Rafael Quinn · Process
Steam valve got trimmed. Loop that was boring is now hunting. PID_Compact, same gains. Do you retune from scratch or only drop gain, and do you still trust the TIA pretune on a slow heat loop?
Siemens / TIA
PID_Compact on a 1500 — good in manual, oscillates in auto after a valve trim
Nora Voss · DCS specialist
Trim changed the process gain. Pretune is fine if you can bump it. If you can't, cut P by a third and leave I until it stops walking. Don't touch D on steam. Put a small output filter on the analog, not a huge PV filter that hides the lag you just created.
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