If a control loop has dead band in it, usually in a valve, but occasionally somewhere else, like in a transmitter, a loop with reset action in the controller will cycle, and following the typical tuning rules will result in the controller being grossly detuned, plus the cycle will persist. For more information you may refer to a booklet "Controller Tuning and Control Loop Performance, a Primer", which is available in the US for $17, if prepaid with a check or money order.
If you want more information on this booklet, refer to:
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or e-mail me for a four page brochure. It has sold 29,831 copies. A page about the companion software ($11) is also described at that site.David W. St. Clair