Protective Performance of Metal Oxide Surge Arrester Based on the Dynamic V-I Characteristics

Metal oxide surge arrester (MOA) is constructed by a series connection of zinc oxide elements having a highly nonlinear resistance. A simple equivalent circuit is proposed to express the dynamic characteristics of zinc oxide element. Using this dynamic model, the effect of lightning strokes to gas insulated substations (GIS) is analized by a computer simulation under various conditions. The results are summarized in a diagram from which the length of GIS bus to be protected by MOA can be determined. Comparing the overvoltage protection performance of MOA with that of a conventional arrester, MOA is found to be more suitable for GIS application.