JP2724721B2 - T branch unit of gas insulated switchgear - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a T-branch unit used to apply a predetermined test voltage for a withstand voltage test to a gas-insulated switch (GIS).

(Technical Background of the Invention and its Problems) Gas-insulated switches are widely used in power plants, substations, and the like from the viewpoint of ease of maintenance and safety.

It is necessary to conduct a predetermined withstand voltage test after assembling the gas insulated switch body or the cable line connected thereto. There are various withstand voltage test methods, and the present inventors have previously developed the following withstand voltage test apparatus.

FIG. 2 is a longitudinal sectional view of a main part showing a withstand voltage test device of the gas insulated switch (GIS).

In the figure, an adapter case 12 specially mounted for a withstand voltage test is mounted on the upper part of three GIS cases 1 for three phases. Inside the GIS case 1, a gas end box 3 is provided.

A T-branch insertion bushing 13 is fixed to an upper part of the adapter case 12. The T-branch insertion bushing 13 is formed by molding an epoxy resin or the like, and is fixed to the upper surface of the adapter case 12, and a connection conductor 14 is disposed at the center thereof in the vertical direction. Also, this connection conductor
A protection resistor 6 is inserted between 14 and the gas end box 3 of the GIS case 1. On the other hand, a T-branch fitting 15 is attached to the upper end of the T-branch insertion bushing 13.

FIG. 3 shows an enlarged longitudinal sectional view of a main part of the T-branch insertion bushing.

The T-branch fitting 15 is a ring-shaped member fixed to the upper end of the connection conductor 14, and the T-branch insertion bushing 13 is
Tapered holes 13a are formed in the left and right openings of the branch fitting 15. The cable 1 is inserted into the through hole 15a of the T-branch fitting 15.
The configuration is such that the connection terminal 18 of the connector 17 attached to the end of the connector 6 is fitted. That is, this T-branch fitting 15
Is a so-called slip-on type, and is configured so that the connector 17 can be easily attached and detached.

Therefore, as shown in FIG. 2, the three T-branch bushings 13 for three phases are electrically connected to each other by the cable 16, and the rightmost T-branch bushing 13 shown in FIG.
The other end of the cable 16 connected to the terminal is terminated inside the aerial terminal box 18. The power application device 7 applies a test voltage to the head of the aerial terminal box 18. As a result, the test voltage is applied to the internal circuits of the GIS case 1 for three phases. The protection resistor 6 is for preventing a surge or the like from entering the internal circuit of the GIS case 1 from the power application device 7 side.

By the way, in assembling such a test apparatus, when the adapter case 12 is attached in advance, the resistor 6 is inserted between the gas end box 3 and the T-branch insertion bushing 13 and the cable is fixed. 16 connections will be made. This type of work requires great care.

Further, in the above-described apparatus, each part is separated separately, and assembling and carrying in are easy. However, since the number of parts is large, further simplification of the assembling work is desired.

(Object of the Invention) The present invention has been made in view of the above points,
Combining branch insertion bushing and protection resistor, etc.
It is an object of the present invention to provide a T-branch unit of a gas insulated switch in which the device is simplified.

(Summary of the Invention) The present invention relates to a T-branch insert in which a connection conductor electrically connected to an internal circuit of a gas-insulated switch via a resistor and a T-branch metal fitting electrically connected to a power application test side are embedded. Insulator rod having a bushing, the resistor is detachably connected to the terminal of the connection conductor, a plurality of disc-shaped resistance elements fitted in a stacked state on the insulation rod, an outer cylinder in which these resistance elements are stored And a disc spring for bringing a plurality of resistance elements into close contact with each other in the outer cylinder.

(Embodiment of the Invention) Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the T branch unit of the present invention.

This T-branch unit has a structure in which a T-branch insertion bushing 20 and a resistor 30 are connected and fixed to each other as shown in the figure.

The T-branch insertion bushing 20 includes a mold portion 21 made of a molded body such as an epoxy resin, a connection conductor 22 buried vertically in the center thereof, and a T-branch fitting 23 provided at an upper end of the connection conductor 22, And a corona shield 24 provided at the lower end of the connection conductor 22.

On both sides of the T-branch 23, the mold portion 21 is provided with a tapered hole 21a as described above with reference to FIG. This is a hole for attaching a cable connector as described above.

