JPH05274926A - Insulated divided conductor cable having bridged polyethylene insulated wires - Google Patents

Abstract

PURPOSE:To ensure easy manufacture and improve such capability as preventing the occurrence of skin separation by using a polyamide enameled wire as a conductor wire, and specifying the skin thickness of the enameled wire. CONSTITUTION:The divided conductor of a CV power cable comprises six segments 1 and each conductor wire 2 constituting each segment 1 has a coaxial multilayer structure. For the surface of the wire 2, an amide enameled wire 4 covered with a polyamide insulation skin 3 is used, and the thickness of the skin is taken at a value between 10 and 20mum. The wire 4 has excellent characteristics in terms of heat resistance, chemical resistance, oil resistance, abrasion resistance, hydrolysis resistance or the like. Thus, the separation of the skin does not occur even in a wire twisting work similar to a conventional case, so far as the skin thickness between 10 and 20mum is maintained. Also, the wire 4 is not affected by high temperature (approximately 210 deg.C) at the time of extruding and bridging an insulator, and the occurrence of decomposition, adhesion or the like due to a bridging agent and a residue after reaction can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is particularly applicable to large size conductor C.
It relates to a V power cable.

[0002]

2. Description of the Prior Art Large size conductor power cables, such as O
The F (oil-filled) power cable uses a split conductor to reduce the AC resistance of the conductor. The AC resistance is greatly reduced by using the conductor as an insulated wire divided conductor made of a conductive element. The strands of the split insulated conductors are those obtained by forming a cupric oxide film on the surface of a conventional copper line, polyvinyl formal (hereinafter referred to as PVF).
Enamel wire and phenol aldehyde resin coated insulated wire with a film thickness of about 10 μm (for example, Japanese Patent Publication No. 62-12
Japanese Patent Laid-Open No. 603) is known.

[0003]

In forming the cupric oxide film on the surface of the copper wire as described above, the conductor is held in a humidified atmosphere in which ions or ionic compounds coexist in order to form the film, or at a high temperature. It is difficult to manufacture because it requires the use of a strongly corrosive chemical such as immersing the conductor in sodium hydroxide. In addition, when a film is formed with an elemental wire and twisted, the film is relatively weak and, furthermore, peeling occurs because it is thin (about 1 μm). On the other hand, in the process after twisting, whether the inter-wire contact surface is sufficiently coated,
In addition, there is a concern that chemicals may not remain after the treatment.

A problem with the above PVF coating method is that the strength of the coating is relatively weak and heat resistance and chemical resistance are poor.

Further, a problem with the above-mentioned phenol aldehyde resin-coated wire is that the CV cable has a large surface pressure between the wires and cannot obtain sufficient performance.

An object of the present invention was made in view of the above circumstances, and an object thereof is to provide a wire insulated split conductor CV (crosslinked polyethylene) cable which is easy to manufacture and has excellent performance.

[0007]

According to the present invention, a polyamideimide enameled wire is used as a conductor element of a crosslinked polyethylene insulation element insulated divided conductor cable, and the polyamideimide enameled wire has a coating thickness of 10 to 20 μm. It is a polyethylene insulated wire insulated split conductor cable.

[0008]

By using an amide-imide enameled wire having a film thickness of 10 to 20 μm as the wire, the heat resistance, chemical resistance and mechanical strength of the cross-linked polyethylene insulation wire insulated divided conductor can be remarkably improved. ..

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings. The split conductor 1 of the CV power cable is shown in FIG.
As shown in, for example, it is composed of six fan-shaped segments. The conductor wire 2 constituting each segment 1 has a concentric multi-layer structure as shown in the sectional view of the upper right one segment, and the surface of the conductor wire 2 is covered with an insulating film 3 of polyamide-imide. An amidimide enameled wire 4 is used.

The polyamide-imide insulating film 3 has the structural formula shown in FIG. 2 as the material of the enamel, and at the time of manufacturing the enamel wire, the enamel is made of an N-methylpyrrolidone solvent having the structural formula shown in FIG. It is manufactured by applying the liquid dissolved in the above to the surface of the same filament and baking it in a high temperature furnace. The heating loss of this enamel wire is extremely small up to a temperature of 200 ° C. as shown in FIG. Also, 2
At a temperature of 00 ° C, some moisture and residual solvent are absorbed in the film, but at 100 ° C, it is not extracted at all.

