JPH0326018B2 - - 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, conventionally it has been necessary to increase the size of the cable conductor at the termination connection part to reduce loss in the termination box, or to introduce a forced cooling system, but the former requires a different diameter joint, and the latter requires a dedicated cooling system. It is extremely disadvantageous in terms of the large size of the junction box, economical efficiency, ease of maintenance, and long-term reliability.

An object of the present invention is to provide a self-cooling type air or oil submerged termination junction box that is highly reliable, economical, easy to maintain, relatively small, and has an excellent cooling effect. The aim is to achieve large capacity.

According to the present invention, in a self-cooling type air or oil submerged termination junction box that utilizes natural circulation, double inner and outer insulator tubes each having upper and lower electric field shields are used to secure a flow path, thereby achieving the above-mentioned Achieve your purpose.

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, an oil-submerged terminal connection box is shown, and since its structure is concentric, only its right half is shown in cross section. In FIG. 1, the junction box of the present invention is separated into a cable main body and a terminal end by an oil-tight portion 10, and the cable main body is cooled by a suitable refrigerant 11 as in the conventional case. An electric field relaxation section consisting of an insulation reinforcing layer 3 and a bell mouth 4 is arranged on an insulator of a cable 1 having a conductor pull-out rod 2 having a hollow flow path at its end. Inner insulator tube 5 made of epoxy resin and having a lower bell mouth 15 on the outside and an embedded shield 25 on the upper side.
and an outer insulator tube 6 are arranged.

Further, a radiator 7 is provided at the top of the insulator tubes 5 and 6 between the hollow part of the conductor pull-out rod 2 and the outer insulator tube 6,
An oil connecting pipe 8 is provided at the lower part of both the insulating pipes to communicate with each other, and is filled with an insulating oil 9 such as OF oil or silicone oil. Insulating oil 9 is cable 1
The conductor passes through the gap between the cable 1 and the inner insulator tube 5, passes through the hollow part of the hollow conductor pull-out rod 2 connected to the tip of the cable 1, and is guided to the radiator 7, and then from the radiator 7 to the inner insulator tube 5 and the outer insulator tube 6. A circulation loop as shown by the arrow is formed through the gap between the connecting pipe 8 and the connecting pipe 8.

According to such a configuration, heat generated by the current flowing through the conductor of the cable 1 is absorbed by the insulating oil 9 in the gap between the cable 1 and the inner insulating tube 5 through the insulator of the cable 1, increasing its temperature. Inflate. As a result, the specific gravity of the insulating oil in this portion decreases and rises toward the radiator 7. Thereafter, as before, the insulating oil whose specific gravity has increased due to heat being radiated by the radiator 7 descends according to gravity through the gap between the inner insulator tube 5 and the outer insulator tube 6, and circulates through the connecting tube 8.

In terms of electric field, if there is no lower bell mouth 15 of the inner insulator 5, the electrode part of the bell mouth 4 is the outer insulator 6.
It will be shielded by the electric field shield provided at the bottom of the bell mouth, but the distance increases due to the presence of the inner insulator tube 5, and a sufficient shielding effect cannot be obtained, so it is necessary to increase the curvature of the tip of the bell mouth 4. However, in the present invention, the above-mentioned problem does not occur because the lower bell mouth 15 is integrated with the lower part of the inner insulator tube 5.

FIG. 2 is a view similar to FIG. 1 showing another embodiment of the invention, and like numbers indicate the same or similar parts. In the embodiment shown in FIG. 2, the conductor pull-out rod 2 is not hollow, and the radiator function is performed on the surface of the outer insulator tube 6.
Although the cooling effect is somewhat reduced compared to the embodiment shown in the figure, it still provides a sufficient cooling effect. In addition, as shown by the dotted line in the embodiment of FIG.
It is also possible to improve the cooling effect by adding .

According to the present invention described above, since the inner insulating pipe is used as the partition wall of the insulating oil flow path, the structure is simple and maintenance is easy, and an economical air or oil submerged termination junction box with high self-cooling effect can be obtained. It will be done.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of one embodiment of the present invention, and FIG.
The figures are similar views of other embodiments. DESCRIPTION OF SYMBOLS 1... Cable, 2... Conductor pull-out rod, 3... Insulating reinforcing layer, 4, 15... Bell mouth, 5... Inner insulator tube, 6... Outer insulator tube, 7... Heat sink, 8... Connection tube , 9... Insulating oil, 10... Oil-tight part, 11...
Cable refrigerant, 25...Embedded shield.

Claims (1)

[Scope of Claims] 1. A double inner and outer insulator tube, a cable inserted into the inner insulator tube, an electric field relaxation part formed on the insulator, a conductor pull-out rod connected to the conductor of the cable, and the cable and an insulating gas/liquid filled in a first gap between the electric field relaxation part and the inner insulator tube and a second gap between the inner insulator tube and the outer insulator tube, and an insulating gas/liquid provided at the top to radiate heat from the insulating gas/liquid. It is composed of a heat dissipation part and a connecting pipe that communicates the first and second gaps at the lower part, the insulating gas/liquid passes from the first gap along at least a part of the conductor pull-out rod, and further A self-cooling terminal connection box for a power cable, characterized in that the heat can flow from the heat radiating portion through the second gap and the connection pipe, and circulate to the first gap. 2. The heat radiating part is a heat radiator provided at the top, and the insulating gas/liquid flow path along the conductor pull-out rod is provided inside the conductor pull-out rod and communicates with the upper part of the first gap. A self-cooling type terminal junction box for power cables according to claim 1. 3. The heat dissipation part is formed by a portion of the pull-out rod,
2. The self-cooling type terminal junction box for power cables according to claim 1, wherein the insulating gas/liquid flow path along the conductor pull-out rod is provided along the surface of the conductor pull-out rod.