done if the sole has a Teflon or nickel-plated coating; there are special pastes for cleaning such irons;

– under no circumstances should you clean the soleplate of the iron with sharp objects or abrasive materials: the resulting scratches will accelerate the formation of a brown coating. In addition, it is not possible to remove plaque from scratches;

– you can protect the surface of the iron sole from contamination by treating it with paraffin: rubbed paraffin is poured between two pieces of cotton fabric and ironed with a slightly heated iron.

Fridge

Refrigerators are number two in the list of home electrical equipment.

The main feature of the classification of refrigerators is the principle of cold production. Depending on this, all refrigerators are divided into absorption and compression.

Absorption refrigerators, the operating principle of which is based on the physical property of an aqueous solution of refrigerant (ammonia) to absorb a large amount of heat during evaporation, have excellent consumer characteristics: they are quite easy to repair and extremely reliable in operation; they work almost silently.

Their only drawback is their high energy consumption: the annual electricity requirement of an absorption refrigerator is about 1400 kW/h (for comparison: a compression refrigerator consumes only about 400 kW/h over the same period). The disadvantage, although the only one, is quite significant; This is why this type of refrigerator is not widely used.

The cooling circuit in compression-type refrigerators (Fig. 87) is a closed system filled with refrigerant.

Rice. 87. Design of a compression-type refrigerator: a – rear panel; b – refrigerator diagram; 1 – motor-compressor; 2 – capacitor; 3 – part nob; 4 – tube; 5 – start-protection relay; 6 – vessel for collecting water; 7 – evaporator; A – high pressure refrigerant vapor; B – liquid refrigerant; B – mixture of liquid refrigerant with its vapor; G – low pressure refrigerant vapor.

The components of the cooling system are: motor-compressor, evaporator, condenser, control valve and pipelines by which these elements are connected to each other.

In compression-type refrigerators, two types of compressors are used: with an external casing suspension and with a compressor suspension inside the casing - next to the motor.

The cooling system operates as follows: the motor-compressor pulls refrigerant vapor from the evaporator, as a result of which low pressure is created in the evaporator. In the compressor, the refrigerant vapor is compressed and supplied to the condenser, where, as it cools, it turns into a liquid, which again enters the evaporator and turns into steam again.

The entire process of heat exchange of the cooling system occurs directly in the evaporator and condenser: turning into steam, the refrigerant absorbs heat through the surface of the evaporator (which is located in the freezer compartment of the refrigerator), and turning into liquid, it gives off excess heat through the surface of the condenser (which is located outside the refrigerator, to its rear panel). The evaporator and condenser are connected to each other by a control valve; it has a small flow area, which does not lead to pressure equalization and allows you to always maintain a rarefied pressure in the evaporator and an increased pressure in the condenser.

The compressor is driven by an electric motor, which is a consumer of electricity.

A breakdown of the refrigerator not only causes housewives a feeling of discomfort; it also raises the question of preserving perishable foods: it’s good if it’s winter outside and you can save them on the balcony; What if it’s summer outside and the heat is 35°C? This is when maximum efficiency in correcting problems will be required.

Of course, the design of a refrigerator is quite complex; not every malfunction can be fixed at home (for example, repairing a cooling system requires not only extensive special knowledge, not only certain skills, but also very specific devices that are hardly available to a home handyman). If the breakdown affected the electrical system, then you can try to cope on your own.

The first thing you need to check in a broken refrigerator is the serviceability of the wiring: if the light bulb is on when the door of the refrigerator connected to the network is open, then the wiring is intact. If the light does not light up, you need to check the serviceability of the cord and plug connection (both plug and socket); how to do this has been said more than once.

The next part of the refrigerator that is checked (if the cord and plug connection are in good condition) is the start-up relay. Check the reliability of the connection of the wires to the terminals of the relay and thermostat and the connection between the feed-through contacts and the relay sockets. Then they check the relay itself - call it with a tester; Often this is the culprit of the malfunction.

Next on the list is checking the thermostat: turn it on and off several times. If you hear a characteristic click when you turn on the thermostat, then the thermostat is normal. If there is no click, this means that the thermostat is faulty; it should be replaced.

If the refrigerator is working properly, but the light does not come on when the door is open, it may be. the light bulb has burned out. To replace it, compress the horizontal walls of the lampshade at the rear and remove it from engagement with the cabinet walls, replace the light bulb and install the lampshade in place.

If the situation is exactly the opposite: the light bulb is on even when the refrigerator door is closed, then most likely the spring of the switch button has weakened. It is unlikely that you will be able to replace the spring yourself (to do this you will have to remove the inner lining of the cabinet, which may break its tightness), so you can use this advice: cut out of plastic (textolite, copolymer, etc.) a small circle 1 mm thick, with a diameter of 15–20 mm and glue it to the door panel opposite the switch button with universal glue.

If the electric motor hums but does not start (the thermal relay is triggered), then perhaps the voltage in the electrical network is reduced by more than 15% relative to the nominal value. You need to turn off the refrigerator and check the voltage in the network with a voltmeter, and if it is really less than permissible, you should refrain from using the refrigerator.

In fact, the stability of the voltage in the network affects the proper operation and service life of the refrigerator to a fairly large extent, therefore, if the voltage in the network fluctuates greatly, you must use a voltage stabilizer to connect the refrigerator without waiting until the refrigerator begins to malfunction.

A metallic knock when the compressor is turned on, off and running, accompanied by vibration of the cabinet, is not the norm for a working refrigerator - this indicates that the cooling system tubes are touching the cabinet. To eliminate this drawback, you need to turn the refrigerator with the back wall and examine the panel; Having found the place where the tube touches, you need to carefully bend it.

Sometimes knocking can be caused by a completely different reason - strong swinging of the compressor casing. The repair consists of tightening (or loosening) the bolts on the suspension springs or placing gaskets under the supports.

Sometimes the cause of the knocking is not a malfunction, but loosening of the capacitor mounting screws or a foreign object caught behind the back panel, behind the condenser or behind the motor-compressor.

A refrigerator causes a lot of trouble, the evaporator of which quickly freezes, and it itself often turns on (which leads to irrational waste of electricity). As a rule, the cause of this is a violation of the door seal. Adjusting the door hinges will help restore the tightness, and you can check the quality of the tightness using a strip of thick paper. They place it between the door seal and the cabinet itself anywhere around the perimeter, close the door and try to pull out the strip: if the paper is clamped tightly, it means that the tightness has been restored (it is preferable to check along the entire perimeter of the seal).

Damage to the paint layer on the cabinet and refrigerator door can lead to corrosion of the metal from which they are made, therefore, if scratches are found on the outer surface of the refrigerator, they should be repaired in a timely manner. For a shallow scratch, when the metal of the case is not visible, it is simply painted over with white enamel. If the depth of the scratch reaches the metal, then you first need to clean it with emery cloth, degrease it with a swab dipped in acetone, dry the surface thoroughly and only then apply a layer of white enamel (if necessary, after it has completely dried, you can apply another layer).

You can significantly extend the life of your refrigerator if you strictly follow all recommendations for its operation and care. What are they?

Firstly, it is not recommended to place the refrigerator in close proximity to heat sources (stoves, stoves, heating appliances, etc.). In addition, it is advisable to choose a shaded place for it - this will reduce the flow of heat into the refrigerator compartment and reduce energy consumption. And in order for the rear panel to be accessible for free air circulation (which prevents engine overheating), the distance between the wall and the rear panel must be at least 3–4 cm.

Secondly, it is necessary to ensure that the refrigerator is completely stable when installing it; This can be achieved using adjusting supports screwed into the rear and front heels. The adjustment should be made in such a way that the cabinet has a slight (no more than 1°) deviation from the vertical towards the rear wall; in this case, the refrigerator door will close with a slight push.

Thirdly, it is recommended to turn the refrigerator on and off only with the thermostat knob; Therefore, before inserting the cord into the wall outlet, make sure that the thermostat knob is set to the “Off” position. When checking the functionality of the refrigerator, it can be forced to be turned on again no earlier than 5 minutes after it is turned off (if this time is not maintained, the refrigerator will not turn on - the thermal relay will operate).

Fourthly, if a snow coat of more than 5 mm forms on the evaporator, it is necessary to turn off the freezer (freezer). If the refrigerator is working properly and the airtightness is normal, defrosting is carried out once every 2-3 weeks.

The refrigerator is turned off (by setting the thermostat knob to the “Off” position), and for faster thawing, the doors of the refrigerator and freezer compartment are left open. You can speed up this process in several ways: place a vessel with hot water in the freezer, direct warm air from a vacuum cleaner or hair dryer into it, in the summer, use a stream of air from a fan, etc.

But it is prohibited to use sharp metal objects to remove ice: there is a possibility of damage to the walls of the evaporator, this will render it unusable, and a complete replacement of the evaporator will be required.

After the snow cover has thawed, wipe the internal surfaces of the evaporator and refrigerator cabinet with a soft cloth soaked in slightly soapy water or soda solution (water should not get into the interior lining of the cabinet and door), dry and ventilate for 30–40 minutes.

Before loading the freezer after thawing, it is necessary to cover its bottom with a plastic bag, and place portions of perishable products in the bags; otherwise, the food may freeze to the bottom of the freezer, making it difficult to remove it from there, and if excessive force is applied, microcracks may appear in the walls of the evaporator.

Washing machine

By and large, in everyday life you can do without a washing machine: you can, for example, wash clothes by hand, or use the laundry service. But for many, this prospect does not seem bright, which is why a washing machine is an indispensable attribute of almost every apartment or house.

Depending on the degree of automation of the washing process, all washing machines are divided into four types: SM - washing machine without spinning; SMR – washing machine with manual spin; SMP is a semi-automatic washing machine in which washing, rinsing, spinning, and pumping out water are mechanized; some models also include automatic devices for regulating washing and spinning time; SMA is an automatic washing machine, in which the processes of supplying water, washing, rinsing, pumping out water and spinning are not only mechanized, but also automated.

A washing machine without a spin has the simplest device (Fig. 88).

Rice. 88. Structure of a washing machine type SM: 1 – washing tank; 2 – tank cover; 3 – time relay handle; 4 – time relay; 5 – capacitor; 6 – electric motor; 7 – cord; 8 – belt drive; 9 – pulley; 10 – activator; 11 – cover with scale; 12 – thermal relay.

Machines of the SM type (“Malyutka”, “Fairy”, “Alesya”, etc.) belong to the class of small-sized ones. Machines of this type are installed on a special stand that is placed on the sides of the bathtub. Such machines are simple both in design and in operation. They are equipped with a reversible cyclic time relay, which ensures the machine operates according to the following cycle: operating period of electric motor rotation in one direction (50 s) – pause (10 s) – operating period of electric motor rotation in the other direction (50 s) – pause (10 s) . The relay allows you to adjust the washing time in the range of 1–6 minutes.

The electric motor is protected by a thermal relay; it stops the engine when the machine is overloaded or the activator is jammed.

The structure of the SMR type washing machine (Fig. 89) is similar to the structure of the SM type machine.

Rice. 89. Construction of a SMR type washing machine: a – general view; b – longitudinal section; 1 – body; 2 – washing tank; 3 – tank filling level with water; 4 – handle; 5 – manual spin rollers; 6 – spin adjustment screw; 7 – spring; 8 – handle of the squeezing device; 9 – relay; 10 – activator; 11, 12 – drain and connecting hoses; 13 – cord; 14 – grate; 15 – pump; 16 – electric motor; 17 – frame; 18 – bracket for holding the machine during spinning; 19 – video.

The design and operating principle of construction and installation works are as follows. The upper 2/3 of the body is occupied by a washing tank, in which a disk activator is installed on the shaft, causing the water to rotate. At the other end of the shaft holding the activator, there is a centrifugal pump, which, if necessary, pumps water out of the tank; the shaft is driven by an electric motor via a belt drive. The electric motor is mounted on an inclined frame in such a way that it can be moved along it by adjusting the tension of the drive belt.

The electric motor of the washing machine is connected to the network using a cord with a plug, and is turned on by pressing the start relay, which stops the electric motor after a certain period of time. For ease of transportation, the machine is equipped with carrying handles and rollers for rolling, and in order for it to remain stable during spinning, it is held with a foot by the bracket.

The manual spin device is mounted on the top of the machine body. It consists of two rubber-coated rollers pressed against each other by a flat spring. The rollers are driven by a handle.

The dimensions of the washing tank and the motor power (350 W) are designed for simultaneous loading of up to 1.5 kg of dry laundry.

The design of semi-automatic machines such as SMP (Fig. 90) is somewhat more complicated, since they have a higher level of mechanization of the processes of washing, spinning and pumping out water.

Rice. 90. Construction of a SMP type washing machine: a – longitudinal section; b – control panel; 1 – washing tank; 2 – activator; 3 – activator drive electric motor; 4 – centrifuge tank; 5 – centrifuge drive electric motor; 6 – centrifuge; 7 – pump; 8 – valve; 9 – pipes; 10 – liquid level indicator; 11 – control knob for the operation of the washing unit; 12 – spin unit control handle; 13 – knob for switching washing modes.

Structurally, the semi-automatic washing machine is divided into two units: washing and spinning. The washing unit consists of a washing tank with a tray, an activator (paddle disk), which is mounted on the side wall of the washing tank; An activator drive with an electric motor is installed on the pallet. Rotational movements to the activator are transmitted from the electric motor via a belt drive.

The spinning unit includes a centrifuge tank, to the bottom of which the centrifuge drive electric motor is suspended on shock absorbers, the centrifuge itself, mounted on the motor shaft, and a pump installed on the lower shield of the electric motor.

The units are connected to each other by a system of pipes with a valve.

To control the washing and spinning processes, three knobs are installed on the top cover of the case: wash and spin control knobs, which are equipped with clock mechanisms (time relays) that automatically turn off the corresponding electric motors after a certain time, and a knob for setting the washing mode.

The total power of electric motors is 500–600 W. The activator motor develops a rotation speed from 600 to 1500 rpm; centrifuge rotation speed – up to 3000 rpm. If during operation it becomes necessary to dismantle the electric motors (for repair work), then they can be reconnected using the diagram shown in Fig. 91.

Rice. 91. Schematic diagram of connecting electric motors of an SMP type washing machine.

Thanks to the special design of the activator blades, when it rotates clockwise or counterclockwise, a solution flow of varying power (different degrees of activation) is created in the washing tank. Therefore, the SMP provides two washing modes:

– hard (I) – more intense solution flow created by counterclockwise rotation of the activator;

– gentle (II) – less intense solution flow created by clockwise rotation of the activator.

The maximum one-time load depends on the brand of the machine and reaches 3 kg of dry laundry for hard washing and 2 kg of dry laundry for gentle washing.

The most advanced household washing machines today are SMA type machines. Domestic automatic machines provide up to 12 programs that allow you to automate the processes of filling and pumping out water, heating it to a given temperature, soaking laundry, and introducing the required amount of detergents. Such machines independently (in accordance with a given program) wash, rinse and spin clothes.

According to existing rules, it is necessary to obtain permission from electricity supply and utility services to connect automatic washing machines to the electrical network and water supply system.

As a rule, the more operations a particular washing machine can perform, the more complex its design and, accordingly, the more difficult it is to repair. But there are a number of problems that are standard for machines of all types, which a home handyman can easily handle.

