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US 4,841,404 AGranted
Pump and electric motor protector
AssigneeSpring Valley Associates, Inc.
InventorsWilliam W. Marshall, Lamar D. Springer
Life of this patent
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AssigneeSpring Valley Associates, Inc.
InventorsWilliam W. Marshall, Lamar D. Springer
Estimating the term…
An electrical circuit for providing electrical energy to an electric motor which operates a liquid pump. The motor and the pump are adapted to be submerged in the liquid which is pumped by the pump. The circuit disclosed herein senses the phase angle between the current and the voltage applied to the electric motor. When the phase angle indicates that the motor is operating without a load, the circuit deenergizes the electric motor. Thus, the motor and the liquid pump are protected against damage. Recognizing that harmonics may exist in the current flow through the motor, the circuit provides for obtaining a filtered signal proportional to the fundamental frequency of the current flowing through the motor. Thus, an accurate measurement of the loading of a motor is obtained. The circuitry of this invention also provides an accurate method of compensation for applied line voltage variations, so that a change in the applied line voltage does not produce a false indication that the motor loading has changed.
An electric circuit for energization of an electric motor and for protection of a fluid pump operated by an electric motor which is joined to a source of alternating current electrical energy and in which the alternating current which flows through the electric motor may include harmonic frequencies and in which the source of the alternating current voltage has a fundamental frequency which may vary in amplitude, comprising:
The method of protecting a liquid pump which is operated by an electric motor to which alternating current electrical energy having a fundamental frequency is applied through a plurality of electric conductor members, and a switch operable to connect and to disconnect the electric motor with respect to the electric conductor members comprising:
A protective circuit for a liquid pump which is operated by an electric motor, which is energized by electric circuit means to which alternating current electrical energy is applied, including switch means for connection of the electric motor to the electric circuit means for energization of the electric motor, the alternating current electrical energy being of the type having a given fundamental frequency which may vary in amplitude, the protective circuit also being of the type which includes phase angle detector means which senses the phase angle between the voltage of the alternating current electrical energy applied to the electric circuit means and the alternating current flow in the electric circuit means, the phase detector means providing an output voltage related to the phase angle between the voltage of the alternating current electrical energy and the alternating current flowing in the electric circuit means, voltage level detector means, means joining the voltage level detector means to the phase detector means for providing a signal from the phase angle detector means to the voltage level detector means in accordance with the phase angle sensed by the phase angle detector means, the voltage level detector means having an output terminal, wherein the voltage level detector means provides a signal at the output terminal thereof during the time that phase angle exceeds a predetermined magnitude, and connection means joining the output terminal of the voltage level detector means to the switch means for operation of the switch means for deenergization of the electric motor, the improvement comprising:
The method of protecting a liquid pump which is operated by an electric motor to which alternating current electrical energy having a fundamental frequency is applied through a plurality of electric conductor members, and a switch operable to connect and to disconnect the electric motor with respect to the electric conductor members comprising:
A protective circuit for an alternating current electric motor to which electric energy is applied through a plurality of electric conductor members, and in which the amplitude of the applied voltage may vary comprising:
A protective circuit for a fluid pump which is operated by an alternating current electric motor to which electric energy is applied through a plurality of electric conductor members, and in which the amplitude of the applied voltage may vary, the protective circuit being of the type provided with first signal means, the first signal means presenting a signal representing the voltage applied to the conductor members, second signal means, the second signal means presenting a signal representing the current flow through the conductor members, phase detector means, the phase detector means being joined to the first signal means and to the second signal means, the phase detector means sensing the phase angle between the signal of first signal means and the signal of the second signal means, voltage comparator means, means connecting the voltage comparator means to the phase detector means, whereby the phase detector means provides a voltage signal to the voltage comparator means, switch means, connector means connecting the switch means to the voltage comparator means and to the conductor members for deenergization of the electric motor,
A protective circuit for a fluid pump which is operated by an alternating current electric motor to which electric energy is applied through a plurality of electric conductor members, and in which the amplitude of the applied voltage may vary, the protective circuit being of the type provided with first signal means, the first signal means presenting a signal representing the voltage applied to the conductor members, second signal means, the second signal means presenting a signal representing the current flow through the conductor members, phase detector means, the phase detector means being joined to the first signal means and to the second signal means, the phase detector means sensing the phase angle between the signal of first signal means and the signal of the second signal means, voltage comparator means, means connecting the voltage comparator means to the phase detector means, whereby the phase detector means provides a voltage signal to the voltage comparator means, switch means, connector means connecting the switch means to the voltage comparator means and to the conductor members for deenergization of the electric motor in accordance with a predetermined phase angle sensed by the phase detector means,
The method of protecting a liquid pump which is operated by an electric motor to which alternating current electrical energy having a fundamental frequency is applied through a plurality of electric conductor members, and a switch operable to connect and to disconnect the electric motor with respect to the electric conductor members comprising:
A protective circuit for a fluid pump which is operated by an alternating current electric motor to which electric energy is applied through a plurality of electric conductor members, and in which the amplitude of the applied voltage may vary comprising:
Dependencies are inferred from the claim text.