JPS60124313A - 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 The present invention relates to improvements in internally cooled power cables.

In general, internally cooled cables that directly cool the conductor from the inside use water, oil, or fluorocarbon as the refrigerant used for cooling.

Then, as illustrated in FIG. 1, the refrigerant is cooled in a refrigerant cooling section 2 installed in the circulation path 1, pressurized with a metal bonder 3, and passed through an insulating pipe 4 into a cable 6 of a high voltage section 5. The liquid is cooled by being pumped into the air, and is then refluxed to the circulation path 1 via another insulating pipe 4a'5.

However, internally cooled power couples, which can only be used in furnaces, inevitably suffer from various problems as described below.

(1) When water is used as a refrigerant, even when water quality is strictly controlled such as ion exchange water, its volume resistivity is 1.
04 to 106 Ω-(7), and is exposed to a high voltage when it takes heat from the high voltage conductor and returns to the heat dissipation circuit of the earth potential, and approximately W=V/, (W: amount of heat, ■：
It generates heat corresponding to the voltage (R: resistance), and there is a risk of sudden boiling if the refrigerant flow were to stop.

The refrigerant needs to be completely insulated in the above-mentioned insulating pipe, but water is so low that it has to be kept for a long time.

(11) By using insulating oil such as mineral oil or alkylbenzene as a refrigerant, the above-mentioned problems with aqueous media due to carbon dioxide can be almost solved. If a pinhole were to occur in the refrigerant pipe, serious problems may occur due to a decrease in insulation performance.

Furthermore, in the event of a cable ground fault, if the refrigerant pipe ruptures and some insulating oil spouts out, there is a risk of fire due to the VCN catching fire.

[011] Freon easily boils under high temperatures, and there is a risk of the above-mentioned pressure loss accident in the refrigerant circuit, and other problems such as unavoidable instability in cooling performance in general.

As a result of intensive studies to solve all of these problems, the inventors have determined that tyc phosphate ester alone as a refrigerant is a synthetic hydrocarbon with a viscosity of 15 cst or less at 40°C in an amount of 5 Q vol% or less. The present invention has found that the above problems can be solved by using a mixture substituted with oil or one or more oils selected from the group of silicone oils or mineral oils. It was completed.

That is, the present invention provides an internally cooled vehicle cable in which a refrigerant passage is lined inside the conductor and polyethylene, cross-linked polyethylene, or oil-impregnated insulating paper is used as the insulator, and the refrigerant is a monophosphate-based phosphate ester alone or the like. 50v
j below oL%! :'(] Viscosity at 1-40℃ is 1
5 Refrigerant using synthetic hydrocarbon oil or mineral oil or mixture substituted with silicone oil below C5l? This is an internally cooled car cable that is characterized by the use of

One embodiment of the present invention cable structure is shown in full in FIG.

In the figure, reference numeral 11 denotes a refrigerant flow path defined by refrigerant pipes 12 made of aluminum, copper, etc., through which the refrigerant flows. 13 is a divided conductor, and 14 is polyethylene.

Insulator made of cross-linked polyethylene or oil-impregnated insulating paper, 1
Reference numeral 5 denotes a capture sheath, and the structure and material thereof are selected in a known manner.

In this invention, at least 50 vot% of the above-mentioned refrigerant
Specifically, the phosphate esters used for binding include tricresyl phosphate (hereinafter referred to as TCP),
) lyxylenyl phosphate), ('i'xP).

) IJ (ethylphenyl) phosphate (TEP)
.

Tri(isopropylphenyl)phosphate (TPP)
.

Cresyl diphenyl phosphate) (CDP)'4f#
yi used.

〃) The volume resistivity of phosphoric acid ester is 1012 to 1018 Ω, which is significantly higher than that of water, does not completely swell polyethylene, etc., and the above cooling performance for Schiff 11 is at least equivalent to mineral oil, alkylbenzene, etc. Moreover, it has the characteristics of not having flammability, etc., and are these the above problems? It will be resolved.

Next, the above-mentioned phosphate-based phosphate esters tend to have a viscosity of approximately 30 CP (30° C.), which tends to increase the load on the circulation pump during cable cooling.