If the electric motor(s) do not work when the time relay is turned on, then perhaps there is no voltage in the network or the plug socket is faulty (you need to check with an indicator screwdriver or by plugging a known-good electrical appliance into the same socket); or maybe there is a problem with the power cord (you need to test the cord with a tester - there may be a wire break); there is a possibility that there is a malfunction in the time relay itself (it should be replaced).

If, when the relay is turned on to the “Wash” position, the electric motor hums, but the activator does not rotate, then most likely the position of the “Mode” knob is not fixed. To eliminate this malfunction, turn off the washing relay, set the “Mode” knob strictly to the required number and start the electric motor again.

If during the washing process in the centrifuge tank the level of foam in the solution reaches the bottom of the centrifuge itself, then it will not gain momentum. To eliminate such a malfunction, it is necessary to remove the centrifuge neck insert, unscrew the fastening nut (turn counterclockwise), remove the washer and the centrifuge itself, and remove the pin from the shaft hole. After this, you need to pump out the water from the centrifuge tank into the washing tank, remove the foam and install all the removed parts in place (in reverse order). Attention! Before disassembling and reassembling, be sure to unplug the machine.

A clogged valve may be to blame for solution flowing from the washing tub into the centrifuge tank. It should be washed, for which 4–5 liters of hot water are poured into both tanks and the spin relay is turned on for 2–3 minutes. If it is not possible to eliminate the leakage by flushing the valve, then most likely the valve membrane has turned upside down. To restore normal operation of the pump, it is necessary to remove water from the machine, disconnect it from the electrical network, disassemble the valve and install the membrane in the correct position.

If there are signs of a solution leak from the machine, it is necessary to establish its cause: if the connections of hoses and pipes are leaking, then to eliminate the leak it is enough to tighten the clamps at the connections; If the cause of the leak is a leaky hose, it should be replaced with a new one. If the leak occurs due to a leak in the diaphragm located under the bottom of the centrifuge tank, then in most cases it is impossible to fix this problem yourself, so it is best to call a specialist.

The appearance of some vibration when starting and stopping the centrifuge is not a malfunction; this is a completely normal phenomenon.

Like any other electrical household appliance, a washing machine needs to comply with operating rules, namely:

– it is permissible to store and operate the washing machine in rooms with an ambient temperature of at least 5 °C;

– the machine should not be overloaded;

– long-term operation of the machine without water is not allowed, since this significantly reduces the service life of the sealing cuffs of the machine components (activator unit, pump, as well as the diaphragm of the centrifuge tank);

– the electrical equipment of the machine should be protected from penetration of soap solution and water;

– after using the machine, its tank (or tanks) should be rinsed with clean hot water to remove any residual detergent and thoroughly wiped dry;

– to avoid jamming of the washing and spinning units, it is recommended to lubricate the electric motor bearings once every 2–3 months.

Water heating devices

The principle of design and operation of devices combined general purpose– heat the water, the same. The difference lies only in their design features.

The basis of these devices is a tubular electric heater - heating element (Fig. 92), which is a thin-walled metal tube made of carbon steel grade 10 or 20 with a wire spiral enclosed in it with a very high electrical resistivity.

Rice. 92. Design of a tubular electric heater (TEH): 1 – thin-walled tube (shell); 2 – spiral; 3 – contact rod; 4 – insulator; 5 - a layer of mastic; 6 – porcelain bushing; 7 - contact nut; L is the total length of the heating element; Act I – active (working) length of the heating element; I к – length of the contact rod; dtr – inner diameter of the tube; d cn is the diameter of the spiral; d sp. nar. – outer diameter of the spiral; d is the wire diameter; h is the pitch of the helix.

The ends of the spiral are connected to rods that come out of a hermetically sealed tube and serve as contacts for connecting the heating element to the network. To avoid shorting the spiral to the tube body, the latter is filled with a bulk insulator that conducts heat well and does not conduct electric current at all (quartz sand or crystalline magnesium oxide - the so-called periclase). The insulator that fills the tube under high pressure turns into a monolith, so it not only performs an insulating function, but also reliably fixes the spiral along the axis of the tube.

The heating element is a fairly universal device intended for use in various water heating devices. Therefore, depending on the purpose, heating elements are made from various materials (including refractory ones) and various shapes (after crimping, the tube can be bent in any way).

The working surface temperature of heating elements has a fairly wide range: from 450 °C (for household electric heating devices) to 800 °C (for heating fats, oils, fusible metals in industrial installations). The average service life of heating elements with proper operation is up to 10,000 hours of continuous operation.

Since, as already mentioned, there are a large number of types of heating elements, when purchasing them, you should pay special attention to the marking, which indicates not only the metric parameters of its elements, but also the rated power in kW and voltage in V, the tube material, the environment for which The heating element is intended, as well as the type of climatic modification according to GOST.

Among the disadvantages of heating elements, one should note their high metal consumption, the use of expensive materials in them (nichrome, stainless steel) and, as a result, their high cost. In addition, heating elements cannot be repaired.

The simplest household water heating device that uses a heating element is an electric boiler; in essence, a boiler is a heating element with a handle and a cord. The handle of the boiler has a hook (or is itself made in the form of a hook), thanks to which the boiler is secured to the edge of the container in which the water is heated.

All kinds of electric kettles, samovars, coffee pots are containers for heating water, in the lower part of which a heating element of one form or another is mounted.

When installing a hot shower in a summer cottage, low-pressure storage water heaters (EVAN type) are often used with the same tubular heating element with a power of up to 1.24 kW. The diagram of its connection to the water pipe and shower sprayer is shown in Fig. 93.

Rice. 93. Design of an EVAN type electric water heater: 1 – water tank; 2 – heat-insulating casing; 3 – mixer tube; 4 - thermostat; 5 - mixer; 6 – pipe for cold water input; 7 – signal lamp; 8 – power cord; 9 – temperature control knob; 10 – heating element.

EVAN heaters are available in capacities of 10, 40 and 100 liters. Warming up of water to the temperature at which the thermostat knob is set occurs, respectively, in 1, 2, 3, and 7, 8 hours.

The serviceability and service life of electric water heating devices depends on how correctly they are operated and cared for. The operating rules for such devices are simple, so remembering and adhering to them will not be difficult.

It should be remembered that devices intended for heating water (electric kettles, coffee pots, etc.) can only be connected to the electrical network when they are filled with water to at least 1/3 of their volume, otherwise the heating element will burn out (and repair , as is known, it is not subject to).

There are special marks on the heating tube of the boiler, indicating the lower and upper limits of how full the container is with water before turning on the boiler. If the water does not reach the bottom line, you can burn the device; if the water rises above the top line, then there is a possibility of a short circuit.

A sharp temperature change has an unfavorable effect on the heating element’s spiral, so you should not pour water from a kettle, samovar, etc. until the heating element is exposed, until it has cooled down. Also, do not pour or add cold water onto the heated surface of the tubular heater.

Long-term operation of water heating devices (especially with hard water) leads to the formation of scale (precipitation of mineral salts) on the surface of the heating element, which reduces thermal conductivity and leads to irrational waste of electricity. Therefore, scale should be removed periodically using one of the suggested recipes:

– carefully pour 4 volume parts of water into 1 volume part of hydrochloric acid; rinse the inner surface of the device container and the surface of the heating element with the resulting solution, after which the device is thoroughly rinsed with clean water;

– if the kettle is plastic, then instead of rather aggressive hydrochloric acid it is better to use soft citric acid. To do this, boil 0.5 liters of water in a kettle and add 25 g of citric acid powder. Leave to soak for 15 minutes, then rinse the kettle thoroughly with clean water;

– you can pour 0.5 liters (or until the heating element is completely covered) of 8% white vinegar into the kettle, leave for 1 hour without boiling, then drain the liquid and rinse the kettle with clean water;

- can also be used folk remedy– pour clean potato peelings into a container and add water, boil, remove the peelings and rinse the container with the heating element with plenty of clean water.

And now about the malfunctions of electric water heaters.

If the device is connected to the network, its cord, plug and socket are in working order, but the water does not heat up, you need to check the heating element (heating element), or rather, the serviceability of its contact connections. To do this, disconnect the device from the network, remove all water from the container, and dry it. Then you should unscrew the screws securing the tray and remove it (this will make the heating element more accessible).

Very often the cause of the malfunction is hidden in broken contacts at the connection points of the heating element leads; Therefore, first of all, they are checked: they unscrew the fastening screws and remove the clamping washer. If the connections are truly broken, they are restored.

If everything is in order with the contacts, then perhaps the heating element itself is faulty and should be replaced: the contacts of the heating element outputs are opened, the heating element is replaced with a new one.

Vacuum cleaner

A vacuum cleaner is not an essential electrical appliance, such as an iron or refrigerator. And yet, having a vacuum cleaner in a house or apartment makes life much easier for housewives, helping them with cleaning.

But a little more than a century ago, people had no idea that there could be any other equipment for cleaning a home, besides a broom and a damp rag. Therefore, the appearance at the very end of the last century in the USA of a device consisting of a manually driven pump and a nozzle-broom for collecting dust was a truly revolutionary event. The first vacuum cleaner was serviced by two people: one was responsible for the operation of the pump - he turned the handle, the other - collected dust with a nozzle-broom; The size of such a vacuum cleaner was impressive: its height reached 1.5 m.

A modern vacuum cleaner is a fairly portable (compared to the first) device. Its air suction apparatus consists of a fan rotated by a commutator electric motor and a chamber with an opening for air suction. Dust suction occurs due to the fact that the fan creates a vacuum of air inside the chamber.

Depending on the path that the air flow takes inside the vacuum cleaner body, they can be direct-flow or vortex.

In direct-flow type vacuum cleaners, the sucked air, carrying dust and small debris, directly enters a fabric filter (garbage collection bag). Leaving all the debris, both large and small fractions, on the filter, the air flow enters the electric motor, cooling it. Next, the air is sucked out of the chamber by a fan.

Throughout the entire path of the air flow (from the inlet to the outlet), its direction does not change, hence the name of vacuum cleaners of this type - direct-flow.

In vortex-type vacuum cleaners, the air flow, together with the sucked debris, flows around the lower part of the electric motor and, under the influence of centrifugal force, is freed from debris and the heaviest dust particles. Then the air flow enters the filter, where it is finally cleaned, after which the air is discharged outside.

Modern vacuum cleaners often use a double cleaning system: instead of one cloth filter, double filters are used, which are arranged in a sequential chain. The first filter – flannel – retains debris and large dust particles; the second - calico - frees the air flow from small dust particles. Of course, the quality of air stream cleaning in such vacuum cleaners is much higher.

According to their functional purpose, they are divided into hand-held vacuum cleaners, car vacuum cleaners and floor vacuum cleaners. They differ from each other in size, power and number of attachments, but their operating principle is basically the same, with the exception of some points. Car vacuum cleaners have a device that allows you to connect them to a car battery.

And floor-standing vacuum cleaners, in addition to their intended purpose, are used as a pressure compressor: if the corrugated hose is connected not to the inlet, but to the outlet, then using a special attachment included with the vacuum cleaner, you can carry out painting work (whitewashing and painting).

What problems can you encounter while using vacuum cleaners?

After 250–300 hours of operation of the vacuum cleaner, the brushes of the electric motor wear out. To replace them, you need to disconnect the vacuum cleaner from the network, disassemble it, remove the brush holder caps from the electric motor, remove the worn brushes, and install new ones in their place (if the old brushes were connected to the motor contacts by twisting, then the same type of connection should be used; if the connections were soldered, it is best to use an electric soldering iron). For preventive purposes, it is necessary to wipe the electric motor armature commutator with gasoline.

The hose, pipe or nozzle of the vacuum cleaner may become clogged, so the vacuum cleaner stops sucking air and collecting debris and dust. It is very easy to fix this problem: each of these parts can be cleaned with a long, smooth rod. To prevent clogging of the hose, pipe or nozzle, before you start cleaning with a vacuum cleaner, you need to remove large debris with a broom or brush.

The service life of a vacuum cleaner depends on how it is used correctly.

Particular attention should be paid to caring for filters: their surface must be clean at all times so that dust does not clog the electric motor, so they must be cleaned after each use of the vacuum cleaner; It is not recommended to wash filters (dust collectors), dry cleaning with a brush is preferable; Do not use a damaged dust collector; if a hole has formed on it, you need to put a patch on it, preferably from the same material.

The design of many modern vacuum cleaners involves the use of replaceable paper disposable filters, which are thrown away immediately after filling. If the vacuum cleaner does not have disposable filters, you can make some semblance of them yourself: to do this, cut a piece from an old nylon stocking slightly longer than the length of the dust collector, tie one end with a knot; the resulting filter is placed in a dust collector. Now it takes much less time to clean the vacuum cleaner.

Do not overload the electric motor: if cleaning involves long-term use of the vacuum cleaner, it is recommended to take 10-minute breaks every 30 minutes to cool the electric motor.

The corrugated hose of a vacuum cleaner can also become unusable due to improper storage: it should not be folded at an angle; It is better to store it rolled into a snail.

The vacuum cleaner motor should be protected from moisture: it is strictly forbidden to collect spilled water and other liquids with a vacuum cleaner.

Electric floor polisher

To care for parquet, linoleum and painted floors, an electric floor polisher is often used, equipped with hair brushes rotated by an electric motor that develops a high rotation speed.

The motor is mounted in one housing with a brush holder.

Floor polishers also provide for the suction of dust that is raised by rotating brushes when polishing floors.

Before rubbing, mastic is first applied to the floor and left for half an hour, then a second layer is applied and again allowed to dry for half an hour. If necessary, apply a third layer at the same intervals. Then start polishing with a polisher.

The floor polisher has high performance. With its help you can process about 80 m2 of floor in 1 hour. When working, you should not press on the polisher bar; the working unit of the polisher is moved along the surface to be rubbed with smooth back-and-forth movements.

After rubbing, you can polish the floor, for which polishing washers are fixed on the brushes and the process of treating the floor is repeated until the required shine is obtained. If the rubbing brushes and polishing washers become dirty, wash them with soap and water or washing powder, rinse and dry. This procedure is repeated periodically.

The powerful electric motor of the floor polisher heats up during prolonged operation, so after every 30–40 minutes of continuous operation it must be turned off for 20 minutes. After the engine has cooled down, you can continue working.

To prevent brushes from becoming contaminated with dust during storage, it is recommended to store the polisher in a case. At the same time, you should not place the polisher on hair brushes, which will become wrinkled during long-term storage, which will affect the quality of the floor polish.

Once a year, the bearings of the moving parts of the floor polisher must be lubricated, this is done by a specialist mechanic in the workshop.

Microwave ovens

Microwave ovens, which use a completely different method of cooking food than in ovens, gas or electric stoves, are widely used today. Microwave ovens use the energy of ultra-high frequency electromagnetic oscillations (microwave waves) generated by a magnetron.

The advantages of microwave ovens are widely known: food cooked in them does not burn, completely retains vitamins, does not dehydrate or fry. The cooking process itself is 4–8 times faster than, for example, on a gas stove.

The microwave oven does not heat up, does not emit any combustion products, and the air in the kitchen remains fresh and clean.

An attractive point for many is the fact that cooking food in a microwave oven can significantly reduce fat consumption, which is often an important condition for dietary nutrition.

In a microwave oven you can not only cook, but also reheat food. Reheat on plates immediately before serving. Sometimes sealed containers are used, as the product may boil over and contaminate the oven walls.

There is one limitation regarding cookware used for microwave cooking. It is prohibited to use metal utensils for this purpose. This prohibition also applies to utensils that have metal decorations (for example, gold rims on the edges of plates or cups). You can use any other utensils - glass, porcelain, earthenware, plastic, paper, ceramic, etc.

