JPH0373826B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for performing a withstand voltage test by applying a test voltage from the outside to the internal circuit of a gas insulated switchgear.

All general electrical equipment, not just gas-insulated equipment, is required to undergo a pressure test based on electrical equipment technical standards after being installed on-site. In this withstand voltage test, with air-insulated electrical equipment, which is commonly used, the voltage application point is in the air, so there is no problem in applying the test voltage, but with gas-insulated equipment, the situation is completely different. That is, in the case of a gas-insulated switchgear, all of the live parts are housed in a grounded container, and there is no risk of the live parts coming into direct contact with the human body.

However, even if you try to apply a test voltage on-site, the application point is not exposed to the air, so testing cannot be performed in the same way as with air-insulated electrical equipment. Therefore, conventionally, voltage application points for on-site testing are generally provided in advance when manufacturing equipment.

FIG. 1 shows an example in which a voltage application point is provided on the connection side of a gas insulated switchgear to a transformer. To explain the figure, the gas insulated switchgear 1 has a connection case 3 filled with insulating gas on the side connected to the transformer, and a bushing pocket 4 of the transformer is connected to the bottom surface of the case 3 via a partition plate 5. Oil-gas bushings 6 for three phases of the transformer are installed through the partition plate 5. The bushing 6 of each phase has a connecting conductor 7 attached vertically to the gas side terminal, and a conductor 2 extending from the switchgear 1 is connected to this connecting conductor 7. Test terminals 7a are provided at the upper end and are formed to have the same height. 8 is a test bushing that is attached to the upper part of the connection case 3 after on-site installation via an adapter 9, and the contact plate 10 attached to the lower terminal of this bushing 8 contacts the test terminals 7a for the three phases,
By applying a test voltage through the bushing 8 during a withstand voltage test, it is possible to perform a withstand voltage test on the internal circuit for three phases at once.

However, since the above device has a configuration in which the test bushing 8 is attached during the pressure test, a part of the internal space of the switchgear is exposed to the atmosphere when the bushing is attached or disassembled, and the insulation is required each time. It is necessary to refill the gas. This requires a lot of effort and work time, and it is also necessary to prepare a space in the switchgear in advance to take air insulation space into consideration in order to install the test bushings, which limits the configuration of the equipment. There were other problems.

The purpose of the present invention is to make it possible to apply a test voltage from the outside while maintaining the gas-tightness of the switchgear without any complicated work during a withstand voltage test.
Another object of the present invention is to provide a withstand voltage testing device for a gas insulated switchgear that can be easily switched to an operating state after the test.

An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 2 and 3, 1 is a gas insulated switchgear, 2 is a current-carrying conductor of the device, 3 is a connection case,
4 is a bushing pocket for the transformer, 5 is a partition plate,
6 is an oil-gas bushing of the transformer, 7 is a connecting conductor, and 7a is a test terminal, and each of the above parts corresponds to the parts shown with the same symbols in FIG. 11 is an upper cover of the connection case 3, and 12 is a cable connecting device that is attached to the upper cover 11 and is detachable from the test cable 21 that is inserted from the outside. As shown in FIGS. 4 and 5, the cable connection device 12 includes a rod 14 that is movable in an airtight state and is installed in an insulating tube 13 that is gas-tightly attached to the back surface of the opening 11a of the cover 11. A contact 15 is attached to one end of 14.
A two-shaped contact plate 16 is elastically supported at the other end via a spring 17. When the test cable 21 is inserted from the outside, the rod 14 is automatically connected to the cable terminal 22 via the contact 15 at a predetermined lowered position as shown in FIG. Pressure contact is made with the terminal 7a. The internal circuit provided with this terminal 7a is connected to an external test power source. When the test cable 21 is in the inserted state, the opening 11a of the cover 11 is closed by the cable sheath 23. Further, insulation of the cable end portion within the jacket 23 is ensured by the insulating collar 25 pressurized by the spring 24 coming into pressure contact with the inner surface of the insulating tube 13.

