Arcing Behavior on TMF Contacts at Intermediate-Frequency

In this paper, the morphological changes and arc-voltage characteristics of vacuum arc at intermediate frequency (400Hz similar to 800Hz) were investigated under transverse magnetic field (TMF). The experiment was performed on cup-type TMF contacts with a contact diameter of 40mm and a contact gap of 2mm in single-frequency circuit. With high-speed photography, we characterized the appearance of the arc at different current of intermediate frequency. When current value increases from 3kA to 10kA the arc morphology changes obviously. When current value is 3kA (current frequency 400Hz-800Hz), there is almost no split arc, while more than 6kA (current frequency 400Hz-800Hz), the arc rotates at high speed and also split arc can be observed. The split arc can be observed at different frequency and the arc-voltage with no noise component when it occurred. Furthermore, the arc voltage at the peak current increases almost linearly with the total current at the same frequency. As the current frequency increases, the arc voltage at the peak current also increases at the same current.