The microwave oven allows you to prepare meat dishes with different depths of processing of the product, that is, lightly, medium and deep fried. This is explained by the fact that the working chambers of microwave ovens are made in such a shape that the microwave waves generated by the magnetron are repeatedly reflected from the walls and bottom and spread freely throughout the entire volume of the chamber. This ensures that food is heated evenly on all sides. But, penetrating into the food, the waves are weakened, so the outer layers of the processed product warm up somewhat faster than the inner ones, which allows, by changing the cooking time of the dish, to obtain different depths of processing.

Power tools

A home craftsman may have a large number of power tools if he is seriously involved in carpentry, making furniture, renovating an apartment, or building a country house with his own hands. Here we talk about some of them.

Electric soldering iron

An electric soldering iron occupies not the last place in the arsenal of a home craftsman: whether electrical wiring is being laid, whether it is being repaired, whether electric motors are being repaired, solder connections will be required everywhere.

Household electric soldering irons can have continuous or intermittent heating.

A continuous heating electric soldering iron is a simple device consisting of a massive soldering rod (a heating coil wound on a metal tube insulated with a layer of mica plastic), ending with a soldering tip, a heat-resistant handle and an electrical cord.

The electrical circuit of the intermittently heating soldering iron includes a step-down transformer, which prevents the soldering tip from overheating. The design of such a soldering iron is shown in Fig. 94.

Rice. 94. Electric soldering iron of periodic heating: 1 – transformer; 2 – body; 3 – tire; 4 – soldering rod; 5 – signal lamp; 6 – switch; 7 – electrical cord.

The soldering rod of the intermittent heating device is made of thick wire in the form of a loop; It has a very small mass, so it heats up to operating temperature in a few seconds.

The power range of electric soldering irons is quite wide: from 10–26 W for low-power radio installation irons to 40–65 W for electrical soldering irons and up to 100 W for copper soldering irons.

Electric drill

The electric drill has become one of the most necessary tools. Not a single repair can be done without it. A number of additional attachments, which are equipped with the latest models, allow you to expand the range of application of this tool.

Electric drills are designed for drilling holes in a wall, in solid wood, etc. This tool consists of an electric motor, which is connected to the drill chuck spindle through a series chain of fasteners. Most often, twist drills are used for this operation. In addition to its direct purpose, an electric drill is used for polishing, grinding, stirring paints, etc.

During work, the drill should penetrate into the array gradually, without jerks or jolts. If it is necessary to make a through hole, then the pressure on the wood must be reduced as the drill moves.

Power saws

Electric saws are used for cross-cutting and longitudinal cutting of materials, such as boards and bars. In addition, they can be used to cut at a certain angle.

When making furniture, for example, it is recommended to use electric hacksaws, the set of which includes various replaceable saw blades, allowing you to cut not only plywood and wood, but also modern coated sheet material. An electric hacksaw can handle materials such as hard wood, drywall, plastic and brick.

Electric circular and chain saws significantly reduce the time spent cutting timber, but they are not suitable for performing delicate work. The following brands of saws are most widely used: IE-5107, K-5M, EP-5KM.

For sawing unhewn logs and ridges, saws of the EP-K6 brand are needed.

The cutting part of such saws is a saw chain, which consists of teeth connected to each other by hinges.

Working with the listed saws requires compliance with safety regulations.

1. When sawing in a damp room, the mains voltage should not exceed 36 V.

2. The saw can only be transported by placing it in a case.

3. After finishing work, the saw must be put away in a specially designated place.

When working with an electric saw, you should remember that this is a tool that is a source of increased danger. Having purchased such a saw, first of all you should carefully study the structure of the saw and the rules for its operation. Before starting work, remove the bushing and fill the oil seal with grease. Lubrication is repeated every 25–30 hours of operation.

The hand-held circular saw IE-5107 has a fairly high disc rotation speed - 2940 rpm, which is provided by a 750 W electric motor, so it can be used to saw wood materials up to 65 mm thick, and a special device allows you to change the angle of inclination of the cutting part from 0 to 45°.

This saw has an electric motor with a single-phase commutator and operates from a regular electrical network with a voltage of 220 V.

Before work, check the correct sharpening and setting of the saw teeth and the firm fit of the disc on the spindle. The disc must not have cracks or damage. To check the condition of the gearbox, turn the disk slightly. If it is difficult to turn the disk, the lubricant should be made more liquid. This can be achieved by idling the tool for 1 minute.

Before starting work, the material to be cut is secured on a workbench. After this, grab the rear handle of the saw with your right hand, and the front handle with your left hand and install the cutting part of the saw on the material. Guide the saw along the intended line easily and smoothly, since sudden jerky movements can jam the tool disk, which can result in damage to the electric motor.

If the disk nevertheless jams, move the saw back. This is done so that the disk comes out and reaches the required rotation speed. Only after this they continue to work.

After finishing work, turn off the tool and wipe it with a rag soaked in kerosene.

Working with an electric saw requires increased attention and strict adherence to operating technology. Deviations from work procedures and inattention can result in serious injury. Therefore, if any deviation from the normal operation of the electric saw is detected, it should be turned off immediately and the cause of the failure should be investigated. If the breakdown is serious, it is best to seek help from a specialized workshop.

Electric planers

Electric planers are used to level the surface of a wood board or board along the grain. The surface is planed using rotating cutters driven by an electric motor. The lowering and rising front ski changes the depth of penetration of the cutting cutter into the solid wood. If you remove the protective cover and attach the plane to a workbench, you will get a machine that is often used in woodworking.

electric planer IE-5707A helps to quickly process a large surface area. A plane can be used to process wood surfaces 100 mm wide and 3 mm deep. Its cutting elements are rotating cutters driven by an electric motor. You can vary the depth of processing. The electric planer can operate from a household network. Before working with an electric planer, be sure to secure the board to the workbench. Move the plane only in the direction of fiber growth and make sure that shavings and sawdust do not fall under the skis. After two or three passes, take a break, firstly, to check the degree of processing of the part, and secondly, to avoid overheating of the tool’s electric motor. Planer knives become dull after 2–3 hours of operation, and the quality of planing becomes significantly worse. When taking a break from work, place the plane on its side or with its skis facing up.

Chips and sawdust can get under the guides of the ski plane, then the cutting depth of the wood layer can change, so you need to keep an eye on this.

The reasons for uneven processing of the wood surface may be incorrect and uneven placement of cutters and dullness of their cutting part. It is also possible that the sliding surface becomes clogged with a large amount of sawdust or shavings.

Overheating of the electric planer motor and its failure can occur due to pressing the tool from above during operation and lack of lubrication in the seals.

The surface processed with an electric planer is not always even and smooth. The first defect occurs when the cutting cutters are incorrectly and unevenly positioned in the groove relative to the level of the skis. The second defect is the result of using dull cutters.

Safety measures when working with an electric planer consist mainly of proper wiring, careful handling of the cutting tool, and turning off the tool during breaks.

After working with an electric planer, you need to remove the cutters from the grooves, clean them with kerosene and put the tool in the box.

Electric Shaper

An electric cutter is used to select wood for rectangular sockets for fastening parts. The main part of this tool is a slotting chain, which consists of small cutters connected to each other by hinges.

To obtain nests of different sizes, you only need to change the plate on which the slotting chain is attached, and the depth of the sampling is adjusted by lowering the handle.

To get smooth edges of the mounting socket, first sharpen or clean the cutters, and only then prepare the machine for work. Then they fix the board or part on the workbench, install the machine on it and turn it on.

If you attach an electric shaper to a workbench, you will get a stationary machine. When working with a slotting machine, precautions must be taken. First of all, they consist in the correct fastening of the slotting chain, the serviceability of the electrical wiring, and the correct supply of solid wood when using a fixed machine. If the machine is not secured, then be sure to ensure that the block is well secured. Do not operate an ungrounded machine.

Electric pumps

In rural areas where there is no centralized water supply, among the household electrical equipment there is probably an electric pump for raising water from wells and boreholes.

Structurally, any electric pump consists of two parts: a motor powered by an electrical network, and the pump itself. Based on the principle of operation, there are two types of pumps: centrifugal (Kama, Agidel, Ural) and vibration (Malysh, Strumok, Rodnichok).

The centrifugal pump mechanism (Fig. 95) consists of an impeller with blades, a suction pipeline and a receiving device with a check valve.

Rice. 95. Centrifugal electric pump “Kama”: 1 – stand; 2 – base of the body; 3 – gasket; 4 – noise suppression device; 5 - electric motor; 6 – pump cover; 7 - stuffing box; 8 – impeller; 9 – receiving device.

Water is collected from an aquifer, well or reservoir and transported to the point of consumption as follows: when the impeller rotates, a vacuum is created in the suction pipe, due to which water continuously flows into the suction pipeline and, under the influence of centrifugal force, is thrown out of the pump housing into the pressure pipeline , through which it enters the reservoir or for distribution.

A prerequisite for the operation of centrifugal pumps is the presence of water in the impeller and suction pipeline before connecting it to the network. To retain water in these parts while the pump is inactive, a receiving device is equipped with a filter and a check valve. When installing the pump, it is necessary to ensure that the receiving device is positioned strictly vertically, since the check valve closes under its own weight. Before putting the pump into operation for the first time or after repair, water should first be poured into its housing.

In order to protect the electric motor from moisture, the shaft coming out of the pump for the electric motor attachment is sealed with an oil seal, which consists of two rubber cuffs and an insert between them; The oil seal is secured using two washers and a tightening nut.

To maximize the efficiency of a centrifugal pump, the gap between the protrusions of the impeller and the bores in the cover and pump body should not exceed 0.15 mm. Capacity of centrifugal pumps – up to 1.5 m 3 /h; They are designed for a head of 17 m, the maximum suction height is up to 7 m.

The operation of vibration-type pumps is based on the use of electromagnetic oscillations: under the influence of the frequency of the current, the electromagnet creates oscillations that are transmitted to the float valve, the membrane of which begins to vibrate, capturing water from the aquifer and pushing it through the pipeline. The valve design prevents reverse flow of water.

When operating, the vibration-type pump must be completely immersed in water (Fig. 96).

Rice. 96. Installation of a vibration-type electric pump: a – in the well casing; b – in a well; 1 – pump; 2 – ring; 3 – bundle of wire with hose; 4 – nylon suspension; 5 – spring suspension; 6 – wire; 7 – hose.

Operating parameters of vibration-type electric pumps: power - up to 300 W, pressure - up to 40 m, maximum suction height - up to 40 m, productivity - from 0.5 to 1.5 m 3 / h (depending on the brand), continuous operation time – 2 hours (after which there is a break for 15–20 minutes).

Undoubtedly, the list of household electrical appliances is not limited to only those devices that were discussed here. Surely many people have fans, hair dryers, convectors, split systems, dishwashers, but all these devices are devices that are quite complex (and expensive) for you to try to repair them yourself without special knowledge. And enough has already been said about how to fix minor problems in the form of a damaged electrical cord or plug.

Concluding the conversation about household electrical appliances, I would like to remind you once again that the quality of work and service life depend not only on their technical characteristics, but also on the attitude towards them. Therefore, you should remember some useful tips for caring for your home electrical appliances and wiring.

1. An unexpected blackout in the apartment is not yet a reason to go into the common electrical panel in search of the cause. First, it is better to make sure that the fault is not hidden in the internal wiring. The easiest way is to disturb your neighbors and ask if they have electricity. If the problem is common, then the fault lies in the external wiring, and the only thing that can be done is to call a specialist from the DEZ.

If your neighbors have complete order with their electricity, you should start looking for problems in the internal electrical wiring.

2. Often, the operation of circuit breakers or fuses occurs not due to a short circuit, but due to overload of the home power line (that is, the total power of all devices connected to the network is very high); in other words, the current required to power the switched-on devices is greater than that for which the fuses are designed. Therefore, when the fuses trip, you don’t need to immediately run in search of a short circuit; it’s wiser to do the calculations.

Let’s assume that the total power of simultaneously operating devices is 2500 W. If the voltage in the network is 220 V, then the current required to power the devices is 2500: 220 = 11.4 A. Therefore, if the fuses on the electric meter or panel are designed for 10 A, then the issue is not a short circuit at all - fuses should be installed, designed for high current.

But when equipping a meter or panel with fuses designed for a current greater than the electrical wiring allows, you can get rid of flying plugs, but it is unlikely that you will be able to get rid of failed electrical wiring (due to wires burning out).

3. Do not rush to repair complex household electrical appliances yourself if you are not sure that everything will work out. After all, it may well be that the result of repair experiments will be a completely unusable device and a handful of extra spare parts remaining after assembly.

It is more advisable to entrust the repair of complex equipment to specialists.

Electric motors

In the previous chapter, electric motors were mentioned among the structural elements of many devices, but not a word was written about motor problems. This question is quite capacious and deserves a separate chapter. This chapter is entirely devoted to electric motors: their classification, design, operating parameters, operating rules.

Classification of electric motors

Depending on the type of current used in an electric machine, all motors are divided into DC and AC motors, as well as universal (commutator) motors. Each type of engine has both advantages and disadvantages.

The design of AC motors is simpler, therefore, it is much easier to work with them. However, it is almost impossible to regulate the rotation speed of such engines. This limits their scope of application to devices in which there is no need to regulate the rotation speed, for example in electric saws and similar mechanisms.

Structurally, in the most general form, AC electric motors consist of two main parts: a stationary part - the stator and a rotating part - the rotor (Fig. 97).

Rice. 97. Design of a three-phase motor of the 4A series: 1 – shaft; 2 – fixing key; 3 – bearing; 4 – stator; 5 – stator winding; 6 – rotor; 7 – fan; 8 – terminal box; 9 – paw.

They are produced in single-phase and multi-phase, and the power consumption ranges from 0.2 to 200 kW or more.

The design of DC motors also includes a moving part - the armature and a stationary part - the stator. The stator and armature windings in these motors can be connected in series, parallel and in combination. Their undeniable advantage over AC motors is the ability to regulate the rotation speed. They are mainly used in industrial installations where there is a precise speed limit.

Household electrical appliances - refrigerators, vacuum cleaners, juicers, etc. - use universal commutator motors designed to operate on both alternating current with a frequency of 50 Hz (voltage 127 and 220 V) and direct current (voltage 110 and 220 V) .

Commutator motors have low power - up to 600 W; maximum rotation speed – up to 8000 rpm. The rotation speed in them is regulated by changing the voltage supplied to their windings: if the engine is low-power, then the voltage change is made by connecting a rheostat; For more powerful motors, a transformer is used.

The advantage of commutator motors is primarily their versatility. The disadvantages include the impossibility of operating at low loads, that is, idling (the engine overheats in this mode); low efficiency when operating on alternating current; the occurrence of radio interference during engine operation. True, the last drawback can be reduced if the excitation winding is balanced, that is, connected on both sides of the armature.

Technical data sheet of the electric motor

Since there are a large number of types and brands of electric motors, it is not possible to present all their technical parameters in this book. Yes, this is not required, since each factory-made engine has a technical passport, made in the form of a metal plate, which is attached directly to the engine body. But you need to be able to read this passport correctly.

The engine passport indicates all its technical characteristics necessary for its connection, namely: engine type; its serial number; the type of current from which the motor operates; rated frequency of alternating current (in Hz); rated net power on the engine shaft; Power factor; type of connection of the stator winding and the network voltage required in each of these cases (in V); current consumption at rated load (in A); operating mode by duration; rotation speed at rated load; nominal efficiency; degree of protection; as well as GOST, winding insulation class, weight and year of manufacture.

