Characteristics confirmation of MOV for DC application under long-duration impulse current

Lightning protection using surge arrester have an important role for reliability of power system. In this study, we focused on the effect of impulse current on the degradation of MOVs used for DC surge arrester. Surge arresters for DC applications, especially in railway applications, are used to protect equipment from switching overvoltages, which has long-duration waveform, as well as lightning overvoltages. Degradation of MOVs were confirmed by measuring the varistor voltage before and after energy injections in this study. 10/350-mu s waveform and 2-ms waveform were adopted to confirm the varistor voltage change for the long-duration current impulse. As a result, it was confirmed that the characteristics change after each waveform were different in each waveforms, and symmetric characteristic change was occurred on 2-ms waveform. In addition, asymmetric characteristics change and dependence on current peak value were confirmed in the 10/350-mu s waveform.