Non-metal shields and use of foamy materials in vacuum interrupter, and switchgear employing same

Abstract

An arc-shield made of an insulating material surrounding the contact gap is provided to alleviate equipotential line congestion around metal parts and lessen electrical field concentration. Non-metal encapsulation of a metal shield for triple junction protection, and a non-metal plug to block line-of-sight of a triple junction, are devised to reduce exposed metal surfaces at a floating potential to minimize possible breakdown paths and limit metal vapor flashing onto the inside walls of the insulator members of the vacuum envelope. External triple junction protections are additionally applied, with a conformal coating and/or heat-shrink sleeve, to holistically address both internal and external dielectric performances. Foamy materials are employed to make existing or new parts inside arc chamber to boost capture of metal vapor and particles, to accelerate dielectric recovery of the vacuum interrupter in a warm condition during small load current switching or a hot condition during high fault current switching.

Dependencies are inferred from the claim text.