Experimental Study on Voltage Fluctuation at Arc Blowing with External DC Magnetic Field

Parameters on electromagnetic compatibility (EMC), as well as lifetime and reliability, are important properties for electrical contacts. This paper newly attempts to clarify the mechanism of the generation of high frequency EM noise caused by breaking contact according the arc discharge, and the effect of the external DC magnetic field on the EM noise as well as arcing phenomena under high-speed separation, which allows to study possible means for developing the long lifetime and low noise electrical contact. Firstly, preliminary experiments under the conditions: open-voltage 30V and closed-current 3.6A, and DC magnetic field 0mT to 52mT, which correspond to our previous studies, were carried out. Breaking waveforms, frequency spectrum and time-frequency domain characteristic of voltage fluctuation are studied by comparison with and without external magnetic field. It was demonstrated that although applying external magnetic field is effective in reduction of duration of gaseous phase in arc (9%), higher variation of contact voltage in the gaseous phase above several hundred Megahertz is caused by external magnetic field. More importantly, the applied DC magnetic field under high-speed separation does not work to suppress the arc-duration well. These results are basic and useful finding and consideration to clarify not only the contact-breaking phenomena but also the design methodology of electrical contact from view point of EMC.