New type of ultrafast circuit breaker: its principle and performance

Abstract

The replacement of conventional voltage sources by inductive storage techniques in high-voltage pulse generation requires the successful operation of a suitable circuit breaker. The proposed device is composed of two different parts, the mechanical switch and the energy absorber. The magnetically activated mechanical switch operates in nitrogen under pressure and requires a low command energy (10%–15% of the primary stored energy). We present the mechanical switch basic principle and its performances, namely its restriking voltage and the parameters which affect it. The complete circuit breaker (switch plus energy absorber) can be used to open successfully currents up to 70 kA in times less than 10 μs. The restriking voltage (here, 40 kV after 20 μs) is proportional to the number of knives and can be improved by having longer conductors and a large number of knives. The switch jitter is very low (≃1 μs).