JPH0577784U - Vacuum leak detection device for vacuum switch - Google Patents

Abstract

(57) [Abstract] [Purpose] To make it easy to detect vacuum leaks in vacuum switches. A grounding transformer 5 is connected to a load side circuit of a switchgear 2 having three-phase vacuum switches 2R to 2T. The exciting coil 601 of the relay 6 is connected between the open ends of the secondary windings 5b that are open-delta connected to the grounding transformer. When one of the vacuum switches 2R to 2T is opened in a state where a vacuum leak occurs in one of the vacuum switches and the dielectric strength thereof is lowered, 2
The exciting coil 601 is excited by the zero-phase voltage generated between the open ends of the next winding 5b, and the contact 602 of the relay 6 is closed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a device for detecting a vacuum leak of a vacuum switch provided in a three-phase AC circuit.

[0002]

[Prior Art]

 In a three-phase switchgear that uses a vacuum switch such as a vacuum circuit breaker or a vacuum switch, if a vacuum leak occurs in the vacuum tube of a vacuum switch of either phase, the insulation performance and blocking performance of the vacuum switch will deteriorate. The operation of the switchgear will be hindered. Therefore, conventionally, the energization was periodically stopped to perform a withstand voltage test on each vacuum switch, and the presence or absence of vacuum leakage was determined from the test results. This withstand voltage test was performed by disconnecting each vacuum switch from the circuit and applying a test voltage across it.

[0003]

[Problems to be solved by the device]

 Conventionally, it was necessary to perform a withstand voltage test for each vacuum switch with the switchgear open and the load energized, so it was not possible to constantly monitor the vacuum switch for vacuum leaks during operation. There was a problem of poor reliability.

Further, since it is necessary to disconnect each vacuum switch from the circuit one by one, the work at the time of the withstand voltage test is troublesome, and there is a problem that it takes a long time to check the vacuum leak.

An object of the present invention is to provide a vacuum leak detection device for a vacuum switch, which can check a vacuum leak each time the vacuum switch is opened without disconnecting the vacuum switch from a circuit. ..

[0006]

Means for Solving the Problems According to the present invention, a vacuum leak occurs in a vacuum switch of either phase of a three-phase switchgear using a vacuum switch as a switch for opening and closing each of the three-phase main circuit currents. In the present invention, a zero-phase component detecting device for detecting zero-phase voltage or zero-phase current is connected to the three-phase circuit on the load side of the three-phase vacuum switch. Then, when the zero-phase voltage detector detects a zero-phase voltage or a zero-phase current with the three-phase vacuum switch open, it is detected that a vacuum leak has occurred in the vacuum switch of one of the phases.

[0007]

[Action]

 If a vacuum leak occurs in any of the three-phase vacuum switches, the dielectric strength of the vacuum switch in which the vacuum leak occurs decreases, and the three-phase vacuum switch becomes an asymmetric three-phase load with respect to the power supply. Zero phase is generated in the three-phase circuit. Therefore, if a zero-phase detector is connected to the circuit on the load side of the three-phase vacuum switch as described above, and if vacuum leakage occurs in any of the vacuum switches, the vacuum switch Zero phase is detected when is opened. Therefore, by checking whether or not the zero-phase component is detected each time the vacuum switch is opened, it is possible to know whether there is a vacuum switch in which a vacuum leak has occurred.

As described above, according to the present invention, since it is possible to check the presence or absence of a vacuum leak each time the vacuum switch is opened, it is possible to always perform a vacuum leak without the troublesome work of disconnecting the vacuum switch from the circuit. The presence / absence of the switch can be monitored, and the reliability of the switchgear using the vacuum switch can be improved.

[0009]

【Example】

 FIG. 1 shows an embodiment of the present invention. In FIG. 1, 1 is a three-phase AC power supply, and 2 is a switchgear equipped with vacuum switches 2R, 2S and 2T for opening and closing a main circuit current of three phases. 3 is a load to which electric power is supplied from the power source 1 through the vacuum switches 2R to 2T, and 4R to 4T are capacitances to ground. A primary side of a grounding transformer (GPT) 5 is connected to a three-phase circuit between the switchgear 2 and the load 3. This grounding transformer includes a primary winding 5a connected in star and a secondary winding 5b connected in open delta, and the neutral point of the primary winding 5a is grounded. The exciting coil 601 of the relay 6 is connected between the opened ends of the secondary winding 5b. This relay has a normally open contact 602 which is closed when the exciting coil 601 is excited, and the auxiliary contact 7 of the vacuum switch is connected to the contact 602 in series. The auxiliary contact 7 is a contact that is opened when the vacuum switches 2R to 2T are turned on. When the contact 602 is closed while the vacuum switches 2R to 2T are open, the auxiliary power source 7 outputs contacts 602 and 7 from a control power source (not shown). Current flows through the series circuit of. In this embodiment, the grounding transformer 5, the relay 6 and the auxiliary contact 7 constitute a zero phase component detecting device.

