JPH01227319A - Detector for insufficient vacuum - Google Patents

Abstract

PURPOSE:To improve electric cutoff characteristic between fixed and movable electrodes by providing grounding electrodes opposing each other outside a vacuum breaker via an opening-closing device with discharge detector. CONSTITUTION:By the energization of an electrode releasing relay coil TC, a movable electrode 3 begins to part from a fixed electrode 2. The signal given to an electrode controlling relay coil R2 is also given to a retention circuit 19. The retention circuit 19 is energized by a signal and energizes a high dielectric strength relay R1 from the point where the movable electrode 3 begins to part from the fixed electrode 2 to the point where the electrode 3 is in the position most released from the electrode 2. Namely, the normally closed contact point 17 becomes in an open condition from the point where the movable electrodes 3 begins to part from the fixed electrode 2 to the point where the movable electrode 3 is in the position most released for the fixed electrode 2. In this way, a grounding electrode 10 is completely cut off from a grounding potential point G simultaneously with the parting of the movable electrode from the fixed electrode 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a vacuum defect detection device for detecting a vacuum defect in a vacuum circuit breaker.

(Prior Art) Conventionally, there is a discharge current detection method as a means for monitoring the degree of vacuum of a vacuum circuit breaker. An example of this method is shown in FIG. A fixed electrode 2 and a movable electrode 3 are attached to the vacuum circuit breaker 1 so as to face each other. The fixed electrode 2 is attached to one end of the rod portion 4, and the other end of the rod portion 4 penetrates the wall portion 5 of the vacuum circuit breaker 1 and is exposed to the outside of the vacuum circuit breaker 1. The exposed end of this rod portion 4 is connected to a system power source 7 via a conducting wire 6. The movable electrode 3 is attached to one end of a rod portion 8, and the other end of the rod portion 8 is exposed to the outside while being kept airtight by a bellows 8a on the wall portion 5 of the vacuum circuit breaker 1. The rod portion 8 operates so that the movable electrode 3 comes into contact with and separates from the fixed electrode 2 by a drive mechanism (not shown). A conductor 6 is connected to the exposed end of the rod portion 8, and a load 9 is connected to the conductor 6. With such a configuration of the vacuum circuit breaker 1, when the movable electrode 3 comes into contact with or separates from the fixed electrode 2, current flows from the system power supply 7 to the load 9 or is interrupted.

When the degree of vacuum inside the vacuum circuit breaker 1 configured as described above decreases,
It is well known that the dielectric strength within a vacuum circuit breaker decreases according to Paschen's law.

When the dielectric strength decreases, discharge occurs between the fixed electrode 2 and the movable electrode 3 due to the voltage value of the system power supply 7.

This discharge is detected by the ground electrode 10 facing the wall 5 of the vacuum circuit breaker 1. The ground electrode 10 is the vacuum circuit breaker 1
In order to accurately detect discharge within the shield, it is shaped like a flat plate, and the coupling capacitance between the ground electrode 10 and the intermediate shield 11 is increased. Further, the ground electrode 10 is usually molded with an insulator. A ground conductor 12 is connected to the ground electrode 10, and this ground conductor 12 is connected to one end of a detection impedance 13 made of a resistor, etc., and the other end of the detection impedance 13 is connected to a ground potential point G through the ground conductor 12.
It is connected to the. A signal processing device 14 is connected to both ends of the detection impedance 13, and the movable electrode 3 and the fixed electrode 2
The signal processing device 14 detects the current flowing through the detection impedance 13 when a discharge occurs between the two. By this detection, it is known that the degree of vacuum within the vacuum circuit breaker 1 has deteriorated.

(Problem to be solved by the invention) However, since the conventional discharge current detection method described above uses a ground electrode, the electric field distribution inside the vacuum circuit breaker is divided into strong and weak parts due to the influence of the ground potential. Become. In particular, in the electrically open state of the picture electrode when the movable electrode is separated from the fixed electrode, the ground potential of the ground electrode disturbs the electric field distribution between the two electrodes. This disturbance in the electric field distribution causes areas with strong electric field strength and areas with weak electric field strength. Therefore, when the electric field strength between the fixed electrode and the movable electrode is strong, a discharge is likely to occur between the two electrodes, and both electrodes There is a problem in that the electrical isolation between the two ends is reduced.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a vacuum defect detection device that improves electrical isolation between a fixed electrode and a movable electrode.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a vacuum circuit breaker in which a fixed electrode and a movable electrode are surrounded by a shielding plate, a ground electrode facing the outside of the vacuum circuit breaker, It is equipped with a discharge detection device connected to this ground electrode via a switching device.

(Function) In the vacuum defect detection device configured as described above, when the movable electrode separates from the fixed electrode, the switching device is activated and the ground electrode is separated from the ground potential point. Therefore, the electric field distribution between both electrodes is not disturbed by the ground potential.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figure shows an embodiment of a vacuum circuit breaker 1 equipped with a vacuum defect detection device 15 of the present invention. This vacuum defect detection device 15
has the same structure as that already explained in the prior art section with reference to FIG.

