Basic Parameters in Determining the Insulation Requirements of Transmission Lines

This paper presents the insulation requirements of transmission lines ranging in voltage from 69 to 500 kv. voltages, switching surges, and lightning surges which are basesd on 60-cycle voltages, switching surges, and lightning surges which are applied to the line insula-tion under normal operating and transient conditions. Consideration is also given to factors such as contamination which affect performance of insulation. For lines that are designed to be relatively free from lightning flashovers, minimum insulation requirements are determined generally by lightning considerations up to and including 345 kv. For 500-kv lines minimum resquurigreesm, ents are determined by switching surges.