557 / 2022-03-29 21:53:07

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

Vacuum arc,Transverse magnetic field,Amplitude-frequency characteristics

Purpose

The vacuum arc tended to be unstable in the presence of the external transverse magnetic field (TMF), where an violent fluctuation of the arc voltage was observed. This phenomenon could be used to develop a passive resonace high-voltage DC vacuum circuit breaker. The objective of this paper is to analyze the arc voltage amplitude-frequency characteristics of the vacuum arc subjected to an external TMF.

Researching methods

In the experiments, the contact gap was fixed at 10 mm. An AC current with 50 Hz was used to simulate the fault current of DC grids. The peak value of the arc current varied from 0-6 kA. The intensity of the TMF ranged from 30-200mT. The characteristics of the arc voltage was analyzed by using the signal processing techniques such as FFT and time-frequency analysis.

Results

The amplitude-frequency characteristics of the arc voltage of the vacuum arc were obtained in the presence of the external TMF. Firstly, the DC component was dominant. The response of the high-frequency signal decayed exponentially with the frequency. The typical characteristic frequency was varied from 300-1000 Hz. Secondly, the characteristic frequency would decrease with the increase of the arc current, which suggested the arc voltage tended to be stable under a large arc current. Thirdly, the characteristic frequency would increase with the increase of the magnetic field intensity. It indicated the large TMF made the arc voltage fluctuate more violently.

Conclusions

Based on the results, the conclusions could be drawn as following.

1) Arc voltage amplitude-frequency characteristics were obtained. The frequency response of the arc voltage decayed exponentially with increasing frequency.

2) With the increase of arc current, the characteristic frequency of arc voltage decreased.

3) The increase of the magnetic field strength intensified the oscillation of the arc voltage.