Analysis of failure data to determine the failure pattern of HV circuit breaker components

This paper presents an analysis of historical failures of HV circuit breakers in Thailand´s transmission network. The historical data of circuit breakers installed since 1989 to 2011 at three voltage levels as 115 kV, 230 kV and 500 kV are analyzed. The data has been classified into different types of circuit breakers and components. The main components are classified as major HV components, operating mechanism, and control circuit and others whereas the sub-components are also differentiated. The failure frequencies of those sub-components are then assessed in order to observe their failure characteristics in form of Bath-tub pattern, which is classified into three zones as teething, random and ware-out zone. The results show failure frequency of sub-components of only 115 kV circuit breakers. Finally, the preventive maintenance for the circuit breakers can be effectively managed due to actual failure behavior. Consequently, the failure rate of the equipment can be reduced resulting in better power system reliability.