Motorized load stepping switch for transformer using comparison of position signals from proximity switches and cam switches for operation of protection switch for electric drive motor

摘要

The load stepping switch has a selector for pre-selection of the new winding tap-off, the selector and the load switching device both operated via the motorized drive, which provides direct operation of the selector and tensioning of a force storage mechanism for subsequent operation of the load switching device. Inductive proximity switches (S70,S71) detect each position of the load switching device, with cam switches operated by cams attached to the motorized drive shaft, the signals from both switches compared for operation of a motor protection switch for the electric drive motor upon detection of an abnormality.