Do you know the various anti-trip circuits of vacuum circuit breakers?

The vacuum circuit breaker anti-trip circuit mainly uses mechanical and electrical means to prevent the circuit breaker from jumping and closing in the event of a fault, ensuring the safe and stable operation of the power system. The following are the main anti-trip circuit types and characteristics:

Operating Principle: The current coil of the anti-trip relay (TBJ) is connected in series with the trip circuit, and the voltage holding coil is connected in parallel with the closing coil. When the protection is activated, the TBJ's normally closed contact disconnects the closing circuit, while the normally open contact connects the voltage holding coil, preventing the vacuum circuit breaker from closing repeatedly.

Advantages: It combines anti-tripping and arc-failure prevention functions, offering high reliability and wide application.

Voltage Coil Parallel Method

The voltage coil of the anti-trip relay (KO) is connected in parallel with the closing circuit. After closing, the auxiliary contact closes, activating the anti-trip relay, while its normally open contact disconnects the closing circuit. This method is suitable for vacuum circuit breaker such as the VD4.

Spring Energy Storage Method

When closing, the spring stores energy, and the auxiliary switch (such as S3) closes, activating the anti-trip relay. The normally open contact automatically disconnects the closing circuit. This method is commonly used in circuit breakers such as the Siemens 3AF.

Mechanical Anti-tripping: Some vacuum circuit breaker use mechanical mechanisms (such as locking devices) to directly prevent tripping, but this must be used in conjunction with electrical anti-tripping to improve reliability.

Microcomputer Anti-tripping: This function is implemented through a control circuit, but care must be taken to prevent parasitic effects from affecting the effectiveness.

Combined Anti-tripping: Mechanical and electrical anti-tripping must be combined to prevent failure of either method alone.

Fault Handling: If the microcomputer protection output fails, voltage division within the anti-tripping relay coil or a self-protection mechanism must be used to prevent accidental closing.

The above anti-tripping circuits must be selected based on the specific circuit breaker model and system requirements to ensure effective prevention of circuit breaker tripping under abnormal conditions such as overvoltage and short circuits.