Reply To: System Startup Problem 3 PID loops

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<p style=”text-align: left;”>Something like that been tried in the past, problem is when the system sits in standby for extended periods of time or is quickly restated after having ran the temperature can be over the set point which would negate the CV hold. Another control philosophy that has been tried¬† was limiting the close possition of the valve depending on how open the level valve was. Problem is we still end up with a guessing game of what % open CV to use for the temperature control valve, which is what I’m trying to get away from. I also have to be careful not to overheat the feed water if this is done I basically will be feeding steam instead of water into the system which causes other problems.</p>
Any experience with using ratio mode in PIDE’s