JPH0326016B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas/liquid circulation self-cooling terminal junction box for power cables that utilizes natural convection.

For large-capacity power transmission cables (cross-linked polyethylene insulated vinyl sheathed cables, oil-filled cables, etc.), a method has been adopted in which the cable itself is directly or indirectly cooled with water or the like in order to suppress an increase in resistance due to heat generation in the cable. In this case, the capacity of the cable itself can be increased by forced cooling, but unless the capacity of the cable termination junction box can be increased, it is impossible to increase the capacity of the system as a whole.

For this reason, in the past, it was necessary to increase the size of the cable conductor at the end connection or to install a specialized cooling system, and for reasons of economy and ease of maintenance, a heat sink was installed at the top of the connection box. It has been proposed to form a self-cooled terminal junction box using the natural convection circulation of insulating oil. However, in conventional self-cooling systems, heat is absorbed from the cable conductor, and the temperature of the insulating oil, which has risen in temperature, decreases while being carried to the radiator, making it impossible to obtain sufficient convection circulation and, therefore, reducing the cooling effect. is also not sufficient. In other words, the heat generated by the current in the cable conductor raises the temperature of the insulating oil filled through the cable insulator, which causes the insulating oil to expand and reduce its specific gravity, which causes the oil to move upward. , heat radiation from the oil occurs within the tubes of the radiator, increasing its specific gravity, canceling out the circulation driving force of the oil and causing a loss of cooling effect. Therefore, conventionally, even if such a self-cooling system was used alone, it did not sufficiently contribute to increasing the capacity of the cable.

An object of the present invention is to provide a self-cooling type terminal junction box with excellent cooling effect by eliminating the conventional causes of inhibiting the natural convection of insulating oil, thereby increasing the capacity of power transmission cables.

According to the present invention, the above object is achieved by using a conductor pull-out rod as a gas/liquid passage to the radiator provided at the top of the connection box, and further surrounding the pull-out rod with a heat insulating member.

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 is a partial sectional view showing one embodiment of the present invention. In FIG. 1, since the structure of the terminal junction box is concentric, only the right half thereof is shown in cross section. Note that FIG. 2 is a sectional view taken along the line of FIG. 1. 1 and 2, on the insulator of the cable 1 inserted through the insulator tube 2, there is an electric field relaxation part consisting of an insulation reinforcing layer 3 and a bell mouth 4, and the cable 1
A capacitor 5 is arranged on the periphery of the electric field relaxation part with a gap therebetween. Further, a radiator 9 is provided at the top of the insulator tube 2, and the inside thereof is filled with an insulating oil 7 such as OF oil or silicone oil.
The insulating oil 7 passes through the gap between the cable 1 and the capacitor 5, passes through the hollow part of the hollow conductor pull-out rod 8 connected to the tip of the cable 1, and is guided to the radiator 9.
Furthermore, it passes through the gap between the radiator 9 and the insulator tube 2 of the condenser 5, forming a circulation loop as shown by the arrow.

The conductor pull-out rod 8 is hollow as shown in FIG. 2, and a heat insulating layer 10 is provided around it.

According to this configuration, heat generated by the current flowing through the conductor of the cable 1 is absorbed by the insulating oil 7 in the gap between the cable 1 and the capacitor 5 through the insulator of the cable 1, increasing the temperature. Inflate. As a result, the specific gravity of the insulating oil in this portion decreases and rises toward the radiator 9. that time,
Since the rod body pull-out rod 8 is surrounded by the heat insulating layer 10, heat radiation from the insulating oil flowing through the hollow passageway to the outside air is prevented, and the radiator 9 can be removed without lowering the specific gravity.
carried to the top of the Thereafter, as before, the insulating oil whose specific gravity has increased due to heat being radiated by the radiator 9 descends through the gap between the insulator tube 2 and the capacitor 5 according to gravity.

As described above, according to the present invention, factors that weaken the circulation driving force due to natural convection are removed, sufficient circulation can be obtained, and therefore a sufficient cooling effect can be obtained.

Although the present invention has been described above in detail with respect to an oil termination box, the present invention is equally applicable to an air termination box such as an SF ₆ gas termination box, and in any case, similar cooling is required. It is effective. Furthermore, in the above embodiment, the conductor pull-out rod is hollow and that part is used as an insulating oil passage, but the same effect can be obtained by separately providing a passage and making it a heat-insulating structure. I can do it.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of one embodiment of the present invention, and FIG.
The figure is a sectional view taken along the line of FIG. 1... Cable, 2... Insulator tube, 3... Insulation reinforcing layer, 4... Bell mouth, 5... Capacitor, 7...
…Insulating oil, 8…Conductor pull-out rod, 9…Radiator, 1
0...Insulating layer.

Claims (1)

[Claims] 1. An electric field relaxation section placed on a cable insulator inserted into the insulator tube, and an insulator tube filled with an insulating gas or liquid, with a capacitor or insulating tube arranged with a gap between the cable and the electric field relaxation section; In a terminal box consisting of the above-mentioned heat radiator capable of circulating insulating gas/liquid, a hollow space connected to the cable conductor is used as a gas/liquid passage connecting the above-mentioned capacitor or the insulating gas/liquid in the insulating cylinder to the top of the above-mentioned radiator. A self-cooling type terminal junction box for power cables, which uses a pull-out rod and is characterized in that a heat insulating layer is provided around the pull-out rod.