Load and speed sensitive motor starting circuit
First Claim
1. In an AC motor having a main winding and an auxiliary winding both connectable to an AC power source, and having a switch for disconnecting said auxiliary winding from said AC source, an improved control circuit for said switch comprising:
- main voltage detector means for sensing the magnitude of the AC main winding voltage;
auxiliary voltage detector means for sensing the magnitude of the AC auxiliary winding voltage;
initialization means sensing main winding voltage at initial energization of said motor;
flip flop means responsive to said initialization means to output a turn-on signal to said switch to connect said auxiliary winding to said AC source;
voltage comparator means responsive to said main and auxiliary detector means and comparing the magnitude of the auxiliary winding voltage against the magnitude of the main winding voltage;
said flip flop means also being responsive to said voltage comparator means to output a turn-off signal to said switch to disconnect said auxiliary winding from said AC source when the magnitude of the auxiliary winding voltage increases above a predetermined value relative to the magnitude of the main winding voltage as a function of motor speed.
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Accused Products
Abstract
A speed sensitive, load sensitive and AC line voltage fluctuation insensitive, motor starting system is provided for an AC motor having a main winding (1) and an auxiliary winding (2) both connectable across an AC power source (3). Relative magnitudes of main and auxiliary winding voltages are sensed and compared. The auxiliary winding is disconnected (5) from the AC source when the auxiliary winding voltage, including the components from the AC source and from rotationally induced voltage, rises above a predetermined value relative to the main winding voltage as a function of motor speed. After starting, when the motor is in a run mode and the auxiliary winding is disconnected from the AC source, only the rotationally induced auxiliary winding voltage is sensed. The auxiliary winding is reconnected to the AC source when the rotationally induced auxiliary winding voltage decreases below a given value relative to the main winding voltage corresponding to a given stall condition, to automatically restart the motor.
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Citations
8 Claims
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1. In an AC motor having a main winding and an auxiliary winding both connectable to an AC power source, and having a switch for disconnecting said auxiliary winding from said AC source, an improved control circuit for said switch comprising:
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main voltage detector means for sensing the magnitude of the AC main winding voltage; auxiliary voltage detector means for sensing the magnitude of the AC auxiliary winding voltage; initialization means sensing main winding voltage at initial energization of said motor; flip flop means responsive to said initialization means to output a turn-on signal to said switch to connect said auxiliary winding to said AC source; voltage comparator means responsive to said main and auxiliary detector means and comparing the magnitude of the auxiliary winding voltage against the magnitude of the main winding voltage; said flip flop means also being responsive to said voltage comparator means to output a turn-off signal to said switch to disconnect said auxiliary winding from said AC source when the magnitude of the auxiliary winding voltage increases above a predetermined value relative to the magnitude of the main winding voltage as a function of motor speed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification