Connection diagrams for three-phase electric motors. Connecting a three-phase motor to a single-phase network How to connect a 3-phase motor
Before we consider the question of how to connect a three-phase electric meter with your own hands, let’s make a reservation that with three-phase meters the situation is more complicated than with single-phase ones, where the connection diagram is, in principle, unambiguous.
The connection diagram for a three-phase meter depends on its type. In any case, three-phase meters support single-phase measurement.
There are 4 types of three-phase meters
These are the devices:
- Direct connection (also called direct connection)
- Indirect inclusion
- Semi-indirect inclusion
- Reactive energy metering
Accordingly, their connection methods are different, let’s consider them in order.
Three-phase direct connection meter
Devices of this type are connected directly to the network, as they are designed for a relatively low throughput power, up to 60 kW (accordingly, a current of up to 100 A). It is simply not possible to connect a direct-connection electricity meter to a power exceeding that specified in the passport, since their input and output blocks are designed for a cross-section of connected wires of 16 or 25 mm.
The connection diagram for a direct connection meter, just like for single-phase meters, except for the passport, is indicated on the back of the cover.
Wires, from left to right:
- First - phase A input
- Third - phase B input
- Fifth - phase C input
- Seventh - zero input
As you can see, there is no difficulty here.
Semi-indirect counter
These are electricity metering devices that are focused on measuring power consumption exceeding 60 kW. Use is possible only in conjunction with a current transformer, and the connection is made according to four schemes.
The digitization of a metering device here differs from a direct (direct) switching device.
Connection diagram - wires, from left to right:
- phase A current winding input
- phase A voltage measurement winding input
- phase A current winding output
- phase B current winding input
- phase B voltage measurement winding input
- phase B current winding output
- phase C current winding input
- phase C voltage measurement winding input
- phase C current winding output
- neutral
- neutral
Let's consider the contacts of current transformers. There are four of them:
- L1 - power line input
- I1 - input of the meter measuring winding
- I2 - output of the meter measuring winding
Contacts L1 and L2 are always connected to the power network.
When using current transformers, the meter readings are multiplied by the transformation ratio. The inter-verification period of a current transformer is 4-5 years.
Connection diagrams for semi-indirect meters
There are several connection methods:
This circuit is good because the circuits for measuring current and voltage are not interconnected, which increases its electrical safety. However, it requires more wires than other circuits.
Subsequence:
- Contact 3 is connected to I2 of phase A
- Pin 6 is connected to I2 phase B
- Contact 9 is connected to I2 phase C
- Pin 10 is connected to the neutral wire
Allows you to save on installation of secondary wires.
Execution sequence:
- Contacts 3, 6, 9 and 10 are connected to each other and connected to the neutral wire
- All contacts I2 are closed to each other and to contact 11
- Contact 1 is connected to I1 of phase A
- Contact 4 is connected to I1 of phase B
- Contact 7 is connected to I1 phase C
- Contact 2 is connected to L1 phase A
- Contact 5 is connected to L1 phase B
- Contact 8 is connected to L1 phase C
Connecting a meter with combined current and voltage circuits
This circuit is outdated because it is electrically unsafe and is not used today.
Connecting the meter via the test terminal box
In fact, it repeats the ten-wire connection diagram, only in the gap between the electric meter and the other elements an adapter box is installed, which allows you to painlessly remove and install the metering device.
Indirect meters
Such meters are used to account for electricity consumption at voltages above 6 kV, so we will not consider them here.
Reactive energy meters
The connection method does not differ from active energy metering devices. Although there are still induction meters that take into account the reactive component separately, they are no longer installed at present.
In the following articles we will look at them, try to understand their advantages and disadvantages, and, if possible, identify the best brands of electric meters.
UZM-3-63 is a multifunctional device that provides control of 3-phase voltage in the network. It also has built-in varistor protection against surges and has the function of monitoring the frequency of the power supply from an autonomous generator.
The UZM-3-63 connection diagram is quite simple and its basic version can be found on the device body or in its passport. Here I provide a clear and more understandable connection diagram for a 3-phase voltage relay UZM-3-63 with circuit breakers, from which you can understand the essence of the connection.
All contacts of the device are marked on the housing. Therefore, without seeing the diagram itself, you can understand what is connected where. What is often confusing here is that the output phase contacts are marked U, V and W, which misleads many. How to connect this device?
