JPH0215512A - Semiconductive fabric tape for power cable - Google Patents

Abstract

PURPOSE:To reduce the force that tightens a cable core at heat cycle by constituting it out of a woven fabric tape and a conductive rubber layer filling and covering its inside and outside so as to equip specific characteristics. CONSTITUTION:This is constituted of a woven fabric tape 1 and a conductive rubber layer 2 filling and covering its inside and outside, and the thermal shrinkage factor at 1000 deg.C in the longitudinal thread 1a direction is set to below 0.5%. To give thermal shrinkage factor like this to the semiconductive fabric tape, conductive rubber 2 excellent in adhesion with the woven fabric 1 is filled and spread, and the thread of woven fabric tape 1 is heat-set by applying a hot tenter style heat fixing method at the temperature of 100 deg.C or more to the direction of the longitudinal thread 1a of the woven fabric tape 1. Hereby, the force of tightening a cable core at the time of heat cycle becomes small, and as a result irregularity generation and twisting generation can be removed from the surface of the cable core.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a semiconductive cloth tape for power cables, and more specifically, it is effective for suppressing unevenness and twisting on the surface of a cable core when energized. This invention relates to a semiconductive cloth tape.

(Prior Art) A semiconductive cloth tape is wound around the outer periphery of a cable core of a power cable.

As shown in a partially cutaway perspective view in FIG. 1, this semiconductive cloth tape has a woven cloth tape 1 consisting of warp threads 1a extending in the longitudinal direction of the tape and weft threads 1b woven across the warp threads 1a. and a conductive rubber layer 2 that densely fills and covers both surfaces of the textile tape 1 and the voids between the yarns.

This semiconductive cloth tape has greater elasticity in the tape width direction (weft direction) than in the tape longitudinal direction (warp direction) to provide flexibility against repeated bending of the cable. As such, the yarn selection or weaving method is employed.

Generally, synthetic fibers such as nylon fibers and polyester fibers are used as thread materials. As warp yarns, yarns such as filament yarns and spun yarns are used, and as weft yarns, stretch yarns or non-hygroscopic elastic yarns such as stretch-treated Subandix, its core yarns, and cover yarns are used. has been done.

In addition, as for the weaving method, an appropriate weaving method is adopted depending on the purpose, such as plain weaving, twill weaving, satin weaving, and diagonal weaving.

Since the conventional semiconductive cloth tape has the above-described structure, its thermal shrinkage rate is also larger in the warp direction than in the weft direction. Usually, the heat shrinkage rate in the warp direction is 1
It is about 1% at 00°C.

(Problem to be Solved by the Invention) A laid power cable is subjected to a heat cycle due to fluctuations in the amount of electricity supplied during use.

In some cases, the cable core reaches a temperature of about 100°C. Therefore, the cable core repeatedly expands when the temperature rises and contracts when the temperature falls.

On the other hand, the semiconductive cloth tape wrapped around the outer circumference of the cable core shrinks when the temperature rises to alleviate internal strain until it becomes thermally stable. shows.

Therefore, as a result of their opposite behavior at elevated temperatures, the cable core will be tightened by the semiconductive cloth tape. In particular, the greater the thermal shrinkage rate of the semiconductive cloth tape in the warp direction, the more strongly the cable core will be tightened.

As a result, the surface pressure exerted by the semiconductive cloth tape causes problems such as unevenness on the surface of the cable core and twisting of the cable core itself.

The object of the present invention is to provide a semiconductive cloth tape for power cables that does not cause the above-mentioned problems.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention consists of a woven fabric tape and a conductive rubber layer filling and covering the inside and outside of the woven fabric tape. The rate is 0.
Provided is a semiconductive cloth tape for power cables, characterized in that the electrical conductivity is 5% or less.

The material of the thread constituting the woven fabric tape in the semiconductive fabric tape of the present invention may be any of the various synthetic resins described above, and the weaving method may be any of the various weaving methods described above. It may be selected appropriately.

The conductive rubber that fills and covers both sides of this woven fabric tape and the voids between the threads has a volume resistivity of 10
It is preferable that the resistance is 5Ω-1 or less. It is preferable that the surface of the conductive rubber layer formed by filling and coating conductive rubber be as smooth as possible.The reason is that when it is wound around the cable core, it makes smooth contact with the cable core. It's for a reason. This is because if there are irregularities on the surface, there is a risk of corona generation due to electric field irregularities.

