Internal charging of vacuum interrupters under simulated lightning impulse tests

Vacuum interrupters are used in power frequency distribution systems at line voltages between 6 kV and 40 kV. They are usually to be found in three phase circuit breakers where they act as load on-off switching devices at values of current up to 3000 amperes, and as interrupters at fault currents up to 40000 amperes. The author describes charge build up on the insulators of vacuum interrupters, a phenomenon that has been experienced during the test phase of the manufacturing cycle. He also describes briefly the vacuum interrupter, its purpose, design and construction