Fault analysis of an explosion caused by circuit breaker closing not in place

The article analyzes a pole explosion accident of the LW30-72.5 circuit breaker in the automatic switching state. Through the disassembly and analysis of the circuit breaker, it is found that the spring pin of the insulating rod and the connecting pin of the operating rod of the circuit breaker is not installed in place, resulting in the displacement of the connecting pin and the occurrence of a premature failure, resulting in the difference between the moving arc contact and the static arc contact. Continuous arc discharge occurs, and due to the continuous friction between the displaced connecting pin and the pole sleeve, the deformation of the insulation rod gradually accumulates, and the unclosed distance between the moving arc contact and the static arc contact accumulates. To 42mm, the moving arc contact and the static arc contact will eventually melt, and the molten metal will flow down the insulating tie rod, causing excessive creepage of the insulating tie rod, which will eventually cause the phase to be grounded and destroyed, and finally cause a support seat in the pole pole explosion. It is recommended to conduct non- destructive testing and X-ray enhanced testing based on resistance testing and gas composition testing for the same batch of LW30-72.5 circuit breakers to avoid similar accidents caused by similar faults.