C2-17
IM 34M06H62-02E 2nd Edition : June 2008-00
Setting the Cooling Gain
In heating/cooling PID control, control output is calculated based on heating parameters.
Parameters other than proportional band, namely, integral time and derivative time, are
common to both heating and cooling output calculations. The proportional band for
cooling output is adjusted using the cooling gain as follows:
- Proportional band for heating output = Proportional band
- Proportional band for cooling output = Proportional band ÷ cooling gain
For example, with the cooling gain set to 200% in P control with manual reset = 0%, if a
deviation produces 10% heating output, the same deviation in the reverse direction will
produce 20% cooling output.
Figure C2.10 When Cooling Gain is Larger Than 100%
Figure C2.11 When Cooling Gain is Smaller Than 100%