Cascade control has many potential benefits:
1. It will catch certain load changes sooner and correct
for them faster.
2. It will effectively linearize the secondary variable.
3. It can and should shorten the natural period of the
4. Some instrumentation tricks can be played.
For more information on these subjects and others you may
refer to a booklet "Controller Tuning and Control Loop
Performance, a Primer" , which is available in the US for $17,
postpaid if prepaid. It has sold 29,944 copies to date.
Control Engineering Magazine has referred to it as "PID
Without the Math".
Information may be found at A page on Companion Software ($11) is there also.
If you wish, I could e-mail you the same information.
David W. St. Clair
Straight-Line Control Co.
- posted 17 years ago