RU77491U1 - SINGLE-PHASE POWER CABLE FOR MEDIUM VARIABLE VOLTAGE - Google Patents

Abstract

The proposed utility model relates to the cable industry, namely, to the designs of power cables intended for use in distribution networks of electric energy for voltage from 6 to 35 kV AC with a frequency of 50 Hz. The purpose of this utility model is to create such a design of a single-phase power cable for medium alternating voltage, which would significantly improve its operational properties, namely, reliability and degree of protection against mechanical influences when laying in various soils, and therefore increase the service life. To do this, it is proposed to use as an armor that protects the cable from axial and radial influences, armor wire of non-magnetic material, namely, aluminum alloy.

Description

The proposed utility model relates to the cable industry, namely, to the designs of power cables intended for use in distribution networks of electric energy for voltage from 6 to 35 kV AC with a frequency of 50 Hz.

A power cable is known (see RF patent for utility model No. 42689), containing an aluminum or copper conductive core, a screen for a conductor from a semiconducting cross-linked composition based on polyethylene, insulation from a cross-linked composition based on polyethylene, an insulation screen from a semiconducting cross-linked composition based on polyethylene, a layer of electrically conductive tape, sequentially applied to a layer of electrically conductive tape, a lead sheath, an anti-corrosion layer, a pillow for armor, armor made of tapes of non-magnetic metals or alloys, and polymer aruzhnuyu shell. In this design of a single-phase cable, tape armor of non-magnetic material is used. In this regard, this cable can only be used in conditions where only radial loads can act on the cable. When laying the cable in soils subject to displacement, when both radial and axial tensile loads act on the cable, wire armor should be applied, which is specified in paragraph 2.3.45 of the PUE. Thus, the known cable has limitations on the possibility of use.

An additional disadvantage of the prototype is the use in this power cable lead sheath, which performs the function of a metal screen and a sealing sheath. Such a sheath has low thermal stability, which leads to insufficient cable reliability.

The purpose of this utility model is to create such a design of a single-phase power cable for medium alternating voltage, which would significantly improve its operational properties, namely, the reliability and degree of protection against mechanical stress when laying in various soils and conditions where the cable may be subjected to axial tensile loads, therefore, increase the service life.

1. To achieve this goal, it is proposed in a single-phase power cable for medium alternating voltage, including aluminum or copper conductive core, conductive shield on the core, insulation made of polymeric material, conductive shield on insulation, the first separation layer, armor and the outer sheath, conductive core to perform in the form of a round multi-wire sealed core, and the armor is made of a round wire of aluminum alloy, on top of which a layer of winding from polymer tapes is applied.

At the same time, an armor cover made of aluminum alloy wires is used as a metal screen. In this case, the use of a screen of copper wires and a separation layer is excluded.

An additional difference is that between the first separation layer and the armor a shield of copper wires fastened with copper tape, a second separation layer and an inner shell can be applied.

Another additional difference is that on top of the separation layer under the inner shell, a laminated aluminum-polymer tape can be applied, which provides sealing from radial migration of water into the insulation.

In the proposed cable, the first separation layer may be made of electrically conductive paper or an electrically conductive water blocking tape, and the second separation layer may be made of electrically conductive paper or rubberized fabric or an electrically conductive water blocking tape.

In this utility model, it is proposed to use armor wire made of non-magnetic material, namely, aluminum alloy, as armor protecting the cable from axial and radial influences. An aluminum alloy with additives of magnesium, silicon, and iron, while remaining a non-magnetic material, acquires almost twice as much tensile strength (not less than 295 MPa) compared with electrotechnical aluminum, high corrosion resistance, and creep resistance. The density of the alloy remains the same as that of electrical aluminum - 2.7 g / cm ³ .

This combination of aluminum alloy properties allows it to be used as armored wires in the protective covers of single-phase medium-voltage cables instead of galvanized steel armored wires when laying cables in the ground with moving soils, or on tracks where axial tensile forces are possible.

