Danfoss VLT AQUA Drive FC 200 Programming Manual page 136

Parameter Description
decrease the speed of the fan if all feedbacks are above
the setpoint.
3 3
Damper
Damper
Damper
Figure 3.46
Example 2: Multi-zone, multi setpoint
The previous example can be used to illustrate the use of
multi-zone, multi-setpoint control. If the zones require
different pressures for each VAV box, each setpoint may be
specified in 20-21 Setpoint 1, 20-22 Setpoint 2 and
20-23 Setpoint 3. By selecting [5] Multi setpoint minimum in
20-20 Feedback Function, the PID controller will increase
the speed of the fan if any one of the feedback results is
below its setpoint and decrease the speed of the fan if all
feedback results are above their individual setpoints.
20-20 Feedback Function
Option:
[0] Sum
[1] Difference
3-110
VLT
FC 102
Supply
air fan
Cooling/
heating coil
Return air fan
Function:
[0] Sum sets up the PID controller to use the
sum of Feedback 1, Feedback 2 and Feedback 3
as the feedback.
The sum of Setpoint 1 and any other references
that are enabled (see parameter group 3-1*
References) will be used as the PID Controller's
setpoint reference.
[1] Difference sets up the PID controller to use
the difference between Feedback 1 and
Feedback 2 as the feedback. Feedback 3 will not
be used with this selection. Only setpoint 1 will
be used. The sum of Setpoint 1 and any other
references that are enabled (see parameter
group 3-1*) will be used as the PID controller's
setpoint reference.
MG20O622 - VLT
®
AQUA Drive Programming Guide
P P
P P
P P
20-20 Feedback Function
Option:
[2] Average
[3] Minimum
[4] Maximum
[5] Multi
Setpoint
Min
®
is a registered Danfoss trademark
Zone 1
VAV
Box
Zone 2
VAV
Box
Zone 3
VAV
Box
Function:
Sets up the PID controller to use the average of
Feedback 1, Feedback 2 and Feedback 3 as the
feedback.
Sets up the PID controller to compare Feedback
1, Feedback 2 and Feedback 3 and use the
lowest value as the feedback. Only setpoint 1
will be used. The sum of Setpoint 1 and any
other references that are enabled (see parameter
group 3-1* References) will be used as the PID
Controller's setpoint reference.
Sets up the PID controller to compare Feedback
1, Feedback 2 and Feedback 3 and use the
highest value as the feedback.
Only Setpoint 1 will be used. The sum of
Setpoint 1 and any other references that are
enabled (see parameter group 3-1* References)
will be used as the PID Controller's setpoint
reference.
Sets up the PID controller to calculate the
difference between Feedback 1 and Setpoint 1,
Feedback 2 and Setpoint 2, and Feedback 3 and
Setpoint 3. It will use the feedback/setpoint pair
in which the feedback is the farthest below its
corresponding setpoint reference. If all feedback
signals are above their corresponding setpoints,