Comparison of Vacuum Arc Current Transfer Characteristics of a Novel AMF-TMF Contact under Different Opening Velocities

The objective of this paper is to experimentally determine the vacuum arc current transfer characteristics of a novel AMF-TMF contact under different opening velocities. The novel AMF-TMF contact consists of a pair of inner movable TMF contacts and a pair of outer fixed AMF contacts. Contact diameter of the outer AMF contact was 85 mm, and the material of inner and outer contacts were all CuCr25 (25% Cr). Arc current transfer characteristics were obtained from the drawn arc experiments carried out in an L-C discharging circuit. Arcing current was up to 20 kA rms. Opening velocity of the inner movable contact was set as 1.60, 1.75 and 1.90 m/s. From the results, the peak value of current transferred to outer AMF contact and the charge transfer in outer AMF contact both increased with the increasing of opening velocity of inner movable contact. When arc current level was 20 kA rms, opening velocity was 1.9 m/s, and upper contact worked as anode, the charge transfer in outer AMF contact got its maximum value and reached 23.0% of the charge transfer in the whole contact system.