220kV GIS母联断路器辅助触点氧化短路故障诊断与分析OA

Aiming at the problems that the hidden faults of the auxiliary contacts of 220 kV GIS bus coupler circuit breakers are prone to misjudgment and difficult to locate,an unplanned tripping accident of a bus coupler circuit breaker in a power plant is taken as the research object.A multi-dimensional step-by-step diagnosis process is established,including relay calibration,insulation measurement,fault recording analysis,and micro-disassembly of contacts.Through step-by-step investigation,conventional fault factors such as relay maloperation,DC grounding,single-phase accidental tripping,and parasitic circuits are eliminated,and the fault root cause is finally located at the circuit breaker position auxiliary switch S1.The results show that the direct cause of the tripping is the internal oxidation shortcircuit of the B-phase auxiliary contact,which leads to the maloperation of the three-phase inconsistency protection.After replacing the auxiliary switch with the same type,the equipment operates normally,and the dynamic characteristics and protection logic verification are qualified.This step-by-step diagnosis process can effectively locate micro-contact faults,reducing the average troubleshooting time for similar faults from 48 hours to less than 8 hours,and can provide a promotable standardized method for the diagnosis of concealed faults in the auxiliary circuits of high-voltage switchgear.