A thorough description of the structure of all types of electric motors is not the purpose of this book. Since repairing electric motors is a complex matter, requiring not only special knowledge, but also the availability of the necessary equipment, it is better to entrust it to specialists. The task of a home electrician is to ensure the correct operation of a serviceable engine.

Designation of motor winding terminals of various types

Undoubtedly, a home electrician must be able to correctly connect an electric motor to the network, and the main problem here is the number of terminals of various types of windings: there are quite a lot of them, it is difficult to understand them. Knowledge of the conventional unified designations applicable to domestic electric motors will be of great help.

The greatest difficulty is connecting the DC motor; here the number of pins can be more than ten. They are designated by the initial letters of words reflecting their functional purpose:

Ya1 and Ya2 – the beginning and end of the armature winding;

K1 and K2 – the beginning and end of the compensation winding;

D1 and D2 – the beginning and end of the winding of additional poles;

C1 and C2 – the beginning and end of the serial (serial) excitation winding;

Ш1 and Ш2 – the beginning and end of the parallel (shunt) excitation winding;

U1 and U2 are the beginning and end of the equalizing wire, respectively.

It is much easier to deal with AC motors, which have a significantly smaller number of terminals:

– if the stator windings of three-phase AC motors are star-connected, then the beginning of the stator windings is designated as C1, C2 and C3 (first, second and third phases, respectively); zero point - 0. If the stator winding has six terminals, then the designations C4, C5 and C6 indicate the ends of the windings (first phase - 4, second - 5 and third phase - 6, respectively);

– if the stator windings are connected in a triangle, then the designations C1, C2 and C3 determine the terminals of the first, second and third phases, respectively.

Three-phase asynchronous motors have rotor winding terminals designated as P1, P2 and P3 (first, second and third phases, respectively), 0 indicating the zero point. The terminals of the windings of asynchronous multi-speed motors are designated: for 4 poles - 4С1, 4С2 and 4С3; for 8 poles – 8С1, 8С2 and 8С3. In asynchronous single-phase motors, the terminals of the main winding are designated: C1 - beginning, C2 - end. For the terminals of the starting winding of the same motors, the following designations are adopted: P1 – beginning, P2 – end.

The terminals of the exciter winding of synchronous motors, which are called inductors, are designated as I1 and I2 (the beginning and end of the winding, respectively).

In order to ensure that there is as little confusion as possible when connecting the terminals of the windings of commutator machines, they are marked in different colors at manufacturing plants and repair shops: the terminals of the armature winding are white; serial field winding - red (if it has an additional output, then it is marked in red and yellow); parallel field winding - green. To determine the beginnings and ends of the windings, the latter are always marked with black added to the main one; Thus, it turns out that the beginnings of the windings have one-color marks, and the ends have two-color marks.

The color marking of the terminals of the electric motor windings is in addition to the letter marking. However, in low-power electric motors, the windings are made of wires, the thickness of which does not allow the use of a letter designation, so color marking is the main and only one here.

In three-phase motors, the beginning of the first phase is indicated by yellow, the beginning of the second by green, the beginning of the third by red, and black indicates the zero point. With six pins, the marking of the beginning of the windings is preserved, and the ends are marked in the main color with the addition of black.

The winding terminals of single-phase asynchronous motors are marked in the following colors: the beginning of the main winding is indicated by a red wire, the beginning of the starting winding by a blue wire, and in the marking of the ends of the windings, as usual, in addition to the main color, there is black.

Changing the parameters of a three-phase asynchronous motor

As you know, our electrical networks do not have constant current parameters. Therefore, it is necessary to know how the parameters of electric motors change under conditions different from the nominal ones.

If the voltage in the power supply network of a three-phase asynchronous motor decreases (while maintaining the rated frequency of the alternating current), its torque decreases and the efficiency drops. As the voltage increases (while maintaining the rated frequency of the current), the torque increases, which leads to overheating of the motor and a decrease in efficiency.

As they say, changing the places of the terms does not change the sum. Therefore, if the voltage remains constant and the frequency of the alternating current decreases, then the efficiency still deteriorates: the engine speed decreases and it begins to heat up. An increase in the frequency of alternating current while maintaining the rated voltage leads to a similar result.

Connecting a three-phase motor to a single-phase network

Electric motors, as you know, are single-phase and three-phase; The household electrical network has one phase. The question arises: is it possible to connect a three-phase motor to a single-phase network. Despite the seemingly insoluble contradiction, such a connection can be made, and there are several ways.

The first two methods of connecting electric motors (Fig. 98) are based on the use of working (Cp) and starting (Sp) capacitors.

Rice. 98. Scheme for connecting a three-phase electric motor to a single-phase network using capacitors: a – when the electric motor is turned on “in a star”; b – when the electric motor is turned on “in a triangle”.

The starting capacitor increases the starting torque, and after starting the engine it is turned off. But if the engine is started without load, then the capacitor Cn is not included in the circuit.

For a working capacitor included in the circuit, it is necessary to calculate the capacitance. The calculation is made using the formula: Cp = K (Inom/U), where Cp is the working capacitance of the capacitor for the rated load (in microfarads - µF); Inom – rated current (in amperes – A); U – rated voltage in a single-phase network (in volts – V); K is a coefficient that depends on the engine switching circuit. When the electric motor is turned on “in a star”, K = 2800, when turned on “in a triangle” K = 4800.

The rated current and voltage are taken as the values ​​of the specified parameters given in the technical data sheet of the electric motor.

To connect three-phase motors to a single-phase network using capacitors, the following types are used: KBGMN (paper, hermetic, in a metal case, normal), BGT (paper, hermetic, heat-resistant), MBGCh (metal paper, hermetic, frequency).

If there is a need to change the direction of rotation of the electric motor (reversal), this can be easily done by switching the power cable from one terminal of the capacitor to another.

Starting capacitors can have the following technical parameters: the voltage on the capacitor at rated load must be equal to the network voltage (and when the engine is operating under underload, the voltage on the capacitor must be 1.15 times the network voltage); the starting capacity should be 2.5–3 times the working capacity.

A cheap electrolytic capacitor of the EP type is most often used as a starting capacitor. But when using an electrolytic capacitor, you should remember that it has a large discharge current, remaining charged even after the voltage is turned off. Therefore, after each shutdown, the capacitor must be discharged using some kind of resistance, for example several incandescent lamps connected in series.

The use of capacitors to connect a three-phase motor to a single-phase network is very effective, since it allows you to obtain power that is 65–85% of that indicated in the motor passport. But here it may be difficult to select the required capacitor capacity. Therefore, switching methods using active resistances have become much more widespread (Fig. 99).

Rice. 99. Scheme for connecting a three-phase electric motor to a single-phase network using active resistance: a – connecting the electric motor “in a triangle”; b – turning on the electric motor “in star”.

Immediately before connecting the electric motor to a single-phase network, the starting resistance should be turned on; The starting resistance is turned off only after the engine reaches a rotation speed close to the rated speed.

Unfortunately, when using methods for connecting a three-phase motor to a single-phase network using active resistance, it is possible to obtain power from the motor that does not exceed half of its rated value.

Connecting DC motors to the network

In a home workshop equipped with machines with electric motors, DC motors may need to be wired and powered. There are several schemes for this.

The most widely used switching circuit is using a starting rheostat, which reduces the starting current, since when the engine is turned on, a starting current arises that exceeds the nominal value by 10–20 times. The winding of the electric motor may simply not withstand it, and this will lead to failure of both the motor itself and other elements of the circuit.

Connect the starting rheostat in series with the armature circuit (Fig. 100).

Rice. 100. Scheme for connecting a DC motor to the network: L – clamp connected to the network; M – clamp connected to the excitation circuit; I am a clamp connected to an anchor; 1 – arc; 2 – lever; 3 – working contact.

This scheme is most suitable for engines with a power of more than 0.5 kW.

The value of the starting resistance of the rheostat is calculated by the formula:

where R p is the starting resistance of the rheostat (Ohm); U – network voltage (110 or 220 V); I nom – rated motor current (A); R i – resistance of the armature winding (Ohm).

The procedure for connecting a DC motor to the network is as follows:

– the lever on the rheostat is set to idle contact – 0;

– turn on the mains switch and move the rheostat lever to the first intermediate contact.

In this case, the engine will be excited, and a starting current will flow in the armature circuit, the magnitude of which will depend on the large resistance consisting of all four sections of the starting rheostat;

– with an increase in the armature rotation speed, the starting current should decrease, which will also reduce the starting resistance; To do this, move the rheostat lever to the second, then to the third contact, etc., until it is on the working contact (the rheostat lever cannot be held for a long time on the intermediate contacts, since starting rheostats are designed for a short operating time and are delayed in this mode leads to overheating and failure).

There is also a procedure for disconnecting DC motors from the network, since they do not turn off immediately: first, the rheostat handle is moved to the extreme left position (of course, the engine will turn off, but the excitation winding will still remain closed to the resistance of the rheostat) and only then the power to the engine is turned off. If you neglect this shutdown procedure and turn off the electric motor immediately, then at the moment the circuit opens, the following may occur in it: high voltage that the engine will fail.

Degree of serviceability of the commutator motor

Anyone who, by the nature of his work or due to natural curiosity, dealt with DC motors, certainly had to pay attention to the constant sparking present on the motor commutator during its operation.

Sparking itself does not necessarily indicate a malfunction of the engine or the impossibility of its operation, since the causes of sparking are very different: from the presence of blackening on the commutator or carbon deposits on the brushes to their incorrect installation and poor fit of the brushes to the commutator or increased vibration of the brush device.

Practice shows that it is not possible to completely get rid of sparking on the commutator even in cases where the engine brushes are installed absolutely correctly, according to factory standards, with a tight fit to the commutator; if there is no vibration, if the surface of the commutator and brushes is free of dirt, blackening and carbon deposits.

The task of a home electrician working with a DC motor is to learn how to correctly determine the degree of permissible sparking on the commutator. And for this, there are certain sparking standards, knowing which you can easily distinguish a serviceable engine (despite the presence of sparking) from one that needs preventive maintenance in a repair shop.

The standards are determined according to a specially developed class scale, the so-called switching classes (Table 9).

Table 9. Degree and characteristics of sparking on the DC motor commutator

Operation of motors of 1, 1.25 and 1.5 commutation classes is possible without restrictions.

Motors with sparking of the 2nd commutation class can be operated only if it occurs only at moments of a sharp increase in load or when operating in overload mode.

The third switching class limits the possibility of further operation of the engine. If both the commutator and the brushes are in a suitable condition for operation, then such sparking is permissible only at the moment of direct switching on without the use of rheostatic stages or reversing the machine.

An experienced electrician can determine the degree of possibility of further operation of the electric motor not only by the sparking characteristics and the condition of the commutator and brushes, but also by the color of the sparks appearing on the commutator:

– small bluish-white sparks, almost always present on the running edge of the brush, allow further operation of the engine without any restrictions; such sparks are typical for switching classes 1, 1.25 and 1.5;

– the appearance of elongated sparks of a yellowish tint indicates that the spark belongs to the 2nd switching class; further operation of the engine is possible with minor reservations;

– if the sparks have acquired a green color, and there are copper particles on the working surface of the brushes, then the electric motor can no longer be operated, since there is mechanical damage to the motor commutator.

The only repair operation that a home electrician without special knowledge of electrical engineering can undertake is replacing worn brushes. To do this, you need to remove the motor housing cover and brush holder caps, disconnect the worn brushes and install new ones, observing the type of connection to the contacts (twisting or soldering).

It is strongly recommended to entrust other repairs of electric motors to professional specialists, since both AC and DC motors are mechanisms that are quite complex and expensive to carry out experiments on them.

DIY design

If you have the engineering talent, you can make a lot of things with your own hands. This book offers several fairly simple schemes, by collecting which you can not only enjoy doing what you love, but also make very specific devices that are useful from a purely practical point of view.

All these devices were constructed by schoolchildren from the Tula youth scientific and technical creativity club “Electron”. At one time, the diagrams of these devices were published in periodicals, but since the publications were mainly intended for a narrow circle of specialists, these devices did not become widely known.

We invite a wide audience of readers to use the diagrams of these devices.

Device for stripping electrical wires from insulation

The first point in the procedure for making any type of connection of wires is: “Release the ends of the connected wires from insulation for a length …”. To do this, it is usually suggested to use: a knife, scissors, side cutters, but as a result of such stripping, as a rule, the metal core itself is damaged. In addition, if there is a silk braid in the wire insulation, it is very difficult to remove it with these tools.

What if you try to automate the operation of removing insulation from electrical installation wires? The device, the scheme of which is shown in fig. 101, will not only allow you to quickly and efficiently remove the insulating sheath from the ends of the wires, but also keep their metal cores intact.

Rice. 101. Device for removing insulation from installation wires: 1 – nichrome wire; 2 – holder; 3 – screw; 4 - textolite plate; 5 – button; 6 – screw; 7 - conductive wires; 8 – clamp.

Required: textolite plate 6–10 mm thick and about 120 x 30 mm in area; nichrome wire with a diameter of 0.7–0.9 mm, holders, screws, pieces of electrical wire, a button and a metal clamp. Assembling the device is not difficult even for a novice electrician: all parts are mounted on a textolite plate using screws. Now you need to take care of the power supply of the device with electric current. It cannot be connected directly to the home electrical network, due to the fact that the thin nichrome wire is not able to withstand a voltage of 220 V. Therefore, the device is connected to the network through a transformer, the secondary winding of which is designed for a voltage of 4–5 V at a current of 4–5 A.

If such a transformer is not at hand, you can wind it yourself: the TVK-110L-1 brand transformer is taken as a basis, from which all secondary windings are removed; then a new secondary winding is wound, consisting of 45 turns of PEV-1 wire with a diameter of 1.2 mm. During operation of the device, the primary winding of the transformer must always be connected to the network, and a nichrome wire is briefly connected to the secondary winding (closing the circuit using a button).

The device works like this: press the button for 2–3 seconds, the end of the wire being processed is inserted into the working part of the nichrome wire, and the wire is turned 1–1.5 turns. The insulation cut in this way can be easily removed with tweezers.

Electric soldering iron power regulator

To everyone who has ever encountered soldering (even if it was in childhood, in a circle " Young technician"), it is well known how important it is to correctly select the power of an electric soldering iron for making soldered connections. After all, high power gives a high temperature of the soldering tip, and overheating of the soldering iron leads to oxidation of the solder, solder joints are not strong enough, and when soldering semiconductor devices, they may be damaged.

Even an experienced craftsman, not to mention novice electrical engineers, is not always able to determine by eye the degree of heating of a soldering iron. A regulator can come to the rescue, allowing you to change the power supplied to the soldering iron within a wide range (Fig. 102).

Rice. 102. Electronic circuit for the power regulator of an electric soldering iron and a printed circuit board for assembly.

All parts of the power regulator are mounted on a printed circuit board made of foil fiberglass. The finished device is placed in a soldering iron stand body made of plywood. In the case it is necessary to strengthen the socket for connecting a soldering iron and the terminal for connecting the device to the network. For ease of use, cans of solder and flux can be attached to the lid of the same housing.

Soldering irons with power from 40 to 90 W can be connected to this regulator.

Automatic lighting

One of the points of the energy saving program was the organization of efficient lighting in rarely visited places.

