JPS6285614A - Self-cooling type terminal joint box of 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 gas/liquid circulation self-cooling type roadside junction box using natural convection for a turtle cable.

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 terminal connection or to install a dedicated cooling system.For economic efficiency and ease of maintenance, a heat sink was installed at the top of the connection box. It has been proposed to utilize natural convection circulation of insulating oil to form a self-cooled roadside junction box.

However, in this conventional self-cooling system, the temperature of the insulating oil, which has risen in temperature due to heat absorption from the cable conductor, drops while being carried to the radiator, making it impossible to obtain sufficient convection circulation and, therefore, the cooling effect is insufficient. It is not.

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 l# pipe of the radiator, increasing its specific gravity, canceling out the circulation and driving force of the oil and causing a loss of cooling effect. Therefore, conventionally, even if this self-cooling method was used alone, it did not contribute sufficiently to increasing the capacity of the cable.

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

The above objective is achieved by selecting a temperature equal to that of the temperature.

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 and is denoted by 2. Note that FIG. 2 is a sectional view taken along the line II-IT in FIG. 1. 1.2
In the figure, on the insulator of the cable 1 inserted through the insulating tube 2, there is an electric field relaxation part consisting of an insulation reinforcing layer 3, a l-bell mouth 4, and a wire around the electric field relaxation part. The capacitors 5 are arranged with a gap 5 between them.
At the top of the insulator tube 2, there is provided a 1° vent 9, inside which there is -OF oil (insulating oil 7 such as silicon oil)
is already filled. 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 turret 1, is led to the radiator 5), and then from the radiator 9 to the capacitor. 5 and the insulator tube 2, forming a circulation loop as shown by the arrow.

The conductor pull-out rod 8 is made of aluminum or copper, and the second
As shown in the figure, it is hollow, and the cross-sectional area of the metal part is selected so that the electric current flowing through it generates heat to the same temperature as the insulating oil 7 in that part.

According to this configuration, the insulating oil 7 is thermally isolated from the outside air temperature due to the heat generated by the current flowing through the conductor pull-out rod 8, so the oil temperature does not drop, and the heat generated by the cable conductor is transferred to the cable 1 and the capacitor. The insulating oil 7 is absorbed by the insulating oil 7 in the gap between the insulating oil 5 and the insulating oil 7, and its temperature is increased and expanded to lower the specific gravity of the insulating oil in this area, and the insulating oil is raised toward the top of the radiator 9 in that state. 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, the 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.

FIG. 3 is a diagram showing an embodiment in which the present invention is applied to an SF6 gas termination box, in which an epoxy insulator tube 12 is used in place of the insulator tube 2 in FIG. 1, and an insulating tube 15 is used in place of the capacitor 5. The structure is basically the same as that shown in FIG. 1, and the effects are also the same.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of part a of one embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line 1--2 of FIG. 1, and FIG. 3 is a partial sectional view of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Cable, 2...Insulator tube, 3...Insulation reinforcing layer, 4...Bell mouth, 5...Capacitor, 7...
- Insulating oil, 8... Conductor pull-out rod, 9... Heat radiator. Agent Patent Attorney Sato Fut, Yu K 5 No Ishi 1 [

Claims (1)

[Claims] An electric field relaxation section placed on a cable insulator inserted into the insulator tube, a capacitor or an insulating cylinder having a gap between the cable and the electric field relief section, and filled with an insulating gas or liquid, and the above insulation tube. In a terminal box consisting of a heat radiator that allows circulation of gas and liquid, air and liquid are connected to the top of the heat radiator and the insulating gas and liquid in the capacitor or insulating cylinder.
A hollow draw-out rod connected to the cable conductor is used as a liquid passage, and the cross-sectional area of the draw-out rod in the air/liquid passage section is brought to a temperature equivalent to the temperature of the air/liquid in that part by means of an electric current flowing through it. A self-cooling type terminal junction box for power cables, characterized in that the rod is selected so as to generate heat.