Dielectric Performance of Vacuum Interrupters after Switching

Vacuum interrupters are widely used in power distribution systems and have proven their outstanding reliability in service for medium voltage applications up to 40.5kV. The IEC or ANSI standard requires a power frequency voltage withstand of an interrupter mounted in a breaker of at least 80% of the rated value after type testing. Nevertheless there is an ever increasing demand from several markets that have additional requirements as full power frequency or even full lightning impulse withstand after switching operations. In this paper the authors present the results of an investigation on the evolution of the dielectric performance of commercial and prototype interrupters after short circuit interruption to an internal test procedure. The results will be compared with full scale short circuit interruption tests according to the IEC short circuit type tests and electrical endurance E2 of interrupters for rated voltages up to 40.5kV