Operational Status Evaluation of Circuit Breaker by Detecting SF_6 Decomposition Products

Discontinuous sound had been heard in some SF6 pillar circuit breakers during operation.By disassembling these breakers,this sound was found to be caused by the intermittent discharge due to the suspension potential between the axle pin and hole of the metal joint on an insulated draw rod.Th edischarge eroded or even broke the axle pin and hole.UHF,ultrasonic and hearing detection methods have been used to diagnose this fault,however the results were not satisfactory,and the hearing method might bring about misjudgement.Through the analysis of an axle pin fracture fault of draw rod on an SF6 pillar circuit breaker and the treatment method,this study presented a method for evaluating operational status of the breakers by detecting the SF6 decomposition products in order to detect and eliminate early internal-discharge in the breakers.This method was validated by a real case.