A comparative study has been made for tungsten and tungsten carbide based contact materials for low voltage contactors. The materials investigated include WAg, WCAg and WCCu. Tests include lifetime measurements under AC4 conditions at 400 A, as well as determination of the chopping current. The results are compared to those of a standard CuCr40 material. The WCAg materials are preferred to the other tested contact materials in terms of chopping current; in addition, the contact erosion rate is considerably lower than that of CuCr and WAg. The WCCu materials, on the other hand, show a tendency towards an even lower erosion rate, although the chopping current is higher than that of WCAg materials, but still considerably less than those of WAg and CuCr. WC-based contact materials promise to extend the range of applications of low voltage contactors, in particular in terms of lifetime and low surge requirements.
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