RDDS (rate of decrease of dielectric strength) measurement for gas circuit breaker

RDDS (rate of decrease of dielectric strength) is one of the important characteristics of the circuit breaker for applying controlled closing technology. This characteristic is supposed to be affected by contacts roughness and consumption of the circuit breaker caused by rated current or short circuit current interruptions. Also the number of interruptions of the circuit breaker influences the RDDS characteristic. In this paper, the influence of the contact wearing of the circuit breaker by current interruptions to the RDDS was investigated. In a high-power laboratory, the RDDS of a high-voltage one-break circuit breaker was measured at three conditions as follows: before current interruptions; after rated current interruptions; and after short circuit current interruptions. In the field, the RDDS characteristics using another one-break circuit breaker were measured. The results showed that current interruptions have little influence on the RDDS. It is possible to apply controlled closing to circuit breakers after current interruptions. The RDDS calculated by electric field analysis was in good agreement with measurements.