Abstract: Instrumentation for high reliability electric submersible pumps (ESPs) is provided. Comprehensive sensors placed throughout ESP components enable monitoring, analysis, and intervention to improve performance of ESP components and provide high reliability and long life for components. Example ESP sensors used to protectively monitor an ESP string may include electrical current leakage detectors, temperature sensors at the pothead, fiber optics used as distributed temperature sensors in the motor stator and windings of the motor, water cut sensors to determine quality of hydrocarbon being produced, tachometer and torque sensors to detect the speed of rotating shafts of the motors and pumps, temperature and vibration sensors for rotor bearings and thrust members, and wye-point imbalance detectors for balancing electrical loads on the three phases in a wye system. Interpretation and control modules analyze the sensor input and apply actions that improve performance and lengthen lifespan of components.