| 摘要 |
A standard, unmodified induction motor starts with reduced input current, energy consumption and mechanical stress and is further protected from AC power source "phase loss", excessively low or high voltage or a locked-rotor condition during start-up or any subsequent moment while running when its stator winding is energized from a sine wave source through a signal-responsive wave modifier operative to control the portion of each cycle of the sine wave which is coupled from said source to the stator winding. A stator current sampling arrangement, and a motor current demodulator responsive to the first few hundred microseconds of stator winding initial inrush current each time said current increases from zero cooperate under certain conditions to produce signals for an associated wave modifier, thereby to achieve a preferred magnitude of motor starting current under rated load conditions and achieve near-optimum motor operating efficiency during start-up and subsequent running with reduced loads and associated motor protection circuits which inhibit said wave modifier thereby to de-energize said stator winding under locked-rotor conditions that occur when motor start-up is attempted or later when the motor is running, or an AC power source anomaly occurs which would otherwise cause start-up stalling, excessive motor running current or motor stalling under rated loads.
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