Precautions for overhauling low voltage circuit breakers

Precautions for overhauling low voltage circuit breakers

(1) It is necessary to ensure a safe distance between the external arc-extinguishing chamber of the low-voltage air circuit breaker and the conductive part and the grounding part of the adjacent electric appliance, and to prevent the arc-insulation board of the missing circuit breaker. The low-pressure air circuit breaker can only be put into operation after the arc-insulation board is installed in strict accordance with the requirements of the “Low-Voltage Automatic Air Switch Maintenance Regulations”. Otherwise, an arc is easily generated when the circuit is cut, causing a phase-to-phase short circuit.

(2) It is necessary to regularly check whether the signal indication of the low-voltage air circuit breaker matches the circuit's branching and closing status, and check whether there is overheating at the connection point with the busbar or the outgoing line. During the inspection, the dust on the surface of the low-pressure air circuit breaker should be thoroughly removed in time to avoid affecting the operation and insulation performance. After the power failure, remove the arc chute, check the integrity of the arc chute, and remove the smoke marks and metal powder on the surface. The outer casing should be intact and replaced if it is damaged.

(3) Care should be taken to check the dynamic and static contacts of the low-voltage air circuit breaker. If there are burrs and metal particles on the contact surface, it should be cleaned and trimmed in time to ensure good contact. If the surface of the contact silver-tungsten alloy burns more than 1mm, it should be replaced in time.

(4) It is necessary to carefully check whether the contact pressure of the low-voltage air circuit breaker is overheated and fail, and adjust the position and pressure of the three-phase contacts in time to keep the three phases closed at the same time, to ensure the contact surface is complete and the contact pressure is consistent. Slowly divide and close by hand, check whether the broken and closed working state of the auxiliary contact meets the requirements of the "Low-pressure automatic air switch maintenance regulations".

(5) To fully check whether the connection of the low-voltage air circuit breaker release and the spring activity are normal, the action should be free of jamming, and the working surface of the electromagnet should be clean and smooth without rust, burrs and dirt; No damage, whether the clearance meets the requirements of the "Low-pressure automatic air switch maintenance regulations". If there is any abnormality, it should be cleaned or adjusted. It is also necessary to regularly lubricate the friction parts to ensure correct operation and reliable operation.