INSULATION CHARACTERISTICS AND WELDING BEHAVIOR OF VACUUM SWITCH CONTACTS MADE FROM VARIOUS CUCR ALLOYS

CuCr is generally accepted and applied as contact material in vacuum s witches. Although CuCr has many well-known advantages it has, compared to CuBi, the disadvantage of welding more easily at high current-clos ing operations of circuit breakers. Thus, a currentless separation of the welds occurring after closing operations affects the dielectric pr operties of the open contact gap. In this paper welding forces as well as field enhancement factors beta and breakdown voltages of the conta cts after currentless opening are investigated and used as diagnostic tools in order to study the influence of different CuCr compositions a nd manufacturing processes on the performance of butt-type contacts in stalled in a model vacuum breaker chamber.