RU237003U1 - Power flexible shielded cable - Google Patents

Abstract

The utility model relates to cable technology, namely to the design of a power cable for connecting mine mobile machines and mechanisms to an electric network. The technical result consists in reducing the time of disconnecting a cable line in case of damage. The technical result is achieved due to the fact that the cable contains three main conductive cores with rubber insulation and a screen, twisted around the core, insulated auxiliary cores, on top of which a split ground core is applied, a two-layer sheath and armor. An elastic, easily removable screen is applied on top of each split ground core. The profiled core and the elastic, easily removable screen are made of a semiconducting polymer material on the insulation, the inner layer of the sheath is made of a semiconducting thermoplastic elastomer, and the outer layer is made of thermoplastic polyurethane. The resistance of the semiconducting polymer material and the semiconducting thermoplastic elastomer is no more than 500 Ohms. A combined armor is applied between the inner and outer shells. 1 fig.

Description

Scope of application

The utility model relates to cable technology, and more specifically to the design of a power cable that can be used to connect mine mobile machines and mechanisms to an electrical network with a rated alternating current voltage of up to 3.3 kV, a frequency of up to 50 Hz on the main cores and up to 220 V on the auxiliary cores.

State of the art

The design of a flexible shielded power mine cable is known from information sources (Patent RU 211321 published on 31.05.2022). The cable contains three main copper insulated conductive cores of increased flexibility with elastic conductive screens, copper auxiliary cores in rubber insulation and a split ground core, twisted around a profiled core, with an internal screen made of conductive rubber along the twist of the cores, with inner and outer sheaths made of rubber. Between the inner and outer sheaths there is a monitoring core located concentrically to the cable axis. The monitoring core is made in the form of a winding of copper or tinned copper wires, and can also be made in the form of a combined winding of copper or tinned copper wires with synthetic threads or a combined winding of steel wires with copper or tinned copper wires. The technical solution allows to increase the mechanical strength and operational reliability of the cable and the ability to control cable damage during operation.

However, under increased mechanical loads, the monitoring core and the grounding core are destroyed, thereby increasing the active resistance of the conductor, which leads to accelerated thermal and electrical aging of the insulation materials and internal components of the cable, resulting in an unpredictable short circuit in the network, and a spark discharge with the possibility of its spreading into the environment of mines containing explosive gases.

The closest analogue known from the prior art is a flexible shielded power cable (Patent RU 178217 published on 28.03.2018). The cable contains three main conductive cores made of copper wires with ethylene-propylene rubber insulation and a screen made of conductive rubber over the insulation. The main conductive cores are twisted around a profiled core made of conductive rubber. In the spaces between the main conductive cores, there are auxiliary cores made of copper wires, on top of which a braid of steel wires is applied. Rubber insulation is made on top of the braid. A split grounding core is applied to the insulation of the auxiliary core by winding tinned copper wires. On the outside, the cable has two sheaths: an internal, two-layer one, and an external one made of oil-resistant hose rubber with increased resistance to abrasion and tearing. The inner layer of the inner sheath is made of conductive rubber, and the outer layer is made of oil-resistant, flame-retardant hose rubber. Between the inner and outer sheaths there is armor made of strands twisted from steel and copper wires. When using the cable, an impulse is instantly transmitted to turn off electrical equipment, since the metal armor and the grounding core are short-circuited through the inner conductive layer of rubber of the inner sheath of the cable and an instantaneous impulse is transmitted to turn off electrical equipment. The cable has increased explosion hazard and high strength.

A shielding layer of conductive rubber in the cable structure, applied over each insulated core, transmits an impulse to the high-speed switching equipment to switch off the electrical equipment and prevent an accident when mechanically applied to the cable sheath. However, the presence of only such a protective element is insufficient to ensure advanced disconnection (voltage relief) from the cable when the outer sheath of the cable is damaged before the insulation of the main cores is damaged and a short circuit occurs.

Disclosure of a utility model

The technical problem solved by the utility model is to eliminate spark discharges into the environment by early (before the insulation of the main cores is damaged and a short circuit occurs) disconnection of the cable when exposed to a crushing external load, as well as to ensure explosion safety and increase the strength of the cable.

The technical result achieved by using the proposed cable design is to reduce the time it takes to disconnect the cable line in the event of damage.

