SURGE-ABSORBERLESS VACUUM CIRCUIT INTERRUPTER

摘要

A small-sized, light weighted vacuum circuit interrupter is provided. The interrupter comprises a vacuum container confining a vacuum atmosphere of a pressure less than 10-5 mmHg and a pair of electrodes at least one of which is a movable electrode for making and breaking an electric circuit including either a transformer of a rated surge voltage strength of less than 45 kV or a motor of a rated surge voltage strength of less than 25 kV. At least one of the electrodes has a contact made of a porous body of a refractory conductive material and an impregnate selected from the group consisting of silver telluride, silver selenide and mixtures thereof impregnated in the porous body in an amount sufficient to give the interrupter a chopping current of not more than 1A and an arc extinguishing capability at 1MHz of not more than 27 A/ mu s when measured in a circuit of 6 kV. The interrupter can be connected to the load without a surge absorber for protecting the breaker from a surge voltage generated at the time of interrupting the circuit.