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29 Jul 15: Applications 22: Control Systems cont'd.

To take control systems a bit further this week, there are at least two major problems we see with control systems today.


1. The actual programming ends up being patch upon top of patch.  It seems as though no one ever takes the time to clean up the endless programming patches that plague programs. Further, if these patches are not properly documented, they are very difficult for anyone to follow, especially anyone who is not the originator of the patch.


2. Which leads to this: a complete lack of documentation. Many programmers are disciplined about their work, but their approach to documenting it off line is atrocious.


What do we do about this?  Champion and promote better standards for implementing patches and documenting the entire process of programming.  And do all of this in language anyone can understand.


Jim Thompson


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Comments from last week:



Hi Jim, You certainly got the control systems point exactly right. I've been observing control systems for 20 years and consistently find that they have been largely ignored since the initial installation/commissioning and operators rarely understand the strategies or tools available to them. The systems should be constantly "tuned" as parameters evolve or limits are tested and new strategies should always be explored in light of new technological advances (how much energy is wasted when a pump pushes flow into a valve 80% closed? Or how effective is a control loop whose valve stem is broken or stuck? How sensitive or reliable is the sensor/transmitter feedback if there has been no maintenance or calibration conducted?) This can help producers stay on target, determine better baselines, and optimize costs more than most managers and executives realize. Process Control skills for new Paper Science graduates has been diminishing for quite some time, and I hope we can change that in the future with curriculum design and targeted co-op experience. Control systems are prevalent in all aspects of pulp/paper/tissue manufacturing!!! Don't young people gravitate towards computers, databases, graphical interfaces, and networks naturally?


One additional point to make though is the value of the information hiding in those control systems (and I might add power meters) can be key to understanding relationships and correlations of seemingly unrelated variables. Most knowledge is never discovered because it is too popular and easy to lean on trends in the systems/historians or get lost in the shear volume of data collected. That investigative process is reactionary when decisions need to be made in real time to save the most money. Also, when are we ever going to get to supervisory control targets for strength, smoothness, stiffness, stretch instead of basis weight, moisture, and caliper? Entrepreneurs needed!!! 


Steve Sena

Cincinnati, Ohio





LGMI Design Practices
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Brian Brogdon, Ph.D.
Executive Director




Jim Thompson

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