JPS58195420A - Method of cooling 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 a method for cooling a radial flow internal oil-cooled power cable.

The background of the invention will be described.

1 and 2 are explanatory diagrams of a conventional radial 70 type internal oil cooling system.

10 is the entire cable, 12 is its internal oil passage, 14 is a conductor, 16 is an insulating layer, 18 is an external oil passage, and 20 is a sheath. In FIG. 1, the cable 10 is shown only by an internal oil passage 12 and an external oil passage 18.

A is one cooling section, and there are usually two refueling junction boxes at both ends.
2A and an oil removal connection box 22B are provided. A cooling base 24 includes a cooling device 26, a pressure pump 28, and the like.

In the cooling station 24, pressurized and cooled oil (refrigerant) is fed into the internal oil passage 12 of the cable 10 at one end of the cooling section A, for example at the oil supply junction box 22A. The conductor 14 is then cooled while flowing toward the oil outlet connection box 22B at the other end.

At the same time, the oil flows in the radial direction (hereinafter referred to as radial 70-) through the insulating paper itself and between the layers of the insulating layer 16.
It exits to the external oil passage 18. The oil discharged to the external oil passage/path 18 flows, for example, in the same direction as the oil in the internal oil passage 12, and is taken out of the cable 10 at the oil extraction connection box 22'B.

Then, at the cooling base 24, it is cooled under pressure again, and fed into the cable 10 in the same manner as described above, and this process is repeated thereafter.

This radial flow type cooling system reduces the apparent radial thermal resistance of the insulation layer 16 and makes it possible to realize a high capacity internally oil-cooled cable.

However, this radial flow type cooling system also has 11...
“I have the following problems:...

In other words, compared to normal internal oil q + t (not radial flow type), the external oil passage 18 has a considerably higher temperature □□□
A large amount of oil flows. In particular, when the direction of the oil flowing in the internal oil passage 12 and the external oil passage 18 is the same as shown in FIG. The flow rate and temperature in the passage 18 become higher, and the temperature difference between them becomes smaller. As a result, the amount of heat dissipated in the radial direction from the conductor 14 is reduced,
The cooling effect of the conductor 14 decreases, which also limits the length of the cooling section A.

Furthermore, in the case of a cable installed inside a tunnel, there is a risk that the temperature inside the tunnel will rise excessively.

As a result, the length of the cooling section A may be limited by the temperature within the tunnel rather than by the temperature of the conductor 14.

Generally, the distribution of oil temperature and flow rate in a certain section of a radial flow type internal oil-cooled cable as shown in Figure 7 is 1. The origin of the iron is the oil cooling base 24 side, and the cooling oil from the cooling base 24 is connected to the oil supply pipe.
1. Supply the cable through the oil supply junction box 22A.
1 shows the distribution when oil is supplied into the internal oil passage.

From this figure 3 (a) (1:,), oil is held within this section. The amount of heat can be expressed in "Conclusion 3 (C)". That is, since the flow rate of oil flowing through the external oil passage 18 increases gradually toward the cooling base 24 side (near the cooling base, it becomes almost equal to the internal oil passage meat supply flow rate).
, the amount of heat it possesses also increases, and is within 1/3 of the distance between the cooling base 24 and the refueling junction box 22A (as seen from the cooling base side).
In this case, the heat amount of the oil in the external oil passage is more than 50% of the total.

Therefore, especially within this section, if the oil in the external oil passage is taken out to the outside and cooled, more than half of the heat held by the oil will be taken out, so the cooling effect will be extremely large.

This invention has been made with attention to the above points, and as shown in "Fig. 4 and Fig. S", an oil stopper 38 is provided in the ordinary connection box 30 provided in the cooling section A. At the same time, the oil in the external oil passage 18 is taken out from the upstream side immediately near the oil stopper 68, cooled, and returned to the external oil passage 18 from the downstream side of the oil stopper 38.

Embodiment (Fig. 1, Fig. S) Reference numeral 30 denotes a normal connection box, which is usually provided at several locations within one cooling section A). 32 is a conductor connection sleeve;
34 is a reinforcing insulating layer, and 36 is a connecting pipe.

An oil stopper 68 is provided within the external oil passage 18. This need not be severe enough to completely stop the flow of oil within the external oil passage 18. For example, it may be so different that a ring is fitted between the reinforcing insulating layer 34 and the connecting pipe 66.

When viewed from the oil stopper 68, an oil outlet 040 is provided on the upstream side of the flow of oil in the external oil passage 18, and an oil return port 42 is provided on the downstream side.
are provided respectively.

Reference numeral 44 denotes an oil cooler, for example, an air-cooled heat exchanger equipped with a fan 46.

The oil whose temperature has increased in the external oil passage 18 is taken out of the cable 10 through the outlet 40, cooled in the cooler 44, and returned into the external oil passage 18 through the return opening 42. The returned oil flows toward the oil stopper connection box 22B at the other end of the cooling section A, as in the conventional case.

The location where such a cooling section is provided is close to the cooling station run side where the flow rate of oil in the external oil passage is high, which will have a great cooling effect, but it may also be located approximately midway between the cooling station and the oil supply junction box. There are no particular limitations.

Effects of the Invention (1) Since the temperature of the oil in the external oil passage 18 is lowered, the above-mentioned problem caused by the high temperature of the oil in the external oil passage 18 is solved. In particular, in radial flow cables, the amount of oil flowing through the external oil passages is much larger than in conventional OF cables, so this effect is significant.

(2) Since the oil flowing in the external oil passage 18 in the normal connection box 30 is taken out to the outside of the cable 10, compared to taking out the oil in the internal oil passage 12, IJP+c,=*m''
″′° 謔.

(3) Cable installation route: (,・□If there is a residential complex located somewhere in the middle and there is a request to use the cable as a heat source for a heat pump for heating or hot water supply, this can be accommodated.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the cooling technology of a conventional radial flow type internal oil-cooled electric cable, Fig. 2 is an enlarged explanatory diagram of the cable 10, and Fig. 3 (a)
(b) and (c) are distribution diagrams of the temperature, flow rate, and retained heat of the oil in the cable shown in Figure 1, Figure al1 is a detailed explanatory diagram of the present invention, and Figure 5 is a diagram of the ordinary connection box 60. An enlarged explanatory diagram of a portion. 10: Cable 12: Internal oil passage 14: Conductor 18: External oil passage 22A: Oil supply connection box 22B = Oil removal connection box 24: Cooling base 60: Normal connection, box/Ill", 38 2 oil stops - 1 44: Cooler
1 Patent Applicant Fujikura Electric Cable Co., Ltd. Agent Kei Kuniya 1f! ! II 3rd fljJ

Claims (1)

[Claims] Pressurized and cooled insulating oil is fed into the internal oil passage of the cable from one end of the cooling section, flows toward the other end of the cooling section, and flows radially within the insulation layer. Radial-flow internal oil-cooled electric current flows through the external oil passage, is taken out of the cable from one end of the cooling section, is cooled under pressure again, and is sent into the internal oil passage of the cable. In the cable cable cooling method, an oil stop is provided in the external oil passage in a normal connection box provided in the cooling section, and the oil flowing in the external oil passage from the upstream side of the oil stop flows outside the cable. A method for cooling a power cable, characterized in that the power cable is taken out, cooled, and returned to an external oil passage below the oil stopper.