I received this question in an email and wanted to post it for your guidance on what to look for to solve it... thanks.
Presently we are using DeltaV DCS for our xxxxxxx Plant. I came across a strange behavior for all PID blocks especially for level control PID blocks.
The controller behaves differently when the error(SP-PV) is positive & behave completely differently when the error is negative.
In short, for level loops, when the PV values goes below SP, the controller action is very aggressive, however, when the PV is above the SP, the controller behaves as required.
Do you have any idea why the controller behaves very aggressively when the error(SP-PV) is positive & behaves normal when the error is negative?
Is there any feature in the PID block we can activate to avoid this kind of behavior?
Thanks for your insights.
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