On fig. 103 shows a schematic diagram of a lighting machine, the assembly and connection of which to the network will once and for all solve the issue of saving energy in this area.

Rice. 103. Electronic circuit of the lighting machine.

This device is especially convenient for staircase lighting in the entrances of multi-storey buildings and for outdoor lighting in the courtyards of private houses.

Such an automatic machine works quite well simple principle charging and discharging the capacitor: when you press and release the S1 button, the lighting starts to work, as power begins to be supplied to the E1 device; capacitor C2 is discharged at this moment of switching on; As the capacitor charges, the voltage on its upper (according to the circuit) plate increases, and when it reaches a critical value, the device turns off the lighting.

It is advisable to equip light switches with neon bulbs, which will help you find the switch in the dark.

The technical parameters, the observance of which is mandatory when assembling and connecting the lighting machine to the network, are as follows:

– maximum total power of light bulbs in the circuit – no more than 2 kW;

– SCR V6 should be installed on a radiator with a cooling surface of about 300 cm 2;

– diodes V7–V10 are installed on four radiators with an area of ​​70 cm 2 each; if the load power does not exceed 0.5 kW, then these diodes and the thyristor can be mounted without radiators.

The assembled device must be adjusted (adjusted) for a certain lamp glow time. The adjustment is made by selecting resistor R2. If the 2.4 MΩ resistor suggested in the diagram is used, the duration of the lamps burning after switching on will be 2–3 minutes. If it is necessary for the lighting to work for a longer time (for example, you urgently need to repair the lock on an apartment door) than the resistor allows, then a regular switch should be provided in the circuit.

The device is placed in an insulating housing and placed on one of the floors. S1 buttons with neon lights are installed on each floor. With a total lamp power of 2 kW, the cross-section of the wires that connect the switch buttons to the device must be at least 1.5–2 mm 2.

thermostat

When developing photographs, breeding fish in an aquarium, growing flowers or vegetables in a greenhouse, quite often you have to face the problem of maintaining a constant temperature of a certain environment (water or air). Another homemade device can help with this - an electronic thermostat (Fig. 104).

Rice. 104. Electronic thermostat: a – diagram; b – location of parts on the circuit board.

Its basis is a trigger (a circuit of logic elements D1.1, D1.2 and resistors R4, R5), the input of which receives voltage from a divider consisting of resistors R1, R2 and R3 (resistor R3 also serves as a temperature sensor). An increase in the temperature of the environment leads to the fact that the resistance of resistor R3 decreases, and therefore the voltage supplied to the input of the trigger decreases, causing the latter to switch. In this case, a low level voltage is set at the output of the trigger, transistor V2 and thyristor V3 are closed, and the heater connected to output X1 is de-energized.

When the temperature drops (at a certain value), the trigger switches again, this time turning on the heater.

The temperature values ​​at which the trigger switches occur are set using a variable resistor R1; The resistance of resistor R4 is responsible for the accuracy of maintaining the set temperature (the lower its resistance, the more sensitive the device will be, however, using a resistor with a resistance of less than 10 kOhm is not recommended). The diagram shows the brands of elements for using a thermostat with a heater power of 200 W. If the heater power is about 2 kW, then a KU202M thyristor and D246 diodes (4 pieces) are used. In this case, the thyristor and diodes are installed on radiators for heat removal.

The second life of a fluorescent lamp (not an innovation of the Electron club)

If lamps with fluorescent lamps are used to illuminate the house, then it must be taken into account that their cost (compared to incandescent lamps) is significant. And although the lamps daylight They serve for quite a long time; the need to replace them still arises from time to time.

A chokeless circuit for connecting them to the mains power supply will help extend the life of fluorescent lamps and even give a second life to lamps with a burnt-out filament. This scheme has been around for more than a quarter of a century; it is quite popular and is presented in this book (Fig. 105).

Rice. 105. Network supply diagram for a fluorescent lamp with burnt-out filaments.

It should be noted that the characteristics of all elements of the proposed circuit depend on the power of the lamp itself. These characteristics are given in table. 10.

Table 10. Characteristics of power circuit elements for fluorescent lamps with burnt-out filaments

The circuit of diodes VD1 and VD2 with capacitors C1 and C2 is a full-wave rectifier with double the voltage; in this case, the capacitances of the capacitors determine the voltage value supplied to the electrodes of the HL1 lamp (the relationship is direct: the larger the capacitance, the higher the voltage).

When connected to the mains power supply, the voltage pulse at the output of the rectifier reaches 600 V. The combination of diodes VD3 and VD4 with capacitors C3 and C4 further increases the ignition voltage, bringing its value to approximately 900 V. At this voltage, a glow discharge between the lamp electrodes occurs even in the absence of filaments. (Capacitors C3 and C4 have another function - they dampen radio interference that occurs during an ionization discharge inside the glass tube of the lamp).

The lamp lit, its resistance decreased, and therefore the voltage on the electrodes of the lamp decreased, which ensures its normal operation at a voltage of about 220 V (a typical indicator for household electrical networks). The operating voltage for the lamp is determined by the value of resistor R1.

In principle, the circuit of diodes VD3 and VD4 and capacitors C3 and C4 can be excluded from the circuit, but in this case the starting reliability of the lamp (ignition reliability) is reduced.

To create such a circuit, you will need the following radio components:

– as capacitors C1 and C2, use paper or metal capacitors of the MBG, KBG, KBLP, MBGO or MBGP types, designed for a voltage of 600 V;

– capacitors C3 and C4 can be of the KSG, KSO, SGM or SGO type (with mica dielectric). They must be designed for an operating voltage of at least 600 V;

– resistor R1 is a wire resistor, its power must correspond to the power of the lamp being switched on; you can use resistors such as PE, PEV, PEVR;

– if the circuit contains diodes of the D205 or D231 brands (when connecting lamps with a power of 80 or 100 W), then they should be installed on radiators (to remove heat).

The presented diagram for connecting a fluorescent lamp to the mains power not only does not have a bulky choke and an unreliable starter, but also ensures that the lamp turns on without delay, its silent operation and the absence of unpleasant blinking.

Such devices, designed according to the proposed schemes, usually do not gather dust in closets and attics, but take their rightful place in the electrical network of the house or in the tool box.

Security systems

It has always been human nature to protect himself, his home and his loved ones, his property from possible danger. For this he used everything available ways and methods. At first these were the simplest means of physical protection, over time they were transformed into security alarms, and now modern multifunctional security systems work for people and effectively cope with their security tasks.

When buying an apartment or a house, opening a store, or organizing your own company, a person is faced with the problem of organizing security. He is faced with the task of ensuring the proper level of protection of his values. When solving this problem, everyone turns, first of all, to their life experience. Based on it, taking into account your field of activity and business contacts, subjective and objective assessments of the likelihood of a threat are given.

When choosing security means, such important factors as the location of the facility in need of protection and the crime situation in the area must be taken into account.

Along with current commercial enterprises and banks, consumers of security systems are also individuals: entrepreneurs, farmers who own shops, cottages, farms, etc. An increasing number of Russian businessmen, in order to protect their business from unwanted interference from competitors and criminal structures resort to security measures. This is evidenced by the great demand for such equipment.

For example, just a few years ago, video intercoms for many of our compatriots seemed something exotic and inaccessible. Now they are in great demand, they are offered by many manufacturing companies. Along with an apartment video intercom, which is a simple system and is not that expensive, there are also security systems used to protect private houses or cottage communities. Such devices, in their technical complexity, do not lag behind the systems that are used to protect serious organizations.

When purchasing them, the consumer is inevitably faced with concluding an agreement for the installation of equipment. To protect against low-quality products, there is mandatory state certification of security systems.

To protect an object as effectively as possible, it is necessary to use products that meet certain requirements and have a special certificate.

In Russia, the State Standard of Russia applies to security devices, compliance with which must be confirmed by certificates. Certificates are issued by the Certification Center for Security and Fire Alarm Equipment of the Main Directorate of Private Security of the Ministry of Internal Affairs of the Russian Federation (CSA OPS GUVO GUVO of the Ministry of Internal Affairs of the Russian Federation).

GOST of Russia takes into account the peculiarities of the use of such equipment in our country and for some positions, unlike Western standards, assumes more stringent requirements. Equipment that has passed certification must have a marking mark corresponding to the certification (Fig. 106).

Rice. 106. Russian markings.

Since a large number of leading security equipment manufacturing companies that supply their products to the Russian market are American, US standards are of interest. Security products produced there must meet UL (Underwriter Laboratories Inc) requirements. Equipment manufactured to these requirements carries the UL mark (Figure 107).

Rice. 107. UL Mark.

There are international standards that certify equipment that has gone through various stages of production with certain requirements imposed on it (Fig. 108).

Rice. 108. Sample international standard marking.

Gosstandart of Russia constantly maintains general records of funds that have various certificates. In our country, all safety equipment must first of all comply with Russian standards.

Having determined the required level of security and acquired the necessary technical means of protection, it is very important to install them reliably and correctly. Otherwise, the costs will be unjustified, since inefficiently operating devices make what needs to be protected from a possible threat practically unprotected. The presence of a weak lock, a fragile door, as well as an alarm system that does not meet the necessary requirements, facilitate the penetration of an attacker into the facility and the theft of valuables.

Today, the task of protecting a particular object, as a rule, is solved in a comprehensive manner. Alarm systems are installed, first of all, taking into account such factors as ensuring reliability, ease of use and the possibility of upgrading the system. Particular attention is paid to fire safety, since, according to statistics, losses from fires are much greater than from thefts.

But despite this, many people try not to think about possible troubles. Hoping for the Russian “maybe”, they will not worry once again about reliable protection and thereby endanger not only their property, but also their own health. In some cases, the lack of reliable security measures can cost your life and that of your loved ones.

Assessing the level of costs for additional security devices or modernization of old ones, it must be said that these are disproportionately small funds in comparison with the damage from a single break-in or fire.

When equipping premises with security systems, you should contact specialists, since only they can carry out installation work efficiently. Installed security devices must always be used correctly, which may require prior training.

It is worth spending some time on this - thereby you can avoid various troubles and shocks.

In matters of ensuring external and internal security, locks are of paramount importance. They ensure, above all, the preservation of valuables, peace of mind and a safe environment.

Lock security level

The determining factor when choosing a lock should not be the price, but the degree of its protection. The rim lock is installed on the outside of the door. Mortise locks, accordingly, are mounted in the door leaf. Rim locks weaken the door leaf less than mortise locks and require less installation time. The exception is multi-point mortise locks. When the door is locked with such a lock, its mechanism extends the locking bolts in four directions. In this case, locking the door with sufficient strength ensures high resistance to burglary.

In the production of locks, modern manufacturers use materials that cannot be drilled. This is achieved by using tungsten alloys. Improvement of locks from year to year becomes possible due to the constant competition of manufacturers, on the one hand, and the increasing level of skill of burglars, on the other. This chapter does not cover mechanical locks because it is not within the scope of the book.

Combination locks

To increase the level of security, mechanical locks are combined with electronic code dialing or reader devices. To open a door with such a lock, it is no longer enough to have only a key. The door will open with the key only if the code is entered correctly.

Combination locks can be either mechanical or electronic. But the locking device remains mechanical in any case. Mechanical locks are less protected from external influences than electronic ones.

In simple mechanical combination locks, the sequence of digits does not matter. This reduces the number of dialing combinations and reduces the degree of protection of such locks. They can be used in conjunction with other devices for conditional access to a room or, if necessary, to restrict access somewhere.

Electronic locks

Unlike mechanical locks, electronic locks provide a higher degree of security. The number of combinations they have is unlimited. In addition, they can be used in conjunction with alarm and security systems to control access to premises. This lock is equipped with a liquid crystal display and can be programmed to organize conditional access to the protected object.

The combination of mechanical and combination locks provides a greater degree of security and user convenience.

Electromagnetic locks

This lock is made in the form of a powerful electromagnet. It is mounted on the frame of the door frame. A counter part is installed at the top of the door - a steel plate (anchor). When connected to power, the lock holds the anchor with a force of up to several hundred kilograms.

Electric trigger locks

The lock is opened from the outside using the door key, and from the inside using the exit button. Its cost is low, but it has one significant drawback: when the door is open, the lock bolt will be inside it until the door slams. A situation may arise that a person pressed the exit button in order to open the door and leave the room, but suddenly changed his mind about leaving. At the same time, the bolt will remain in the cocked state, and the door will be open, which will allow a stranger to safely enter the room.

Door status sensors

Door sensors with magnetic or sealed contacts are used to determine what state the door is in (open or closed). Depending on the type of mounting, sensors are either mortise or overhead.

Intercoms

Intercoms are widely used nowadays. Their isolated position among a variety of security equipment and systems is determined by a combination of audio and video monitoring functions, as well as remote control of access to the facility. Using an intercom, you can identify a visitor by voice, by image, and without approaching front door let him in.

Practice shows that most cases of fraud, robbery, robbery associated with the seizure of citizens' property and an attack on their life and health are committed after the victims themselves voluntarily opened the doors. The intercom acts as a link between the owner of the apartment and the visitor, allowing you to find out everything you need at a safe distance and make a decision about admission to the house or blocking the door.

The modern Russian market offers a wide range of audio and video intercoms. Most of them are made by foreign manufacturers who have been specializing in the production of similar products for decades and continue to constantly improve. The buyer should be attracted not only by the carefully selected design of the intercom, but also by its functional qualities. Not every beautiful plastic box containing a complex mechanism can last a long time in harsh climatic conditions. Manufacturers take into account the peculiarities of the Russian market and are developing more and more reliable devices that are designed to withstand not only the onslaught of weather conditions, but also the influence of external destructive forces, and, simply put, the blows of hooligans.

When choosing an intercom, it is necessary to take into account not only the beautiful design, but also its reliability, adaptability to the conditions of the upcoming work, and, importantly, cost. It is important to remember that expensive does not always mean high quality.

By carefully selecting equipment, the manufacturer or supplier, and considering the issues of long-term operation and maintenance, you can avoid unnecessary costs.

Classification of intercoms

According to their technical design, intercoms are divided into audio intercoms and video intercoms.

Audio intercom provides two-way voice communication between the subscriber and the visitor, which allows the latter to be identified by his voice.

An intercom for the front door of an apartment is a simple technical device that can eliminate attempts at burglary and robbery, thereby increasing the safety of residents. Equipping the door with an intercom eliminates the need to leave the house once again.

Intercoms, such as an audio intercom, can be installed at the entrance to the entrance. It performs the following functions:

– doorbell;

– two-way communication and telephone;

– electric lock control.

The body of this device can be made of plastic or metal. For external installation, aluminum housings with a resistant coating are used, for internal installation - plastic (Fig. 109).

Rice. 109. Audio intercom.

Video intercoms

Systems that perform the functions of a door peephole and intercom are called video intercoms. The video intercom is shaped like a telephone. It consists of a monitor and an intercom.

When you pick up the handset, the video intercom automatically turns on, which allows you to see the limited space in front of the door and talk with the person behind it. In addition, the video intercom functions as a bell. The intercom on the visitor's side is a candy bar that houses a camera, an intercom and a call button.

Video intercom is the simplest television security system. It is small in size and, as a rule, is installed at the entrance door to a room (for example, an apartment). As a monitor, you can use a regular TV that is installed indoors. The camera turns on when you press the doorbell button.