An additional difference of the proposed design is the use of a screen made of copper wires with high heat resistance. As you know, domestic medium-voltage distribution networks operate according to an isolated neutral circuit. In the case of a two-phase short circuit, a large current flows (tens of kA) along the cable screen, which leads to the heating of the metal screen and, subsequently, to the disconnection of the line. The heating temperature of the screen made of copper wire, can, without compromising the performance of the line, reach 350 ° C. Whereas, the lead shell does not withstand such a temperature

Figure 1 shows one of the embodiments of the proposed cable in the context, where:

1. round multi-wire sealed aluminum or copper conductive core,

2. internal extruded conductive screen,

3. XLPE insulation,

4. external extruded conductive screen,

5. the first separation layer of electrically conductive paper or electrically conductive water blocking tape,

6. aluminum alloy round wire armor

7. a layer of polymer tapes,

8. the outer shell.

Figure 2 shows the second embodiment of the proposed cable in the context, where:

1. round multi-wire sealed aluminum or copper conductive core,

2. internal extruded conductive screen,

3. XLPE insulation,

4. external extruded conductive screen,

5. a layer of electrically conductive paper or electrically conductive water blocking tape,

6. aluminum alloy round wire armor

7. winding layer with polymer tapes

8. the outer shell.

9. a screen made of copper wires fastened with copper tape,

10. the second separation layer of cable paper, rubberized fabric or water blocking tape,

11. laminated aluminopolymer tape,

12. the inner shell of PVC compound, or PVC compound of reduced fire hazard, or from a halogen-free polymer composition,

A power cable manufactured in accordance with the proposed design is highly resistant to longitudinal and axial tensile loads and can be used when laying cable lines in the ground with moving soils or on routes where axial tensile forces are possible. In addition, the cable corresponding to the proposed design is highly resistant to thermal effects in the event of a short circuit.

The sequence of operations in the manufacture of the proposed cable is as follows:

- twisting of round conductors is carried out on lamp twisting machines,

- the application of the inner screen for the core, insulation made of cross-linked polyethylene and the screen for insulation is made simultaneously on an inclined extrusion line,

- the imposition of a winding of electrically conductive paper, a screen of copper wires fastened with a copper tape, a separation layer and a layer of laminated aluminopolymer tape - on a 100 roller twisting machine,

- the imposition of the inner shell of the polymer composition on the extrusion line,

- the imposition of armor from round wires of aluminum alloy - on a universal machine "drum tram",

- the imposition of the outer shell of the polymer composition on the extrusion line.

For the production of the proposed cable, it is supposed to use the available equipment of OJSC SEVKABEL.

Materials used to manufacture this cable:

- aluminum or copper wire,

- copper tape

- conductive crosslinkable polyethylene,

- pyroxide crosslinkable polyethylene,

- tape conductive paper,

- water blocking tapes,

- laminated aluminopolymer tape,

- PVC plastic compound, PVC compound of low fire hazard, weatherproof high density polyethylene, halogen-free polymer composition,

- aluminum alloy wire

Claims (5)

1. A single-phase power cable for medium alternating voltage, including an aluminum or copper conductive core, an electrical conductive shield along the core, insulation made of a polymeric material, an electrical conductive shield for insulation, a first separation layer, armor and an outer sheath, characterized in that the conductive core is made in the form round multi-wire sealed core, armor made of round aluminum alloy wire, over which a layer of winding from polymer tapes is applied. 2. The cable according to claim 1, characterized in that between the first separation layer and the armor can be additionally imposed a screen of copper wires fastened with copper tape, the second separation layer and the inner shell. 3. The cable according to claim 2, characterized in that over the second separation layer can be applied alumina tape. 4. Cable according to any one of claims 1 to 3, characterized in that the first separation layer may be made of electrically conductive paper or electrically conductive water blocking tape. 5. The cable according to any one of claims 1 to 3, characterized in that the second separation layer may be made of cable paper, or rubberized fabric, or an electrically conductive water blocking tape.