Well pump-off controller

摘要

A system for measuring current or load for shutting down a motor of a walking beam type pumping unit in the event that pump-off occurs. The system employs a peak picker which picks either minimum current or maximum load and an integrator coupled to the peak picker for integrating current or load during each stroke cycle. A threshold device coupled to the output of the integrator produces a control signal for shutting down the motor if the integrator output fails to reach a predetermined threshold during each stroke cycle.