JPH02270218A - Insulated wire - Google Patents

Abstract

PURPOSE:To prevent partial discharge deterioration by a method wherein an insulation layer comprises polyetherketone and a semiconductor layer comprises intimate mixture of specific polymer and conductive carbon black. CONSTITUTION:A semiconductor layer 2 and an insulation layer 3 are provided on a conductor 1 wherein the insulation layer 3 comprises polyetherketone(PEEK) and the semiconductor layer 2 comprises intimate mixture of polymer which is not subjected to thermal decomposition even if it is heated to 400 deg.C for 5 seconds, such as PEEK, polyetherketone and conductive carbon black. Therefore electric field gradient between the insulation layer 3 comprising PEEK and the conductor 3 is relaxed. Thus partial discharge deterioration can be prevented thereby obtaining stable electric characteristics over long-term electric charge.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an insulated wire having an insulating layer made of polyetheretherketone.

[Conventional technology]

BACKGROUND ART Recently, PEEK insulated wires having an insulating layer made of polyetheretherketone (hereinafter abbreviated as PEEK) have been attracting attention as insulated wires with extremely excellent heat resistance.

This is because PEEK has a high melting point of 340°C or higher and excellent thermal stability in a high bulk region of about 100 to 300°C.

[Problem to be solved by the invention]

However, in such PEEK insulated wires, PEEK is a very rigid and inflexible polymer, so if the insulated wires are bent or stretched,
If the adhesion between the PEEK insulating layer and the conductor deteriorates, creating a gap between the insulating layer and the conductor, and as a result is subjected to high electrical stress over a long period of time, corona will form in the gap. There are problems such as dielectric breakdown due to the occurrence of.

[Means to solve the problem]

In this invention, the above-mentioned problem can be solved by interposing a semiconducting layer made of a mixture of polymer and carbon black that does not cause thermal decomposition by short-time heating at 400°C for 5 seconds between the PEEK insulating layer and the conductor. I tried to solve it.

The present invention will now be described in detail.

FIG. 1 shows a first example of an insulated wire according to the present invention, and reference numeral 1 in the figure indicates a conductor. The conductor 1 is a twisted conductor made by twisting together a plurality of metal wires. A semiconducting layer 2 is provided on this conductor l. This semiconductive layer 2 is formed by coating the conductor 1 with a mixture of a polymer and conductive carbon black that does not undergo thermal decomposition when heated for a short time at 400° C. for 5 seconds, using an extrusion coating method or the like. . The polymer used here may be any polymer that does not undergo thermal decomposition even when heated for a short time of 5 seconds at 400°C.
For example, PEEK, polyetherketone, silicone resin, silicone rubber, fluororesin, 7) bare rubber, polyamide, polypropylene, polyethersulfone, polyacrylate, polyester, etc. are used. Further, as the carbon black, well-known carbon blacks such as acetylene plaque and furnace black, which have conductivity, can be used. The amount of carbon black added to the polymer is determined depending on the required conductivity, but it is usually about 20 to 150 parts by weight per 100 parts by weight of the polymer, and it is designed to have a volume resistivity of 10° to 10'' Ω・cIll. adjusted to.

Here, the reason why we selected a polymer that does not cause thermal decomposition when heated at 400°C for 5 seconds is as follows.
When extrusion coating the insulating layer 3 made of PEEK on the semiconductive layer 2, heat of about 400°C is applied to the semiconductive layer 2 for about 5 seconds, so even if subjected to this thermal history, the semiconductive layer 2 This is to prevent problems such as foaming due to thermal decomposition.

An insulating layer 3 made of PEEK is provided on this semiconductive layer 2. This insulating layer 3 is formed by extrusion coating PEEK. When extrusion coating PEEK, PE
Since EK is a crystalline polymer, it is preferable to increase the degree of crystallinity by slow cooling after extrusion, since good electrical insulation and mechanical properties can be obtained.

Note that the semiconductive layer 2 and the insulating layer 3 can be extruded and coated simultaneously by coextrusion.

In the insulated wire having such a structure, since the semiconducting layer 2 is interposed between the insulating layer 3 made of PEEK and the conductor l, deterioration of the insulating layer 3 due to partial discharge etc. is prevented. . Further, when the insulating layer 3 made of PEEK is extruded and coated, the semiconductive layer 2 is not thermally decomposed by the heat of the extruded coating, and the function of the semiconductive layer 2 is not deteriorated. Furthermore, since there is a gap between the conductor 1 and the semiconducting layer 2, it has excellent flexibility.

FIG. 2 shows a second example of the insulated wire of the present invention. In this example, the voids of the stranded conductor 1 are also filled with the semiconducting layer 2, so the semiconducting layer 2 acts as a watertight material. also works.

FIG. 3 similarly shows a third example.

In this example, the conductor l is a single wire conductor. P.E.
As mentioned above, EK is a hard polymer, so even if the insulated wire is a single conductor like this example, if it is repeatedly bent, a gap will be created between the conductor l and the insulating layer 3.
Although it is still a cause of partial discharge deterioration, conductor 1 and insulating layer 3
This can be prevented by interposing the semiconductive layer 2 between the two.

〔Example〕

Seven copper wires with a diameter of 0.2 as are twisted together to form a twisted conductor, a mixture of silicone rubber and carbon black is extruded and coated on top of the wire, and a semiconductive layer with a thickness of 0.2 a + i is provided. An insulating layer was provided on this by extrusion coating PEEK to obtain an insulated wire.

AClokV was applied to this insulated wire, and the time until dielectric breakdown occurred was determined.

The results are shown in Table 1.

As is clear from Table 1, in the case of the semiconductor device provided with the semiconductive layer, the time required to reach dielectric breakdown is longer, and it can be seen that it is effective in preventing partial discharge deterioration.

〔Effect of the invention〕

As explained above, the insulated wire of the present invention is an insulated wire in which a semiconducting layer and an insulating layer are provided on a conductor, the insulating layer is made of polyetheretherketone, and the semiconducting layer is heated at 400° C. for 5 seconds. Since it is made of a mixture of a polymer that does not cause thermal decomposition and conductive carbon black, the electric field gradient between the insulating layer made of polyetheretherketone and the conductor is slowed down, preventing partial discharge deterioration. This is prevented, and it has stable electrical characteristics over a long period of time.

[Brief explanation of drawings]

1 to 3 are schematic cross-sectional views showing examples of the insulated wire of the present invention. 1...Conductor, 2...Semiconducting layer, 3...
...Insulating layer.

Claims (1)

[Claims] An insulated wire having a semiconducting layer and an insulating layer provided on a conductor, wherein the insulating layer is made of polyetheretherketone, and the semiconducting layer is thermally decomposed by heating at 400°C for 5 seconds. An insulated wire characterized in that it is made of a mixture of a free polymer and conductive carbon black.