A new synthetic test installation for testing vacuum interrupters

A synthetic test installation using voltage injection and medium voltage off-communication schemes has been constructed to conduct dynamic performance testing on vacuum interrupters. The test circuit in its present setup is capable of simulating variable forward currents up to 10kA, conduction time of interrupters in vacuum-arc made up to approximately 15ms, di/dt up to 100A/µs and recovery voltages in the forward direction up to 120kV. The deionization margin can be varied practically from 0 to a few milliseconds and the dv/dt range extends up to approximately 15 kV/µs. The simulated stress corresponds to the duty the vacuum interrupters would experience during their operation as (1) an off-switch in inductive energy storage circuits and (2) an hvdc circuit breaker. It is planned to extend the scope of testing by increasing the current capability from 10kA to 20 kA at a later date. If necessary, arrangements will also be made in the future to be able to optionally change the output polarity of the high voltage supply, HVS which is at present a modified 6 stage Marx-Bank. This will enable us to test vacuum interrupters also with inverse recovery voltages. The major design considerations and the operating characteristics of the test installation are discussed.