...MVA (short-time emergency) . A transformer is a device consisting of a winding with tap or taps, and two or more coupled windings, with or without a magnetic core, for inducing mutual coupling between electric circuits. A phase-angle regulating transformer or phase-shifter is a special transformer application....

...Institute of Electrical and Electronics Engineers, Inc. (IEEE) has defined a transformer as follows: "A static device consisting of a winding, or two or...coupled windings, with or without a magnetic core, for introducing mutual coupling between circuits. Note: Transformers are extensively used in electric power...