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A water pump protector unit which includes electrical circuitry through which an electric motor is energized. The pump protector unit is primarily adapted for operation of a capacitor-start induction-run electric motor which operates a water pump. The electrical circuitry includes components for ene

A water pump protector unit which includes electrical circuitry through which an electric motor is energized. The pump protector unit is primarily adapted for operation of a capacitor-start induction-run electric motor which operates a water pump. The electrical circuitry includes components for energization and deenergization of the start winding of a capacitor-start induction-run electric motor. The electrical circuitry senses the phase angle between the voltage and the current applied to the electric motor. When the phase angle indicates that the electric motor is operating without a load, the circuitry deenergizes the electric motor. Thus, the water pump is protected against damage which may occur when the water pump is operated without pumping water. Preferably, all of the components of the water pump protector unit are housed within a single cabinet.

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A protective circuit for a liquid pump which is operated by an electric motor, of the type having a start winding and a run winding, alternating current electric circuit means for connection to a source of electrical energy and for energization of the electric motor, the alternating current electric

A protective circuit for a liquid pump which is operated by an electric motor, of the type having a start winding and a run winding, alternating current electric circuit means for connection to a source of electrical energy and for energization of the electric motor, the alternating current electric circuit means being of the type provided with a first conductor and a second conductor, the combination comprising: sensing means including first sensing means, the first sensing means sensing the alternating current voltage applied to the electric circuit means and providing a constant direct current voltage during each half cycle that the voltage applied to the electric circuit means has a given potential, second sensing means, the second sensing means sensing the alternating current flow in the electric circuit means and providing a constant direct current voltage during each half cycle that alternating current flow is in a given direction, phase detector means, first connection means, the first connection means joining the first and second sensing means to the phase detector means, the phase detector means providing a direct current voltage output during the time one of the first sensing means and the second sensing means produce a direct current voltage, voltage level detector means, second connection means, the second connection means joining the voltage level detector means to the phase detector means and to the alternating current electric circuit means and providing a direct current potential during the time that the average direct current voltage output of the phase detector means exceeds a potential applied to the voltage level detector means from the electric circuit means, third connection means, the third connection means joining the voltage level detector means to the sensing means for deenergization of the electric motor when the average current voltage output of the phase detector means provides a direct current potential in excess of a given magnitude, a start switch, means connecting the start switch to the start winding of the electric motor, a switch actuator coil, means connecting the switch actuator coil to the start winding of the electric motor, a capacitor, means connecting the capacitor to the first conductor and to the start switch, means connecting the run winding to the first conductor and to the second conductor, and enclosure means mounting said sensing means and said phase detector means and said first connection means and said voltage level detector means and said second connection means and said third connection means within a common enclosure.