Multi Zone, Single Setpoint; Multi Zone, Multi Setpoint - Danfoss vlt FC 102 Operating Instructions Manual

6. How to programme the frequency converter
NB!
Any unused feedback must be set to "No function" in its Feedback Source parameter: 20-00, 20-03 or 20-06.
The feedback resulting from the function selected in par. 20-20 will be used by the PID Controller to control the output frequency of the frequency
converter. This feedback can also be shown on the frequency converter's display, be used to control a frequency converter's analog output, and be
transmitted over various serial communication protocols.
The frequency converter can be configured to handle multi zone applications. Two different multi zone applications are supported:
6
•

Multi zone, single setpoint

•

Multi zone, multi setpoint

The difference between the two is illustrated by the following examples:
Example 1 – Multi zone, single setpoint
In an office building, a VAV (variable air volume) HVAC system must ensure a minimum pressure at selected VAV boxes. Due to the varying pressure
losses in each duct, the pressure at each VAV box cannot be assumed to be the same. The minimum pressure required is the same for all VAV boxes.
This control method can be set up by setting
The PID Controller will increase the speed of the fan if any one feedback is below the setpoint and decrease the speed of the fan if all feedbacks are
above the setpoint.
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 par. 20-21, 20-22 and 20-23. By selecting
Controller will increase the speed of the fan if any one of the feedbacks is below its setpoint and decrease the speed of the fan if all feedbacks are above
their individual setpoints.
96
NB!
If only two feedback signals are used, the feedback that is not to be used must
No Function
be set to
erence will be the sum of its respective parameter value (20-21, 20-22 and 20-23)
and any other references that are enabled (see par. group 3-1*).
Feedback Function
, par. 20-20 to option [3], Minimum, and entering the desired pressure in par. 20-21.
Multi setpoint minimum
MG.11.A6.02 - VLT ® is a registered Danfoss trademark
®
VLT HVAC Drive Operating Instructions
in par. 20-00, 20-03 or 20-06. Note that each setpoint ref-
, [5], in par. 20-20, Feedback Function, the PID