Mobile QR Code QR CODE : The Transactions of the Korean Institute of Electrical Engineers
Title Effects of Lightning Surges on the Life of ZnO Varistors
Authors 이봉(Lee, Bong) ; 이수봉(Lee, Su-Bong) ; 강성만(Kang, Sung-Man) ; 이복희(Lee, Bok-Hee)
Page pp.257-262
ISSN 1975-8359
Keywords Zinc Oxide Varistor ; Lightning Surge ; Resistive Leakage Current ; 8/20μs Impulse Current ; Surge Simulator System
Abstract To evaluate the change in protective levels of zinc oxide (ZnO) varistors after the surge absorption, this paper investigated the effects of the number of injection and amplitude of lightning surges on the life of ZnO varistors for low voltages. Leakage currents flowing through ZnO varistors subjected to the 8/20μs impulse currents under 60 Hz AC voltages were measured. The surge simulator system ECAT that can generate 8/20μs impulse currents with a peak short-circuit of 5 [kA_p] was used. The ZnO varistor leakage current increases with exposure to impulse current, and the number of injection of 8/20μs impulse currents to breakdown was inversely proportional to the amplitude of the test current. Behaviors of ZnO varistor leakage currents were strongly dependent on the number of injection and amplitude of 8/20μs impulse currents. ZnO varistors degrade gradually when subjected to impulse current, and the resistive leakage current flowing through ZnO varistors subjected to the 8/20μs impulse currents under 60 Hz AC voltages was significantly increased after a certain number of injection that is dependent on the amplitude of the test impulse current. As a result, the life of ZnO varistors mainly depends on the amplitude and occurrence frequency of lightning surges.