cable in rubber insulation flexible in a rubber or plastic sheath is used to connect moving parts to the mains.

Flexible rubber insulated cables

Cables of this segment have a copper stranded core, for the production of insulation ethylene-propylene rubber is used in combination with butyl rubber - these materials have increased strength. The product is distinguished by special performance characteristics. It has:

• oil resistance;
• frost resistance;
• counteracting the spread of combustion;
• ozone immunity.

A flexible rubber-insulated cable may be used when connecting network elements with moving elements. The cable product withstands alternating voltage at the level of 660 V at a frequency of up to 400 Hz, and is also capable of carrying a constant voltage within 1000 V. It can be used in conjunction with welding equipment, construction equipment, ventilation or climate systems. Production is carried out in three types of execution:

• cold-resistant;
• tropical;

Copper cables with rubber insulation

The copper cable in rubber insulation has a twisted copper conductor, which can be tinned. The product of the type is wrapped with a layer of PET-E film. Rubber insulation belongs to the RTI-1 type and is made using butadiene, and, in some cases, natural rubber. Multi-core cables have a digital or color coding, and polyester threads are used as the core. Such a copper cable in rubber insulation is allowed to be twisted without using a core. The sheath is made of rubber resistant to oil, it does not spread combustion, since chloroprene is used as a base.

The cable is operated in land and water conditions, as well as in rooms with natural ventilation. It is important that there is no exposure to ultraviolet radiation and precipitation. It can be used in rooms with a high level of humidity, where there is frequent condensation.

Marine, rubber-insulated wires

There is a ship-type rubber-insulated cable, the cores of which can be shielded, as well as armored with galvanized steel wire braid. It is used in telephone and control circuits, can be used to connect to movable current collectors indoors and outdoors, but subject to UV protection.

Structurally, the wire consists of copper wire conductive twisted strands. The steel braid of the product must be primed. It is allowed to bend the wire up to 5 outer radii, it can withstand 100% humidity.

Advantages and disadvantages of rubber insulated cables

Rubber insulated cable have advantages and disadvantages, the positive point is the increased elasticity achieved due to the rubber insulating layer. Wires are resistant to moisture and aggressive environments:

• oil;
• alkalis;
• acid.

The rubber insulated cable is able to withstand high temperatures in the event of short circuits. At the same time, it cannot tolerate direct sunlight, due to the rounded shapes that conduct the current, an excess outer diameter is formed, in comparison with products with a sector shape.

Cable KG power flexible copper, multi-wire with rubber insulation is designed for connecting mobile mechanisms to electrical networks at an alternating voltage of 660 V with a frequency of up to 400 Hz or a constant voltage of 1000 V.

Design:

Conductor - copper, multiwire, round shape, class 5 according to GOST 22483.
The separating layer is a synthetic film; it is allowed to apply insulation without a film in the absence of rubber sticking.
Insulation - insulating rubber.
The isolated veins have a distinctive coloring solid or in the form of a longitudinal strip.
The insulation of the zero core is blue; if there is no neutral conductor, the blue color is used for the color of any conductor except for the grounding one.
The ground conductor is green-yellow or marked with the number 0.
The color of single-core and two-core cables is not standardized.
The colors red, grey, white and, if not combined, green and yellow are not used for core colors in multicore cables.
Twisting - insulated cores are twisted with a twisting pitch of no more than 16 twist diameters.
Separating layer - over twisted strands - synthetic film or talc or other similar material.
Sheath - from rubber hose.
In single-core, it is allowed to replace the insulation and sheath with an insulating-protective sheath.
The nominal thickness of the insulating-protective sheath is equal to the sum of the nominal thicknesses of the insulation and sheath, or twice the thickness of the insulation.

Application:

In various mobile electrical installations such as gantry crane, excavator or welding machine.
It is possible to operate in closed and open structures, in areas with a temperate climate.
Since the rubber insulation is resistant to sunlight, the cable can be used outdoors.

