JPS59184408A - Internal cooling type power 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〕 The present invention relates to the structure of an internally cooled power cable.

[Background technology]

Internal cooling power cables, which flow a cooling medium through the internal passages of the conductor to directly cool the heat source inside the conductor, are being developed as future large-capacity power cables for introduction into urban centers, and an example is shown in Figure 1. is shown in cross-sectional view.

In the figure, 1 is a refrigerant passage, 2 is a metal pipe for forming the refrigerant passage, 3 is a copper stranded wire for a current passage, and 4 is an insulator such as crosslinked polyethylene.

In this way, the conductor part is generally composed of the internal refrigerant passage pipe 2 and the conductor made of the copper stranded wire 3 as the current passage, but as the refrigerant passage forming pipe 2, a light and airtight pipe is used. Aluminum was chosen because it allows for the manufacture of long pipes, and copper stranded wire conductors were chosen because they are flexible even in large cross-sections and are highly conductive as current paths.

In the case of a power cable having such a conductor structure and having a solid insulating material such as crosslinked polyethylene or non-crosslinked polyolefin as an insulator thereon, there are the following drawbacks.

In the case of a solid insulator, an air layer is left between the aluminum pipe 2 and the external steel wire 3, and this air layer causes large contact between each strand of the aluminum pipe 2 and the copper stranded wire 3. A thermal resistance, also called thermal resistance or film thermal resistance, occurs. When the heat generated in the conductor is absorbed by the refrigerant, this thermal resistance creates a large temperature gradient between the refrigerant temperature in the refrigerant passage and the maximum temperature of the conductor, reducing the cooling effect.

In addition, the moisture present in the air layer forms a contact battery of different metals, resulting in corrosion. However, this drawback does not occur in OF cables where the gaps between the conductors are filled with oil, and is unique to solid insulated cables.

[Disclosure of the invention]

In order to solve the problems that the conventional internally cooled solid insulated cable described above has poor cooling effect and corrosion, the present invention has been developed to This is intended to prevent corrosion due to the boundary by enclosing a compound that is a good thermal conductor. In addition to the gap between the copper stranded wire and the aluminum pipe, there is also a gap within the copper stranded wire as a gap within the conductor, and if this portion is also filled with the compound, it will be more favorable in terms of heat conduction.

FIG. 2 shows a cross-sectional view of an embodiment of the conductor of the present invention.

In the figure, the same parts as in FIG. 1 are given the same reference numerals.

A refrigerant passage 1 is formed by the aluminum pipe 2, and a current passage for the twisted wire 3 is formed around the outer periphery of the twisted wire 3 using the aluminum vibrator 2 as the core.
between each strand of wire and between the stranded wire 3 and the aluminum pipe 2,
Although not shown, the insulator side semi-conductive polyester) is a corrosion-resistant compound with non-swellability and good heat conductivity for the ethylene layer 5
For example, a silicone grease-based compound or EVA mixed with metal powder is sealed, and the outer periphery thereof is coated with a semiconducting material as described above, or a solid insulating material (for example, a crosslinked polyethylene insulating material).

By enclosing such a good heat conductive anti-corrosion compound 5, the thermal resistance of the film between the aluminum pipe and the copper wire is reduced, and by eliminating the moisture present in this area, the copper,
Corrosion caused by dissimilar aluminum batteries can be prevented.

Note that in the present invention, copper stranded wire means all stranded wires such as compression molded stranded wire, round stranded wire, and flat stranded wire.

Table I shows test examples conducted to confirm the effects of the present invention.

A refrigerant was flowed through a cable having a conductor size of 2000 tnrJ and a semiconductive polyethylene layer and a cross-linked polyethylene insulator applied to the conductor portion as a test product, and then electricity was applied to examine the results.

In Table 1, A indicates that there is no compound between the wire and the aluminum pipe, B indicates that a polybdenum compound is sealed, and C indicates that a silicone grease compound is filled as an example of the present invention. This is a term that indicates what has been done.

Also, ■ indicates the temperature difference between the I) wire and the refrigerant when energizing at 15 KA, ■ indicates the presence or absence of swelling after energizing in an underwater heat cycle at 80°C for 100 days, and ■ indicates the .

This section shows the state of the conductor after being subjected to a 100-day underwater heat cycle.

Table 1 [Function and Effect] As shown in Table 1, if the film is filled with a good thermally conductive compound, the thermal resistance of the film will be significantly lower than that without filling. Materials that cause swelling in semiconducting layers and crosslinked polyethylene insulators are unsuitable.

Therefore, if a non-swellable compound that does not cause swelling to the semiconducting layer or insulator and has good thermal conductivity is used as in the present invention, a large-capacity battery that can be used stably for a long period of time can be used. You can get Kacaple.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a typical internally cooled power cable. FIG. 2 is a sectional view of one embodiment of the present invention. 1 refrigerant passage, 2 metal nozzle for forming refrigerant passage, 3.
... Stranded wire, 4. Insulator, 5. Good thermal conductive conductor land. Figure 1-Figure 2

Claims (1)

[Claims] (+) In an internally cooled power cable that uses a solid insulator as the insulator, the conductor part is composed of an aluminum pipe and copper stranded wire, and the insulator, etc. is placed in the gap formed between the steel stranded wire and the aluminum pipe. An internally cooled electrical cable that is characterized by being filled with a compound that does not swell and has good thermal conductivity.