Contents I. Introduction
The circuit breaker is an extremely important equipment in the power system, and its reliability will directly affect the reliability and stability of the entire power system [1–2]. Many fault statistics on circuit breakers have been carried out, and the statistical data and analysis results have been published in [3] and [4], which is helpful to the design and improvement of circuit breakers. As circuit breaker manufacturers and power departments pay more attention to the reliability of circuit breakers, the research on the reliability of circuit breakers has gradually attracted more attention. The failures of high-voltage circuit breakers put into operation are counted in [5], and the reliability analysis model of high-voltage circuit breakers is proposed. The reliability of high-voltage circuit breakers was initially evaluated. The reliability of vacuum circuit breakers with spring-operated actuator is studied in [6]. In Reference [7], the mechanical reliability of a vacuum circuit breaker equipped with a spring operating mechanism is studied, and the mechanical reliability design and failure analysis of the operating mechanism are given. In [8], the accident statistics of high-voltage circuit breakers in East China Power Grid are carried out, and the fault tree model of circuit breakers and the life analysis model of circuit breakers are established. Reference [9] studied the influence of temperature, current and other factors on the reliability of permanent magnet actuator. Based on the above research, this paper focuses on the reliability study of the widely used permanent magnet mechanism vacuum circuit breaker. The main failure modes and failure mechanisms of vacuum circuit breakers are analyzed, and the weak points in the operation process are explored. Routine mechanical life tests are carried out for vacuum circuit breakers with permanent magnet actuator. Based on the maximum likelihood estimation model, the reliability of the actuator vacuum circuit breaker is evaluated.
