Prestrike Characteristics of Double-Break Vacuum Circuit Breakers in Making Power Frequency Voltage

Vacuum circuit breakers (VCBs) have been extensively employed in switching shunt capacitor banks. However, research on the prestrike characteristics of double-break VCBs in making power frequency voltage remains limited. This study aims to investigate the influence of different closing time differences on the prestrike characteristics of double-break VCBs in making power frequency voltage, and to compare these influences with those of single-break VCBs. Experiments were conducted using vacuum interrupters rated at 24 kV, with contacts made of CuCr40 alloy doped with 1 wt% graphene. Taking the closing time of the high-voltage break as the time zero point, three closing time differences (0 ms, 0.727 ms, and −0.347 ms) were set, and experiments were carried out at six closing phase angles (from 0° to 150° in 30° increments) for each condition. The experimental results demonstrate that when the closing of the high-voltage break lags behind that of the low-voltage break by 0.347 ms, the double-break VCB exhibits optimal prestrike performance, where prestrike is almost entirely suppressed except at the 90° phase angle. Furthermore, the prestrike performance during the closing of the double-break VCB is significantly superior to that of the single-break VCB, characterized by a steeper RDDS curve. These findings provide a theoretical basis for the design of control-switching double-break VCBs.