Switch valve issue
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How does the central control system ensure that the on-site valves are opened or closed fully? For example, when the central control sends a signal to close a valve on site, the valve stem moves downward; but how does it know when the stem has reached the bottom and the valve is completely closed? I’m not sure if the experts here understand my question
It is recommended to find a manual for the valve positioner and take a look.
Where does a valve positioner come from for a on/off valve?
Install a valve position switch at the open and closed positions. The valve position switch outputs a digital signal (DI) which is connected to the DCS or PLC.
I know, but the limit switch serves only as a detection mechanism. Wouldn’t the valve fail to close or open fully if no limit switch were installed?
Do you really understand what a limit switch is? Limiting, right? It means that once you drive to a certain point, there’s a limit in place; if there’s no limit, then you can keep driving on
For example, if I adjust the current limit position, will it stop moving when it reaches the limit?
It depends on the type of limit switch; there are many different types of them, and it’s not certain whether they can be adjusted. But if they can be adjusted, then of course they should have that functionality.
Maybe I’m wrong; it should be called switch feedback, not switch limit