The Influence of Mechanical Properties of Contact Materials on the Contact Performance

Abstract

Mechanical properties of two sorts of CuCr(75/25) contact materials adopted widely for vacuum interrupters were determined by standard tensile test and impact test, and fracture characteristics of these two materials after tests were analyzed by optical and SEM equipped with EDS. It was shown that the tensile strength, ductility and impact strength of Cu-25Cr alloy contact material by vacuum casting are superior to that of CuCr25 p/m contact material by sintering technique; Fractographs of these contact materials revealed distinct fracture mechanisms, i.e. dimply ductile fracture of Cu-25Cr alloy materials, in contrast with primarily cleavage fracture of Cr-particles and interfacial fracture between Cr and Cu-matrix in CuCr25 p/m materials. The influence of strength, ductility and interfacial bonding strength between Cr/Cu phases on the contact performance of contact materials were discussed.

Welding behavior of vacuum interrupters equipped with CuCr contact material caused by making and breaking operations under short circuit current interruption

“…Four production methods were used to produce suitable CuCr contact materials: Solid state sintering, infiltration, arc melting, and vacuum casting [3,4]. The studies were carried out with a focus on the solid state sintered and vacuum cast material, both with material added to reduce the welding strength after inrush or making operation under short circuit current load.…”