Circuitry innovation for three-phase motor operation on single-phase power

Power companies restrict the largest single-phase motors that they permit o n their single-phase power distribution lines because of the high starting current of ordinary single-phase motors. These ordinary single-phase motors have low efficiency and power companies routinely restrict motor power to 7.5 horsepower (hp) or less without special permission. The operation of hi gher-power three-phase motors connected to a single-phase line have been pr eviously inconvenienced by the need of a phase converter. This need has bee n overcome by the use of an Enabler(TM) circuit that connects the three-pha se motor to the single-phase line. High-efficiency three-phase motors of 10 hp and 40 hp have now been running for several years on single-phase distr ibution lines. The starting currents are low and acceptable for the single- phase distribution lines. The running currents are high power-factor. The c urrents are balanced in the windings of these three-phase motors connected to the single-phase lines by capacitors in the Enabler circuit. Motor perfo rmance has been reliable.