The video peephole allows you to conduct covert surveillance of the visitor. Outwardly, the video peephole resembles an ordinary door, but in terms of its technical equipment it is a miniature video camera with a special lens. Some types of such lenses, such as pin-holes, can be masked and made invisible to the visitor. It is impossible to detect such a video peephole without special means.

By the number of subscribers served, individual, group and access intercoms are distinguished.

The individual intercom is designed to serve one subscriber and is used to protect individual apartments, offices, country houses, as well as small security posts.

A group intercom allows you to serve a small number of subscribers (usually from two to six) and is used to protect closed (that is, having one common entrance) halls located nearby offices, cottages for several families, etc.

Individual and group intercoms differ in the number of blocks of the same type.

The entrance intercom allows serving a large number of subscribers (from tens to several hundreds) and is used to protect the entrances of apartment buildings, office buildings, etc. Modern technology allows the production of integrated multi-subscriber, that is, designed for several entrances, intercom systems. They are designed to protect complexes of residential and administrative buildings. Thanks to one such system, it is possible to serve several thousand subscribers and close the doors of dozens of entrances.

The design of any type of intercom consists of the following parts:

– external block (call block);

– subscriber internal unit;

– processor unit;

– control equipment;

– main power supply;

– backup power supply;

– communication lines;

– remote-controlled electric lock;

– door closer.

In the future, to avoid discrepancies, the following objects will be indicated as protected objects:

– apartments for individual intercoms;

– closed halls for group intercoms;

– entrances of residential buildings for access intercoms;

– residential building complexes for multi-entry intercoms.

Determining the intercom configuration

The delivery of intercoms to the consumer is carried out, as a rule, in the form of separate blocks, from which intercom systems of various configurations can be built, and the use of microprocessor technology and modern technologies gives intercoms wide functionality.

Understanding all this diversity and offering an acceptable option to the customer (in most cases unfamiliar with this technology) is very difficult.

It is recommended to start getting acquainted with a specific intercom model by finding out the following details:

– the maximum number of subscribers that the intercom can serve (it must be greater than or equal to the actual number of subscribers served);

– the required number of subscriber units (several units can be installed at the subscriber’s request);

– type of apartment owner identification device. These can be the following miracles of technology: a code, a regular key, an optical or magnetic card, a Touch memory electronic key;

– the maximum number of codes that must exceed the maximum number of subscribers served.

The most common configurations of individual and entrance intercoms.

A two-wire individual video intercom is one of the simplest. The intercom consists of external and internal blocks. An additional device designed to create maximum convenience is an audio tube installed in another room, with which you can talk with the visitor without going to the monitor.

Advanced individual video intercoms, built on the basis of four-wire modules, have found wide application in multi-room apartments and small offices.

The design of such an intercom includes one external unit (camera), two internal units (monitors) and an additional audio tube. Indoor units and audio tube are installed in different rooms. The electric lock is controlled from each of these devices.

For apartments and offices with two entrances, extended individual intercoms with two external and one internal blocks are used. The intercom is also built on the basis of four-wire modules. One external unit is installed for each input. At the same time, the indoor unit, turning on on a call from any of the doors, can control electric locks on all doors.

To create increased reliability when equipping facilities with intercom systems, the principle of two-level protection is often used (this mainly applies to video intercoms). The first level is formed by an entrance intercom, limiting the entrance to the entrance, the second - individual or group intercoms installed on the doors of apartments and closed halls.

The configuration of both a single-level entrance audio intercom and a two-level entrance video intercom can be selected individually for each case. For example, the first level forms an entrance audio intercom, and the second - individual or group audio intercoms (or video intercoms).

Night vision systems

For night surveillance and security in poor visibility conditions, special spotlights are used that illuminate the space with infrared rays invisible to the human eye. The maximum sensitivity of television cameras is ensured by special matrices. The power of the floodlights used ranges from 20 to 500 W. It must be said that 100 W is enough to illuminate an object at a distance of 100 m.

Specialized surveillance systems

Cameras for covert surveillance are used as specialized surveillance systems. Instead of a lens, such television cameras have a special attachment, at the end of which a lens is attached using a fiber-optic cable, and the cable is passed through small holes in the walls or ceiling. The diameter of such a cable is 10 mm, length – 50 cm.

Organization of security and fire alarm systems

Fire alarms are installed in all rooms of the protected facility (with the exception of rooms with high air humidity, in which technological processes directly related to the use of water or other non-flammable liquids take place). Fire detectors are independent alarm loops and are connected to the central security panel of the facility without the right to be disconnected. The fire alarm system operates 24 hours a day.

The facility must have a centralized warning system for fire and other alarms. In a small building, it is permissible to use sound signals that differ from others for this purpose. The fire station is combined with the main security post.

Manual fire call points of the IPR type or the like are installed inside the facility on evacuation routes (in corridors, passages, staircases, etc.) and in separate rooms.

Alarm organization

To promptly transmit messages about the intrusion of criminals to the duty units of the internal affairs bodies or to the security center, facilities are equipped with various alarm systems (buttons, pedals, optical-electronic detectors, etc.). It is advisable to place such devices in storerooms, weapons rooms, trading floors, at the workplaces of cashiers, facility management, at the doors of the main and emergency exits, at the security post and in the security room. Alarm detectors are also installed along routes for moving valuables.

The simplest security and fire alarm schemes (FS)

For a clearer understanding of the principles of operation of the fire alarm system, below are elementary diagrams of security and fire alarm systems that give an audible or light signal in the event of a fire or unauthorized entry into the facility.

In security alarms, as a rule, electrical contacts that open or close are used. To the type of sensors where electrical circuit closes or opens mechanically, include wire loops, magnetic switches, mechanical switches, etc. A number of such circuits are connected to a control device (Fig. 110).

Rice. 110. Alarm device with contact sensors of various types.

Very often, a security system uses a light sensor, the operating principle of which is based on the use of a photocell (Fig. 111).

Rice. 111. Placement of photosensor components.

A light source is installed at one end of the protected area, which illuminates a photocell located at the opposite end of the area. The sensor operates in standby mode until the flow of light falling on the photocell is stopped: for example, the intruder blocks it with his body. In this case, the alarm will sound.

On fig. 112 presents a multi-sensor system that allows you to control a large area, divided into separate sectors according to the number of photocells. In this case, the only light source is in the center of the protected area. To protect a small object (for example, a safe or other metal objects), a proximity detector can be used - a device that reacts to the approach of someone. Rice. 113 shows the use of this tool to protect a safe.

Rice. 112. Alarm system with several photocells and a common light source.

Rice. 113. Connecting a proximity detector to a floor safe.

On fig. Figure 114 shows a block diagram of such a detector.

Rice. 114. Block diagram of a proximity detector.

Two variable capacitors in series are connected to the output of the oscillator, which has a low frequency (LFO) (10–100 kHz).

The protected object is connected to the connection point of two capacitors, through which a control circuit is connected to the generator output. It is necessary to adjust the capacitors in such a way that the energy from the LFO is supplied to the circuit in sufficient quantities, and the contacts that turn on the siren are not closed.

When a potential intruder approaches an object or sensor at a certain distance, part of the electromagnetic energy begins to flow onto it, thereby reducing the signal level at the input of the control circuit and causing the alarm to go off.

To protect the premises inside the facility, an ultrasonic device is used that responds to any movement. The operation of this sensor is based on the Doppler effect. The operating principle of ultrasonic alarm is shown in Fig. 115.

Rice. 115. Block diagram of ultrasonic signaling.

The receiver receives part of the reflected signal, then it is amplified to a certain level that makes the mixer possible. Then, for comparison, the signal is sent from the emitter block to the other input of the mixer. If it encounters a moving object on its way, then the signal entering the circuit changes its frequency by an amount that is determined by the speed of the object.

If the ultrasound emanating from the transmitter is not reflected from moving objects, then both inputs of the mixer receive signals of the same frequency.

In security alarms, a switch contact is used as a sensor. Single-channel control devices are triggered by the closure of the sensor contacts (HP sensor) (Fig. 116).

Rice. 116. Security alarm with normally open sensors.

All sensors are connected to each other in parallel, the alarm is triggered when one or more contacts are closed.

There are security devices that also work with normally closed (NC) sensor contacts. In this case they are connected in series with each other. When one of the sensors opens, an alarm is triggered (Fig. 117).

Rice. 117. Security alarm with normally closed sensors.

Multi-channel security alarms operate with both NO sensors and NC sensors. The siren turns on if one of them changes its normal position (Fig. 118).

Rice. 118. Multi-channel security alarm.

Domestic OPS market

The domestic security market is currently filled with numerous security equipment from both Russian and foreign manufacturers.

All of them successfully master and implement advanced technologies into production, which allow them to produce high-quality products.

Among domestic manufacturers, first of all, it should be noted large enterprises in the electronics industry, specializing in the production of equipment and equipment for defense purposes. Security systems are manufactured using the most advanced technological means, tested and proven in the production of military equipment. The availability of qualified personnel is of great importance.

Nowadays, electronics industry enterprises are forced to deal with enormous competition from domestic commercial manufacturing companies that also produce security equipment.

This is one of the reasons why developers, designers and technologists are united within one enterprise, making it possible to reduce the time from development to the introduction of a product into production.

A large production volume, even when using imported components, allows some enterprises to set competitive prices and at the same time take into account all the requirements of buyers (customers) for security systems.

In 1988, serial production of the Rubin-6 security and fire alarm system began in our country, recognized as the most reliable and widespread means of this class (Fig. 119).

Rice. 119. "Rubin-6".

Currently, the development and implementation of advanced technologies has made it possible to increase the reliability of products and extend their warranty period. One of the latest developments are PKOP "Rubin-2" and "Argus-4" (Fig. 120), which monitor the status of security and fire alarm lines around the clock, sound an alarm in the event of a fire or intrusion into a protected facility, and transmit a message about this to the security center.

Rice. 120. "Argus-4".

The devices are protected from unauthorized intervention into their system by a special anti-sabotage line.

"Argus-4" allows you to work with any sensors and alarms. It has a backup power supply, which does not trigger a false alarm when automatically switched to it.

Each of the loops has the ability to work according to any of two algorithms - without the right (BPO) or with the right to connect (SPO) of the duty operator. The device can operate in the “Self-Security” mode with a delay in turning on the first alarm loop for 60 seconds. The system provides separate indication of the “Alarm” and “Fault” states. The ACS outputs allow direct control of a load up to 50 mA at a voltage of up to 24 V. The load is powered from an external DC source.

The small dimensions of Argus-4 (330 x 85 x 320 mm) make it possible to use it not only for the protection of industrial enterprises, but also for small institutions, offices, private homes, etc.

In Russia, various exhibitions of technical security equipment are held every year. The most famous of these MIPS exhibitions is “Security, Safety and Fire Protection” (Moscow), in which domestic manufacturing companies, as well as representatives of companies from the USA, Japan, England, Israel, Germany and other countries take part.

The exhibitions cover almost the entire domestic security systems market. During the period of their holding, as a rule, trends and prospects for development in this area are outlined.

You can get acquainted with the latest achievements of electronic technology not only by visiting the exhibition, but also by purchasing numerous directories and catalogs of manufacturers and suppliers of protective equipment. It must be said that in Lately In our country, the range of periodicals covering security issues has expanded significantly.

Comprehensive security systems

Today, many large and medium-sized facilities for protection are increasingly using integrated security systems.

In our country there are serial manufacturers and suppliers of certified equipment for fire safety systems, manufacturers of installation work for the installation of complex security systems (fire extinguishing systems, fire and security alarms, video surveillance, local computer networks) based on certified domestic and imported equipment.

The production of smoke fire detector IP-212-41 has been widely established. The product has small dimensions, modern design, and high sensitivity. A special operating algorithm, digital information processing and noise immunity give additional reliability to this device (Fig. 121).

Rice. 121. IP-212-41.

Telephone line security

Heads of various organizations, entrepreneurs and other business people cannot do without a telephone. Quite often they communicate, make various decisions, and clarify emerging issues using the telephone, so it is not surprising that they want to make sure that conversations are not accessible to outsiders, if possible.

However, it should be noted that today on the technical equipment market you can see many types of telephone message interception devices from both domestic and foreign manufacturers.

Methods for intercepting telephone messages

There are six main listening areas on a telephone line. These include:

– telephone set;

– telephone line, including distribution box;

– cable zone;

– multi-channel cable;

- radio channel.

A diagram of a telephone communication line with listening areas is shown in Fig. 122.

Rice. 122. Diagram of a telephone communication line.

It's easiest to connect in the first three zones. For listening, a parallel device is most often used.

In the cable zone, connection is more difficult, since this requires penetrating the telephone communications system, consisting of pipes with cables laid inside them, and selecting the desired pair among many others.

Telephone radio repeaters

Telephone radio repeaters are radio extenders for transmitting telephone conversations over radio channels.

Bookmarks installed in phones are automatically turned on when the handset is picked up and transmit information to the interception and recording point. The radio transmitter receives power from the telephone network voltage. Due to the lack of batteries and microphone in the repeater, it may be small in size. The disadvantages of these devices include the fact that they are easy to detect by radio emission, therefore, to reduce the likelihood of their detection, the radiation power of the transmitter installed on the telephone line is reduced.

A powerful repeater is installed in a separate room. It re-radiates the signal in encrypted form.

Radio repeaters can be made in the form of capacitors, filters, relays and other standard components and elements included in telephone equipment.

To listen to a telephone line, you can use a telephone with a radio extender consisting of two radio stations. The first is located in the handset, the second in the telephone. The receiver is tuned to the desired frequency.

Listening to premises

Using a telephone line, you can also wiretap premises. For this purpose special devices are used. A diagram of possible listening to premises via telephone line is shown below (Fig. 123).

Rice. 123. Scheme for listening to premises via telephone line.

The operating principles of such a device are as follows: the subscriber’s number is dialed. The first two beeps are absorbed by the device, meaning the phone does not ring. The handset is put on hold, and a minute later they start dialing the same number again. After this, the system enters listening mode. On fig. 124 shows one such device.

Rice. 124. “Box-T” device.

Box-T is capable of monitoring a room by telephone at any distance.

There are also call-free systems for transmitting acoustic information over telephone lines, making it possible to listen to rooms without installing any additional equipment.

Technical means of information security

Regardless of what type of activity a person is engaged in, for example, whether he is the head of a large enterprise or a commercial bank, he will probably be interested in learning how information leakage can occur and how he can protect himself from it.

Protection of telephones and communication lines

The telephone has long become an integral part of human life; telephone lines carry streams of various information, and that is why it is important to protect them from harmful use. The telephone set and the PBX communication line are the main channels for information leakage.

Methods of information leakage

1. Changes are made to the design of the telephone to transmit information or special equipment is installed with high-frequency radiation in a wide frequency band, modulated by an audio signal, which serves as a channel for information leakage.

2. The design flaws of telephone sets are taken into account and used to obtain information.

3. There is an external influence on the phone, resulting in information leakage.

Phone protection

Bell circuit protection. An information leakage channel may arise due to electroacoustic conversion. When talking indoors, acoustic vibrations affect the bell pendulum connected to the armature of the electromagnetic relay. Sound signals are transmitted to the armature, and it makes micro-oscillations. Next, the oscillations are transmitted to the armature plates in the electromagnetic field of the coils, resulting in microcurrents modulated by sound. The amplitude of the EMF induced in the line in some types of telephone sets can reach several millivolts.

For reception, a low-frequency amplifier with a range of 300–3500 Hz is used, which is connected to the subscriber line. To protect the bell circuit, use a device with the circuit shown in Fig. 125.

