Patent ID: 8480376

Claim:
A system for determining whether a motor in an electrical submersible pump is backspinning, the system comprising: a sensor mounted in a well bore proximate to a ground surface, the sensor outputting a backspin signal, the sensor comprising one of the following: a temperature sensor for measuring a temperature drop associated with a backflow of fluid through a pump connected to the motor, a pressure sensor for measuring a pressure reduction associated with a backflow of fluid through a pump connected to the motor, and a flow sensor for monitoring a direction and change in fluid flow through well production tubing connecting the pump to a surface of the wellbore; a communication link connected to the sensor, the communications link communicating the backspin signal; and a controller receiving the backspin signal from the communications link and processing the backspin signal to determine whether the motor is backspinning, the controller comprising a processor and non-transitory computer readable storage media including computer readable instructions stored thereon that when executed cause the controller to perform a process of determining whether the motor is backspinning and a process of determining when the motor has stopped backspinning, the computer readable instructions performing the steps of: monitoring the signal to determine whether the signal is above a threshold to thereby determine whether the signal is a noise signal or a backspin signal, and outputting the backspin signal when so determined; impeding operable AC 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 AC power to the motor responsive to the determination that the backspin signal is below the threshold.