Performance improvements in metal oxide surge arresters for extremely fast transients
Gas-insulated substations can generate very fast transient overvoltages (VFTO) in the power system due to isolating switch operations. Current designs of metal oxide arresters may not be effective for these VFTs and therefore the arrester cannot operate under VFTO. At this point, improving the electrical performance of the arrester becomes crucial. Some possible measures to improve the electrical performance of arrester blocks are obtaining higher voltage gradients, reducing arrester capacitance effects and reducing the time lag between residual voltage and current surges. In this context, the microstructural and electrical parameters of the arrester block were modified by doping with scandium trioxide with basic composition and samples were prepared using different sintering processes. Subsequently, the voltage gradient, capacitance and time lag of the prepared samples were found. The performance of the new arrester blocks was studied for VFTO and the results were compared with conventional arrester blocks. It can be seen that the new arrester sample has improved parameters and can be used to protect VFTO in power systems.