Specifications:

Temperature regime of cable operation: from -40° to +50° degrees Celsius.
The maximum allowable tensile load on the cable during operation: no more than 24.5 N (2.5 kgf).
Minimum allowable bending radius: - 8 external cable diameters.
Test alternating voltage of rated frequency 50 Hz (test time 5 min.): 15 kV - for the main current-carrying conductors, 2 kV - for the additional conductor.
Warranty period: 6 months from the date of commissioning, but no later than 12 months from the date of manufacture.
Service life (from date of manufacture): 4 years

cable type	Outer diameter, mm	Specific gravity kg/km
KG 1x4	8,0	110
KG 1x6	9,0	150
KG 1x10	11,1	230
KG 1x16	12,4	310
KG 1x25	14,6	450
KG 1x35	16,4	590
KG 1x50	19,0	820
KG 1x70	21,5	1090
KG 1x95	24,3	1400
KG 1x120	27,7	1730
KG 1x150	30,1	2070
KG 1x185	32,7	2490
KG 1x240	36,8	3190
KG 1x300	40,1	3910
KG 1x400	43,4	4980
KG 2x0.75	8,2	90
CG 2x1.0	8,5	100
KG 2x1.5	9,4	130
CG 2x2.5	11,2	190
KG 2x4	13,5	280
KG 2x6	15,5	380
KG 2x10	21,1	680
KG 2x16	23,7	920
KG 2x25	28,4	1340
KG 2x35	31,2	1680
KG 2x50	38,0	2450
KG 2x70	42,2	3170
KG 2x95	47,4	4040
KG 2x120	50,7	4800
KG 2x150	57,5	6050
KG 3x0.75	8,9	110
KG 3x1.0	9,1	120
CG 3x1.5	10,1	160
CG 3x2.5	12,0	230
KG 3x4	14,5	350
KG 3x6	16,6	460
KG 3x10	22,3	840
KG 3x16	25,4	1130
KG 3x25	30,4	1660
KG 3x35	34,0	2150
KG 3x50	39,5	2970
KG 3x70	44,7	3930
KG 3x95	50,9	5100
KG 3x120	54,4	6150
KG 3x150	63,0	7870
CG 4x1.0	10,1	150
KG 4x1.5	11,1	200
KG 4x2.5	13,3	290
KG 4x4	16,0	420
KG 4x6	18,5	590
KG 4x10	24,4	1000
KG 4x16	27,8	1400
KG 4x25	33,7	2100
KG 4x35	37,7	2730
KG 4x50	43,8	3700
KG 4x70	49,7	5000
KG 4x95	56,6	6500
KG 4x120	62,0	8120
KG 4x150	69,2	9880
KG 5x1.0	11,1	190
KG 5x1.5	12,2	240
KG 5x2.5	14,6	350
KG 5x4	17,8	530
KG 5x6	20,2	720
KG 5x10	26,8	1250
KG 5x16	30,9	1700
KG 5x25	37,4	2600
KG 5x35	44,5	3440
KG 5x50	50,1	4580
KG 5x70	54,9	5920
KG 5x95	63,3	7820
KG 5x120	67,0	9360
CG 2x0.75+1x0.75	8,9	110
CG 2x1+1x1	9,1	100
CG 2x1.5+1x1.5	10,1	160
CG 2x2.5+1x1.5	11,8	220
CG 2x4+1x2.5	13,9	310
KG 2x6+1x4	16,3	440
KG 2x10+1x6	21,0	740
KG 2x16+1x6	25,0	1070
KG 2x25+1x10	30,0	1550
KG 2x35+1x10	32,4	1890
KG 2x50+1x16	37,9	2600
CG 2x70+1x25	42,7	3400
KG 2х95+1х35	48,6	4500
KG 2x120+1x35	54,4	5880
KG 2x150+1x50	58,1	6590
CG 3x2.5+1x1.5	13,2	280
CG 3x4+1x2.5	15,5	400
KG 3x6+1x4	18,0	560
KG 3x10+1x6	23,5	950
KG 3x16+1x6	27,6	1300
KG 3x25+1x10	33,1	1950
KG 3x35+1x10	36,5	2400
KG 3x50+1x16	42,4	3400
KG 3x70+1x25	47,7	4500
KG 3x95+1x35	54,5	5890
KG 3x120+1x35	60,9	7280
KG 3x150+1x50	64,9	8630

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KG - Flexible power cables with copper stranded conductors with rubber insulation in a rubber sheath.

