CT secondary circuit multipoint grounding on-line monitoring device and monitoring method thereof

Abstract

The invention discloses a CT secondary circuit multipoint grounding on-line monitoring device and a monitoring method thereof. The CT secondary circuit multipoint grounding on-line monitoring device comprises a one-point grounding connecting line, a current transformer, a transmitter U1, a PLC, a relay set, a resistor set and an alarm device, wherein the one-point grounding connecting line is connected between a CT secondary circuit grounding point N and a secondary equipotential grounding grid M; the current transformer is connected to the one-point grounding connecting line in series; the transmitter U1 is electrically connected with the secondary side of the current transformer; the PLC is electrically connected with the output end of the transmitter U1; and the relay set is used for receiving and executing a command of the PLC. According to the CT secondary circuit multipoint grounding on-line monitoring device and the monitoring method thereof, the structure is simple, the use isconvenient, the purpose of monitoring the grounding condition of the CT secondary circuit grounding point in real time is achieved by adopting the PLC program control and the mutual cooperation of relays; and potential safety hazards are found and eliminated in time, and safe and stable operation of a unit and a power grid is guaranteed.

Description

technical field [0001] The invention relates to the field of CT secondary circuit monitoring, in particular to a CT secondary circuit multi-point grounding online monitoring device and a monitoring method thereof. Background technique [0002] The secondary side of the current transformer must have one and only one grounding point, because if the secondary circuit does not have a grounding point, the high voltage on the primary side of the current transformer will pass through the distributed capacitance between the primary and secondary coils of the current transformer. The transmission to the secondary side will cause danger to personal equipment. Once the secondary circuit is grounded, it is equivalent to "fixing" the secondary side to ground capacitance at zero potential; if there are multiple points grounded, the thermal power plant grounding grid is not ideal Potential, there will be a potential difference between multiple points, which will cause inaccurate sampling o...

AI Technical Summary

Problems solved by technology

[0005] A patent published on 2013.01.02 with the publication number CN202649370U and titled "PT secondary circuit multi-point grounding online monitor" discloses a PT secondary circuit multi-point grounding online monitor, including a point in the control room Ground connection wire (1), lightning arrester F, milliampere meter A, small knife switch K and sliding wire rheostat R, under the premise of ensuring that the running PT secondary circuit does not lose the ground point and does not affect the normal operation of the protection equipment, it can be judged There are hidden dangers of multi-point grounding, but it monitors the multi-point grounding situation of the PT (voltage transformer) secondary circuit, and it needs to judge whether multi-point grounding occurs by observing the change of the mA meter, which is very inconvenient , at the same time, if the signal disappears due to the return of the ground wire current, the maintenance personnel cannot know

[0007] 1. It is impossible to eliminate multi-point grounding faults in time, and there are likely to be potential safety hazards;

[0008] 2. Unable to troubleshoot without affecting the normal operation of the relay protection equipment

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