iWorx® MPU2
22
505-009, Effective: April 28, 2014
© 2014 Taco Electronic Solutions, Inc.
To prevent the integral component from becoming too large, there is anti-wind up reset protection. This protection
clamps the integral value when all of the components add up to more than 100% or less than 0%. The following equa-
tions are used for P+I control:
Kp = Proportional Gain
Ki = Integral Gain
Error = HeatingLoopSp - SpaceTemp
Heating with Stages and Modulation
The controller can combine its staged and modulated modes. In the combined mode of operation, the modulated out-
put is considered to be one of the stages. The stage to be associated with modulation is selected in the
Staged Heating
configuration page.
Modulation starts when the selected stage would normally start (i.e., if stage 2 is selected as the modulating stage, it
starts if stage 1 has been active for the staging interval and the temperature is still below the heating control band).
If the modulating stage is not the last stage, subsequent stages are activated once the
Stage Threshold
percentage
has been met by the modulating output and has remained there for the duration of the
Staging Interval
.
In order to maintain a smooth total heating output, the modulating output responds to subsequent stages activating or
deactivating. It does so by clearing its interval output when a subsequent stage is activated:
I =0
Modulating Output = K_p × Error
It forces its interval output to the
Staging Interval
whenever a subsequent stage is deactivated. This feature prevents
large jumps in overall heating output.
I = Staging Threshold
Modulating Output =(K_p × Error) + I
