| 摘要 |
A three-phase transformer having a variable output utilizes an auxiliary winding to minimize the number of switches or taps required to provide a plurality of output voltages. At least two output windings or coils each have a plurality of taps corresponding to varying percentages of output voltages. Although each output winding has at least one tap at the same voltage level, one of the output windings has an additional tap corresponding to a different output voltage level. The auxiliary winding, which preferably has a number of coil turns equal to that corresponding to the spacing between the different voltage levels on the output winding, permits one output winding to be set at a different voltage level than the other output winding. The auxiliary winding includes a pair of terminals which are alternately operable to balance the level and phase of the overall output voltage of the three-phase transformer. The device can be used as a motor starter having more variable, and hence more precise control for motor starting voltage.
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