Patent ID: 8334666

Claim:
A system for detecting a backspin condition of a motor in an electrical submersible pump, the system comprising: a variable speed drive for powering the motor via a power cable; and a computer implemented as a controller, the controller having a 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 a current on the power cable to determine if the motor is backspinning, the computer program product comprising the instructions of: monitoring an input current or impedance on the power cable to determine changes in motor current impedance, comparing changes in the motor current impedance to a historical threshold value for backspin events to determine whether the motor is backspinning; impeding operable power to the motor when it is determined the motor is backspinning; supplying small AC power to the motor after it is determined the motor is backspinning; and determining whether or not the motor has stopped backspinning by monitoring the small AC voltage.