The reason why the circuit breaker does not close involves various aspects, such as improper operation method during closing, inadequate closing phase voltage quality, control circuit disconnection, or equipment failure. Specifically, there are two categories of reasons: one is the electrical secondary circuit fault, and the other is the mechanical fault of the power switch operating mechanism.
When the circuit breaker fails to close, operators should distinguish between electrical secondary circuit faults and operating mechanism failures. The key indicators include:
(1) When the control switch is turned to the "closing" position, the indicator lights do not change (the green light remains flashing and the red light is off), the closing ammeter shows no movement, and the audible alarm sounds.
(2) When the control switch is turned to the "closing" position, the green light turns off and the red light remains off. After returning to the "post-closing" position, both the red and green lights are extinguished, and the fault alarm is activated, indicating that the power switch is not closed at all. This is likely caused by a blown fuse or poor contact during operation. If the fault alarm is not given, the closing ammeter shows activity, and load current is detected on the circuit while the mechanical equipment status shows "closed". In this case, the operator should trip the breaker, troubleshoot the fault, and reclose it.
(3) When the control switch is turned to the "closing" position, the green light turns off and then relights or flashes, and the closing ammeter of the smart electric circuit breaker fluctuates. This condition may occur for two reasons:
● The closing power supply voltage is too low, preventing the operating mechanism from lifting the power switch rod and completing the transmission mechanism posture.
● The operating mechanism is poorly adjusted, such as excessive or insufficient transformer core stroke or improper latch adjustment.