The same configurations are designated by the same reference numerals, and detailed description thereof will be omitted. The ground electrode 10 of the vacuum defect detection device 15 is connected to the conductor 1
2 to one end of a parallel connection point between a capacitor 16 and a normally closed contact 17, which are part of the switching device. The other end of the parallel connection point between the capacitor 16 and the normally closed contact 17 is connected to one end of the detection impedance 13 via the conductor 12, and the other end of the detection impedance 13 is connected to the ground potential point G via the conductor 12. There is. Capacitor 16 is several PP
~ several tens of PF. The normally closed contact 17 is opened when the high voltage relay R1 is energized.

A description will be given of how the ground electrode 10 is separated from the ground potential point G when the high voltage relay R1 is in the open state. First, when changing the fixed electrode 2 and movable electrode 3 from a contact state to an open state, a signal is given to the electrode control relay coil R2. This signal energizes the electrode control relay coil R2 and closes the normally open contact 18 of the electrode control relay coil R2.

When the normally open contact 18 is closed, the electrode opening relay coil TC is energized. This electrode opening relay coil TC
Due to the bias, a drive mechanism (not shown) is activated, and the movable electrode 3 begins to separate from the fixed electrode 2. The signal given to the electrode control relay coil R2 is also given to one holding circuit. The holding circuit 19 is energized by receiving a signal,
This holding circuit 19 energizes the high voltage relay R1 until the movable electrode 3 begins to separate from the fixed electrode 2 and reaches the position where the movable electrode 3 is most released from the fixed electrode 2.

That is, the normally closed contact 17 remains open until the movable electrode 3 begins to separate from the fixed electrode 2 and the movable electrode 3 is at the most open position from the fixed electrode 2.

After the holding circuit 19 measures a predetermined time, the high voltage relay R1 is deenergized and the normally closed contact 17 of the high voltage relay R1 is closed. In this manner, the ground electrode 10 is completely separated from the ground potential point G at the same time as the movable electrode 3 begins to separate from the fixed electrode 2. Therefore, the movable electrode 3 and the fixed electrode 2
This eliminates the influence of the ground potential between the

By the way, when the normally closed contact 17 of the high voltage relay R1 is in an open state and a discharge occurs between the movable electrode 3 and the fixed electrode 2, a voltage is generated at the ground electrode 10. At this time, even if the normally closed contact 17 of the high voltage relay R1 does not have sufficient voltage resistance, the voltage generated at the ground electrode 10 will be divided between the capacitor 16 and the detection impedance 13. The capacitor 16 is charged according to the voltage generated at the ground electrode 10, and a current flows through the detection impedance 13 connected to the capacitor 16 based on this impedance. When this current is detected by the signal processing device 14 as a discharge detection device, it means that a discharge between the movable electrode 3 and the fixed electrode 2 has been detected. When this discharge is detected, it is determined that the degree of vacuum within the vacuum circuit breaker 1 is insufficient. The capacitor 16 is discharged through the detection impedance 13 when the normally closed contact 17 of the high voltage relay R1 is closed.

r11 When the movable electrode 3 separates from the fixed electrode 2, if there is no discharge between the movable electrode 3 and the fixed electrode 2, the capacitor 1
6 separates the ground electrode 10 from the ground potential point G, and of course the normally closed contact 17 of the high voltage relay R1 is in the open state, so there is no ground potential between the movable electrode 3 and the fixed electrode 2. There is no effect.

Note that the normally closed contact 17 of the high voltage relay R1 shown in FIG. 1 may be a normally open contact. When using normally open contacts,
After the discharge is detected by the signal processing device 14, the high voltage relay R1 is energized, the normally open contact is closed, and the capacitor 16 is discharged.

Furthermore, a normally open contact is used instead of the normally closed contact 17 and the capacitor 16 of the high voltage relay R1 shown in FIG. 1, and the normally open contact is opened only when the signal processing device 14 detects discharge. You can also do it.

〔Effect of the invention〕

As described above, in the vacuum defect detection device according to the present invention, when the movable electrode separates from the fixed electrode, the ground electrode connected to the ground potential point can be separated from the ground potential point. Disturbances in the electric field between the two electrodes no longer occur, and unlike in the past, due to the influence of the ground potential between the two electrodes, there are areas where the electric field strength is strong and areas where the electric field strength is weak, and for this reason, discharge is more likely to occur in the areas where the electric field strength is strong. However, since this problem has been resolved, the electrical isolation between the two electrodes can be maintained in a better state than before.

[Brief explanation of the drawing]

FIG. 1 is a device configuration diagram showing a vacuum defect detection device according to the present invention, and FIG. 2 is a device configuration diagram showing a conventional vacuum defect detection device. DESCRIPTION OF SYMBOLS 1... Vacuum breaker, 2... Fixed electrode, 3... Movable electrode, 7... System power supply, 9... Load, 10... Ground electrode, 14... Discharge detection device ( signal processing device), 1
6.17.18.19...Switching devices (capacitors, normally closed contacts, normally open contacts, holding circuits). Applicant's agent Mr. Sato

Claims (1)

[Claims] Equipped with a plurality of vacuum circuit breakers in which fixed electrodes and movable electrodes are surrounded by shielding plates, a ground electrode facing the outside of the vacuum circuit breakers, and a discharge detection device connected to the ground electrode via a switchgear. A vacuum defect detection device characterized by: