Index
CNT-APG002-EN 63
®
S
sampling frequency, 12-16, 53
aliasing, 12
calculating, 14-15
causing output to oscillate, 13,
46, 48
example, 16
in different controllers, 14
recommended values, 14
system time constant, 15
troubleshooting, 45, 46, 48
sensor resolution, 20, 32
setpoint
high limit, 36
in PID calculation, 2
low limit, 36
settings, 9-21
action, 17-18
error deadband, 19-21
gains, 10-11
sampling frequency, 12-16, 53
throttling range, 9-10, 53
staging, 20-21, 37-44
advantages of PID control, 37
and PID control, 52
cooling tower fans, 37-44
determining staging points, 42
examples, 43-44
hysteresis, 42
PCL program, 38
TGP program, 38
static pressure control, 11, 12, 18
steam valve control, 6
system time constant, 15
T
TGP, see Tracer graphical
programming editor
thermistors, 20
throttling range, 9-10, 53
time constant, 15
Tracer graphical programming
editor, 23, 26-27
cascade control program, 35
example of TGP program, 27
hot water valve program, 30
Limit block, 27
Or block, 39
PID block, 26
PID Properties dialog box, 26
relief damper program, 32
staging program, 38
troubleshooting, 45-50
at maximum output, 45, 46, 51
at minimum output, 45, 46, 51
examples, 47-50
gains, 45, 46, 50
oscillating output, 13, 31, 51
overshoot, 46
procedure for, 45
sampling frequency, 45, 46, 48
undershoot, 46
U
undershoot, 46
V
variable-air-volume control, 20
velocity model, 5, 7, 55
W
windup, integral, 5, 7