Development of High Voltage Vacuum Circuit Breakers in China

This paper introduces research work on development of high voltage vacuum circuit breakers (VCBs) in China, which is from 1989 to 2006. In this period a 126kV two breaks VCB prototype and a 126kV single break VCB prototype were developed. A latest 252kV single break interrupter prototype is introduced. 5 high voltage VCBs technologies are discussed, which include high voltage vacuum insulation, high current interrupting technology with long gap, nominal current increasing, operating mechanism characteristics and contact bouncing damping. In vacuum insulation, adding a metal ring can decrease breakdown possibilities in the gap between back of electrodes and main shield. For interrupting high current with long contact gap, strong axial magnetic field (AMF) is needed for a better vacuum arc control. Therefore a single coil AMF electrode is introduced. Cooling fin is effective to increase nominal current of VCBs. There is an optimum opening characteristics that is helpful to improve interrupting performance of VCBs. Contact bouncing in high voltage VCBs can be damped by installing contact spring and bellows on stationary end of VCBs