JPS6040124B2 - OF cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal oil-cooled cable in which a cooling medium and an insulating oil are shared, particularly an OF cable used in a radial flow type oil-cooled cable described below.

The radial flow type cooling system, as shown in FIG.
In this method, the insulating oil discharged from the sheath-side oil passage 18 is taken out of the cable, passed through a cooler 30, and fed back into the cable by a pump 32 for circulation.

This cooling method has the effect of reducing the thermal resistance of the insulating oil 16.

However, there are also concerns.

In this cooling method, the cooling medium and the insulating oil of the cable are shared.

The circulating insulating oil contains the following fine solid particles,
'11 Welding debris from the cooling pipe 34, '2) Metal powder due to wear of the rotating part of the pump 32, '31
During the connection work, metal powder generated by cutting the conductor 14 and the metal sheath 20 is mixed in.

They are mainly metal, and many of them have a size of several meters to several hundred Amps. The radial flow of insulating oil (hereinafter referred to as radial flow) within the cable 10 includes a second flow.
In the figure, there is one that penetrates the insulating paper 160 as shown by the {1' arrow 36, and one that passes through the butt gap 162 and the waste space 164 as shown by the arrow 38.

The flow indicated by the arrow 38 is approximately 60 to 80% of the radial flow when the insulating oil 16 is made of kraft paper, and is 100% when the insulating oil 16 is made of plastic laminated paper.

Solid particles contained in the insulating oil flowing in the direction of arrow 36 are filtered only by the innermost layer of insulating paper 1601.

However, the solid particles contained in the insulating oil flowing in the direction of arrow 38 enter the insulating layer together with the insulating oil, and the butt cap 16
2 and the interlayer 164.

In addition, the insulation properties of the insulating oil 16 are deteriorated. Note that in a typical internal oil-cooled forced cooling circulation system, a metal mesh filtration device is installed in the middle of the piping.

However, the filtration accuracy is usually about 100 to 150 mm. Increasing the filtration accuracy increases pressure loss, and a large filtration area is required to compensate for this. This makes the filter large and expensive. Moreover, the solid particles generated when the legs are connected remain in the cable and cannot be removed by the filter in the circulation system. The present invention eliminates the above drawbacks and prevents solid particles from entering the insulating oil 16. Embodiment (FIG. 3) A layer of conductive or semiconductive cloth 40 is provided over the hollow conductor 14 (between the conductor 14 and the semiconductive paper 22), thereby preventing the radial flow of the insulating oil. Do this.

Examples of the conductive or semi-conductive cloth 40 include:
Ultra-fine copper wire, or thread made of oil-resistant plastic (polyester, polycarbonate, etc.) mixed with carbon, is used in the form of a tape made from a woven fabric that is tied at intervals of several meters.

Also, oil-resistant plastic fibers (such as polyester)
A nonwoven fabric bonded with a conductive adhesive (such as carbon-containing acrylic resin) may also be used.

The cloth 40 that can be stretched to this extent has low oil flow resistance.

Therefore, all of the radially flowing insulating oil flows through the layered filter cloth 40, so that the solid particles contained in the insulating oil are caught by the filter cloth 4 and do not penetrate into the insulating oil 16. Effect of the invention '1} Since the layer of filter cloth 40 is provided on the hollow conductor 14, solid particles do not enter into the insulating oil 16 as described above.

{21 Even if solid metal particles accumulate on the filter cloth 40, the insulation properties of the cable 10 will not be adversely affected because the filter cloth 40 is conductive or semiconductive.

[3' If you try to install a filter with several m in diameter in an insulating oil circulation system, you will need a very large filter with a wide filtration area as described above.

However, in the case of the present invention, the layer of filter cloth 40 corresponding to the filter is a long cylindrical layer surrounding the internal oil passage 12 over the entire length of the cable 10, so the filtration area is very small.

Therefore, as mentioned above, the fine solid particles of the insulating oil can be filtered out using the cloth 40 that extends to the extent that it does not obstruct the flow of the insulating oil. ■
Metal particles generated during cutting of the cable 10 and remaining in the connection can also be removed by the layer of filter cloth 40.

{5} Since the filter cloth 40 is wrapped around the hollow conductor 14, the workability is good.

[Brief explanation of drawings]

Figure 1 is a general explanatory diagram of the radial flow type internal oil cooling system, Figure 2 is an explanatory diagram of the method of radial flow of insulating oil,
FIG. 3 is an explanatory diagram of the main parts of the embodiment of the present invention. 10... Cable, 12... Internal oil passage, 14... Hollow conductor, 16... Insulating layer, 18... Sheath side oil Aisle, 40...
・Filter cloth. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A radial flow type OF cable characterized by having an overlapping layer of semiconductive or conductive filter cloth provided on a hollow conductor.