A current loop can also be used to control a valve positioner or other output actuator.
2.
It was later determined the primary valve positioner had a loose mechanical connection, resulting in erroneous feedback of valve position.
3.
With the development of cheap industrial micro-processors, " smart " valve positioners have become available since the mid-1980s and are very popular for new installations.
4.
They work on a variety of systems including primary control elements, transmitters, analyzers, sensors, detectors, signal conditioners, recorders, controllers and final control elements ( actuators, valve positioners, etc . ).
5.
The industry standard ranges of either 3-15 psi ( USA ), or 0.2-1.0 bar ( metric ), is normally used in pneumatic PID controllers, valve positioner servomechanisms and force balance transducers.
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