Influence of Sealed Gas and its Pressure on Arc Discharge in Electromagnetic Contactor

In this study, DC source voltage is kept at 100 V, and the closed contacts currents are changed from 5 to 30 A with a resistive load. Four types of gases, air, nitrogen, helium, and hydrogen were investigated. The atmospheric pressure is set in the range of form 0.05 MPa (0.5 atm) to 0.4 MPa (4 atm). The arc duration is measured from voltage and current waveforms of break arc discharge. In addition, contact resistance is measured. As a result, it was found that the influence on arc voltage waveform differs depending on the kind of gas. In helium, the arc voltage waveform rises stepwise and transitions from metallic phase to gas phase arc. However, with nitrogen and air, the arc voltage continuously increased and transited to the gaseous phase arc. On the other hand, the arc duration time was the longest in helium and the shortest in hydrogen. The result was as follows: 112 < N2 < Air < He. And with the same gas, it became clear that the higher the gaseous pressure, the shorter the arc duration time.