Connects to the top contacts entrance:
- N - incoming zero working conductor;
- L1 - incoming conductor of phase A;
- L2 - incoming phase B conductor;
- L3 - incoming phase C conductor.
Connects to the bottom contacts exit:
- N - outgoing neutral working conductor;
- U - outgoing conductor of phase A;
- V - outgoing conductor of phase B;
- W - outgoing conductor of phase C.
Here is a photo of the UZM-3-63 device itself. The contacts of its polarized relay are designed for a long-term flow of a maximum current of 63A through them. If your load consumes more current, then this relay will no longer suit you or you will have to turn it on through a powerful contactor.
The options for completing the shields can be varied, but the essence of connecting the device always remains the same.
When using UZM-3-63, remember that when the load is disconnected, the neutral working conductor is not switched, i.e. doesn't break. Here only the phase conductors are broken.
The device settings are adjusted manually using three special switches. They set the high and low voltage limits and the restart delay time.
The relay light indication is intuitive. Next to all the indicators on the body there is their designation.
Someone, instead of a 3-phase UZM-3-63 relay, uses three single-phase UZM-51M. That is, one single-phase relay is installed on each phase. In principle, this option has the right to life, but it requires more space in the shield and costs almost twice as much.
Do you use a three-phase voltage relay UZM-3-63?
Let's smile:
As you know, the resistance of the human body is about 100 kOhm. Every 100 g of vodka taken internally reduces body resistance by 1 kOhm. How much vodka do you need to drink to achieve a state of superconductivity?
First of all, before choosing and purchasing, you need to decide what it is - a pass-through switch, what it is needed for, and how it differs from the usual one, two and three-key switches.
A single-key pass-through switch is necessary to control one circuit or lighting line from several points located in different parts of the room or the entire house. That is, with one switch you turn on the lighting when entering a room or corridor, and with another, but at a different point, you turn off the same lighting.
Very often this is used in bedrooms. I went into the bedroom and turned on the light near the door. I lay down on the bed and turned off the light at the headboard or near the bedside table.
In two-story mansions, he turned on the light bulb on the first floor, climbed the stairs to the second and turned it off there. 
Selection, design and differences of pass-through switches
Before assembling such a control scheme, here is what you should pay special attention to:
1 To connect a pass-through light switch you need three-wire cable - VVGng-Ls 3*1.5 or NYM 3*1.5mm2
2 Do not try to assemble a similar circuit using ordinary switches. The main difference between regular and pass-through ones is the number of contacts. Simple single-key ones have two terminals for connecting wires (input and output), while pass-through ones have three! 
In simple terms, the lighting circuit can be either closed or open, there is no third option.
It is more correct to call a pass-through not a switch, but a switch.
Since it switches the circuit from one working contact to another.
In appearance, from the front they can be absolutely identical. Only the pass key can have an icon of vertical triangles. However, do not confuse them with reversible or crossover ones (more about them below). These triangles point in a horizontal direction. 
But from the reverse side you can immediately see the difference:
- the pass-through has 1 terminal on top and 2 on the bottom
- a regular one has 1 on top and 1 on the bottom
Due to this parameter, many people confuse them with two-key ones. However, two-key ones are also not suitable here, although they also have three terminals. 
The significant difference is in the operation of the contacts. When one contact is closed, pass-through switches automatically close the other, but two-key switches do not have such a function. 
Moreover, there is no intermediate position when both circuits are open at the gateway.
Connecting a pass-through switch
First of all, you need to correctly connect the switch itself in the socket box. Remove the key and the overhead frames. 
When disassembled, you can easily see the three contact terminals. 
The most important thing is to find the common one. On high-quality products, a diagram should be drawn on the reverse side. If you understand them, you can easily navigate through it. 
If you have a budget model, or any electrical circuits are a bit of a mystery to you, then an ordinary Chinese tester in circuit continuity mode, or an indicator screwdriver with a battery, will come to the rescue.
Using the tester's probes, alternately touch all the contacts and look for the one on which the tester will “squeak” or show “0” at any position of the ON or OFF key. It's even easier to do this with an indicator screwdriver. 
After you have found the common terminal, you need to connect the phase from the power cable to it. Connect the remaining two wires to the remaining terminals.
Moreover, which one goes where does not make a significant difference. The switch is assembled and secured in the socket box. 
