Transmission line arresters application for control of switching overvoltages on 500-kV transmission line

This report describes investigations and actions on a 500-kV transmission line operated by the US utility Salt River Project (SRP) and initiated by new considerations regarding the transmission lines´ reliability program by the US North American Electric Reliability Corporation (NERC). Based on NERC´s new system clearance requirements for certain switching surge overvoltage levels, SRP decided to apply high energy transmission line arresters (TLAs) for limiting those overvoltages to levels that would avoid the need for much more expensive capital improvements to increase clearance to ground, for example to replace or enlarge the tower construction. The correct location of the TLAs and the line span to be protected were determined by a software study by analyzing transmission line energization overvoltages for different cases. The utility and the arrester manufacturer jointly decided about the design of the surge arrester to be developed, a high strength polymer housed station class surge arrester with high energy handling capability of 13 kJ·kVMCOV−1. As agreed between SRP and the manufacturer, the energy rating test was repeated by Siemens per the latest IEEE/ANSI std. C62.11-2012.