Patent ID: 8400093

Claim:
An electrical submersible pump, comprising: a motor and a pump adapted to be suspended in a wellbore; a sensor for measuring non-electrical parameters in the wellbore, the sensor mounted downhole proximate to the motor, the sensor selected from the group consisting of: a vibration sensor placed on a shaft of the motor to determine whether the motor is backspinning, by measuring the frequency of vibrations in the shaft, a pressure sensor connected to the pump to determine whether the motor is backspinning by measuring the pressure across the pump, a rotational sensor connected to a shaft of motor to determine whether the motor is backspinning by measuring the speed and direction of the motor, an accelerometer connected to a shaft of the motor to determine whether the motor is backspinning measuring acceleration in the shaft, a strain gauge connected to a shaft of the motor to determine whether the motor is backspinning by measuring the torque of the shaft, and a flow meter connected to the pump to determine whether the motor is backspinning by measuring fluid flow across the pump; a power cable connected between a motor and a controller, the power cable supplying a three phase AC current to the motor; electronics connected to the sensor, the electronics receiving a signal from the sensor and transmitting the signal to a controller through the power cable or a communication line connecting the electronics to the controller; a computer defining the controller, the controller having a non-transitory memory, a computer processor, and a computer program product stored on the memory and executable by the processor, the computer program product performing a process of controlling the variable speed drive of the motor and a process of monitoring the signal from the sensor to determine if the motor is backspinning, the computer program product comprising the instructions of: monitoring the signal to determine whether the signal is above a threshold, the threshold for determining whether the signal is a noise signal or a backspin signal, and outputting the backspin signal; impeding operable levels of power to the motor, responsive to the backspin signal; monitoring the backspin signal to determine whether the backspin signal is below the threshold; and returning power to the motor responsive to the determination that the backspin signal is below the threshold.