Development of 765 kV Externally Gapped Line Arrester by John M. Schneider

Line surge arresters (LSAs) to improve lightning flashover rate of distribution and transmission lines are generally not automatically applied due to concerns over cost, reliability and maintenance. Rather, investigation of a line’s grounding, shielding and proper insulation coordination typically remain the initial focus and LSAs are resorted to only when conventional mitigation methods are seen as either too costly or relatively ineffective. Yet application of LSAs has become a reliable solution these days thanks to the advanced design of their polymeric housings combined with the performance of metal oxide technology. LSAs are now also comparatively low in acquisition cost while also providing a variety of benefits. Non-gapped line arresters are often the type selected in most countries based on previous experience and the comfort of using applicable IEC/IEEE standards, which are identical to those for substation arresters. Externally gapped line arresters (EGLAs), by contrast, have been gaining popularity as a viable alternative and are already standard components in countries such as Japan, South Korea, France and Mexico. This is because they offer unique advantages in comparison to NGLAs. This presentation provides technical knowledge to assist in correctly specifying EGLAs and also reviews the applicable testing standard intended to verify proper application.