KG - Flexible power cables with copper stranded conductors with rubber insulation in a rubber sheath.

Power flexible cables with copper conductors (KG) - features, design, application, characteristics

KG cable is designed for connecting mobile machines and mechanisms to networks with alternating voltage up to 660 V and frequency up to 400 Hz or with direct voltage up to 1000 V.

The current-carrying core of the KG cable is round, copper, necessarily multi-wire, class 5 of flexibility.

The separating layer is a synthetic film. In the absence of rubber adhesion, it is allowed to apply insulation without a film.

The insulation is made of insulating rubber. The color of the insulation lived solid. It is allowed to use a distinctive color in the form of a longitudinal strip. The insulation of the grounding conductor is only yellow-green or marked with the number 0. The flexible cable (KG) with a zero conductor is marked with the additional letter "n". In this case, the insulation of the neutral core is blue. In the absence of a neutral conductor, the blue color can be used as a distinctive color for any conductor, except for the ground conductor. For one- and two-core cables, the color of the cores is not standardized. For cables with 2-3 main cores and 1-2 auxiliary cores, the letter "c" is added to the name.

Twisting of insulated cores with a pitch of no more than 16 twist diameters.

A synthetic film, talcum powder or similar material is applied over the twisted strands. If the cores do not stick together with the sheath, it is allowed to manufacture without a film.

The sheath is made of hose rubber. In single-core KG cables, the insulation and sheath can be replaced by an insulating-protective sheath.

Operating temperature range - from -40 to +50 0 C

The warranty period of operation is 6 months from the date of commissioning, but no later than 12 months from the date of manufacture. Service life - 4 years from the date of manufacture.

The minimum bending radius is 8 cable diameters.

Maximum allowable temperature core heating +75 0 С.

The construction length of the KG cable with a cross section of the main conductors is 35 sq. mm. inclusive - at least 125 m, with a cross section of 50 sq. mm. - 150 m.

Variants of climatic version of flexible cable (KG):

HL - cold-resistant, for operation in regions with a cold climate. Operating temperatures - from -60 to +50 0 C. Insulation is made of cold-resistant hose rubber.

T - tropical, for operation in regions with a tropical climate. Operating temperatures from -10 to +55 0 C. The shell is made of antiseptic rubber. The cores are made from copper wire tin-plated or tin-lead solder, with a tin content of at least 40%.

Table data:

