Understanding Lags is Essence of Control (Booklet and Software)

Tuning controllers is a matter of matching the time and amount parameters of the controller to those of the process. The time parameters of the controller (reset and derivative) are set in accordance with the natural period (a time parameter) of the loop. It is a paradox that it is the smaller lags in the loop which determine the natural period, not the largest. This is perhaps an oversimplification, but it is essential to understand why this is so.

For more information you may refer to a booklet "Controller Tuning and Control Loop Performance, a Primer, Second Edition", which is available in the US at the cash discounted price of $17, postpaid if prepaid. It has sold 29,866 copies to date. Control Engineering Magazine has referred to it as "PID Without the Math".

Information is available at

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There is a link from there to a page about companion software ($11). If you wish, I could e-mail you a brochure on either.

David W. St. Clair Straight-Line Control Co.

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Dwstclair
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