Switching arrangement for transformer windings

Abstract From the Canadian patent

In a three-phase dual-voltage electro-, magnetic induction apparatus wherein each phase has a primary winding and a secondary winding and each, phase of the primary winding comprises two separate and distinct windings, a switching arrangement comprising tap changers for connecting said distinct windings in either a series or a parallel connection so as to alter the voltage rating of the primary winding between a first level and a second level. These same tap changers also function to provide the "fine" adjustment of the voltage rating that tap changers are normally noted for.