Number and nominal section of conductors, mm 2	Nominal cable outer diameter, mm	Estimated weight of 1 km of cable, kg
Cables brand KG
1 x 2.5	6.7	80
1x4	8.0	110
1x6	9.0	150
1 x 10	11.1	230
1 x 16	12.4	310
1 x 25	14.6	450
1 x 35	16.4	590
1x50	19.0	820
1x70	21.5	1090
1x95	24.3	1400
1 x 120	27.7	1730
1 x 150	30.1	2070
1 x 185	32.7	2490
1 x 240	35.3	3150
1 x 300	40.1	3910
1 x 400	43.4	4980
2 x 0.75	8.2	90
2 x 1.0	8.5	100
2 x 1.5	9.4	130
2 x 2.5	11.2	190
2x4	13.5	280
2x6	15.5	380
2 x 10	21.2	680
2 x 16	23.7	920
2x25	28.4	1340
2 x 35	31.2	1680
2x50	38.0	2450
2x70	42.2	3170
2x95	47.2	4040
2 x 120	50.7	4800
2 x 150	57.5	6050
3 x 0.75	8.9	110
3 x 1.0	9.1	120
3 x 1.5	10.1	160
3x2.5	12.0	230
3x4	14.5	350
3x6	16.6	460
3 x 10	22.3	840
3x16	25.4	1130
3x25	30.4	1660
3x35	34.0	2150
3x50	39.5	2970
3x70	44.7	3930
3x95	50.6	5100
3 x 120	54.4	6150
3 x 150	63.0	7870
4 x 1.0	10.1	160
4 x 1.5	11.1	200
4x2.5	13.2	290
4x4	16.0	420
4x6	18.4	590
4x10	24.3	1000
4x16	27.8	1400
4x25	33.7	2100
4x35	37.7	2730
4x50	43.8	3700
4x70	49.7	5000
4x95	56.6	6500
4 x 120	62.0	8120
4 x 150	69.2	9880
5 x 1.0	11.1	190
5 x 1.5	12.2	240
5x2.5	14.5	350
5x4	17.8	530
5x6	20.5	720
5x10	26.8	1250
5x16	30.9	1700
5x25	37.4	2600
5x35	44.5	3440
5x50	50.1	4580
5x70	54.5	5870
5x95	63.3	7820
5 x 120	67.0	9360
2 x 0.75 + 1 x 0.75	8.9	110
2 x 1 + 1 x 1	9.1	120
2 x 1.5 + 1 x 1.5	10.1	160
2 x 2.5 + 1 x 1.5	11.8	220
2 x 4 + 1 x 2.5	13.9	310
2 x 6 + 1 x 4	16.3	440
2 x 10 + 1 x 6	21.0	740
2 x 16 + 1 x 6	25.0	1070
2 x 25 + 1 x 10	30.0	1550
2 x 35 + 1 x 10	32.4	1890
2 x 50 + 1 x 16	37.9	2600
2 x 70 + 1 x 25	42.7	3400
2 x 70 + 1 x 35	42.7	3400
2 x 95 + 1 x 35	48.0	4500
2 x 120 + 1 x 35	54.4	5800
2 x 150 + 1 x 50	57.5	6510
3 x 2.5 + 1 x 1.5	13.2	280
3 x 4 + 1 x 2.5	15.5	400
3 x 6 + 1 x 4	18.0	560
3 x 10 + 1 x 6	23.5	950
3 x 16 + 1 x 6	27.6	1300
3 x 25 + 1 x 10	33.1	1950
3 x 35 + 1 x 10	36.5	2400
3 x 50 + 1 x 16	42.4	3400
3 x 70 + 1 x 25	47.7	4500
3 x 95 + 1 x 35	53.9	5810
3 x 120 + 1 x 35	59.1	7280
3 x 150 + 1 x 50	64.9	8630
3 x 150 + 1 x 95*	68.3	7500
3 x 150 + 1 x 120*	68.3	7800

The main advantage of rubber insulated cables is their flexibility, which allows smaller bend radii during installation. However, in terms of electrical parameters, such cables are significantly inferior to power cables with impregnated paper or plastic insulation. In addition, the insulating sheaths of cables lose their elastic properties over time; their physical, mechanical and electrical parameters decrease due to rubber aging. Rubber aging can occur under the influence of various factors ( heat, the presence of ozone, oxygen, light, etc.) and is a consequence of the oxidative degradation of the rubber contained in the rubber. All this does not currently allow the production of cables with rubber insulation for high voltages. In particular, in practice, the maximum operating voltage of cables with rubber insulation does not exceed 35 kV, although some foreign companies produce cables with ethylene-propylene rubber insulation for voltages of 66 and 110 kV.

1 - current-carrying core; 2 - isolation; 3 - a layer of rubberized tape; 4 - filling; 5 - a layer of rubberized tape; 6 - soft layer; 7- armor; 8- protective cover

Studies show that the cause of the breakdown of cables with rubber insulation is the destruction of rubber by ozone, which occurs in the cable during the ionization of air inclusions. Therefore, to create cables high voltage it is necessary to use semi-conductive screens on the core and insulation, as well as ozone-resistant rubber.
The most promising rubbers for high voltage cables are rubbers based on butyl rubber and ethylene propylene rubber. Molecules of butyl rubber have a linear structure and contain a small amount of double bonds. Ethylene propylene rubber also has a linear structure, and double bonds are completely absent in it. This explains the high ozone resistance of rubbers based on these rubbers.
Power cables with rubber insulation are made with a lead sheath without armor or armored with an outer cover, with a core cross section of up to 500 mm 2, they are used for fixed laying in installations with voltages up to 660 V AC and up to 1000 V direct current. Brands, applications and conditions for laying power cables with rubber insulation are given in Table. 0.
Rubber insulation is made from a continuous layer of rubber or from rubber bands, followed by vulcanization. Power cables with rubber insulation are used in networks alternating current voltage up to 1 kV and direct current voltage up to 10 kV.
The bulk of power cables with rubber insulation are low-voltage cables. Rubber insulated power cables are usually understood as power cables intended for fixed laying. However large group rubber insulated flexible cables are also designed for the transmission and distribution of electricity and are essentially power cables. Rubber insulated power cables manufactured in Russia are designed for fixed laying in 660 V AC or 1,3,6 and 10 kV AC and DC networks.
The cables have copper or aluminum current-carrying conductors of round shape with a cross section from 1 to 500 mm 2 . The insulation is made of insulating rubber; a sheath of lead, polyvinyl chloride or hose rubber is applied over the insulated cores. If necessary, the cables have reinforcing covers and protective covers of the usual design.
660 V AC (1000 V DC) cables can be one-, two-, three-, or four-wire (Table 2)