The technical result is achieved in that in a flexible shielded power cable, including three main conductive cores made of copper or tinned copper wires with rubber insulation and a screen, twisted around a core, insulated auxiliary cores made of copper wires, on top of which a split grounding core is applied, a two-layer sheath and armor, the new thing is that an elastic, easily removable screen is applied on top of each split grounding core, wherein the profiled core and the elastic, easily removable screen are made of a semiconducting polymer material on the insulation, the inner layer of the two-layer sheath is made of a semiconducting thermoplastic elastomer, and the outer layer of the two-layer sheath is made of thermoplastic polyurethane, wherein the resistance of the semiconducting polymer material and the semiconducting thermoplastic elastomer is no more than 500 Ohm, and a combined armor is applied between the inner and outer sheaths.

Semi-conductive materials of the insulation screen and inner sheath with a resistance of no more than 500 Ohm facilitate instantaneous disconnection of the electrical load on the cable, ensuring safe operation in explosive environments by preventing spark discharges from occurring under crushing loads. The use of an outer sheath made of thermoplastic polyurethane provides increased strength against tearing and abrasion, and minimizes the likelihood of spark discharges in the environment when crushed.

Description of drawings

The utility model is illustrated by a drawing.

Fig. 1 shows a general view of the cable in section.

1 - main conductive core;

2 - insulation applied to the conductive core;

3 - easily removable screen;

4 - auxiliary wires;

5 - insulation applied to auxiliary wires;

6 - split ground wire;

7 - easily detachable screen;

8 - profiled core;

9 - inner shell;

10 - combined armor;

11 - outer shell.

Implementation of a utility model

The cable contains three main conductive cores 1 made of copper or tinned copper wires with insulation 2 made of ethylene-propylene rubber and an easily removable screen 3, applied over the insulation 2, made of a semi-conducting polymer material. The main conductive cores 1 are twisted around a profiled core 8 made of a semi-conducting polymer material. Auxiliary cores 4, made of copper wires and insulated with ethylene-propylene rubber, are located in the outer inter-core space of the main conductive cores 1. A split grounding core 6 is applied over each insulated auxiliary core 4 by twisting in one or more layers and an easily removable screen 7. On the outside, the cable has a two-layer sheath: an inner sheath 9, made of a semi-conducting thermoplastic elastomer, and an outer sheath 11, made of thermoplastic polyurethane. Between the inner shell 9 and the outer shell 11, a combined armor 10 is applied using a braiding method, the strands of which are made of copper and steel wires and synthetic thread.

When the cable is damaged, the metal armor 10 and the split grounding core 6 are short-circuited through the internal semiconductive layer of thermoplastic elastomer of the inner sheath 9 of the cable. The semiconductive materials of the screen on the insulation and the inner sheath with a resistance of 500 Ohm facilitate the instantaneous disconnection of the electric load on the cable, since the impulse for disconnecting the electrical equipment is supplied instantly. The cable line is disconnected from the network 60% faster than when using other materials. Experimental data also showed that the production of the outer sheath from thermoplastic polyurethane increases the strength during tearing and abrasion by 30% in relation to chloroprene rubber, which, when crushed, minimizes the likelihood of spark discharges in the environment.

The flexible shielded power cable meets the criterion of "industrial applicability" since it can be repeatedly reproduced and used for its intended purpose with the achievement of the specified technical result. All materials used in the cable design are known and industrially produced. The cable is manufactured using standard drawing, twisting and extrusion equipment used in the cable industry for the manufacture of electrical cables.

Claims (1)

A flexible shielded power cable comprising three main conductive cores made of copper or tinned copper wires with rubber insulation and a screen, twisted around a core, insulated auxiliary cores made of copper wires, on top of which a split grounding core is applied, a two-layer sheath and armour, characterised in that an elastic, easily removable screen is applied on top of each split grounding core, wherein the profiled core and the elastic, easily removable screen are made of a semi-conducting polymer material over the insulation, the inner layer of the two-layer sheath is made of a semi-conducting thermoplastic elastomer, and the outer layer of the two-layer sheath is made of thermoplastic polyurethane, wherein the resistance of the semi-conducting polymer material and the semi-conducting thermoplastic elastomer is no more than 500 Ohm, and a combined armour is applied between the inner and outer sheaths.