Manual Tuning; The Simplified Method - Omega CN9000A Series User Manual

5.2 MANUAL TUNING

5.2.1 The Simplified Method

If the pre-set PID Default values prove to be unsuitable for a
particular application, the following method can be used to establish
new settings which should be acceptable and which can be
adjusted to give optimum control. Other methods may also be used-
tuning is a trial and error process.
The first step is to control the system with the instrument in
ON/OFF mode and use these results to calculate the new
parameter values for SP1.
Check that all settings are in Default. If required, range
adjustments should be made first (refer to Section 3.3).
Check that the Parameter Lock is in the Parameter Setting Position
(refer to Figure 3-2 in Section 3.13) and proceed as follows:
1. Adjust Proportioning Time to ON/OFF. (This switches off all
other control terms and sets Hysteresis to 1.25% of full scale.)
2. Enter setpoint temperature.
3. Turn ON and allow process to stabilize. Monitor process
temperature, ideally using a chart recorder, or alternatively by
taking readings from the display at regular intervals, as
frequently as possible. The results should look similar to
Figure 5-3.
Figure 5-3. Simplified Tuning Method
57