Trane CNT-APG002-EN, PID Control - page 35

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Chapter 4 Applications
30 CNT-APG002-EN
Figure 20 shows a TGP program to control a hot-water valve. Output Sta-
tus 1 (an analog output) provides the position of the chilled-water valve. If
the chilled-water valve position is greater than zero, the hot-water val ve
will not open.
Figure 20: TGP pro gram to control a hot-water valve
Table10 s hows the initial values the technician used for the hot-water
valve PID loop. Chapter 2, “PID settings,” explains how to select initial
values for various PID applications.
Checks whether fan is off and
heat request is on
Checks whether fan is off or
chilled-water valve is open
If heat request is on and fan is
off, then output = 100, else
PID output controls actuator
Tab le 10 : Hot-water valve control settings
PID setting Initial value Final value
Proportional gain 2.0 4.0
Integral gain 0.5 1.0
Derivative gain 0.0 0.0
Proportional bias 0.0 (not used in PID mode) 0.0
Error deadband 0.5 0.5
Action Reverse Reverse
Sampling frequency 10 seconds 30 seconds