The function of a valve positioner
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This post was last edited by kaminocmyhc on 2010-12-10 13:10. What are the main functions of valve positioners?
The valve positioner is a key accessory for control valves, typically used in conjunction with pneumatic control valves. It receives the output signal from the controller and uses this signal to control the pneumatic control valve. When the control valve moves, the displacement of its stem is fed back to the valve positioner through mechanical mechanisms, and the valve’s position is transmitted to the higher-level system via electrical signals. Valve positioners can increase the output capacity of control valves, reduce the delay in the transmission of control signals, speed up the movement of the valve stem, improve the linearity of the valve, overcome the frictional forces acting on the valve stem and eliminate the effects of unbalanced forces, thereby ensuring the accurate positioning of the control valve.
What was said on the second floor is basically correct. Reply to 2# Zhu Mu: The displacement of the valve stem is fed back to the valve positioner through a mechanical mechanism, and the valve position is transmitted to the upper-level system via electrical signals. Dude, ordinary trackers don’t have this feature; they only receive signals and do not send back any signals. A valve position transmitter needs to be added. Or a smart locator could (haven’t used it).
It is also possible to reverse the action force to achieve step control, and so on.
Reply to 1# zjy2009: (1) Improve the static characteristics of the control valve and enhance the linearity of the valve position； (2) Improve the dynamic characteristics of the control valve and reduce the transmission lag of the control signal ； (3) Change the flow characteristic of the control valve ； (4) Change the response range of the control valve to the signal pressure in order to achieve multi-stage control ； (5) Reverse the valve.
My understanding is that it is capable of accurately fulfilling the control requirements imposed on the valve by the control signal, for example, by overcoming the discrepancy between the actual valve position and the desired control position caused by inertia, fluid flow, and other factors.
Primary function: Converts electrical signals into pneumatic signals, thereby controlling the valve opening degree； Another function is to convert the valve opening signal into an electrical signal for feedback