Abstract: A control system for an AC motor driven cyclic load, such as a beam pumping unit, includes a flywheel, transducer, tachometer, outside set point source, controller, and variable frequency power supply. The flywheel is rotatably connected between the motor and the cyclic load for receiving and storing rotational kinetic energy from the motor and the load during portions of a cycle of the cyclic load when there is excess energy and returning the stored rotational kinetic energy to drive the cyclic load during portions of a cycle when there is an energy demand by the cyclic load. The transducer generates a transducer signal which is a function of the cycle speed. The tachometer means generates a tachometer signal which is a function of the speed of rotation of the motor's rotor. The outside set point source generates an outside set point signal representative of a desired set point cycle speed of the cyclic load.

Abstract: A device for measuring pressure in a submersible well pump motor has features to eliminate the effect of extraneous DC in the ground path. A potentiometer located downhole has a resistor engaged by a wiper which moves along the resistor in response to pressure change. An upper resistor above the potentiometer resistor connects to the transmission line that leads to the surface. A lower resistor below the wiper travel connects the potentiometer resistor to ground. A first zener diode is connected to the wiper between the wiper and ground. A second zener diode having a greater breakdown voltage, is connected to the transmission line above the upper resistor and to ground. Current is gradually increased at the surface from zero to a maximum level, then repeated. Voltages are measured, with the slopes changing as the zener diodes begin to conduct. The values measured can be used to compute the actual position of the wiper on the potentiometer resistor.