Study on Influence of Self-Generated Axial Magnetic Field Upon High-Current Vacuum Arc Behavior at a Long Contact Gap in High-Voltage Vacuum Interrupter

In this paper, the high-current vacuum arc characteristics under self-generated axial magnetic field (AMF) generated by a sinusoidal current flowing through the coil type of AMF contacts are investigated at long contact gaps of 40 and 60 mm. The distributing characteristics of the AMF in the contact gap are studied by a finite-element method, taking eddy current effect into account. Vacuum arc appearance was observed by a high-speed charge-coupled device video camera. The vacuum arc voltage was measured using a high-voltage probe. Capacitor and reactor (LC) discharging-current-interrupting tests were done with a single-frequency oscillating circuit. The vacuum arc behavior of a single coil-type AMF contact and that of a 1/2 coil-type AMF contact were compared. The research results show that both the amplitude and phase shift time of the AMF have great influence upon the high-current vacuum arc characteristics.