Monthly Archive: May 2009

May
28

What Have I Learned? – Writing

I haven’t had any special courses or training in writing and some may say it shows. I wouldn’t advocate anyone following my style, especially if you trying to promote your products or ideas. I tend to lead the reader on path of discovery by laying out the situation and the problems and then some interesting …

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May
19

What Have I Learned? – Wiring and VFD Problems

While wiring problems may not be pervasive, when they do exist, the upset is significant and tends to persistently reoccur for months to years. The intermittent transient occurrence is difficult to diagnose. The short term steps and spikes cause kicks in the controller output from gain and rate action. In my experience, the spikes in …

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May
11

What Have I Learned? – Cost and Source of Oscillations (Part 4)

I need to minimize the time delay to dinner so I will minimize this discussion of how to minimize the oscillation from analyzer sample time delay. So many minimums and so little time. Composition measurements with sample systems and cycle times termed “at-line analyzers” offer incredible opportunities for understanding and controlling what affects what you …

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May
04

What Have I Learned? – Cost and Source of Oscillations (Part 3)

If you want to know how to minimize oscillations from final elements and don’t have time to read the supporting information you can use the following rules of thumb and move on to more important tasks like reading email. The final elements considered here are throttling control valves and variable speed drives (VSD) on pumps …

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