A NEW SILVER GRAPHITE CONTACT MATERIAL MA INLY BASED ON GRAPHITE FIBERS

A new silver/graphite contact material is presented, in which the grap hite component consists mainly of graphite fibres. The performance of this newly developed contact material was tested in a model switch spe cially adapted to the conditions typically found in protective switchg ear and in commercial devices. The investigations presented comprise t ests of service life under rated current and overcurrent conditions as well as tests of welding behaviour after magnetodynamic lift-off unde r short circuit conditions. It was found that the new silver/graphite material is markedly superior to conventional silver/graphite with reg ard to arc erosion behaviour. Welding resistance for the new material in symmetrical application is considerably better than for, e.g., Ag/C 96/4 perpendicular-to vs. Ag/Ni 60/40.