Overvoltage Protection of Shunt-Capacitor Banks Using MOV Arresters

This paper evaluates using metal-oxide-varistor (MOV) surge arresters to protect shunt-capacitor banks from overvoltages. Protection requirements and surge arrester duties are analyzed for both lightning transients and switching-surge overvoltages, using both digital and transient network analyzer (TNA) simulations. Simple analytical expressions are developed for evaluating arrester duty as a function of capacitor bank size. Guidelines and limitations for applying arresters at grounded-and ungrounded-wye capacitor banks are developed based on overvoltage characteristics and arrester capabilities.