Operations troubleshooting - faulty instrumentation

[jeem]

What are the operations best practices to distinguish between instrumentation issues and actual process instability during live troubleshooting?

[ww2i]

Here is where redundancy comes into play. Then adjust the process variables and see if there are changes.
If one measurement is not right, it is probably the instrument fault.
If it is a process problem, it has to be consistent, repeating. Instrument problem will be illogical, you can't get any physics out there.
Check for the correlations, apply them. Like the control actions, if PV changes but OP is steady then suspect instrument; if OP is hunting and PV follows, likely real loop/process instability.
Best practices here is the training itself, competency, knowing about process upsets, learning from the past, and then handling them in real situation.

[opo21]

Likely instrument issue if there is a single tag abnormal, no physical correlation, flatline, spikes, or drift, field device disagrees,lLoop behavior unchanged when isolated.
And it has to a real process issue if multiple variables move together, control output is active and changing, mass/energy balance shifts, disturbance propagates through system, manual mode still shows instability.

[ivani1]

There has to be an operator rule here:
“Is the plant reacting… or is the instrument hallucinating?”
Because: Plants behave like systems (connected, logical, energy-driven) & Instruments fail like electronics (random, isolated, non-physical)

[jeem]

Thanks ww2i. Helping.

Here is where redundancy comes into play. Then adjust the process variables and see if there are changes.
If one measurement is not right, it is probably the instrument fault.
If it is a process problem, it has to be consistent, repeating. Instrument problem will be illogical, you can't get any physics out there.
Check for the correlations, apply them. Like the control actions, if PV changes but OP is steady then suspect instrument; if OP is hunting and PV follows, likely real loop/process instability.
Best practices here is the training itself, competency, knowing about process upsets, learning from the past, and then handling them in real situation.