Abstract: A system for measuring spring pack displacement of a motor-operated valve (MOV) includes at least one power line having a current. The system includes a current sensor for sensing the current and providing a plurality of digital current values, and a personal computer (PC) processor for acquiring a plurality of frequency values of one or more frequency signatures from the plurality of digital current values and calculating the spring pack displacement from the plurality of frequency values. The processor may include data storage for the plurality of digital current values for at least a time interval necessary to stroke the valve stem in either an open or closed direction. The MOV may include a motor pinion gear having a motor pinion tooth-meshing frequency, a worm shaft having a rotational frequency, a worm shaft gear having plural teeth, a worm having a worm lead, a worm gear having plural teeth and a worm gear tooth-meshing frequency, and a spring pack having a displacement.

Abstract: A motor operated valve monitoring system utilizes two diagnostic couplings with quick disconnect electrical connectors. One coupling is used for monitoring switch actuation on the motor operated valve, and the second is for measuring three phase power to an AC motor on the valve. These couplings are connected in-line with the quick disconnect connectors and allows the user to perform a test without having to remove the limit switch cover from the actuator. These couplings will reduce testing time for conventional valve monitoring systems, and provide for readily mountable sensors for installation of an online valve diagnostic system to an existing valve and valve operator.