In the above embodiment, if vacuum leakage occurs in any of the vacuum switches 2R to 2T, the dielectric strength of the vacuum switch in which the vacuum leakage has occurred is reduced, so that the three-phase vacuum switches 2R to 2T. A zero-phase voltage appears across the open ends of the open delta connected secondary windings when open. Therefore, the exciting coil 601 of the relay 6 is excited, the contact 602 is closed, and a current flows through the contacts 7 and 602. By detecting this current, it is possible to know that a vacuum leak has occurred in any of the vacuum switches. The closing of the contact 602 can be detected by any means such as a lamp, a buzzer, and an ammeter.

FIG. 2 shows another embodiment of the present invention. In this embodiment, a zero-phase current transformer (ZCT) 8 is attached to the circuit on the load side of the three-phase vacuum switch. ing. The zero-phase current transformer 8 is obtained by winding a secondary coil 8b around an annular iron core 8a that collectively penetrates three-phase main circuit conductors. The exciting coil 601 of the relay 6 is provided at both ends of the secondary coil 8b. Is connected. The other points are the same as in the embodiment of FIG. In this embodiment, the zero-phase current transformer 8 and the relay 6 constitute a zero-phase component detector.

In the embodiment of FIG. 2, if vacuum leakage occurs in any of the vacuum switches 2R to 2T and the dielectric strength of the vacuum switches decreases, a three-phase circuit is formed when the three-phase vacuum switches 2R to 2T are opened. Zero-phase current flows. Since this zero-phase current is detected by the zero-phase current transformer 8, the exciting coil 601 of the relay is excited and the contact 602 is closed. By detecting the closing of the contact 602, it is possible to know that a vacuum leak has occurred in any of the vacuum switches.

In each of the above-described embodiments, the load has three phases. However, as shown in FIG. 3, even if the load has a single phase, the present invention can be applied as long as the power supply has three phases.

FIG. 4 shows another embodiment of the present invention. In this embodiment, a star-connected three-phase capacitor CR, CS and C is connected to a three-phase circuit between a vacuum switch and a load. A zero-phase capacitor 9 consisting of T and a capacitor Co connected between the neutral point of these capacitors and the ground is connected. The primary coil of the transformer 10 is connected to both ends of the capacitor Co, and the exciting coil 6 of the relay is connected to both ends of the secondary coil of the transformer 10. In this embodiment, the zero-phase capacitor 9, the transformer 10, the relay 6, and the auxiliary contact 7 constitute a zero-phase component detecting device.

In the embodiment of FIG. 4, when the vacuum switches 2R to 2T are opened in a state where any of the vacuum switches has a vacuum leak, a zero-phase voltage appears across the capacitor Co. This zero-phase voltage is applied to the exciting coil 601 of the relay 6 via the transformer 10, so that the exciting coil is excited and the contact 602 is closed.

In each of the embodiments shown in FIGS. 1 to 3, the auxiliary contact 7 that opens when the vacuum switch is turned on is connected in series to the contact 602 of the relay. In the practical example, as shown in FIG. 5, the auxiliary coil 601 is connected in series with the exciting coil 601 of the relay connected between the open ends of the secondary windings 5b connected in the open delta connection, and is closed when the vacuum switch opens. The contact 7 may be connected.

[0017]

[Effect of the device]

 As described above, according to the present invention, the zero-phase component detector is connected to the load side circuit of the vacuum switch, and when either of the vacuum switches has a vacuum leak and its dielectric strength is reduced, Since the zero phase component is detected when the switch is opened, it is possible to check whether or not there is a vacuum leak each time the vacuum switch is opened. Therefore, there is an advantage that the presence or absence of vacuum leak can be constantly monitored without the troublesome work of disconnecting the vacuum switch from the circuit, and the reliability of the switchgear using the vacuum switch can be improved. ..

[Brief description of drawings]

FIG. 1 is a connection diagram showing an embodiment of the present invention.

FIG. 2 is a connection diagram showing another embodiment of the present invention.

FIG. 3 is a connection diagram showing another embodiment of the present invention.

FIG. 4 is a connection diagram showing another embodiment of the present invention.

FIG. 5 is a connection diagram showing a main part of still another embodiment of the present invention.

[Explanation of symbols]

 1 3 Phase AC Power Supply 2 Switchgear 2R ~ 2T Vacuum Switch 3 Load 5 Ground Transformer 6 Relay 601 Excitation Coil 602 Relay Contact 7 Vacuum Switch Auxiliary Contact 8 Zero Phase Current Transformer 9 Zero Phase Capacitor 10 Transformer

Claims (1)

[Scope of utility model registration request] 1. A vacuum leakage detection device for detecting the occurrence of vacuum leakage in a vacuum switch of any one phase of a switch for three phases using a vacuum switch as a switch for opening and closing a main circuit current of each of the three phases. And a state in which the three-phase vacuum switch is open circuited, comprising a zero-phase component detection device connected to a three-phase circuit on the load side of the three-phase vacuum switch to detect zero-phase voltage or zero-phase current. 2. A vacuum leak detection device for a vacuum switch, which detects that a vacuum leak has occurred in a vacuum switch of any phase when the zero-phase voltage or zero-phase current is detected by the zero-phase component detection device.