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Re-ignition is re-establish of arc after arc extinction within one fourth of cycle from final current zero. It may occur because of small distance between two contacts. Due to that, contact gap breakdown and arc re-ignite. The re-ignition is not harmful as it does not give any overvoltage. At next current zero instance only, arc gets quench as the distance between two contact becomes sufficient to withstand Transient Recovery Voltage(TRV). Fig. Current waveform with re-ignition and re-strike Re-strike is re-establish of arc after one fourth of cycle from final current zero. It occurs due to capacitive current switching. In capacitive current switching, a single restike gives 4 times voltage rise. It leads to overvoltage which can damage dielectric medium. Re-striking is more severe than re-ignition.

Previously, Importance of protection against inrush current in stationary device is determined. In this post, different mitigation methods are addressed.  Pre-Magnetizing Transformer: Function:   To magnetize the transformer core at starting with regulated voltage source before connecting with main supply and prevent from saturation of core. Fig. Medium voltage side pre-magnetizing transformer Fig. Low voltage side pre-magnetizing transformer                                                                                           Application:   Marine transformer Limitation : No. of components are more, require external small size auxiliary transformer, cost is more.    Pre-Insertion Resistor/Rheostat with controlled switching: Function:   To mitigate the inrush current by providing external resistance at starting and switching control is used to bypass that rheostat after initial few cycles . Application :  MV transformer energization