〃)71) In the case of 71), an alkylbenzene or alkyldiphenylethane having a viscosity at 40°C of 15 cst or less relative to the phosphate ester.

At least one synthetic hydrocarbon oil such as alkylnaphthalene, silicone oil, or mineral oil 50 v of the total amount of refrigerant
The appropriate viscosity can be obtained by mixing the amount below ot%,
Fire extinguishing properties are also maintained sufficiently for deer.

Specifically, about 50% of the above mineral oil and alkylbenzene
In the case of π mixed with vot%, the viscosity is l0CP (30℃)
However, the fire extinguishing properties were sufficiently maintained.

In the present invention, when the insulator is made of polyethylene, cross-linked polyethylene, etc. and the TC electric cable is used, phosphoric ester alone or silicone oil is used as the refrigerant.
It is preferable to mix 50 vol or less of 1% or less in order to prevent swelling of the polyethylene and crosslinked polyethylene insulators.

The present invention will be made clear from the above description and the explanation of Examples below.
↓The use of phosphate-based phosphoric acid ester as a refrigerant is particularly effective in maintaining the insulation properties of internally cooled vehicle cables, eliminating safety problems such as heat generation, flammability, and damage to refrigerant pipes. Therefore, its industrial utility value is extremely large.

The present invention will be specifically explained below with reference to characteristic tests, examples, etc.

Examples and Comparative Examples (1) Characteristic Test Among the bosphate-based phosphate esters used as refrigerants in the present invention, the characteristics of TCP, TXP, and CJJP described above,
Table 1 shows the results of comparison with alkylbenzenes and the like.

(Note 1) Here, the cooling capacity ratio is the cooling distance approximately expressed by the following formula. It is expressed as a ratio to water.

Here p: pressure drop of refrigerant σ: Refrigerant density θ; temperature rise of refrigerant ξ: Total refrigerant viscosity dNipaizo inner diameter C: Specific heat of refrigerant W: Incurred loss Therefore, the cooling distance ratio k Lt of the two types of refrigerants.

Assuming L2 becomes.

(Note 2) Cross-linked polyethylene sheet (1tym thickness) k
It is expressed as the weight increase rate after 7 days of immersion at 0°C.

(Note 3) (2) Boiling resistance test according to JIS C2101 The following refrigerant is housed in an insulator tube of 10 strokes in diameter x 2 tts in length, the ends are closed, and a voltage of 200 KV is applied to both ends. When I poured it on, the water boiled in 5 seconds.

As a general rule, 5 fluorocarbons, oil, and phosphate-based phosphate esters do not boil at all.

(3) Ground fault test An internally cooled power cable was constructed according to the specifications below, and the characteristic sound of each cable at the time of a ground fault was investigated and the results are shown in the table below. Types of refrigerant within the specifications of the internally cooled cable Water, Freon , todecylbenzene (DDB), silicone oil, and phosphoric acid ester (TCP) were used.

Regarding the example cable and comparative example cable 1 with the above configuration, the conductor and sheath were short-circuited with a shorting lead (nail), and a ground fault current of VrC40KA Ta. The results were as shown in Table 2.

As is clear from the results of the cable characteristic tests and comparative tests shown in Table 2 and above, it is clear that the internally cooled cable of the present invention is extremely superior in stably maintaining cable properties and in various safety aspects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a general use of an internally torsion-resistant helical cable, and FIG. 2 is a sectional view of the cable of the present invention. DESCRIPTION OF SYMBOLS 11... Refrigerant path, 12... Refrigerant pipe, 13... Conductor, 4... Absolute body, 15... Sheath. Patent applicant Furukawa Electric Co., Ltd.

Claims (1)

[Claims] +1) In an internally cooled cable that has a refrigerant passage inside the conductor and uses polyethylene, crosslinked polyethylene, or oil-impregnated insulating paper as an insulator, the refrigerant is a phosphate-based phosphate ester alone, or 5
an alkylbenzenealkyldiphenylethane having a viscosity at 40° C. of 15 cst or less in an amount of 1 ovot% or less;
A mixture substituted with one or more oils selected from the group of hydrocarbon oils such as alkylnaphthalenes, silicone oils, or mineral oils? An internally cooled cable with all the features used.