Trane PID Control User Manual
CNT-APG002-EN
9
®
Chapter 2
PID settings
This chapter describes some of the key variables used to set up and tune
PID loops. The variables discussed here are:
PID loops. The variables discussed here are:
•
Throttling range
•
Gain
•
Sampling frequency
•
Action
•
Error deadband
Throttling range
The throttling range is the amount of error it takes to move the output of
a system from its minimum to its maximum setting. For example, a throt-
tling range of 4°F (2.2°C) means that a controller fully opens or closes an
actuator when the error is
a system from its minimum to its maximum setting. For example, a throt-
tling range of 4°F (2.2°C) means that a controller fully opens or closes an
actuator when the error is
±
2°F (1.1°C) or greater, as illustrated in
Figure 8. Note how the controller response (actuator position) lags behind
the space temperature.
the space temperature.
Figure 8: Throttling range
Time
S
p
ac
e t
e
mp
er
a
tu
re (
°F)
Actuator position
Space temperature
Setpoint = 75°F
A
c
c
tu
a
tor
pos
pos
iti
on (
%
)
)
Throttling range = 4°F