Abstract: A phase-shift transformer circuit providing advance or retard phase shift at any predetermined phase shift angle. The phase shift angle is determined by the ratio of the main and short windings of the transformer primary. Two links are used to provide advance or retard phase shift. One transformer winding is connected directly to a phase conductor of the three-phase power system. The remaining two transformer windings are connected to the remaining two phase conductors via the links. The links are movable such that in the advance configuration, the phase two conductor is connected to one of the transformer windings and the phase three conductor is connected to the other. In the retard phase-shift configuration, the links are moved so that the connections are reversed.

Abstract: A rectifier transformer circuit permitting six-phase double-wye operation with 120.degree. conduction, (without the use of an interphase transformer), and providing any predetermined degree of phase shift. The transformer comprises a zig-zag wye primary winding and a six-phase star secondary winding. By choosing the proper ratio for the turns of the zig and zag portions of the primary winding, any degree of phase shift can be obtained. The rectifier transformer is ideally suited for multiple-phase installations wherein several rectifier transformers are used, each providing a different amount of phase shift, without the use of separate phase-shift transformers.

Abstract: A power transformer having a magnetic core winding assembly disposed within a casing, which contains multiple sensing means to sense abnormalities in fault conditions of the transformer, and an annunciator, having electro-mechanical relay circuits responsive to the sensing means for energizing an alarm circuit. The electromechanical relay circuits are arranged to provide two or more alarm point indication circuits, a pulse circuit and a bistable switching circuit adapted to energize external protective apparatus. The pulse circuit translates one or more sensing means signals of undetermined duration to a single "pulse" signal of predetermined duration. This pulse signal is used to control a switching circuit with a contact connected to operate external protective devices such as an audible alarm. The pulse circuit provides for isolation of the indication circuits from the switching circuit such that each may be reset independently of one another.