Inventory management of power circuit breaker using failure data analysis

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 115 kV voltage levels are analyzed. The data has been classified according to different types of circuit breakers and subcomponents. The main components are classified as live parts and insulation, operating mechanism, and control circuit and others. Subsequently the main components are deeply differentiated into sub-components. 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 patterns of sub-components and overall failure pattern of 115 kV circuit breakers. Finally, the spare parts of sub-components are calculated using normal distribution technique. Therefore, preventive maintenance for the circuit breakers can be effectively managed according to its actual failure behavior. Consequently, the failure rate of the equipment can be reduced, which results in the better reliability of power system.