Suppression of Swirl Arc Re-Strike Under Magnetic Blowing for DC High-Power Application

Probability of arc re-strike increases with the increment of break voltage, especially in an arc chamber of DC bridge-type contacts equipped with permanent magnets. Among all types of arc re-strikes, the most dangerous one is that part of the arc re-enters the contact gap, which is defined as swirl re-strike in this paper. In this paper, the arc images and arc voltage waveforms were analyzed, and the typical features of arc re-strike were identified. In addition, the probability of arc swirl re-strike when the supply voltages range from 270 V to 730 V and the magnetic flux densities ranges from 30 mT to 70 mT were revealed. Mechanism of the swirl re-strike is explained and it is due to the randomness of positions of both the arc igniting and the arc-root transferring on stationary contacts, as well as the non-uniformly distributed magnetic field in the arcing region. Finally, measures to prevent arc re-strike were proposed, and their effectiveness on eliminating re-strike were verified at the voltage range of up to 730V and magnetic flux. Occurrence probability of arc re-strike drops from unity to 13% at 730 V.