Power cables with rubber insulation

Brand of cable with cores		Characteristics of shells and protective cover	Application area
	aluminum
		Lead sheathed with rubber insulation, without protective covers	Indoors, in channels
		In PVC sheath with rubber insulation, without protective covers
		In a non-combustible rubber sheath with rubber insulation, without protective covers	Indoors, in channels
		Lead sheathed with rubber insulation, armored with two steel bands with a protective outer cover
		PVC sheathed with rubber insulation, armored with two steel bands, with a protective outer cover
		In a rubber non-combustible shell with rubber insulation, armored with two steel tapes, with a protective outer cover
		In a PVC sheath with PVC insulation, armored with steel tapes, with a protective outer cover	In the ground, if the cable is not subjected to significant tensile forces
		In plastic sheath with PVC insulation, armored with steel tapes, with an outer cover of PVC hose	In tunnels, channels, ground, if the cable is not subjected to significant tensile forces
		In a PVC sheath with polyethylene insulation, armored with steel tapes, with a protective outer cover	In the ground, if the cable is not subjected to significant tensile forces

660 V Rubber Insulated Cable Range

	Number of cores	Cross-section of conductors, mm 2
		4...240 2,5..240
AVRG.ANRG		4...300 2,5...300
SRV, SRBG, VRBn, VRBG, NRB, NRBG
ASRB, ASRBG, AVRB, AVRBn, AVRBG, ANRB, ANRBG

Note. Two- and three-core cables can be made with an additional ground or neutral conductor

The thickness of the insulation, depending on the voltage and cross-section of the conductors, is 1 ... 2.5 mm. These cables are available in both lead and PVC and rubber sheaths. Stranded cables to obtain a triangular shape have a filling of the inter-core space with rubber bundles, and sometimes with unimpregnated cable yarn or staple fiberglass. Over twisted cores, as well as over the insulation of single-core cables, a tape made of polyethylene terephthalate film or rubberized fabric is usually applied, which plays the role of a separator that prevents the migration of components from the hose, reducing the electrical parameters of the insulating rubber (soot, sulfur, etc.) and accelerating its aging .
Two- and three-core cables (with the exception of armored ones) with a cross section of up to 16 mm 2 inclusive can be made flat, i.e. laid parallel in the same plane. When laying cables in the ground, as well as indoors, if the cable is not subjected to significant tensile forces, the protective covers of the cables must include two armored tapes. If mechanical impacts are minimal during cable laying, then armored covers are not used. Cable sheaths can be made of oil-resistant, flame-retardant rubber.
Cables for voltages of 3, 6 and 10 kV are made only single-core. The thickness of the insulation, depending on the cross-section of the core, is within 1.8 ... 3.8 mm for 3 kV cables and 3 ... 4 mm for 6 kV cables. Cables for a voltage of 10 kV are produced only with large sections (240, 300 and 400 mm 2) and have an insulation thickness of 5 mm.

Table 2. Number of conductors and sections of cables with rubber insulation(GOST 433-73)

Cable brand	Number of cores	Variable 660 (constant 1000), V	Rated direct cable voltage, V
			3000 | 6000 | 10000
			Nominal cross-section of conductors, mm 2
AVRG, ANRG
AVRG, ANRG
SRBGt, ASRBGt
SRBG, ASRBG
SRP, SRBG, VRBn, VRB, VRBG. PRB. RRBG
ASRB, ASRBG. AVRB, AVRBN
AVRBG, A NRB, ANRBG

Note. Two- and three-core cables can be made with an additional ground or neutral conductor.

