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daviddsims
23-05-2012, 02:53 AM
I work at a large industrial facility with 5 Frick RWF 11 270 ammonia compressors. We have various loads depending on product runs and sometimes we might have a couple of compressors only loading 20 or 30 percent. These compressors are connected for sequencing but you have very little control over minimum slide position and therefore we are not loading up evenly. Anyone have any advice on this control or using PLC logic?

Segei
23-05-2012, 04:41 AM
What kind of PLC do you have? Usually, all compressors should operate at 100% load except last one in the sequence. Last compressor should load and unload to handle fluctuation of the refrigeration loads. Actually, Frick compressors have set point of minimum load. You can choose whatever you what.

Sandro Baptista
23-05-2012, 09:16 AM
Doesn't the Quantum's unit controls allow to manage the compressor sequencing? It seems weird if not...maybe it is not properly configured.

I'm not familiar with Quantum but rather with the UNISAB. The UNISAB allow it.

daviddsims
23-05-2012, 11:27 AM
We have Allen Bradley PLC but it is not configured to control the compressors. I will look at the book today but was not familiar with the sequencer.

Sandro Baptista
23-05-2012, 11:42 AM
So the compressor aren't eqquiped with the Quantum unit controler?

bjkmiami
07-06-2012, 12:18 PM
hello david..see if the set points of these compressors are the same..if so try to stagger them meaning that keep the set points apart from eachother in an ascending manner..

Josip
07-06-2012, 08:29 PM
Hi, daviddsims


We have Allen Bradley PLC but it is not configured to control the compressors. I will look at the book today but was not familiar with the sequencer.

This is the problem with PLC's which are not designed and configured to operate refrigeration compressors ... it is quite cheap PLC control with high electric bill ....


hello david..see if the set points of these compressors are the same..if so try to stagger them meaning that keep the set points apart from eachother in an ascending manner..

This is very good advice, each compressor will start or went off independently and you will have less compressors running simultaneously at small load ... anyhow, you must play with timers to obtain slow capacity change i.e. avoid hunting ...

Best regards, Josip :)

AmberB
08-06-2012, 12:12 AM
We control our Fricks with an Allen Bradley Compact Logix PLC. It works very well. Does anyone know anything about a Frick alarm "False Running Inp"?

Segei
08-06-2012, 02:34 AM
We control our Fricks with an Allen Bradley Compact Logix PLC. It works very well. Does anyone know anything about a Frick alarm "False Running Inp"?
I'm just curios. What do you mean by "very well"? Good PLC should run plant at optimum(the best) set points and save energy. It looks like daviddsims' plant doesn't this kind of PLC. How about yours?