Temperature PID loops for Compact Logix platform

plcnovel

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Feb 2006
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Hello Everybody:
After becoming a regular visitor of this forum, i learned the art of tunning pressure loops for SLC plate form (although still learning). Now one step further: Temperature loops, how does it different from pressure control. Here is brief overview of the project/Process:

Project/Process: Burner Management System
Plateform: Compact Logic (1769-L31 Compact Logix 5331 controller with 1769-IF8 and 1769-OF8C anallog input and output cards in a 7 slot chassis, All I/Os are local).
PID Block: Set for Independent operation

The question is what would be the best way to start tunning the pid loops, what are the factors i need to consider while tunning the loops? How would the tunning of temp loops be different then pressure loops? In other words what values of Gain, Integral, and derivatives will be good for this kind of process. The reason my question is still so open is because i never commissioned any BMS before, also the logic is not written by me.......

Regards
 
Your gains will depend on a lot of factors: what you're heating (ex: a 50000 gallon tank of liquid will heat very slow), how you're heating it and what you're heating it with (ex: hot water loop vs high pressure steam), how fast the response needs to be (ex: do you need to get to setpoint in 30 seconds or 30 minutes), how much over/undershoot you can tolerate (ex: is +/- 5 deg.C OK, or do you need +/- 0.5 deg.C), how much load is on the process, etc.

I like to start slow with any loop (low gain and slow integration, no derivative at all) and work my way up. I personally haven't done a BMS so I can't give you any advice specific for one.
 
I believe that Ron Beauford has done a few lengthy discussions using ummm a "hot rod" simulator?

I couldn't find his original topic, but HERE is a link to one started by Peter Nachtwey. It's pretty in depth stuff, but just by reading thru it a few times you should be able to answer most of your questions. (and probably come up with some new ones!) :p
 
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