초록 ▼

A motor control circuit for submersible pumps has features to prevent restarting while the electric motor is backspinning. The circuit includes a sensor for sensing the voltage produced by the residual magnetism in the rotor of the motor while it backspins. The voltage sensed is amplified, then rect

A motor control circuit for submersible pumps has features to prevent restarting while the electric motor is backspinning. The circuit includes a sensor for sensing the voltage produced by the residual magnetism in the rotor of the motor while it backspins. The voltage sensed is amplified, then rectified and compared with a reference voltage that is preset. The reference voltage corresponds to a voltage produced during backspinning at a selected maximum amount tolerable when restarting. The DC pulses are filtered to provide a corresponding voltage, then compared to the reference voltage. The control circuit is disabled from allowing a restart, either manual or automatic, when the corresponding voltage is greater than the reference voltage.

대표청구항 ▼

Means for preventing restarting of a submersible pump AC electric motor while backspinning, comprising: a pair of leads, each connected to one of two motor power connectors for sensing AC voltage differential between the power conductors; amplifying means connected to the leads for amplifying the AC

Means for preventing restarting of a submersible pump AC electric motor while backspinning, comprising: a pair of leads, each connected to one of two motor power connectors for sensing AC voltage differential between the power conductors; amplifying means connected to the leads for amplifying the AC voltage differential sensed and producing direct current voltage pulses; time constant means for providing each of the pulses with a decay time constant, resulting in a corresponding voltage; reference means for providing a level DC reference voltage proportional to a voltage produced by the motor while backspinning at a selected maximum amount tolerable when restarting; comparison means for comparing the amplitude of the corresponding voltage to the reference voltage; disabling means for restarting when the amplitude of the corresponding voltage exceeds the reference voltage, and enabling restarting when the peak amplitude of the corresponding voltage drops below the reference voltage; and the time constant being selected so that the amplitude of the corresponding voltage will not decay below the reference voltage during the interval in which the motor pauses between ceasing to forward spin and commencing to backspin.