Test analysis of dielectric recovery characteristic in high voltage SF6 circuit breaker

In this paper, dielectric recovery characteristic during operation of high voltage SF6 circuit breaker is studied by test method. The test circuit of dynamic breakdown characteristics is built. Circuit breaker closing and opening dynamic breakdown voltage curves under positive and negative polarity are obtained. Impact of inflatable pressure and closing speed to dielectric recovery characteristic are analyzed. Breaking dielectric recovery rate and closing pre-strike time under different experimental conditions are given. The results showed that: the positive polarity breakdown voltage is greater than negative polarity of SF6 gas. The impact of closing speed on the closing pre-strike characteristic is significantly. The maximum closing pre-strike time is 1.18ms under closing speed 6.6m/s. The maximum closing pre-strike time is 2.21ms under closing speed 4.7m/s. It can be seen, to improve the closing speed is an effective method to control pre-strike time. When P=0.7Mpa and P=0.5MPa respectively within 0.5ms and 1ms after contact separation, breakdown may occur again. Therefore, breaking process should be avoided in this time range extinction.