Table‐Lookup Estimation of Overvoltages at 275  <scp>kV</scp> Gas‐Insulated Switchgears

The lightning impulse withstand voltage (LIWV) of electric power equipment in substations has been determined and specified on the basis of lightning surge analyses. The lightning surge analysis needs a huge computation time and considerable expertise. In order to simplify the LIWV estimation, a table‐lookup method based on parametric analyses of lightning surges conducted in advance was proposed for 275‐kV transformers. In this study, lightning surge analyses of a 275‐kV substation with gas‐insulated switchgears (GISs) have been carried out to create a lookup table for estimating the LIWV of a 275‐kV GIS. Evaluations for the correlation between parameters and required LIWV have been shown, and examples to use the table‐lookup estimation have also been explained. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.