JPH05334947A - Device for monitoring consumed quantity of contact - Google Patents

Abstract

PURPOSE:To always monitor the consumed quantity of the contact of a switching device without cutting off the current of a main circuit by accumulatively adding the data of an effective value of current at the time of interrupting the current of a current switching device. CONSTITUTION:Current is interrupted by opening a contact within a current switching device, and the high-frequency component and the commercial frequency component involved with the generated arc-current are detected by a high-pass filter circuit 3 and a low-pass filter circuit 5 through a converter 2, and the level of the high-frequency component at the time of interrupting current is determined by a level determination circuit 4, and when it exceeds a certain value, a pulse signal is outputted to a waveform memory circuit 6. The commercial frequency component is detected by the low-pass filter circuit 5 and outputted to the waveform memory circuit 6. A waveform stored in the waveform memory circuit 6 is operated by an effective value operation circuit 7, and the effective value of current at the time of interrupting current is operated, and the effective value of current is accumulatively added by a data accumulation circuit 8 at the time of interrupting current, and when the accumulatively added data becomes not less than a certain value, an alarm is given out, so that the consumptions of a contact may be always monitored with accuracy without a main current is interrupted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact wear monitoring device for a switchgear.

[0002]

2. Description of the Related Art FIG. 2 shows a contact wear monitoring device for a conventional high pressure vacuum switchgear. In the structure of FIG. 2, the fixed electrode 9 is arranged at the center of the high-pressure vacuum switchgear 12, and the movable electrode 10
Moves with respect to the fixed electrode 9 by a known mechanism. Contact points of the fixed electrode 9 and the movable electrode 10 are built in the vacuum switch tube 13. A scale 11 for measuring the amount of contact wear is attached to the movable electrode 10. Next, the operation of the prior art shown in FIG. 2 will be described. Movable electrode 10 by a known mechanism
Moves relative to the fixed electrode 9 to open / close the current flowing through the high-pressure vacuum switchgear 12. When the electrode surface is consumed by opening and closing a large number of times, the scale 11 attached to the movable electrode 10 moves in proportion to the amount of consumption of the electrode surface.

[0003]

Since the conventional contact wear amount monitoring device of the switchgear 1 is constructed as described above,
When measuring the amount of wear on the electrode surface, the switchgear 1 must be disassembled or the main circuit current of the switchgear 1 must be cut off for the measurement, and therefore the contact wear cannot be constantly monitored. There was a point. This invention is a switchgear 1
It is an object of the present invention to provide a contact wear amount monitoring device capable of constantly monitoring the wear amount of the electrode surface without interrupting the main circuit current.

[0004]

A contact wear monitoring device for a switchgear according to the present invention comprises a high-pass filter circuit for detecting a high-frequency component of a current flowing through the switchgear, and a high-frequency component detected by the high-pass filter circuit. A level determination circuit that determines that the value has exceeded a certain value and outputs a predetermined signal, a low-pass filter circuit that outputs the waveform of the commercial frequency component of the current flowing through the switchgear, and the level determination circuit outputs a predetermined signal. A waveform memory circuit that stores the waveform of the commercial frequency component when output, an effective value calculation circuit that calculates the effective value of the waveform of the waveform memory circuit, and a data accumulation circuit that accumulates the effective value ..

[0005]

[Operation] The amount of contact wear is estimated by accumulating the effective value of the breaking current.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a contact wear monitoring device for a switchgear according to the present invention.

The switchgear 1 in FIG. 1 may be not only the high-pressure vacuum switchgear shown in FIG. 2 but also another switchgear. The current transformer 2 is connected to the switchgear 1 in series.
The output current of the current transformer 2 is input to the high pass filter circuit 3 and the low pass filter circuit 5. The high pass filter circuit 3 detects a high frequency component due to the arc current when the current is cut off. The low pass filter circuit 5 detects the current of the commercial frequency component. The output of the high pass filter circuit 3 is input to the level determination circuit 4. The level decision circuit 4 decides when the high frequency component detected by the high pass filter circuit 3 becomes a certain value or more and outputs a predetermined signal. The output of the low pass filter circuit 5 is input to the waveform memory circuit 6. The waveform memory circuit 6 stores the waveform of the commercial frequency component detected by the low pass filter circuit 5 when the level determination circuit 4 outputs a predetermined signal. The waveform data of the commercial frequency component stored in the waveform memory circuit 6 is input to the effective value calculation circuit 7. RMS calculation circuit 7
Is for calculating the effective current value of the commercial frequency component stored by the waveform data stored in the waveform memory circuit 6. The output of the effective value calculation circuit 7 is input to the data accumulation circuit 8. The data accumulating circuit 8 cumulatively adds the data whose effective value has been calculated by the effective value calculating circuit 7, and outputs an alarm output when the cumulatively added data exceeds a certain value.

Next, the operation of the embodiment shown in FIG. 1 will be described. When the switchgear 1 cuts off the current, a high frequency component is generated in the main circuit due to the arc current when the current is cut off. The high frequency component is detected by the high pass filter circuit 3 through the current transformer 2. The level determination circuit 4 determines the level of the high frequency component and outputs a predetermined pulse signal when the detected value is the level of the high frequency component above a certain value in order to distinguish it from the high frequency component due to noise other than when the current is cut off. The commercial frequency component is detected by the low pass filter circuit 5 and given to the waveform memory circuit 6. The waveform memory circuit 6 stores the waveform of the commercial frequency component detected by the low pass filter circuit 5 when the pulse signal is output from the level determination circuit 4. The waveform stored in the waveform memory circuit 6 is calculated by the effective value calculation circuit 7, and the current effective value at the time of current interruption is calculated. The data accumulating circuit 8 cumulatively adds the effective current value when the current is cut off. Since the contact wear amount of the switchgear 1 is substantially determined by the effective current value when the current is cut off, it has a large correlation with the cumulatively added data. Therefore, when the cumulatively added data exceeds a certain value, a warning is output.
Therefore, the contact wear amount can be accurately monitored by the warning output of the data accumulation circuit 8.

[0009]

According to the present invention, the contact wear amount is estimated and monitored by cumulatively adding the data of the breaking current effective value without actually measuring the contact wear amount of the switchgear 1. Switchgear 1 can be disassembled into
The main circuit current can be constantly monitored without interruption.

[Brief description of drawings]

FIG. 1 shows an embodiment of a contact wear monitoring device for a switchgear according to the present invention.

FIG. 2 shows a contact wear amount monitoring device of a conventional high-pressure vacuum switchgear.

[Explanation of symbols]

 1 Switchgear 3 High-pass filter circuit 4 Level judgment circuit 5 Low-pass filter circuit 6 Waveform memory circuit 7 Effective value calculation circuit 8 Data accumulation circuit

Claims (1)

[Claims] 1. A high-pass filter circuit for detecting a high-frequency component of a current flowing through a switchgear, and a level for determining that the high-frequency component detected by the high-pass filter circuit has exceeded a certain value and outputting a predetermined signal. A determination circuit, a low-pass filter circuit that outputs the waveform of the commercial frequency component of the current flowing through the switchgear, and a waveform memory circuit that stores the waveform of the commercial frequency component when the level determination circuit outputs a predetermined signal, A contact wear monitoring device for a switchgear, comprising: an effective value calculation circuit for calculating an effective value of a waveform of the waveform memory circuit; and a data accumulation circuit for accumulating the effective value.