Do the same operation with the second switch:
- look for the common terminal
- connect the phase conductor to it, which will go to the light bulb
- connect two other wires to the remaining ones
Connection diagram for the pass-through switch wires in the distribution box
Scheme without grounding conductor
Now the most important thing is to correctly assemble the circuit in the junction box. Four 3-core cables should go into it:
- power cable from lighting circuit breaker
- cable to switch No. 1
- cable to switch No. 2
- cable for lamp or chandelier
When connecting wires, it is most convenient to orient them by color. If you use a three-core VVG cable, then it has two most common color markings:
- white (gray) - phase
- blue - zero
- yellow green - earth
or second option:
- White gray)
- brown
- black
To choose a more correct phasing in the second case, follow the tips from the article "" 
Connect the neutral conductor from the cable of the input machine and the neutral going to the lamp at one point using the terminals of the car. 
Similar to the neutral wires, you combine the “ground” from the input cable with the “ground” of the outgoing cable for lighting. 
This wire is connected to the lamp body. 
The phase from the input cable must be connected to the phase of the outgoing wire to the common terminal of the pass-through switch No. 1. 
And connect the common wire from pass-through switch No. 2 with a separate wago clamp to the phase conductor of the lighting cable. 
Having completed all these connections, all that remains is to connect the secondary (outgoing) conductors from switch No. 1 and No. 2 to each other. And it doesn’t matter at all how you connect them. 
You can even mix up the colors. But it’s better to stick to the colors so as not to get confused in the future.
The basic connection rules in this diagram that you need to remember:
- the phase from the machine must go to the common conductor of the first switch
- and the same phase should go from the common conductor of the second switch to the light bulb
- the remaining two auxiliary conductors are connected to each other in the junction box
- zero and ground are supplied directly to the light bulbs without switches
Changeover switches - lighting control circuit from 3 places
But what if you want to control one lighting from three or more points. That is, there will be 3, 4, etc. switches in the circuit. It would seem that you need to take another pass-through switch and that’s it.
However, a switch with three terminals will no longer work here. Since there will be four connected wires in the junction box.
Here a changeover switch, or as it is also called a cross, cross, or intermediate switch, will come to your aid. Its key difference is that it has four outlets - two at the bottom and two at the top. 
And it is installed precisely in the gap between two passageways. Find in the junction box two secondary (not main) wires from the first and second pass-through switch.
You disconnect them and connect a changeover between them. Connect the wires that come from the first to the input (follow the arrows), and those that go to the second to the output terminals. 
Always check the diagram on the switches! It often happens that their entrance and exit are on the same side (top and bottom). For example, the connection diagram for a Legrand Valena changeover switch: 
Naturally, there is no need to stuff the changeover itself into the junction box. It is enough to lead the ends of a 4-core cable from it there. Meanwhile, you place the switch itself in any convenient place - near the bed, in the middle of a long corridor, etc. You can turn the light on and off from anywhere. 
The most important advantage of this circuit is that it can be changed indefinitely and add as many changeover switches as you like. That is, there will always be two passing ones (at the beginning and the end), and in the interval between them there will be 4, 5 or at least 10 crossover ones. 
Connection errors
Many people make a mistake at the stage of searching and connecting the common terminal in the pass-through switch. Without checking the circuit, they naively believe that the common terminal is the one with only one contact.
They assemble a circuit in this way, and then for some reason the switches do not work correctly (they depend on each other).
Remember that on different switches the common contact can be anywhere!
And it is best to call it, what is called “live”, with a tester or an indicator screwdriver. 
Most often, this problem is encountered when installing or replacing pass-through switches from different companies. If everything worked before, but after replacing one circuit the circuit stopped working, it means the wires were mixed up.
But there may also be an option that the new switch is not pass-through at all. Also remember that the lighting inside the product cannot in any way affect the switching principle itself.
Another common mistake is incorrectly connecting crossovers. When both wires are placed from pass-through No. 1 to the upper contacts, and from No. 2 to the lower ones. Meanwhile, the cross switch has a completely different circuit and switching mechanism. And you need to connect the wires crosswise. 
Flaws
1 The first of the disadvantages of pass-through switches is the lack of a specific ON/OFF key position, which is found in conventional ones.
If your light bulb burns out and needs to be replaced, with such a scheme it is not immediately possible to understand whether the light is on or off.
It will be unpleasant when, when replacing, the lamp may simply explode in front of your eyes. In this case, the easiest and most reliable way is to turn off the automatic lighting in the panel.
2 The second drawback is the large number of connections in junction boxes.
And the more light points you have, the greater the number of them will be in the distribution boxes. Connecting the cable directly according to diagrams without junction boxes reduces the number of connections, but can significantly increase either the cable consumption or the number of its cores.
If your wiring goes under the ceiling, you will have to lower the wire from there to each switch, and then lift it back up. The best option here is to use pulse relays.
Not every average person understands what electrical circuits are. In apartments they are 99% single-phase, where the current flows to the consumer through one wire and returns through the other (zero). A three-phase network is a system for transmitting electric current that flows through three wires and returns one at a time. Here the return wire is not overloaded due to the phase shift of the current. Electricity is generated by a generator driven by an external drive.
An increase in the load in the circuit leads to an increase in the current passing through the generator windings. As a result, the magnetic field resists rotation of the drive shaft to a greater extent. The number of revolutions begins to decrease and commands an increase in drive power, for example by supplying more fuel to the internal combustion engine. The speed is restored and more electricity is generated.
A three-phase system consists of 3 circuits with an EMF of the same frequency and a phase shift of 120°.
Features of connecting power to a private home
Many people believe that a three-phase network in the house increases power consumption. In fact, the limit is set by the electricity supply organization and is determined by the following factors:
- supplier capabilities;
- number of consumers;
- condition of the line and equipment.
To prevent voltage surges and phase imbalance, they should be loaded evenly. The calculation of a three-phase system is approximate, since it is impossible to accurately determine which devices will be connected at a given moment. The presence of pulsed devices currently leads to increased energy consumption during their startup.
The electrical distribution panel for a three-phase connection is larger in size than for a single-phase supply. Options are possible with the installation of a small input panel, and the rest made of plastic for each phase and for outbuildings.
Connection to the main line is carried out using underground and overhead lines. Preference is given to the latter due to the small amount of work, low connection cost and ease of repair.
Nowadays it is convenient to make an air connection using a self-supporting insulated wire (SIP). The minimum cross-section of the aluminum core is 16 mm 2, which is sufficient for a private home.
The SIP is attached to the supports and the wall of the house using anchor brackets with clamps. The connection to the main overhead line and the input cable to the electrical panel of the house is made with branch piercing clamps. The cable is taken with non-combustible insulation (VVGng) and passed through a metal pipe inserted into the wall.
Air connection of three-phase power supply at home
At a distance from the nearest support, it is more necessary to install another pole. This is necessary to reduce loads that lead to sagging or broken wires.
The height of the connection point is 2.75 m and above.
Electrical distribution cabinet
Connection to a three-phase network is made according to the project, where inside the house consumers are divided into groups:
- lighting;
- sockets;
- separate powerful devices.
Some loads can be disconnected for repairs while others are running.
The power of consumers is calculated for each group, where the wire of the required cross-section is selected: 1.5 mm 2 - for lighting, 2.5 mm 2 - for sockets and up to 4 mm 2 - for powerful devices.
The wiring is protected from short circuits and overloads by circuit breakers.
Electric meter
For any connection scheme, a metering device is required. A 3-phase meter can be connected directly to the network (direct connection) or through a voltage transformer (semi-indirect), where the meter readings are multiplied by a coefficient.
It is important to follow the connection order, where odd numbers are power and even numbers are load. The color of the wires is indicated in the description, and the diagram is located on the back cover of the device. The input and corresponding output of a 3-phase meter are indicated by the same color. The most common connection order is when the phases come first and the last wire is zero.
A 3-phase direct connection meter for a home is usually designed for a power of up to 60 kW.
Before choosing a multi-tariff model, you should coordinate the issue with the energy supply company. Modern devices with tarifficators make it possible to calculate electricity charges depending on the time of day, register and record power values over time.
The temperature readings of the devices are selected as widely as possible. On average they range from -20 to +50 °C. The service life of the devices reaches 40 years with a calibration interval of 5-10 years.
The meter is connected after the input three- or four-pole circuit breaker.
Three-phase load
Consumers include electric boilers, asynchronous electric motors and other electrical appliances. The advantage of using them is the uniform distribution of the load in each phase. If a three-phase network contains unevenly connected single-phase powerful loads, this can lead to phase imbalance. At the same time, electronic devices begin to malfunction, and lighting lamps glow dimly.
Connection diagram of a three-phase motor to a three-phase network
The operation of three-phase electric motors is characterized by high performance and efficiency. No additional starting devices are required here. For normal operation, it is important to connect the device correctly and follow all recommendations.
The connection diagram of a three-phase motor to a three-phase network creates a rotating magnetic field with three windings connected in a star or delta.
Each method has its own advantages and disadvantages. The star circuit allows the engine to start smoothly, but its power is reduced by up to 30%. This loss is absent in the delta circuit, but the current load is significantly greater at start-up.
The motors have a connection box where the winding terminals are located. If there are three of them, then the circuit is connected only by a star. With six terminals, the motor can be connected in any way.
Power consumption
It is important for the home owner to know how much energy is consumed. This is easy to calculate for all electrical appliances. Adding up all the powers and dividing the result by 1000, we get the total consumption, for example 10 kW. For household electrical appliances, one phase is sufficient. However, current consumption increases significantly in a private home where there is powerful equipment. One device can have 4-5 kW.
It is important to plan the power consumption of a three-phase network at the design stage in order to ensure symmetry in voltages and currents.
A four-wire wire with three phases and a neutral enters the house. The voltage of the electrical network is Between the phases and the neutral wire, electrical appliances are connected to In addition, there may be a three-phase load.
The power calculation of a three-phase network is carried out in parts. First, it is advisable to calculate purely three-phase loads, for example a 15 kW electric boiler and a 3 kW asynchronous electric motor. The total power will be P = 15 + 3 = 18 kW. In this case, current I = Px1000/(√3xUxcosϕ) flows in the phase wire. For household electrical networks cosϕ = 0.95. Substituting numerical values into the formula, we obtain the current value I = 28.79 A.
Now you need to define single-phase loads. Let them be P A = 1.9 kW, P B = 1.8 kW, P C = 2.2 kW for the phases. The mixed load is determined by summation and is 23.9 kW. The maximum current will be I = 10.53 A (phase C). Adding it to the current from the three-phase load, we get I C = 39.32 A. The currents in the remaining phases will be I B = 37.4 kW, I A = 37.88 A.
When calculating the power of a three-phase network, it is convenient to use power tables taking into account the type of connection.
Using them it is convenient to select circuit breakers and determine wiring cross-sections.
Conclusion
With proper design and maintenance, a three-phase network is ideal for a private home. It allows you to evenly distribute the load across phases and connect additional power from electrical consumers, if the wiring cross-section allows.
There are several types of electric motors - three-phase and single-phase. The main difference between three-phase electric motors and single-phase ones is that they are more efficient. If you have a 380 V outlet at home, then it is best to buy equipment with a three-phase electric motor.
Using this type of engine will allow you to save on electricity and gain more power. Also, you do not have to use various devices to start the engine, since thanks to a voltage of 380 V, a rotating magnetic field appears immediately after connecting to the mains.
380 volt electric motor wiring diagrams
If you do not have a 380 V network, then you can still connect a three-phase electric motor to a standard 220 V electrical network. To do this, you will need capacitors, which must be connected according to this diagram. But when connected to a regular power grid, you will observe a loss of power. You might want to read about this.380 V electric motors are designed in such a way that they have three windings in the stator, which are connected like a triangle or star, and three different phases are connected to their tops.
You need to remember that using a star connection, your electric motor will not work at full power, but it will start smoothly. When using a triangle circuit, you will receive a one and a half times increase in power compared to a star, but with such a connection the chance of damaging the winding during startup increases.
Before using an electric motor, you must first become familiar with its characteristics. All necessary information can be found in the data sheet and on the engine nameplate. Particular attention should be paid to three-phase motors of Western European type, as they are designed to operate at a voltage of 400 or 690 volts. In order to connect such an electric motor to domestic networks, it is necessary to use only a triangle connection.
If you want to make a triangle circuit, then you need to connect the windings in series. You need to connect the end of one winding to the beginning of the next and then you need to connect three phases of the electrical network to the three connection points.
Connecting a star-delta circuit.
Thanks to this circuit, we can get maximum power, but we will not have the opportunity to change the direction of rotation. In order for the circuit to work, three starters will be needed. The first (K1) is connected to power on one side, and the ends of the windings are connected to the other. Their origins are connected to K2 and K3. From the K2 starter, the windings are connected to other phases using a triangle connection. When K3 turns on, all three phases are short-circuited and, as a result, the electric motor operates in a star circuit.
It is important that K2 and K3 are not started at the same time, as this can lead to an emergency shutdown. This scheme works as follows. When K1 starts, the relay temporarily turns on K3 and the engine starts as a star. After starting the engine, K3 is turned off and K2 is started. And the electric motor starts working in a triangle pattern. Stopping work occurs by turning off K1.