The semiconductive cloth tape of the present invention has a temperature of 100°C in the warp direction.
The heat shrinkage rate is set to 0.5% or less. If the heat shrinkage rate is greater than 0.5%, the cable core will be tightly tightened during the heat cycle of the cable core, leading to surface irregularities and twisting.

In order to give the semiconductive cloth tape the heat shrinkage rate described above, it is necessary to increase the amount of conductive rubber that is filled and coated on the woven cloth tape, or to use conductive rubber that has good adhesion to the woven cloth tape. There are two methods: one is to fill and cover the woven fabric tape with rubber, and the other is to specify the heat shrinkage rate of the woven tape itself.However, since the latter effect is more dominant, it is best to apply the latter method in practice. is preferred.

In that case, the temperature should be 100℃ with respect to the warp direction of the woven cloth tape.
At the above temperature, the threads of the woven fabric tape may be heat set by applying a hot tenter heat setting method known as one of the shrink-proofing methods.

(Function) Since the semiconductive cloth tape of the present invention has a thermal shrinkage rate of 0.5% or less in the warp direction at 100°C, the force for tightening the cable core during heat cycling is smaller than that of conventional ones. As a result, problems of unevenness and twisting on the surface of the cable core will not occur.

(Example) Example 1 A polyester spun yarn with a diameter of 0.1 mff1 was used as the warp yarn, and a polybutylene terephthalate stretchable yarn (thread made by adding wrinkles to a continuous yarn to give it elasticity) with a diameter of 0.1 mm was used as the weft yarn. A plain-woven woven tape was prepared.

The warp direction of this woven fabric tape was heat set by a hot tenter heat setting method at a heating temperature of 200'C and a heating time of 3 minutes.

Next, conductive butyl rubber (volume resistivity: 104 Ω-cm) was densely filled and coated on both sides of this woven fabric tape to form a conductive butyl rubber layer with a smooth surface.
A semiconductive cloth tape of the present invention having a volume of 8 ml and a width of 50 mm was produced.

Example 2 The woven fabric tape was diagonally patterned using O.1 m diameter polyester spun yarn for the warp and 0.1 rrm diameter polyester stretchable yarn for the weft. Heating temperature and heating time are each 210
A semiconductive cloth tape was produced in the same manner as in Example 1, except that the temperature was 2 minutes.

Comparative Example 1 The woven fabric tape was plain-woven using polyester spun yarn with a warp and weft diameter of 0.1 ws, and the heating temperature and heating time in the hot tenter heat setting method were 180% each. A semiconductive cloth tape was produced in the same manner as in Example 1, except that the temperature was 1 minute.

Comparative Example 2 The woven fabric tape was plain-woven using nylon spun yarn with a diameter of 0.1 ann for both the warp and weft, and the heating temperature and heating time in the hot tenter heat setting method were 170% each. A semiconductive cloth tape was produced in the same manner as in Example 1, except that the temperature was 130 seconds.

The above four types of semiconductive cloth tapes were left in a constant temperature bath at 100"C for 5 minutes, and the amount of shrinkage in the warp direction (longitudinal direction) and weft direction (width direction) at that time was measured and the values were calculated. The heat shrinkage rate was calculated from the following.The results are shown in Table 1.

In addition, these semiconductive cloth tapes can be used at 35KV.

After wrapping 172 wraps on the outer conductive layer of a 50mm" C■ cable, a copper wire shielding layer with a diameter of 1.6mm was placed on top of this, and then a PVC anti-corrosion layer was extruded and coated on top of it. It was used as a power cable.

130℃ by energizing the conductor for each cable
#After applying heat cycles at room temperature 50 times, each cable was disassembled and the condition of the cable core surface was observed. The results are shown in Table 1.

Table 1 (Effects of the Invention) As is clear from the above explanation, the semiconductive cloth tape for power cables of the present invention has a low heat shrinkage rate of 0.5% or less at 100°C in the warp direction, so it is suitable for cables. The force for tightening the cable core during the heat cycle of the core is reduced, making it possible to prevent surface irregularities and twisting of the cable core, which has great industrial value.

4,

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a semiconductive cloth tape. ■... Woven fabric tape, 1a... Warp, ■b... Weft, 2... Conductive rubber layer.

Claims (1)

[Claims] Consists of a woven fabric tape and a conductive rubber layer that fills and covers the inside and outside of the tape, and has a heat shrinkage rate of 0.5 at 100°C in the warp direction.
% or less. A semiconductive cloth tape for power cables.