A new version of the company's PID Loop Analyzer includes a stiction check wizard, which provides a simple way of measuring the stiction in the control loop...
A new version of the company's PID Loop Analyzer includes a stiction check wizard, which provides a simple way of measuring the stiction in the control loop. The wizard works on the installed valve, giving a true measure of the in-service valve stiction. Measuring the in-service stiction is more significant than measuring it when the valve is not in use.
If the measured stiction is larger than 1%, then repairing the valve can result in much better performance and increased product quality. Reducing stiction may eliminate a troublesome cycle, resulting in product made closer to specification with less energy.
Checking a valve for stiction is the third of 5 steps to completely optimize the loop. The complete optimization steps are:
1. Statistical analysis and diagnosis from normal operating data.
2. Power Spectral Density analysis to check for hidden cycles.
3. Check and correct valve problems: stiction, hysteresis and sizing.
4. Test for and characterize non-linearities. Apply a characterizer to linearize the loop.
5. Find optimal PID Tuning parameters.
ExperTune, Inc., 4734 Sonseeahray Drive, Hubertus, WI 53033. Tel: 262-628-0088; Fax: 262-628-0087.