Rice. 125. Bell circuit protection circuit: VD1 and VD2 – silicon diodes; B1 – telephone set; R1 is a resistor.

Silicon diodes are connected back-to-back to the bell circuit of the B1 telephone set. A dead zone for micro-EMF is formed, explained by the fact that in the range of 0–0.65 V the diode has a high internal resistance. Therefore, low-frequency currents induced in the device circuit will not pass into the line. At the same time, the subscriber's audio signal and the call voltage pass freely through the diodes, since their amplitude exceeds the opening threshold of the diodes VDl, VD2. Resistor R1 is an additional noisy element. A similar circuit connected in series to the communication line suppresses the microEMF of the coil by 40–50 dB (decibels).

Microphone circuit protection

Receiving information through a microphone circuit is possible thanks to the high-frequency imposition method. In this case, relative to the common body, high-frequency oscillations (with a frequency of more than 150 kHz) are supplied to one wire, which through the circuit elements of the telephone set are transmitted to the microphone (even when the handset is not picked up), where they are modulated by sound signals. Information is received regarding the common body through the second wire of the line.

The circuit for protecting a microphone using this method is shown in Fig. 126.

Rice. 126. Microphone protection circuit: M1 – microphone; C1 – capacitor.

Microphone M1 is a modulating element, to protect which it is necessary to connect a capacitor C1 with a capacity of 0.01–0.05 μF in parallel with it. In this case, capacitor C1 bypasses microphone capsule M1 at high frequency. The modulation depth of high-frequency oscillations is reduced by more than 10,000 times, making further demodulation almost impossible.

Comprehensive protection scheme

The complex protection scheme includes the components of the first and second schemes given above. In addition to capacitors and resistors, this device also contains inductors (Fig. 127).

Rice. 127. Integrated protection scheme.

Diodes VD1-VD4, connected back-to-back, protect the telephone ringing circuit. Capacitors and coils form filters C1, L1 and C2, L2 to suppress high frequency voltages.

The parts are mounted in a separate housing using hinged mounting. The device does not require configuration. At the same time, it does not protect the user from direct eavesdropping by directly connecting to the line. In addition to all these circuits, there are others that are close in their technical characteristics to similar devices. Many of them are designed for comprehensive protection and are often used in practice.

Cryptographic methods and means of protection

To prevent wiretapping of conversations on a telephone line, you can use a cryptographic method, which is perhaps the most drastic security measure. There are two methods:

1) conversion of analog speech parameters;

2) digital encryption.

Devices using these methods are called scramblers.

An analog scrambler involves changing the characteristics of the original audio signal in such a way that it becomes unintelligible, while at the same time occupying the same frequency band. This allows it to be transmitted over regular telephone communication channels.

The signal change is manifested as follows:

– frequency inversion;

– frequency permutation;

– temporary rearrangement.

A digital scrambler involves changing the characteristics of the original audio signal so that it becomes unintelligible. This device facilitates the preliminary conversion of an analog signal into digital form. After this, the signal is encrypted using special equipment.

Introduction
1. About energy fields
2. Household electrical appliances
3. Cellular
4. Personal computers
5. How does EMF affect health?
List of sources used

Introduction

Significant growth in all sectors of the national economy requires the movement of information in a short time. Supplying cities and remote areas where no car or plane can pass, with telephone and electricity lines.

Therefore, the new era of technology creates computers, cell phones and other equipment that transmit information thousands of kilometers in a fraction of a second and provides firms, enterprises and families with information that previously could not even be known in a year. However, now it is possible.

But all this equipment, wires and various other devices create electromagnetic fields that affect the biosystem of all living beings, including people.

An electromagnetic field is a special form of matter. Through an electromagnetic field, interaction between charged particles occurs. Characterized by the strengths (or inductions) of electric and magnetic fields.

Nowadays, the use of devices that propagate electromagnetic fields is increasing throughout the world. And compared to previous years, there are more and more of them. But some countries, realizing the danger of this, abandon these devices and create new ones.

We will talk here about the invisible pollution that electric power has brought into our everyday life - about harmful man-made electromagnetic radiation (EMR for short), as well as about natural, geopathogenic radiation.

1. About energy fields

Many diseases are caused by magnetic, electrical, electromagnetic and other energy fields. However, classical medicine does not deal with these issues, and future doctors, unfortunately, are not taught this in medical universities...

Every day in our own apartment we are all exposed to weak magnetic fields of industrial frequency. This is radiation from electrical appliances, household appliances and electrical wiring in our apartments.

American and Swedish hygienists, independently of each other, established a safe limit for the intensity of such fields. This is 0.2 µT (microTesla).

What doses do we actually receive?

Table 1. Magnetic field intensity from household appliances

Radiation source	Magnetic field intensity
electric stoves	1-3 µT (at a distance of 20 – 30 cm from the front panel)
Domestic refrigerators (within a radius of 10 cm from the compressor, during its operation); in refrigerators equipped with a “no frost” system – at a distance of 1 meter from the door	0.2 µT
Electric kettle	0.6 µT (at a distance of 20 cm)
electric iron	0.2 µT (at a distance of 20 cm, and only in heating mode)
Washing machine	1 µT (at a height of 1 m, at the console), 0.5 µT (from the side, at a distance of 50 cm)
Vacuum cleaner	100 µT
Electric shaver	several hundred µT (thus shaving is accompanied by magnetic treatment of the face)
House wiring	exceeds 0.2 µT
Microwave	8 µT (at 30 cm distance)

This will be discussed in even more detail later.

Industrial-frequency magnetic fields are only a tiny part of the harmful energy radiation that pollutes our environment. Technical progress brought a lot of useful things to humanity, making life easier and improving the quality of life. These are aviation, cars, television, mobile phones, computers and much, much more. However, along with this, he also caused a lot of trouble.

Nature has given humanity clean, transparent air, clean water bodies and a healing natural electromagnetic background emitted by both space and the plant world. It consists of very weak electromagnetic oscillations, the frequency of which causes harmonization of all systems of the human body. It is this natural background that is suppressed by man-made EMR, which is especially typical for large industrial cities and entire regions.

As a result of the research, the most important conclusion was made: weak EMR, the power of which is measured in hundredths and thousandths of a watt, also called non-thermal or informational, is no less, and in some cases more dangerous than high-power radiation. This is explained by the fact that the intensity of such fields is commensurate with the intensity of the radiation of the human body itself, its internal energy, which is formed as a result of the functioning of all systems and organs, including the cellular and molecular level. Such low intensities characterize the emissions from electronic household appliances found in every family today. These are computers, televisions, cell phones, microwave ovens, etc. This also applies to electronic devices and production devices, which today are equipped with almost all workplaces in industry.

These radiations can disrupt the bioenergetic balance of the body and, first of all, the structure of the so-called. energy information exchange (ENIO) between all organs and systems, at all levels of organization of the human body, between the body and the external environment (after all, a person perceives the energy of external sources, for example, solar, in the form of heat and light).

The most sensitive systems of the human body are: nervous, immune, endocrine and reproductive (sexual). EMFs are especially dangerous for children and pregnant women (embryos), since the child’s body, which has not yet formed, is highly sensitive to the effects of such fields. People with diseases of the central nervous, hormonal, cardiovascular systems, allergy sufferers and people with weakened immune systems are also very sensitive to the effects of EMFs.

Scientists dealing with this problem especially note the negative impact on human health of cell phones, when operating, the electromagnetic waves they emit penetrate directly into the human brain, causing inadequate reactions in the body. More details about cellular communications will be discussed later.

2. Household electrical appliances

All household appliances that operate using electric current are sources of electromagnetic fields. The most powerful are microwave ovens, convection ovens, refrigerators with a “no frost” system, kitchen hoods, electric stoves, and televisions. The actual EMF generated, depending on the specific model and mode of operation, can vary greatly among equipment of the same type. All data below refers to a magnetic field of industrial frequency 50 Hz.

The magnetic field values ​​are closely related to the power of the device - the higher it is, the higher the magnetic field during its operation. The values ​​of the electric field of industrial frequency of almost all electrical household appliances do not exceed several tens of V/m (volts per meter - a unit of measurement of electric field strength) at a distance of 0.5 m, which is significantly less than the MPL (maximum permissible level) of 500 V/m.

Table 2. Magnetic field levels of industrial frequency of household electrical appliances at a distance of 0.3 m.

Possible biological effects

The human body always reacts to the electromagnetic field. However, in order for this reaction to develop into a pathology and lead to disease, a number of conditions must coincide - including a sufficiently high field level and duration of irradiation. Therefore, when using household appliances with low field levels and/or for a short period of time, the EMF of household appliances does not affect the health of the majority of the population. Potential danger can only be faced by people with hypersensitivity to EMFs and allergy sufferers, who also often have increased sensitivity to EMFs.

In addition, according to modern concepts, a magnetic field of industrial frequency can be dangerous to human health if prolonged exposure occurs (regularly, at least 8 hours a day, for several years) with a level above 0.2 microtesla.

1) when purchasing household appliances, check in the Hygienic Conclusion (certificate) the mark on the product’s compliance with the requirements of “Interstate Sanitary Standards for Permissible Levels of Physical Factors when Using Consumer Goods in Domestic Conditions”, MSanPiN 001-96;

2) use equipment with lower power consumption: industrial frequency magnetic fields will be lower, all other things being equal;

3) potentially unfavorable sources of a magnetic field of industrial frequency in an apartment include refrigerators with a “no-frost” system, some types of “warm floors”, heaters, televisions, some alarm systems, various types of chargers, rectifiers and current converters - the sleeping place must be at a distance of at least 2 meters from these objects if they work during your night rest;

4) when placing household appliances in an apartment, be guided by the following principles: place household electrical appliances as far as possible from rest areas, do not place household electrical appliances nearby and do not stack them on top of each other.

A microwave oven (or microwave oven) uses an electromagnetic field, also called microwave radiation or microwave radiation, to heat food. The operating frequency of microwave radiation of microwave ovens is 2.45 GHz. It is this radiation that many people are afraid of. However, modern microwave ovens are equipped with fairly advanced protection that prevents the electromagnetic field from escaping beyond the working volume. At the same time, it cannot be said that the field does not penetrate at all outside the microwave oven. For various reasons, part of the electromagnetic field intended for the chicken penetrates outward, especially intensely, usually in the area of ​​the lower right corner of the door. To ensure safety when using ovens at home, Russia has sanitary standards that limit the maximum leakage of microwave radiation from a microwave oven. They are called “Maximum permissible levels of energy flux density created by microwave ovens” and have the designation SN No. 2666-83. According to these sanitary standards, the energy flux density of the electromagnetic field should not exceed 10 μW/cm2 at a distance of 50 cm from any point of the stove body when heating 1 liter of water. In practice, almost all new modern microwave ovens meet this requirement with a large margin. However, when purchasing a new stove, you need to make sure that the certificate of conformity states that your stove meets the requirements of these sanitary standards.

It must be remembered that over time the degree of protection may decrease, mainly due to the appearance of microcracks in the door seal. This can happen both due to dirt and mechanical damage. Therefore, the door and its seal require careful handling and careful maintenance. The guaranteed durability of protection against electromagnetic field leaks during normal operation is several years. After 5-6 years of operation, it is advisable to check the quality of protection and invite a specialist from a specially accredited laboratory for monitoring electromagnetic fields.

In addition to microwave radiation, the operation of a microwave oven is accompanied by an intense magnetic field created by an industrial frequency current of 50 Hz flowing in the oven's power supply system. At the same time, a microwave oven is one of the most powerful sources of a magnetic field in an apartment. For the population, the level of the industrial frequency magnetic field in our country is still not limited, despite its significant effect on the human body during prolonged exposure. In domestic conditions, a single short-term switching on (for a few minutes) will not have a significant impact on human health. However, now a household microwave oven is often used to heat food in cafes and in similar other industrial settings. In this case, a person working with it finds himself in a situation of chronic exposure to a magnetic field of industrial frequency. In this case, mandatory control of the industrial frequency magnetic field and microwave radiation is necessary at the workplace.

Considering the specifics of the microwave oven, it is advisable to move away from a distance of at least 1.5 meters after turning it on - in this case, the electromagnetic field is guaranteed not to affect you at all.

3. Cellular

Cellular radiotelephony is one of the most rapidly developing telecommunication systems today. Currently, around the world there are more than 85 million subscribers using the services of this type of mobile (mobile) communications (in Russia - more than 600 thousand). It is expected that by 2001 their number will increase to 200–210 million (in Russia - about 1 million).

The main elements of a cellular communication system are base stations (BS) and mobile radiotelephones (MRT). Base stations maintain radio communication with mobile radiotelephones, as a result of which BS and MRI are sources of electromagnetic radiation in the UHF range. An important feature A cellular radio communication system is a very efficient use of the radio frequency spectrum allocated for the operation of the system (repeated use of the same frequencies, use of different access methods), which makes it possible to provide telephone communications to a significant number of subscribers. The system uses the principle of dividing a certain territory into zones, or “cells,” with a radius of usually 0.5–10 kilometers.

Base stations (BS)

Base stations maintain communication with mobile radiotelephones located in their coverage area and operate in signal reception and transmission modes. Depending on the standard, BS emit electromagnetic energy in the frequency range from 463 to 1880 MHz. BS antennas are installed at a height of 15–100 meters from the surface of the earth on existing buildings (public, service, industrial and residential buildings, chimneys of industrial enterprises, etc.) or on specially constructed masts. Among the BS antennas installed in one place, there are both transmitting (or transceiver) and receiving antennas, which are not sources of EMF.

Based on the technological requirements for building a cellular communication system, the antenna radiation pattern in the vertical plane is designed in such a way that the main radiation energy (more than 90%) is concentrated in a rather narrow “beam”. It is always directed away from the structures on which the BS antennas are located, and above adjacent buildings, which is a necessary condition for the normal functioning of the system.

Brief technical characteristics of cellular radio communication system standards operating in Russia

Name of the standard Operating frequency range of BS Operating frequency range of MRI Maximum radiated power of BS Maximum radiated power of MRI Cell radius

NMT-450 Analog 463 – 467.5 MHz 453 – 457.5 MHz 100 W 1 W 1 – 40 km

AMPS Analog 869 – 894 MHz 824 – 849 MHz 100 W 0.6 W 2 – 20 km

D-AMPS (IS-136) Digital 869 – 894 MHz 824 – 849 MHz 50 W 0.2 W 0.5 – 20 km

CDMADigital 869 – 894 MHz 824 – 849 MHz 100 W 0.6 W 2 – 40 km

GSM-900Digital 925 – 965 MHz 890 – 915 MHz 40 W 0.25 W 0.5 – 35 km

GSM-1800 (DCS) Digital 1805 – 1880 MHz 1710 – 1785 MHz 20 W 0.125 W 0.5 – 35 km

BS are a type of transmitting radio engineering objects, the radiation power of which (load) is not constant 24 hours a day. The load is determined by the presence of cell phone owners in the service area of ​​a particular base station and their desire to use the phone for a conversation, which, in turn, fundamentally depends on the time of day, location of the BS, day of the week, etc. At night, the load of the BS is almost zero , i.e. the stations are mostly “silent”.

Studies of the electromagnetic situation in the territory adjacent to the BS were carried out by specialists from different countries, including Sweden, Hungary and Russia. Based on the results of measurements carried out in Moscow and the Moscow region, it can be stated that in 100% of cases the electromagnetic environment in the premises of buildings on which BS antennas are installed did not differ from the background characteristic of a given area in a given frequency range. In the adjacent territory, in 91% of cases, the recorded levels of the electromagnetic field were 50 times less than the maximum limit established for the BS. The maximum measurement value, 10 times less than the maximum limit, was recorded near a building on which three base stations of different standards were installed at once.

