Reliability estimation of high voltage SF6 circuit breakers by statistical analysis on the basis of the field data

•The operational and maintenance data of high voltage SF6 circuit breakers are obtained from the East China Grid.•The actual maintenance measures for a circuit breaker can be withdrawn clearly from the operational data of a statistical survey.•The statistical approach can predict the remaining lifetime of circuit breakers even if the failure time is not observed.•The mathematical model can estimate the reliability of high voltage SF6 circuit breakers.

In order to estimate the reliability of high voltage SF6 circuit breakers, it is necessary to develop a statistical approach which can provide the failure probability, the failure rate and the remaining lifetime for the equipment and components. Useful information about the failure occurrences of 550 kV SF6 circuit breakers is collected from the East China Grid with the operating history. Even if the statistical survey is linked to data records of the unfailed components and maintenance measures, the statistical approach can accurately estimate the reliability of the components assembled in the circuit breakers. It is demonstrated by individual characteristics of 550 kV SF6 circuit breakers such as N2 leakage, SF6 leakage, overheat of primary terminal and defect of protection- and control system, etc. that the statistical approach is able to assess the reliability of equipment and components with reasonable and accurate results.