Loops
Loop Setup
Revision 9
900 Control Station User Guide
155
May 2014
Tuning constants
This display shows the tuning constants for the selected loop.
Item
Description
Switch Tune Set
Lets you select the active tune set (Tune Set 1 or Tune Set 2). Determines
which set of Gain/PB, Rate, and Reset parameters are used by the loop.
Gain #1 Or #2 *
Gain is the ratio of the output change (%) over the measured variable change
(%) that caused it. Gain = 100/Proportional Band.
Proportional Band (Pb) # 1 Or #2
*
PB is the percent of the range of the measured variable for which a
proportional controller will produce a 100% change in its output.
Rate #1 Or #2
Rate affects the controller’s output whenever the deviation is changing; and
affects it more when the deviation is changing faster.
Reset #1 Or #2
Reset, or integral time, adjusts the controller’s output according to the size of
the deviation (SP - PV) and the time it lasts. The amount of corrective action
depends on the value of Gain. Reset is measured as how many times
proportional action is repeated per minute (repeats/minute) or how many
minutes before one repeat of the proportional action occurs (minutes/repeat).
Feedforward Gain**
Applies Gain to the feedforward variable (FFV).
Manual Reset**
Manual Reset is only applicable if you do not use Reset. It allows correction of
output to account for load changes to bring the PV up to setpoint.
* Either Gain or Proportional Band is displayed but not both.
** Visible for PID and Carbon loop types only.