West Control Solutions ProVU 4 - Manual (Page 151)

ProVU4 Controller, Profiler & Recorder/Controller - Product Manual
Page 150 Glossary 59407, Issue 1 – March 2008
Figure 52. Pre-Tune Operation
When Pre-Tune is completed, the PID control output power is applied using the calculated
values. Pre-Tune limits the possibility of setpoint overshoot when the controller is new or the
application has been changed.
Pre-Tune can be selected from the Automatic Tuning Menu. It will not engage if either
primary or secondary outputs on a controller are set for On-Off control, during setpoint/profile
ramping or if the process variable is less than 5% of the input span from the setpoint. As a
single-shot operation, Pre-Tune will automatically disengage once complete, but can be
configured to run at every power up using the Auto Pre-Tune function.
Also refer to: Auto Pre-Tune, Control Type, Derivative Action, On-Off Control, Input Span, ,
Integral, PID, Primary Proportional Band, Process Variable, Secondary Proportional Band,
Self-Tune, Setpoint, Setpoint Ramping, and Tuning.
Power Output Limits
Used to limit the power levels of the primary and secondary control outputs. Normally the
instrument can set these outputs to any value between 0% and 100%. If this is undesirable in
a particular application, individual settings can limit the primary power upper and lower levels
and the secondary power upper and lower levels. The upper limit values must be higher than
the lower limits. These parameters are not applicable if that output is set for On-Off control.
Use with caution: The instrument will not be able to control the process if the limits do not
allow the outputs to be set to the correct values to maintain setpoint.
Lower Limit settings = 0% and 100% Default Value = 0%.
Upper Limit settings = 0% and 100% Default Value = 100%.
Also refer to: Control Type, On-Off Control and Setpoint.
Control Power
Pre-Tune
engaged
here
+100% Power (HEAT output)
Initial PV
Process Variable
SP – Initial PV
2
Setpoint
-100% Power (Cool output)