Cause Analysis and Solution of Rejection and Rejection of High Voltage Circuit Breakers

In the substation, the operation of the load stop and power transmission, the key equipment is the high voltage circuit breaker, also called the high pressure oil switch, its quality directly determines whether the entire power distribution system can operate normally, is high voltage supply and distribution. The weakest link in the system that is most prone to failure has many factors that affect the failure of the high-voltage circuit breaker to work normally. It mainly exists in many factors such as human factors and equipment itself. It is mainly summarized as follows:

1. The high-voltage circuit breaker cannot be normally closed for power transmission. This phenomenon is called the rejection phenomenon of the high-voltage circuit breaker switch. This phenomenon often occurs in the accident scene.

2. The high-voltage circuit breaker cannot be normally disconnected and power-off. This phenomenon is called the phenomenon of refusal of the high-voltage circuit breaker. This phenomenon is more common in the on-site accident handling.

3. There are also many factors that affect the oil switch that cannot be normally divided and closed. It is due to many reasons such as closing, tripping fuse breaking, protection trunk disconnection, control switch failure and so on. Because of these reasons, it is easy to judge in the accident handling of the site. Solve, not detailed here.

How to ensure its reliable and safe operation is the primary problem in the management of substation equipment. The following is a description of the solution to the high-voltage circuit breaker rejection and rejection failure phenomenon that occurs in the substation.

I. Analysis of the reasons for the rejection of high voltage circuit breakers

1. High voltage circuit breaker rejection

After the high-voltage switchgear is overhauled and debugged, when the switch attendant operates the high-voltage circuit breaker, the first closing and opening operations can operate normally, but when the second closing is performed, the retraction phenomenon occurs. The accident alarms are all normal, and sounds and prompts are emitted.

2. Analysis of reasons for rejection of high voltage circuit breaker

The on-site inspection protection circuit wiring is consistent with the original drawing. There is no replacement equipment and wiring change during the maintenance process. What is the reason? The wiring diagram of the circuit electrical principle is shown in the attached figure.

After inspection, it is found that as long as the high voltage circuit breaker is opened, the anti-jump relay TBJ is sucked and held. As can be seen from the last page of the drawing, the TBJ is activated by its current coil when the high voltage circuit breaker is opened. After startup, the TBJ normally open contact is closed, and the signal lamp LD is connected in series with the TBJ voltage coil, so the 220V control power is applied across the LD and TBJ voltage coils. LD is an energy-saving signal lamp, and its equivalent resistance is about 22kΩ TBJ for intermediate relays DZB-15B/220V, 0.5A, and its voltage coil DC resistance is 9kΩ. After searching for the data and calculating, the voltage at both ends of the LD is 156V, and the voltage across the TBJ is 64V. The actual measurement and calculation are basically consistent. The return voltage of the intermediate relay is not less than 3% of the rated voltage according to the factory standard. The repelling phenomenon caused by the second closing is due to the sufficient holding voltage of the TBJ voltage coil, thus cutting off the closing circuit.

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