Available scientific data and the existing system of sanitary and hygienic control during the commissioning of cellular base stations make it possible to classify cellular base stations as the most environmentally and sanitary and hygienically safe communication systems.

4. Personal computers

The main source of adverse effects on the health of a computer user is the means of visual display of information on a cathode ray tube. The main factors of its adverse effects are listed below.

Ergonomic parameters of the monitor screen:

• reduced image contrast in conditions of intense external illumination
• specular reflections from the front surface of monitor screens
• flickering of the image on the monitor screen

Emissive characteristics of the monitor:

• electromagnetic field of the monitor in the frequency range 20 Hz-1000 MHz
• static electric charge on the monitor screen
• ultraviolet radiation in the range 200-400 nm
• infrared radiation in the range 1050 nm - 1 mm
• X-ray radiation > 1.2 keV

Computer as a source of alternating electromagnetic field

The main components of a personal computer (PC) are: a system unit (processor) and various input/output devices: keyboard, disk drives, printer, scanner, etc. Each personal computer includes a means of visual display of information called differently - monitor, display. As a rule, it is based on a device based on a cathode ray tube. PCs are often equipped with surge protectors (for example, “Pilot” type), uninterruptible power supplies and other auxiliary electrical equipment. All these elements during PC operation form a complex electromagnetic environment at the user’s workplace.

PC as a source of EMF

Source Frequency range (first harmonic):

Monitor network transformer power supply 50 Hz

static voltage converter in a switching power supply 20 – 100 kHz

frame scanning and synchronization unit 48 – 160 Hz

line scanning and synchronization unit 15 110 kHz

monitor anode accelerating voltage (only for CRT monitors) 0 Hz (electrostatic)

System unit (processor) 50 Hz – 1000 MHz

Information input/output devices 0 Hz, 50 Hz

Uninterruptible power supplies 50 Hz, 20 – 100 kHz

The electromagnetic field created by a personal computer has a complex spectral composition in the frequency range from 0 Hz to 1000 MHz. The electromagnetic field has electric (E) and magnetic (H) components, and their relationship is quite complex, so E and H are assessed separately.

Maximum EMF values ​​recorded at the workplace:

Field type, frequency range, field strength unit Field strength value along the screen axis around the monitor

Electric field, 100 kHz - 300 MHz, V/m 17.0 24.0

Electric field, 0.02-2 kHz, V/m 150.0 155.0

Electric field, 2-400 kHz V/m 14.0 16.0

Magnetic field, 100 kHz - 300 MHz, mA/m nhp nhp

Magnetic field, 0.02-2 kHz, mA/m 550.0 600.0

Magnetic field, 2-400 kHz, mA/m 35.0 35.0

Electrostatic field, kV/m 22.0 –

Range of values ​​of electromagnetic fields measured at the workplaces of PC users:

Name of measured parameters Frequency range 5 Hz – 2 kHz Frequency range 2 – 400 kHz

Alternating electric field strength, (V/m) 1.0 – 35.0 0.1 – 1.1

Alternating magnetic field induction, (nT) 6.0 – 770.0 1.0 – 32.0

Computer as a source of electrostatic field

When the monitor is operating, an electrostatic charge accumulates on the kinescope screen, creating an electrostatic field (ESF). In different studies, with different conditions measurements of ESTP values ​​ranged from 8 to 75 kV/m. At the same time, people working with the monitor acquire electrostatic potential. The spread of electrostatic potentials of users ranges from -3 to +5 kV. When ESTP is experienced subjectively, the user's potential is the deciding factor in the occurrence of unpleasant subjective sensations. A noticeable contribution to the total electrostatic field is made by the surfaces of the keyboard and mouse, which are electrified by friction. Experiments show that even after working with the keyboard, the electrostatic field quickly increases from 2 to 12 kV/m. At individual workplaces in the area of ​​the hands, static electric field strengths of more than 20 kV/m were recorded.

According to generalized data, in those working at a monitor from 2 to 6 hours a day, functional disorders of the central nervous system occur on average 4.6 times more often than in control groups, diseases of the cardiovascular system - 2 times more often, diseases of the upper respiratory tract – 1.9 times more often, diseases of the musculoskeletal system – 3.1 times more often. As the time spent on a computer increases, the ratio of healthy to sick users increases sharply.

Studies of the functional state of a computer user, conducted in 1996 at the Center for Electromagnetic Safety, showed that even with short-term work (45 minutes), significant changes in the hormonal state and specific changes in the biocurrents of the brain occur in the user’s body under the influence of electromagnetic radiation from the monitor. These effects are especially pronounced and persistent in women. It was noticed that in groups of people (in this case it was 20%), a negative reaction of the functional state of the body does not manifest itself when working with a PC for less than 1 hour. Based on the analysis of the results obtained, it was concluded that it is possible to form special professional selection criteria for personnel using a computer in the process of work.

Influence of air ion composition. The areas that perceive air ions in the human body are the respiratory tract and skin. There is no consensus regarding the mechanism of influence of air ions on human health.

Effect on vision. The visual fatigue of the VDT user includes a whole complex of symptoms: the appearance of a “veil” before the eyes, the eyes become tired, become painful, headaches appear, sleep is disturbed, and the psychophysical state of the body changes. It should be noted that vision complaints can be associated both with the above-mentioned VDT factors and with lighting conditions, the operator’s state of vision, etc. Long-term statistical load syndrome (LTSS). Display users develop muscle weakness and changes in the shape of the spine. In the USA, it is recognized that DSHF is the occupational disease with the highest rate of spread in 1990-1991. In a forced working position, with static muscle load, the muscles of the legs, shoulders, neck and arms remain in a state of contraction for a long time. Since the muscles do not relax, their blood supply deteriorates; Metabolism is disrupted, biodegradation products and, in particular, lactic acid accumulate. In 29 women with prolonged static load syndrome, a biopsy of muscle tissue was taken, in which a sharp deviation of biochemical parameters from the norm was discovered.

Stress. Display users are often under stress. According to the US National Institute for Occupational Safety and Health (1990), VDT users are more susceptible to developing stress conditions than other occupational groups, including air traffic controllers. At the same time, for most users, working on VDTs is accompanied by significant mental stress. It has been shown that sources of stress can be: type of activity, characteristic features of the computer, software used, work organization, social aspects. Working on a VDT has specific stress factors, such as the delay time of the computer’s response (reaction) when executing human commands, “learnability of control commands” (ease of memorization, similarity, ease of use, etc.), method of information visualization, etc. Being in a state of stress can lead to changes in a person's mood, increased aggressiveness, depression, and irritability. Cases of psychosomatic disorders, gastrointestinal dysfunction, sleep disturbances, changes in heart rate, and menstrual cycle have been recorded. A person's exposure to long-term stress factors can lead to the development of cardiovascular diseases.

Personal computer user complaints possible reasons their origin.

Subjective complaints Possible causes:

1) pain in the eyes, visual ergonomic parameters of the monitor, lighting in the workplace and indoors

2) headache aeroion composition of air in the work area, operating mode

3) increased nervousness, electromagnetic field, color scheme of the room, operating mode

4) increased fatigue electromagnetic field, operating mode

5) memory disorder electromagnetic field, operating mode

6) sleep disturbance operating mode, electromagnetic field

7) hair loss electrostatic fields, operating mode

8) acne and skin redness, electrostatic field, aeroionic and dust composition of air in the work area

9) abdominal pain due to improper seating caused by improper workplace design

10) lower back pain due to improper seating of the user caused by the design of the workplace, operating mode

11) pain in the wrists and fingers; incorrect configuration of the workplace, including the height of the table does not correspond to the height and height of the chair; uncomfortable keyboard; working mode

The main types of protective equipment offered are protective filters for monitor screens. They are used to limit the user's exposure to harmful factors from the monitor screen, improve the ergonomic parameters of the monitor screen and reduce the monitor radiation towards the user.

5. How does EMF affect health?

In the USSR, extensive research into electromagnetic fields began in the 60s. A large amount of clinical material has been accumulated on the adverse effects of magnetic and electromagnetic fields, and it was proposed to introduce a new nosological disease “Radio wave disease” or “Chronic microwave damage.” Subsequently, the work of scientists in Russia established that, firstly, the human nervous system, especially higher nervous activity, is sensitive to EMF, and, secondly, that EMF has the so-called. informational effect when exposed to a person at intensities below the threshold value of the thermal effect. The results of these works were used in the development regulatory documents in Russia. As a result, the standards in Russia were set very stringent and differed from American and European ones by several thousand times (for example, in Russia the MPL for professionals is 0.01 mW/cm2; in the USA - 10 mW/cm2).

Biological effects of electromagnetic fields

Experimental data from both domestic and foreign researchers indicate high biological activity of EMF in all frequency ranges. At relatively high levels of irradiating EMF, modern theory recognizes a thermal mechanism of action. At a relatively low level of EMF (for example, for radio frequencies above 300 MHz it is less than 1 mW/cm2), it is customary to talk about the non-thermal or informational nature of the impact on the body. The mechanisms of action of EMF in this case are still poorly understood. Numerous studies in the field of biological effects of EMF will allow us to determine the most sensitive systems of the human body: nervous, immune, endocrine and reproductive. These body systems are critical. The reactions of these systems must be taken into account when assessing the risk of EMF exposure to the population.

The biological effect of EMF under conditions of long-term exposure accumulates over many years, resulting in the development of long-term consequences, including degenerative processes of the central nervous system, blood cancer (leukemia), brain tumors, and hormonal diseases. EMFs can be especially dangerous for children, pregnant women (embryos), people with diseases of the central nervous, hormonal, and cardiovascular systems, allergy sufferers, and people with weakened immune systems.

Effect on the nervous system

A large number of studies carried out in Russia, and the monographic generalizations made, give grounds to classify the nervous system as one of the most sensitive systems in the human body to the effects of EMFs. At the level of the nerve cell, structural formations for the transmission of nerve impulses (synapse), at the level of isolated nerve structures, significant deviations occur when exposed to low-intensity EMF. Higher nervous activity and memory change in people who have contact with EMF. These individuals may be prone to developing stress reactions. Certain brain structures have increased sensitivity to EMF. Changes in the permeability of the blood-brain barrier can lead to unexpected adverse effects. The nervous system of the embryo exhibits particularly high sensitivity to EMF.

Impact on the immune system

At present, sufficient data has been accumulated indicating bad influence EMF on the immunological reactivity of the body. The results of research by Russian scientists give reason to believe that when exposed to EMF, the processes of immunogenesis are disrupted, more often in the direction of their inhibition. It has also been established that in animals irradiated with EMF, the nature of the infectious process changes - the course of the infectious process is aggravated. The occurrence of autoimmunity is associated not so much with a change in the antigenic structure of tissues, but with the pathology of the immune system, as a result of which it reacts against normal tissue antigens. In accordance with this concept. the basis of all autoimmune conditions is primarily immunodeficiency in the thymus-dependent cell population of lymphocytes. The influence of high-intensity EMF on the body’s immune system is manifested in a suppressive effect on the T-system of cellular immunity. EMFs can contribute to nonspecific inhibition of immunogenesis, increased formation of antibodies to fetal tissues and stimulation of an autoimmune reaction in the body of a pregnant female.

Influence at endocrine system and neurohumoral response

In the works of Russian scientists back in the 60s, in the interpretation of the mechanism of functional disorders under the influence of EMF, the leading place was given to changes in the pituitary-adrenal system. Studies have shown that under the influence of EMF, as a rule, stimulation of the pituitary-adrenaline system occurred, which was accompanied by an increase in the content of adrenaline in the blood and activation of blood coagulation processes. It was recognized that one of the systems that is early and naturally involved in the body's response to the influence of various environmental factors is the hypothalamic-pituitary-adrenal cortex system. The research results confirmed this position.

Effect on sexual function

Sexual dysfunction is usually associated with changes in its regulation by the nervous and neuroendocrine systems. Related to this are the results of work on studying the state of gonadotropic activity of the pituitary gland under the influence of EMF. Repeated exposure to EMF causes a decrease in the activity of the pituitary gland

Any environmental factor that affects the female body during pregnancy and affects embryonic development is considered teratogenic. Many scientists attribute EMF to this group of factors.

Of primary importance in teratogenesis studies is the stage of pregnancy during which EMF exposure occurs. It is generally accepted that EMFs can, for example, cause deformities by acting at different stages of pregnancy. Although there are periods of maximum sensitivity to EMF. The most vulnerable periods are usually the early stages of embryo development, corresponding to the periods of implantation and early organogenesis.

An opinion was expressed about the possibility of a specific effect of EMF on the sexual function of women and on the embryo. A higher sensitivity to the effects of EMF of the ovaries than the testes was noted. It has been established that the sensitivity of the embryo to EMF is much higher than the sensitivity of the maternal body, and intrauterine damage to the fetus by EMF can occur at any stage of its development. The results of epidemiological studies will allow us to conclude that the presence of contact of women with electromagnetic radiation can lead to premature birth, affect the development of the fetus and, finally, increase the risk of developing congenital deformities.

Other medical and biological effects

Since the beginning of the 60s, extensive research has been carried out in the USSR to study the health of people exposed to electromagnetic fields at work. The results of clinical studies have shown that prolonged contact with EMF in the microwave range can lead to the development of diseases, the clinical picture of which is determined primarily by changes in the functional state of the nervous and cardiovascular systems. It was proposed to identify an independent disease - radio wave disease. This disease, according to the authors, can have three syndromes as the severity of the disease increases:

1) asthenic syndrome;

2) astheno-vegetative syndrome;

3) hypothalamic syndrome.

The earliest clinical manifestations of the consequences of exposure to EM radiation on humans are functional disorders of the nervous system, manifested primarily in the form of autonomic dysfunctions, neurasthenic and asthenic syndrome. Persons who have been in the area of ​​EM radiation for a long time complain of weakness, irritability, fatigue, weakened memory, and sleep disturbances. Often these symptoms are accompanied by disorders of autonomic functions. Disorders of the cardiovascular system are manifested, as a rule, by neurocirculatory dystonia: lability of pulse and blood pressure, tendency to hypotension, pain in the heart, etc. There are also phase changes in the composition of peripheral blood (lability of indicators) with the subsequent development of moderate leukopenia, neuropenia , erythrocytopenia. Changes in the bone marrow are in the nature of a reactive compensatory stress of regeneration. Typically, these changes occur in people who, due to the nature of their work, were constantly exposed to EM radiation with a fairly high intensity. Those working with MF and EMF, as well as the population living in the area affected by EMF, complain of irritability and impatience. After 1-3 years, some people develop a feeling of internal tension and fussiness. Attention and memory are impaired. There are complaints about low sleep efficiency and fatigue. Considering the important role of the cerebral cortex and hypothalamus in the implementation of human mental functions, it can be expected that prolonged repeated exposure to maximum permissible EM radiation (especially in the decimeter wavelength range) can lead to mental disorders.

List of sources used

1. Bardov V.G. Hygiene and ecology; ed. "New book" 2007.
2. Lepaev D. A. Household electrical appliances; ed. "Light industry" 1993.

Abstract on the topic “Household electrical appliances and their impact on human health” updated: August 17, 2017 by: Scientific Articles.Ru