When a load stop and power system failure occurs in a substation, the core equipment is the high-voltage circuit breaker. Its good or bad is the entire substation and distribution system work properly, the weakest link in the high-voltage power supply distribution system is the most prone to failure, plastic-cased circuit breakers do not work properly for many factors.

The following aspects are mainly summarised.

Circuit breaker operation occurs in the refusal to trip the fault analysis, judgment and processing

When the circuit breaker refuses to trip, the old circuit breaker will trip. This is known as a "phase trip". This extends the scope of the outage, sometimes leading to system disruptions and leading to a major blackout. Therefore, "refusing to jump" is more dangerous than "refusing to meet". A "no jump" error is handled in the following way.

1. according to the accident phenomenon, it can be judged whether it is a circuit breaker "refusal to jump" accident

The "refusal to jump" fault is characterised by the following: the protection signal lights up, the signal shows that the protection is in action, but the red light of the circuit is still on and the overcurrent, circuit breaker fault protection and other upper level backup protection is repeated around. In some cases, the backup protection does not work on time, the component current display increases sharply for a short time, the voltage display decreases, the power changes frequently, the main transformer makes a heavier humming sound and the corresponding moulded case circuit breaker remains in the closed position.

2. Determine the circuit breaker failure, you should immediately manually pull the switch

(1) Before the circuit breaker is found not to work, if the main transformer internal power supply main circuit breaker control current through the indication value is the largest and the abnormal sound is the strongest, the main power supply main circuit breaker should be opened first to prevent the main transformer from burning.

(2) As a first back-up protection measure, if parallel protection action is present at the time of the outage but the circuit breaker has not tripped, pull the rejected circuit breaker to restore the first power supply circuit breaker. If no parallel protection action is found, and if there is no fault, disconnect all parallel circuit breakers and test the parallel circuit breakers one by one after the power circuit breaker has been switched off. The power supply circuit breaker may be identified as an error (rejected) circuit breaker when it trips again after being sent to a sub-circuit. It must be disconnected and power restored to the other circuits.

(3) Check for common electrical faults in "trip-proof" circuit breakers (e.g. low control supply voltage or control voltage, poor contact with control circuit fuses, fuses, etc.)

3. the "refusal to jump" circuit breaker electrical and mechanical aspects of the fault analysis and judgment methods

(1) The circuit breaker refuses to jump to failure, looking for learning methods.

First, the circuit failure or mechanical failure is determined by.

1. Check whether the student has tripped the power supply at too low a voltage level.

2. Check if the tripping circuit is damaged. A mechanical failure is when the tripping core works properly and the circuit breaker does not trip.

3. If the power supply is running well and refuses to trip due to weak core action, blocked cores or faulty coils, there is often some failure in the business due to both electrical and mechanical aspects.

4. Normal working voltage, core does not move after work, mainly electrical faults leading to "no jump".

(2) Electrical causes include.

1. cavity circuit fuse fuse fuse or tripping circuit components poor contact (for example, control switch contacts, circuit breaker work mechanism auxiliary contacts, anti-jump relay, relay protection tripping circuit).

2. Hydraulic (pneumatic) mechanism operating pressure reduced, tripping circuit may be closed, brake control valve may not work.

3. SF6 circuit breaker gas pressure is low, density relay action circuit blocked.

Faulty tripping coil.