Danfoss VLT HVAC FC 100, Instruction Manual

Page: 129 / 205

20-21 Setpoint 1
Range: Function:
0.000 Proc-
essCtrlU-
nit* [-999999.999 - 999999.999 Proc-
essCtrlUnit] Setpoint 1 is used in closed-loop mode to enter a setpoint reference that is used by the adjustable
frequency drive’s PID controller. See the description of par. 20-20
Feedback Function
.
NOTE!
Setpoint reference entered here is added to any other references that are enabled
(see par. group 3-1*).
20-22 Setpoint 2
Range: Function:
0.000 Proc-
essCtrlU-
nit* [-999999.999 - 999999.999 Proc-
essCtrlUnit] Setpoint 2 is used in closed-loop mode to enter a setpoint reference that may be used by the ad-
justable frequency drive’s PID controller. See the description of
Feedback Function ,
par. 20-20 Feedback Function .
NOTE!
The setpoint reference entered here is added to any other references that are enabled (see par. group 3-1*).
20-81 PID Normal/ Inverse Control
Option: Function:
[0] * Normal
Normal
[0] causes the adjustable frequency drive’s output frequency to decrease when the feedback
is greater than the setpoint reference. This is common for pressure-controlled supply fan and pump
applications.
[1] Inverse
Inverse
[1] causes the adjustable frequency drive’s output frequency to increase when the feedback
is greater than the setpoint reference. This is common for temperature-controlled cooling applica-
tions, such as cooling towers.
20-93 PID Proportional Gain
Range: Function:
0.50* [0.00 - 10.00 ]
If (Error x Gain) jumps with a value equal to what is set in par. 20-14
Maximum Reference/Feedb.
the PID controller will try to change the output speed
equal to what is set in par. 4-13
Motor Speed High Limit [RPM]
/ par. 4-14
Motor Speed High Limit [Hz]
but in practice of course limited by this setting.
The proportional band (error causing output to change from 0–100%) can be calculated by means of the formula:
(
1
Proportional Gain
)
× ( Max Reference
)
NOTE!
Always set the desired for par. 20-14 Maximum Reference/Feedb. before setting the values for the PID controller in par. group 20-9*.
6 How to Program the Low Harmonic Drive
VLT HVAC Low Harmonic Drive Instruction
Manual
6-36
MG.16.A1.22 - VLT
®
is a registered Danfoss trademark
6