| 摘要 |
FIELD: power supply to three- phase motors from single-phase mains. SUBSTANCE: method involves generation of forward and reverse voltage phase sequence due to building up magnetic fluxes equal in magnitude and spaced 120 deg. apart. These magnetic fluxes are built up in extreme legs of three-legged transformer and added across central leg. Three- phase system of magnetic fluxes thus produced induces electromotive forces in secondary windings wound on each of three legs. In order to obtain reverse phase sequence of induced electromotive forces, phase of third secondary electromotive force induced due to total magnetic flux in central leg is shifted, in addition, through 180 electrical degrees relative to two first secondary electromotive forces. For forward phase sequence of induced electromotive forces, magnetic fluxes of extreme legs are shifted through 60 electrical degrees to ensure opposing fluxes in central leg and phase of secondary electromotive force induced by leading magnetic flux built up in extreme leg due to single-phase supply is shifter through 180 electrical degrees relative to two secondary electromagnetic forces. EFFECT: provision for both forward and reverse balanced phase sequence. 2 dwgn
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