A CT secondary circuit multi-point grounding online monitoring device and monitoring method thereof

Abstract

The invention discloses a CT secondary circuit multi-point grounding online monitoring device and a monitoring method thereof, comprising a one-point grounding connection line, a current transformer, a transmitter U1, a PLC controller, a relay group, a resistance group and an alarm device; The one-point ground connection line is connected between the CT secondary circuit ground point N and the secondary equipotential ground network M, the current transformer is connected in series on the one-point ground connection line, and the transmitter U1 and the current transformer two The secondary side is electrically connected, the PLC controller is electrically connected to the output end of the transmitter U1, and the relay group is used to receive and execute PLC controller commands. The CT secondary circuit multi-point grounding online monitoring device and the monitoring method thereof of the present invention are simple in structure, easy to use, and adopt PLC program control and relays to cooperate with each other to realize the purpose of real-time monitoring of the grounding situation of the CT secondary circuit grounding point; Discover and eliminate safety hazards in time to ensure safe and stable operation of units and power grids.

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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