METHOD AND DEVICE FOR AUTOMATICALLY SWITCHING THREE-PHASE VOLTAGE FOR POWER SAVING TRANSFORMER

摘要

An electric power saving transformer for three-phase current with an automatic voltage transferring device, in an autotransformer of a three-phase three-wire system or a three-phase four-wire system, is characterized by phase-winding one set or plural sets of main coils which are connected to input terminals on a three-phase core-type core; connecting plural sets of exciting coils mutually connected in series to wind the three-phase core-type core between the 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 the value detected by a voltage sensor connected to the input or output terminals; and connecting and disconnecting between the ends of the main coils and the exciting coils, by switching ON/OFF of the electric switches stepwise on the same value of voltages or currents between the phases in order to automatically change output voltage correspondingly to input voltage onto voltage transferring circuits in an uninterrupted manner. Therefore, when the input voltage decreases or increases, it is automatically detected and the circuits are changed so that the output voltage is kept within the predetermined output voltage range, preventing the load from being influenced. <IMAGE>