A resistor 30 is fixedly connected to the lower end of the T-branch insertion bushing 20 with a disk portion of the corona shield 24 interposed therebetween. It has a configuration in which it is connected and fixed using a rod 32. The insulator rod 32 is screwed and fixed to a screw portion 22a provided at the lower end of the connection conductor 22 of the T-branch insertion bushing 20. The screw portion 22a penetrates the center of the disk of the corona shield 24. Each resistance element 31 of the resistor 30 has its outer periphery covered with an outer cylinder 33. The outer cylinder 33 is made of a non-metallic high-resistance body, and is made of, for example, fiber-reinforced plastic.

In addition, several disc springs 34 are similarly stacked together with the stacked resistance elements 31. A connecting rod 36 made of copper or the like is coaxially connected to a lower end of the insulating rod 32. And the outer cylinder
The lower opening of 33 is closed by a press fitting 35,
Numeral 35 presses the disc spring 34 upward by screwing a lock nut 37 into a thread groove provided on the peripheral surface of the connecting rod 36 and tightening it. Each of the stacked resistance elements 31 is a disk-shaped resistor of about several tens of ohms, and a predetermined resistance value and a creeping distance are secured by being stacked. That is, the distance between the lower end of the corona shield 24 and the press fitting 35 is the creepage distance, and the distance is set to a sufficient distance so that no discharge occurs between them. Further, the disc spring 34 is inserted through the insulator rod 32 together with the resistance element 31, and the press fitting 35 is provided from below.
, The spring force is exerted on the resistance element 31, and an appropriate surface pressure is applied to the resistance element 31.

The corona shield 24 is a T-branch insertion bushing.
The purpose is to reduce the electric field at the connection between the resistor 20 and the resistor 30.
That is, the electric field is prevented from being concentrated on some corners on the lower end surface side of the mold portion 21 and some corner portions on the upper end surface side of the uppermost resistive element 31.

Therefore, as the electric circuit to be applied, the connection conductor 22, the disk portion of the corona shield 24, the laminated resistance element 31, the disc spring 3
4. It is composed of a push fitting 35, a lock nut 37, and a connecting rod 36.

If the T-branch unit having the above configuration is used by fixing it to the adapter case 12 shown in FIG. 2, not only the mounting of the adapter case 12 to the GIS case 1 becomes easy, but also the adapter case 12 The part can be sufficiently reduced in size.

For example, the T-branch unit as shown in FIG. 1 could be manufactured with a total length of about 1,300 mm from the constricted portion 21b of the molded portion 21 to the tip of the connecting rod 36.

(Effects of the Invention) The T-branch unit of the gas-insulated switch of the present invention described above simplifies the work of installing the test device and reduces the size of the test device in the withstand voltage test of the gas-insulated switch. This contributes to improvement in workability and cost reduction.

Also, when the resistor element is broken by applying a large voltage, the insulator rod is removed from the bushing side by inserting the T-branch, the broken resistor element is replaced, and the resistor is assembled again to use the T-branch unit as it is. Can be economical.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a T branch unit of the gas insulated switchgear of the present invention, FIG. 2 is a longitudinal sectional view of a main part of a withstand voltage test apparatus suitable for implementing the T branch unit of the present invention, and FIG. That T
It is a principal part longitudinal cross-sectional view of a branch insertion bushing. 20: T-branch insertion bushing, 22: Connection conductor, 23: T-branch fitting, 24: Corona shield, 30: Resistor, 31: Resistance element, 32: Insulator rod, 33: Outside Tube, 34… Belleville spring, 36 …… Connection rod.

Claims (1)

(57) [Claims] A connection conductor electrically connected to an internal circuit of the gas insulated switch via a resistor; and a T-branch electrically connected to a power application device for applying a test voltage to the gas insulated switch. In a T-branch unit of a gas insulated switchgear provided with a T-branch insertion bushing embedded therein, the resistor is detachably connected to a terminal of the connection conductor, and is stacked on the insulator bar. A plurality of disc-shaped resistive elements fitted with the same, an outer cylinder in which the plurality of resistive elements are housed, and a disc spring disposed in the outer cylinder to closely contact the plurality of resistive elements. T branch unit of the gas insulated switchgear.