Cascade Loop in Honeywell Experion PKS

M

Thread Starter

mostafa_qasemi1987

Dear all

In a cascade loop, if PV of secondary PID goes to NaN control Valve directly control by primary PID, I don't want to put a switch block before AO channel. Is there any option in PIDA block (in Experion PKS R410) to controlling final control element by Primary PID in case of secondary failure?
 
A
Dear mostafa,

I think you can use PIDER block in secondary rather than PIDA with using TRFB input for tracking value in case of S1 become true externally.

With Respect
Amir
 
There is nothing wrong with using a switch block before AO channel BUT it must be a regulatory:switch block. When secondary has failed and shed to manual (?); you can use it's mode and failure condition to switch the valve to the primary if the primary is OK. You will also have to consider the tuning changes that will be required.
 
Top