JPS6237807A - Ground fault resisting high voltage cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a ground fault resistant high voltage cable that prevents the spread of fire in the event of a ground fault.

(Technical background of the invention and its problems) In high-voltage cables such as general KOF cables and Cv cables, the insulation is flammable, so it easily ignites in the event of a ground fault, and once ignited, the cable There was a problem with the fire spreading in the length direction, causing the fire to expand.

In other words, the energy at the time of a ground fault destroys the external shielding layer such as a metal wire on the insulator, and this causes the protective anti-corrosion layer formed by polyvinyl chloride (hereinafter referred to as PVC) etc. directly above it to break down. The combustion of the insulator was likely to spread because the insulator was pushed up and the cracks expanded.O In order to prevent the spread of fire during such ground faults, cables and cables with a highly flame-retardant tape wrapped around the anti-corrosion layer have traditionally been used. Cables with highly flame-retardant corrosion protection layers are used as cables with high ground fault resistance, but the former not only increases costs but also has problems with the installation method; In general, the balance of properties including processability of the flame retardant sheath material was not sufficient.

(Purpose of the Invention) The present invention was made to solve these problems, and is designed to prevent cracks in the plastic protective anti-corrosion layer from expanding in the event of a ground fault, and to prevent the spread of fire in the length direction of the insulator. The purpose is to provide a ground-fault-resistant high-voltage cable.

(Summary of the Invention) In other words, the ground fault resistant high resistance cable of the present invention is provided with an aromatic aramid fiber layer on the outside of the insulating layer, for example, directly above the insulating layer, directly below the anticorrosive layer, directly above the anticorrosive layer, etc. It is characterized by

In the present invention, the aromatic aramid fiber layer is provided by, for example, wrapping or gap winding Kevlar tape (trade name, manufactured by DuPont), which is a thread-like or tape-like aromatic aramid fiber.

In other words, Kevlar Tape has a much larger modulus (6000 to 130004/m") than ordinary synthetic fibers.
Therefore, the wound layer of this tape can absorb the energy at the time of a ground fault extremely well, thereby making it possible to suppress the ground fault hole in the anticorrosion layer to a small size.

Furthermore, it is useful to provide the aromatic aramid fiber layer directly above the anti-corrosion layer of an existing non-disaster prevention high voltage cable, as similar effects can be expected.

Furthermore, in the present invention, aromatic aramid fibers subjected to flame retardant treatment can be used. A lifting platform using such flame-retardant aromatic aramid fibers will significantly shorten the afterflame time and more reliably prevent the spread of fire, although the cost will be somewhat higher.

(Example of the invention) Examples of the present invention will be described below.

Implementation gA11 154Kv, IX120 (C'V'r- of Lw+t
A metal wire was wound on the Pruno insulating layer to form an external confining layer, and a 5.5B thick PVC anticorrosion layer was further extruded*W on top of which a 1/2 lap of Kevlar tape was wrapped.

Next, the ground fault resistance characteristics of the cable thus obtained, that is, the afterflame time at the time of a ground fault and the maximum length of the ground fault hole formed in the PvC anticorrosion layer were measured.

The measurement results are shown in the table below.

Example 2 A cable was manufactured in the same manner as in Example 1 except that the Kevlar tape of Example 1 was wound with a gap of 30 mm.

The obtained cable was measured in the same manner as in Example 1, and the measurement results are shown in the following table.

Actual notice 3: Apply the Kevlar tape of the example just below the external groove layer &cl/
2. A cable was manufactured in the same manner as in Example 1 except for wrapping. The obtained cable was measured in the same manner as in Example 1, and the measurement results are shown in the following table. For comparison, cables were manufactured by forming each layer of tape as shown in the same table, and the results of measuring the earth fault resistance of these cables are also shown in the same table.

Blank space below (effects of the invention) As is clear from the above description, in the cable of the present invention, a strong aromatic aramid tape is wound around the outside of the insulating layer, forming a layer with extremely high tensile strength as a whole. Therefore, cracks in the anticorrosion layer and expansion of the ground fault hole opening are suppressed, and the spread of fire is effectively prevented.

Claims (1)

[Scope of Claims] 1. An earth fault resistant high voltage cable characterized in that an aromatic aramid fiber layer is provided at least on the outside of an insulating layer constituting the earth fault resistant high voltage cable. 2. The earth fault resistant high voltage cable according to claim 1, characterized in that an aromatic aramid fiber layer is provided at the outermost station.