The design and performance of surge diverters for the protection of alternating-current systems

The paper deals with the design of surge diverters which consist of one or more enclosed spark-gaps in series with a column of non-linear resistors. The factors which affect the sparkover voltage of the gaps and their ability to interrupt follow-current are illustrated by consideration of a variety of designs of gap of different complexity. Methods of distributing the voltage between a number of seriesconnected gaps are considered. The characteristics of silicon-carbide non-linear resistors are discussed, and some observations are made on the mechanism of sparkover and puncture at large surge currents. Surge diverters are classified as rural-, line- or station-type according to the surge current which they will safely carry, and performance figures and curves are given for each of the three types.