RU132604U1 - ELECTRIC POWER CABLE - Google Patents

Abstract

1. Electric power cable with cross-linked polyethylene insulation and a metal screen made of aluminum or aluminum alloy wires fastened with tape or a sheaf of electrically conductive material, characterized in that the wires in the metal screen are made of aluminum or aluminum alloy, modified with rare or rare-earth metals, in including copper plated. 2. The power electric cable according to claim 1, characterized in that the wires in the metal shield are made of heat-resistant aluminum alloy of the TAC brand modified with zirconium.

Description

The utility model relates to cable technology, namely, to the designs of high-voltage power electric cables with XLPE insulation and a metal shield used to transmit electrical energy.

In high-voltage cables with a voltage of 6 kV or more, a metal screen as part of a combined shield of electrically conductive materials placed on top of the insulation shunts the distortions of the electric field that arise due to the presence of insulation defects. It was found that the electric strength of the insulation of power cables during shielding increases by 20%, and the pulse strength by 5%.

A known design of a power electric cable with insulation made of cross-linked polyethylene for a voltage of 10, 20 and 35 kV according to TU 16.K71-335-2004, year of entry 2004, Russia, having a metal screen made of copper wires fastened with a copper tape. Disadvantages of a metal screen made of copper wires and copper tape: accelerated destruction of insulation under the influence of copper ions, as well as a large mass and high cost.

The closest in parameters to the utility model is an electric power cable with cross-linked polyethylene insulation according to patent No. 113862, Russia, (prototype), containing a metal screen made of aluminum or aluminum alloy wires fastened with a tape or a pile of electrically conductive material. The electric cable according to the prototype (Fig.) Consists of a multi-wire conductive core 1, a screen along the core 2, insulation 3, a combined screen 4, a separation layer 5, a plastic sheath 6. The electric power cable according to the prototype is made according to the following technology. A screen 2 of an electrically conductive polymer cross-linked composition with a thickness of at least 0.3 mm is applied by extrusion onto a copper or aluminum conductive core 1. On top of the screen 2, insulation 3 is made of cross-linked polyethylene. The thickness of the insulation depends on the brand of cable. On top of the insulation, a combined screen 4 is applied, consisting of an electrically conductive polymer cross-linked composition with a thickness of at least 0.3 mm, a layer of electrically conductive polymer tape and a metal screen of aluminum wires with a nominal diameter (0.7-2.0) mm, fastened with an aluminum tape with a thickness of 0 , 2 mm and a width of 20 mm. On top of the combination screen, a separation layer 5 of at least 0.2 mm thick is applied from crepe or cable paper tapes or polymer tapes. On top of the separation layer, a sheath 6 made of high density polyethylene or polyvinyl chloride plasticate is extruded.

The disadvantages of the prototype include:

- reduced allowable temperature for heating the aluminum screen in the operating mode to 90 ° C and overload mode (not more than 8 hours per day) to 130 ° C;

- reduced permissible short circuit current;

- reduced mechanical strength of the aluminum screen in overload and short circuit mode;

- reduced corrosion resistance of the aluminum screen.

All these disadvantages of the prototype significantly reduce the reliability and durability of cables with insulation made of cross-linked polyethylene.

The technical task of the utility model is the development of a power electric cable that is not inferior to the prototype in basic characteristics, but more reliable and durable.

The technical result is achieved in that the wires in the metal screen of the cable are made of aluminum or an aluminum alloy modified with rare or rare earth metals, including those with a copper coating.

A common feature of the prototype and the proposed technical solution is the presence of a metal screen made of aluminum or aluminum alloy wires, fastened with a tape or a pile of electrically conductive material. At the same time, the proposed cable differs from the known one using aluminum or aluminum alloy wires modified with rare or rare-earth metals, including those with a copper coating, in the metal shield.

Small additives (up to 1 wt.%) Of rare and rare-earth metals from the group of zirconium, scandium, yttrium, cerium, lanthanum, vanadium, hafnium or mixtures thereof can significantly increase the strength, heat resistance and corrosion resistance of aluminum and its alloys without reducing electrical conductivity. For example, the addition of cerium in an amount of 0.5 wt.% Increases the strength and heat resistance of aluminum almost twice. This reduces corrosion by 10 times and significantly increases the electrical conductivity of aluminum. The addition of 0.3 wt.% Yttrium increases the conductivity of aluminum by 7.5%, and also increases its strength and heat resistance. The addition of 0.4 wt.% Scandium increases the strength of aluminum by 35%. This increases the electrical conductivity and heat resistance of aluminum. The addition of zirconium to 0.5 wt.% Allows you to significantly (2-2.5 times) increase the heat resistance of aluminum and its alloys without reducing electrical conductivity. Aluminum and its alloys modified with rare and rare-earth metals have practically no creep under load.

Coating aluminum wires of the metal screen with copper allows the use of standard connecting and grounding fittings.

Advantages of the new cable:

- high permissible temperature for heating the metal screen in operating mode up to 110 ° C and overload mode up to 150 ° C;

- increased permissible short circuit current;

- increased mechanical strength of the metal screen in the operating mode and overload mode;

- increased corrosion resistance of the metal screen;

- high reliability and durability.

Restrictions on the choice of the brand of aluminum or aluminum alloy for metal shield wires are imposed by the conditions for the manufacture, installation and operation of the cable:

- manufacture of wire from wire rod by drawing method;

- cable operation in overload mode;

- the required physical and mechanical characteristics of the wires of the metal shield: maximum breaking strength and elongation, minimum creep, minimum electrical resistance, maximum heat resistance and durability;

- price.

The above requirements are met by aluminum and its alloys modified with rare or rare-earth metals or mixtures thereof. The most affordable and cheapest are aluminum alloys modified with zirconium. The authors of the utility model suggest using wire rod made of heat-resistant aluminum alloy of the TAS brand for the manufacture of wires of a metal shield according to TU 1712-043-50289046-2012, the year 2012, Russia, modified with zirconium.

The design and manufacturing technology of the cable according to the utility model are similar to the design and manufacturing technology of the cable according to the prototype.

Power cables with cross-linked polyethylene insulation and a metal shield made of zirconium-modified TAS aluminum alloy wires underwent comprehensive tests at cable plants in the Russian Federation with positive results. Production of these cables has been established.

Claims (2)

1. An electric power cable with cross-linked polyethylene insulation and a metal screen made of aluminum or aluminum alloy wires fastened with tape or a sheaf of electrically conductive material, characterized in that the wires in the metal screen are made of aluminum or aluminum alloy modified with rare or rare-earth metals, in including copper plated. 2. The electric power cable according to claim 1, characterized in that the wires in the metal screen are made of heat-resistant aluminum alloy of the TAC brand modified with zirconium.

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