The thickness of the lead sheath is in the range of 1 ... 2 mm, the thickness of the sheath made of rubber is 1.2 ... 3.5 mm, and that of polyvinyl chloride is 1 ... 2.6 mm.
Depending on the type of rubber used, the long-term operating temperature of the cables is 65 and 90 °C.
Power cables with rubber insulation for fixed laying are marked according to the same principle and with the same letters as power cables with paper insulation, with the addition to the brand of the letter P, the presence of which indicates that the cable has rubber insulation, and the letter H, indicating that the cable sheath is made of oil-resistant nayrite rubber.
For example, an SRG brand cable has a copper core, rubber insulation and a lead sheath; AVRB brand cable has an aluminum core, rubber insulation and a PVC sheath armored with two steel tapes with a protective outer cover; NRB cable has a copper core, rubber insulation, a nayrite rubber sheath and appropriate protective and reinforcing covers.
Power cables with rubber insulation for non-stationary laying include a large group of cables for various purposes, however, the bulk of these cables are flexible cables for voltages up to 660 V. Cables are designed to connect mobile mechanisms to AC or DC voltage networks. Cable conductors are copper, of varying degrees of flexibility; number of main conductors 3. Four-core cables are used for grounding when necessary. In addition, individual brands of cables have one or two auxiliary cores. The cross section of the main conductors is 0.75 ... 150 mm 2, grounding - from 0.75 ... 50 mm 2, auxiliary - 1.5 ... 10 mm 2. Ground conductor insulation - yellow-green. Insulated cores of 4...6-core cables are twisted around a round or profiled rubber core. A rubber sheath is applied over the twisted cores, which can be oil-resistant and flame-retardant.
Cables with a conductor cross section of 6 mm 2 or more must be resistant to bending at an angle of ±n / 2 rad at a nominal tensile force of 49 N. The diameter of the rollers on which the bend is made, depending on the cross section of the conductors, can be from 200 to 600 mm; number of bends - at least 4000 ... 12000. Cables with a cross section of the main conductors up to 4 mm 2 inclusive must be resistant to multiple kinks through the system of rollers under current load and withstand at least 30,000 kink cycles. A number of cables of this type must be resistant to crushing forces (no more than 8 kN). Long-term operating temperature of cables +75 °С. Depending on the type of materials used, the frost resistance of cables ranges from -10 to -60 °C.
During the operation of cables, tensile forces should not exceed 19.6 N per 1 mm 2 of the total cross section of all cores. The bending radius of cables during installation and operation is within 5 ... 10 cable diameters (depending on the type of cables).
There is a large group of specialized flexible rubber insulated power cables with certain design features. These include, in particular, highly flexible shielded cables for alternating voltage up to 660 V with an insulated neutral, intended for connection of mining power tools; cables for tower cranes designed to connect equipment for controlling mechanisms, signaling equipment and other devices to an alternating current network at an alternating voltage of up to 660 V; mine cables designed to connect mobile machines and mechanisms to the network for alternating voltage of 1140 V on the main conductors and 220 V on the auxiliary ones. A feature of mine cables is the presence of flexible screens made of conductive rubber.
To connect excavators and other mobile mechanisms to electrical networks with an isolated neutral at an alternating voltage of 6 kV, flexible four- and five-core cables with a cross section from 3 x 10 + 1x6 + 1x6 mm 2 to 3 x 150 + 1 x 50 + 1x10 mm 2 are used. The cables have screens along the core and insulation made of electrically conductive rubber. Nominal insulation thickness of main conductors 4 mm, auxiliary conductors 2.0...2.5 mm, electrically conductive screens 0.4...0.6 mm. The voltage of partial discharges in the insulation of the shielded main conductors must not be less than 9 kV, the discharge termination voltage must not be less than 6 kV. The cables are resistant to alternating bends around the rollers at an angle I am glad with a tensile force of 196 N. The diameter of the rollers on which the bend is made is 400 ... 600 mm; the number of alternating bends is 30000...40000. After such impacts, the number of wire breaks in each core should not exceed 30%. The long-term permissible maximum operating temperature of these cables is within +(75...80) °C. Minimum allowable temperature environment- (40...60) °С. The service life of flexible power cables in comparison with the service life of cables for fixed laying (20...25 years) is much less. Thus, the minimum service life of an excavator cable for a voltage of 6 kV is 3 years, and when operated using mechanisms equipped with cable receiving drums, 5 years.
For alternating voltage up to 6-10 kV, a wide range of flexible cables is also produced. general purpose designed to connect mobile machines, mechanisms and equipment to electrical networks and mobile sources of electrical energy. Cables are distinguished primarily by the degree of flexibility of the conductive core. The number of main conductors - 1 ... 3, grounding - 1 ... 2, auxiliary - 1, 2, 3, 5, 7. The nominal section of the main conductor is from 0.75 to 150 mm 2. Service life of cables - from 1 to 6 years.
The specific characteristics of power cables with rubber insulation, especially their increased flexibility, determine their further improvement and development. At present, the issue of replacing such cables with plastic-insulated cables cannot be resolved positively. Perhaps over time this problem will be solved with the introduction of a number of thermoplastic elastomers.
The range of manufactured cables and wires with rubber and plastic insulation is very wide, so below is information only about some the most important types cable products used for the transmission and distribution of electricity.
The widest group of rubber-insulated and rubber-sheathed cables is made up of general-purpose copper flexible cables designed for connecting mobile mechanisms to electrical networks for a rated alternating voltage of 660 V, a frequency of up to 400 Hz or a direct voltage of up to 1000 V. In accordance with GOST 13497-77 seven brands of cables are produced. Cables are produced with 1...3 core cores, the nominal section of which can be from 0.75 to 150 mm 2 . Some cables have a ground conductor and 1...2 auxiliary conductors. The sections of the grounding conductors, depending on the section of the main conductor, are 0.75 ... 150 mm 2; the section of the auxiliary conductors is 0.75 ... 10 mm 2. Cables of the KRTP and KRPTN brands have a core that is inferior in flexibility to the cores of cables of other brands listed in Table. 0 and 1. So if the core of cables of the KRTP and KRPTN brands with a cross section of 70 mm 2 consists of 189 wires with a diameter of 0.68 mm, then for cables of the KRPG, KRPGN, KRPS, KRPSN, KRSHK brands, the same section is performed by 266 wires with a diameter of 0.58 mm each. The main conductors of the cables must be colored to distinguish them from each other, or in other ways to distinguish them. The ground conductor (except for the ground conductor of cables of the KRSHK brand) must be black or yellow-green. The average service life of cables is in the range from 2 to 4 years, and during this service life the cables must withstand from 4000 to 15000 alternating bends with a diameter of at least 200...400 mm (depending on cable brands). The long-term permissible temperature of the conductors of the cables should be no more than 65 °C. Tensile loads on the cable should be no more than 19.6 N per 1 mm 2 of the total cross section of all cores.
Rubber insulation and sheath continue to dominate a number of special purpose cables, among which are the following:

