Molded case electric power switches with cam driven, spring powered open and close mechanism

摘要

Molded case electric power switches such as circuit breakers, disconnects and transfer switches have an energy storage spring which rotates a cam assembly to close and initiate opening of the switch contacts. The cam assembly includes a drive cam with a cam lobe which engages a drive cam follower on the moving contact assembly. Due to space limitations, the cam assembly is positioned so that the drive cam follower initially moves toward the cam assembly during closing. To accommodate for this, the cam lobe has a generally radial leading edge to prevent binding of the drive cam follower. A single latch mechanism latches the cam assembly in a spring charged position and in a closed position. A Y-shaped latch member has one leg which is engaged by a latch, a second leg which engages stops on the drive cam at the charged position and the closed position, and a third leg which sequentially engages the stops to reset the latch mechanism. The cam assembly, a charging mechanism including a rachet wheel and handle, the latch mechanism and the energy storage spring are all mounted between and supported by a pair of side plates. In a multi-pole switch, the drive cam engages the moving contact assembly of one pole which is coupled to the moving contact assemblies of the other poles by a cross-bar.