Patent ID: 6066945
Filing Date: 2000-05-23
Classification: G05F,H01F

Abstract:
A method of changing three-phase voltage in an electric power saving transformer of a three-phase three-wire system or a three-phase four-wire system, comprising the steps of:phase-winding one set or plural sets of main coils which are connected to input terminals on a three-phase core-type core in the transformer;connecting plural sets of exciting coils, mutually connected in series, to wind the core between ends of the main coils by means of plural combinations of connection;connecting plural electric switches between the ends of the main coils and the exciting coils which are switched to ON/OFF based on a voltage value at the input or at output terminals of the transformer; andconnecting and disconnecting between the ends of the main coils and the exciting coils by switching ON/OFF of the electric switches stepwise on a same value of voltages or currents between the phases in order to automatically change an output voltage correspondingly with an input voltage in an uninterrupted manner.