Vacuum Arcs and Postarc Characteristic of Vacuum Interrupters With External AMF at Current Zero

In order to reveal the mechanism of the residual magnetic field in vacuum interrupters (VIs), the vacuum arcs and the postarc characteristic with external AMF at current zero are investigated. The magnetic field of the 10-kV/20-kA VIs is analyzed. And then, the phase shift and the residual AMF are obtained. The test platform is established in the synthetic test circuit. The pulsed AMF is applied at current zero with the pulsewidth of 4 ms, and the magnitude can be adjusted from 0 to 200 mT. The transparency VIs with external AMF at current zero is observed by the high-speed CMOS camera to analyse the vacuum arcs development. The postarc current and transient recovery voltage are measured by the postarc current measuring equipment and the voltage divider so that the postarc characteristic such as postarc current and postarc charge can be obtained. The influence of the pulsed AMF at current zero on the vacuum arc development and postarc characteristic is gained and the mechanism of the AMF at current zero is analyzed, which can be useful to special AMF contact design for different applications.