275 kVCV power cable 1 × 2500
mm ² (5-division conductor, insulation thickness 27 mm) was changed to 5 μm, 10 μm, 15 μm and 20 μm for the film thickness of the wire, and trial production was carried out, and the skin effect of the conductor of each of 20 materials was measured.
The result is shown in FIG. In this figure, the horizontal axis represents the variation of the conductor wire, and the vertical axis represents the skin effect of the conductor wire of this conductor.
The ratio to the theoretical value at 100 ° C. and 50 Hz is shown. That is, it is shown that a coating thickness of 15 ± 5 μm or more is required to obtain a sufficient effect as a wire insulated conductor.

Even with a cable having a coating thickness of 5 ± 3 μm, the skin effect was 102% of the theoretical value when the insulator was longitudinally divided so that no force was exerted on the conductor. That is, in a CV cable, the conductor tightening force of the insulator is large, and thus the insulation effect between the strands cannot be obtained unless the film thickness between the strands of the conductor is sufficiently thick, so that the skin effect becomes large. I understood.

Next, at the time of connecting the wire insulated conductors, it is necessary to remove the film of each wire and then perform a compression connection or the like using a conductor sleeve. To remove the film, the wires are spread and sandblasted. The method etc. are carried out. FIG. 6 shows the test results of the film removal time (sand spraying net time) per terminal of the above conductor by the sand blast method. The film removal time increases depending on the film thickness.
As a matter of course, the shorter the film removal time, the more desirable.

The film thickness on the horizontal axis in FIGS. 5 and 6 is a target value at the time of manufacturing the wire. On the other hand, the measured film values of 20 strands sampled from the manufactured cable are shown in Table 1.
The target value is almost satisfied.

[0015]

[Table 1]

As a result of the above, a film thickness of 10 μm or more is required in terms of skin effect performance, and a thinner film is preferable for removing the film, but in order to secure a minimum of 10 μm in wire production, the range is limited to a maximum of 20 μm. It was done.

[0017]

As described above, according to the present invention, an amide-imide enameled wire is used for the cross-linked polyethylene insulation wire insulated split conductor cable. The amide-imide enameled wire has heat resistance, chemical resistance, oil resistance and wear resistance. It is the best enameled wire in the present condition in terms of properties such as resistance and hydrolysis resistance, and has the following excellent functions as a conductor for CV cables.
Produce an effect.

Even in the same twisting work as in the current situation, 1
If the coating thickness is 0 to 20 μm, peeling of the coating does not occur. No peeling of the coating occurs even during the process from manufacturing to installation or when the wires are slipped due to the bending of the cable during thermal expansion and contraction. It is not affected by the high temperature (about 210 ° C) during extrusion cross-linking of the insulator. No decomposition or adhesion will occur due to the cross-linking agent of the insulator or the residue after the reaction. At 210 ° C. or lower, there is no heating loss and no adverse effect on the insulator.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a divided conductor of a crosslinked polyethylene insulated wire divided conductor cable according to an embodiment of the present invention,

FIG. 2 is a structural formula of a polyimide enamel applied to the present invention,

[Fig. 3] N of polyimide enamel applied to the present invention
-Methylpyrrolidone solvent structural formula,

FIG. 4 is a graph showing the results of thermogravimetric analysis of an enamel film,

FIG. 5 is a graph showing the measurement results of the skin effect of the film thickness of the wire,

FIG. 6 is a graph showing the film thickness of a wire and the time required for sandblasting.

[Explanation of symbols]

 1 Divided segment 2 Conductor element wire 3 Insulation film 4 Amidoimide enameled wire

Claims (1)

[Claims] 1. A crosslinked polyethylene insulation element, characterized in that a polyamideimide enameled wire is used as a conductor element of a crosslinked polyethylene insulation element insulation divided conductor cable, and the film thickness of the polyamideimide enameled wire is 10 to 20 μm. Wire insulated split conductor cable.