A passive crowbar switch for high voltage operation

This paper describes the development of a water-filled passive crowbar switch which is employed to divert energy away from sensitive loads at voltage levels up to 600 kV. The crowbar is self-closing and does not require electrical triggering. The time delay to crowbar operation is determined by the magnitude of the applied impulse voltage and the switch gap spacing. The switch is comprised of a highly nonuniform field electrode configuration immersed in de-ionised water. Electrostatic field analysis of the switch was carried out in order to optimise the insulation performance of the device prior to testing. Characterisation of the passive crowbar switch was accomplished using a Marx generator as the impulse voltage source, and by measuring the time delay to breakdown for different values of applied voltage and electrode spacing. The results have shown that the crowbar design is capable of operating at voltages up to 600 kV.