Behavior Comparison of Metal Oxide Arrester Blocks When Excited by VFTO and Lightning

With the development of the ultrahigh voltage (UHV) and extra high voltage (EHV) electric power industry in China, gas insulated substation (GIS) is applied widely. Very fast transient overvoltage (VFTO) caused by disconnector operations in GIS may damage the insulation of equipment due to its high frequency and amplitude. As one of the main overvoltage protection equipments, the protection behavior of surge arresters has received extensive attention. In this paper, the residual voltage behavior, the impedance behavior, and the response behavior of five different representative arrester blocks when excited by VFTO and lightning are investigated, respectively. Experimental results present that when the current peak keeps constant, the residual voltage under VFTO is approximately 14.7%-18.2% higher than under the standard lightning impulse voltage (8/20 μs, LI). The arrester block presents different impedance behavior under VFTO and LI. It behaves dominantly inductively under LI and expresses an impedance converting behavior under VFTO. Furthermore, the diameter and the shape of arrester blocks have little impact on the ratio of V₀ to V_1mA under VFTO. Therefore, the protective effect of arresters varies slightly under VFTO and LI. Investigating behavior of arrester blocks under VFTO in comparison with under LI could be applied not only in VFTO simulation and insulation coordination but also in the design and the operating of metal oxide surge arrester in GIS.