| 摘要 |
A start switch is provided for a single phase AC motor having a start winding and a start capacitor connected in series with the start winding and a main winding connected in parallel with the start winding and start capacitor. The AC motor is connectable with an AC power source in order to supply AC main winding voltage to the main winding and AC start winding voltage to the start winding. The start switch includes conductors connected with the main winding for sensing the AC main winding voltage and conductors connected with the start winding for sensing the AC start winding voltage. Phase sensor circuitry is employed to sense a difference in voltage phase between the start winding voltage and the main winding voltage. Detector circuitry is connected with the phase circuitry to detect when the difference in the voltage phase reaches a threshold. An AC switch is connected in series with the start capacitor and the start winding to connect and disconnect the start winding and start capacitor to and from the AC power source. Actuator circuitry for the AC switch is responsive to the detector circuitry for actuating the AC switch to disconnect the start winding and the start capacitor from the AC power source when the difference in voltage phase reaches the threshold.
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