Patent ID: 7852190

Claim:
An electrical switching device, comprising: a housing having first and second non-actuated electrical contacts; a base, connected to the housing, having electrical leads configured to receive a first electric current; an actuator assembly supported within the housing and the base, the actuator assembly including a rotatable, substantially non-conductive shaft; a movable contact structure mounted upon the shaft and configured to be activated by the first electric current between a non-actuated position, where the movable contact structure does not provide a conductive path between the first and second non-actuated electrical contacts, and an actuated position, where the movable contact structure provides a conductive path between the first and second non-actuated electrical contacts so that a second electric current may flow therebetween; the actuator assembly further including a rotatable spindle mounted upon the base and configured to rotate with the shaft; the actuator assembly also including a wire element made from a shape memory alloy (SMA), the wire element anchored to the base and threaded upon the spindle, the wire element having a length that is reduced when the first electric current is applied thereto to thereby rotate the spindle, shaft, and the moveable contact structure between one of the non-actuated position and the actuated position and the other of the non-actuate position and the actuated position, wherein the moveable contact structure comprises: a cylindrical drum mounted inside the housing and configured to rotate with the shaft; and a conductive strip applied to an outer surface of the cylindrical drum, and having a length at least as long as a distance between the first and second non-actuated electrical contacts.