Capacitive making of vacuum circuit breakers: Double-break vacuum circuit breaker is superior to single-break vacuum circuit breaker

Previous studies mainly focused on the prestrike phenomena in single-break vacuum circuit breakers (VCBs) under capacitive switching. However, experimental investigations on prestrike characteristics under capacitive making operations of double-break VCBs were not addressed in literatures, which were important for the strategies of capacitive controlled switching. The objective of this paper is to experimentally investigate the prestrike characteristics of single-break and double-break VCBs in switching capacitor banks, to determine the most suitable type of VCBs in capacitive switching. The double-break VCB consists of two commercial 12 kV vacuum interrupters (VIs) with cup-type axial magnetic field (AMF) contacts, which is the same VI in the single-break VCB. The results show that the 50% prestrike gap d(50) of each VI in the double-break VCB, which was calculated based on the complementary Weibull distribution, was significantly reduced by 10.5% compared with the single-break VCB. Due to the voltage-sharing effect in the double-break VCB, scatters in prestrike gaps of the double-break VCB were smaller than the single-break VCB. With the application of the double-break VCB, both the inrush current interruption and the prestrike arcing time can be reduced. The double-break VCB can reduce the erosion caused by the inrush current of the low-voltage side VI. In capacitive switching, the double-break VCB is superior to the single-break VCB, especially in capacitive controlled switching.