Failure rate analysis of circuit breaker and its preventive maintenance application

This paper presents an analysis of failure rates of power circuit breakers at the 230 kV voltage class. First of all, the 20-year historically recorded failure data of existing power circuit breakers (CB) in high voltage substations in Thailand were retrieved. Subsequently, the data were analyzed and classified by causes of failure related to CB sub-component types. The failure rates based on individual sub-component types were examined and then were categorized into three main CB component categories depending upon their functionalities, which are live parts and insulation, operating mechanism, and control. The failure rates of individual CB sub-components were calculated and their associated probability distributions were estimated using Weibull distribution functions. The resulting Weibull distribution parameters were subsequently utilized in CB preventive maintenance application to aid a decision making process for setting maintenance schedule of CB components. The proposed method can also be applied to other high voltage equipment in power systems.