Rockwell Automation 900-TC32 Digital Temperature Controllers, Series B - Manual (Page 264)

Publication 900-UM007D-EN-E - January 2011
5-36 Parameter Functions & Definitions
Proportional action: P refers to control in which the Manipulated Variable
(MV) is proportional to the deviation (control error).
Integral action: I gives a control action that is proportional to the time
integral of the deviation. With proportional control, there is normally an offset
(control error). So, proportional action is used in combination with integral
action. As time passes, this control error disappears, and the control
temperature (process value) comes to agree with the set point.
Derivative action: D gives a control action that is proportional to the time
derivative of the control error. As proportional control and integral control
correct for errors in the control result, the control system will be late in
responding to sudden changes in temperature. Derivative action enables
control that is proportional to a predicted process output to correct for future
error.
➊ Set NONE as the unit for Controllers with 0…50 Millivolt Inputs.
Note: If the settings for RT (robust tuning) are changed, the Proportional
Band (P), Integral Time (I), and Derivative Time (D) will be initiated.
Related Parameter
• AT Execute/Cancel (Adjustment function group, page 5-25)
Cooling Coefficient
Conditions of Use: The control mode must be heating and cooling with the
2-PID control method configured.
Function: If the heating and cooling characteristics of the control target differ
greatly, preventing satisfactory control characteristics from being obtained by
the same PID parameters, adjust the proportional band (P) at the cooling
Control Output side by adding the cooling coefficient to balance control
between the heating and cooling sides (refer to Figure 4.26).
Table 5.AM
Parameters Controller Type Configurable Range Units Default
Proportional Band With Thermocouple or Resistance Detector
(RID) 0.1…999.9 °C or °F ➊ 8.0
With Analog Inputs %FS 10.0
Integral Time 0…3999 Seconds 233
Derivative Time RT is OFF 0…3999 Seconds 40
RT is ON 0.0…999.9 Seconds 40.0
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