On the other hand, after the pressure test and after the cable 21 is pulled out, the rod 14 is pulled up to a predetermined raised position by the stud 26 attached to the screw hole at its end from above, and inserted into the insulating tube 12 in advance, as shown in FIG. It is supported in that position by the insulating stand 27 via a spring 28, and is grounded to the same potential as the cover 11 via a grounding member (not shown) inside the cap 29 attached to the opening 11a. The contact plate 16 is separated from the test terminal 7a by the movement of the rod 14 to the raised position, and is held at a position where a predetermined insulation distance is maintained. The center portion of the contact plate 16 is elastically supported by the rod 14 via several springs 17, and the test terminal 7a
Even if there is some misalignment in the position, it can be freely displaced according to the position and reliably contact the three-phase terminals 7a. Note that 18 is a flexible conductor that connects the rod 14 and the contact plate 16.

According to the above configuration, during a pressure test,
Cable connection device 1 installed in gas insulated switchgear 1
By inserting the test cable 21 from the outside into the switchgear 12, the internal electric circuit is connected via the rod 14 and the contact plate 16 of the switchgear 12 while maintaining this gas-tight state without opening the internal space of the switchgear to the atmosphere. Since it can be automatically connected to the test terminals 7a for the three phases, there is no need for any work such as gas refilling as in the past, and the pressure test can be carried out very easily and quickly. Furthermore, even after the test cable 21 is pulled out after the withstand voltage test, the rod 14 is pulled up to a predetermined position and grounded without opening the switchgear to the atmosphere, so that the contact plate 16 also becomes ground potential and the test terminal 7a is connected to the test terminal 7a. Since they are opened at positions that maintain a predetermined insulation distance, there is no hindrance to steady operation and the operating state can be quickly switched to. Furthermore, one cable connection device 12 common to three phases
Since the test voltage application point is set as the test voltage application point, it can be installed in a small space and there is no need to provide a special air insulation space at the installation part, and therefore, there are no restrictions on the configuration of the switchgear 1. The entire device can be downsized without any problems.

As described above, in the present invention, a test terminal for three phases formed in a part of the electrical path between cases of a gas-insulated switchgear, and a common cable connection for the three phases facing the tip of this test terminal. This cable connection device includes an insulating tube that is gas-tightly attached to the opening of the case, a rod that is movably provided in the insulating tube in an airtight state, and a rod that is movable in an airtight state. The rod has a contact plate elastically supported at one end, and the other end of the rod connects in a predetermined lowered position to a test cable inserted from the outside into the insulating tube. When removed, it is pulled up to a predetermined raised position and grounded,
When the rod is in the lowered position, the contact plates come into contact with the test terminals for the three phases, and when the rod is in the upper position, they are separated from the test terminals, which eliminates troublesome work such as disassembly during withstanding voltage tests. It is possible to easily apply a test voltage from the outside while maintaining the gas-tightness of the gas-insulated switchgear without having to carry out a pressure test. Furthermore, it is possible to provide a safe and compact withstand voltage testing device for gas insulated switchgear.

In addition, since the contact plate is elastically supported at one end of the rod that can be connected to the test cable, even if there is a slight misalignment in the position of the test terminal, this misalignment can be corrected by the free elastic displacement of the contact plate. Therefore, the contact plate can be reliably brought into contact with the test terminals for all three phases at once.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional pressure test device for gas insulated switchgear, and FIGS. 2 and 3 show test and non-test conditions of a pressure test device for gas insulated switchgear according to an embodiment of the present invention. The cross-sectional views shown in FIGS. 4 and 5 are detailed cross-sectional views showing the cable connection device of the same device in a voltage-proof test state and a non-test state. DESCRIPTION OF SYMBOLS 1... Gas insulated switchgear, 3... Case, 7a... Test terminal, 12... Cable connection device, 14... Rod, 16... Contact plate, 21... Test cable.

Claims (1)

[Claims] 1. This cable connection device has a test terminal for three phases formed in a part of the electrical circuit between cases of a gas-insulated switchgear, and a cable connection device common to the three phases that faces the tip of this test terminal. The insulating cylinder is gas-tightly attached to the opening of the case, the rod is movably installed in the insulating cylinder in an airtight state, and the contact plate is elastically supported at one end of the rod. The other end of the rod is connected at a predetermined lowered position to a test cable inserted into the insulating cylinder from the outside, and is pulled up to a predetermined raised position when the test cable is removed. and grounded, and the contact plate contacts each of the test terminals for three phases in the lowered position of the rod, and is separated from the test terminal in the raised position of the rod. withstand voltage test equipment.