1. Cables and wires for mining and earthmoving. These cables are designed to connect various mobile machines and mechanisms, such as excavators, mine combines, mine drilling tools, etc., to electrical networks. Such cables include flexible power excavator cables for voltages of 6 and 10 kV, flexible mining cables, including those with shielded cores, flexible shielded mining cables for drilling tools.
2. High voltage x-ray cables. These cables are designed to supply filament current and high voltage to X-ray tubes. The cables are designed for rectified pulsating voltage up to 150 kV or alternating voltage 55 kV.
3. Cables for radio installations. These cables are designed for mounting radio installations on variable voltages 380, 660 and 3000 V with a frequency of up to 400 Hz or constant 700, 1000 and 6000 V. If protection against radio interference is required, then the cables are shielded.
4. Aerodrome cables. Designed for alternating voltages of 250, 660, 3000 and 6000 V. Low-voltage cables for voltage of 250 V are designed to connect airfield lights or light signs to the secondary winding of transformers, as well as cable glands transformers. Low-voltage cables for 660 V connect airfield lights that illuminate aircraft landing areas. High-voltage cables for voltages of 3 and 6 kV connect the primary windings of the transformers that feed the airfield lights into a common circuit and are used to connect to the dimmers. In addition, 3 kV cables connect high-voltage windings of transformers for aerolight signals.