Bimetallic electric contact system - has central high conductive zone and outer arc resistant zone of high resistance

摘要

An electrical contact carried on an arm (12) has a bi-metallic contact surface (10) presenting a central zone of low contact resistance (28) and an outer zone (18) affording high resistance to electric arcing. The central zone (28) is formed by the end of a silver wire (22) extending through the contact (14) and arm (12), which secures these latter members together by means of solder in countersinks (26). A cheaper contact is provided by using storter lengths of silver wire which penetrate from the contact surface (28) to the intermediate surface (16) between contact (14) and arm (12) or only partially into the contact (14). The outer zone may be constructed from a non oxidizable alloy, copper, cobalt or berylium. The contacting surface is convex with the inner zone of high conductivity at its apex.