Irreversibility of dielectric strength of vacuum interrupters after switching operations

The irreversibility of dielectric strength of commercial vacuum interrupters after a large number of consecutive switching operations is investigated in order to find out how dielectric performance of a vacuum interrupter degrades during its service life. Three types of commercially available vacuum interrupter were tested. Two of these devices were with transverse and one with axial magnetic field, all having CuCr contacts. Breakdown voltage data are measured in appropriate experiments in which type of tested interrupters and arcing conditions are varied.