Analysis on the Arc Voltage Amplitude-frequency Characteristics of DC Vacuum Arc Subjected to an External TMF

The objective of this paper is to determine the amplitude-frequency characteristics of the arc voltage of the DC vacuum arc subjected to an external TMF. The vacuum arc tended to be unstable in the presence of the external transverse magnetic field (TMF), where a violent oscillation of the arc voltage was observed. The oscillation can be used to design a new passive resonance vacuum DC circuit breaker. In addition, the parameters of the parallel branch for the passive resonance were preliminarily selected through the simulation. To obtain the amplitude-frequency characteristics of the arc voltage, the experiments were carried out in C-L-R circuit. The arc currents in the experiments were 490 and 800 A, respectively. An external TMF of 24 mT was provided by a pair of Helmhortz coils. The experimental results showed that, in the unstable stage, the frequency with the largest amplitude of the arc voltage was appeared between 100 kHz and 500 kHz and was unfixed. When the frequency was greater than 500 kHz, the amplitude decayed rapidly. According to the simulation, the parameters of the parallel branch was determined. The simulation results show that the characteristic frequency of L-C value around 200 kHz is appropriate, and the magnitude of the amplitude is negatively correlated with the quality factor of the L-C.