Danfoss VLT AQUA Drive FC 200 Programming Manual page 130

Parameter Description
20-12 Reference/Feedback Unit
Option: Function:
[25] m³/h
[30] kg/s
[31] kg/min
[32] kg/h
[33] t/min
[34] t/h
[40] m/s
[41] m/min
[45] m
[60] °C
[70] mbar
[71] bar
[72] Pa
[73] kPa
[74] m WG
[75] mm Hg
[80] kW
[120] GPM
[121] gal/s
[122] gal/min
[123] gal/h
[124] CFM
[125] ft³/s
[126] ft³/min
[127] ft³/h
[130] lb/s
[131] lb/min
[132] lb/h
[140] ft/s
[141] ft/min
[145] ft
[160] °F
[170] psi
[171] lb/in²
[172] in WG
[173] ft WG
[174] in Hg
[180] HP This parameter determines the unit that is used
for the setpoint reference and feedback that the
PID Controller will use for controlling the output
frequency of the frequency converter.
3.17.3 20-2* Feedback & Setpoint
This parameter group is used to determine how the
frequency converter's PID Controller will use the three
possible feedback signals to control the output frequency
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VLT AQUA Drive Programming Guide
of the frequency converter. This group is also used to store
the three internal setpoint references.
20-20 Feedback Function
This parameter determines how the three possible
feedbacks will be used to control the output frequency of
the frequency converter.
NOTE
Any unused feedback must be set to "No function" in its
Feedback Source 20-00 Feedback 1 Source, 20-03 Feedback 2
Source or 20-06 Feedback 3 Source.
The feedback resulting from the function selected in
20-20 Feedback Function 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:
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) water
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
Feedback Function, 20-20 Feedback Function to option [3]
Minimum and entering the desired pressure in
20-21 Setpoint 1. 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.
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MG20O602 - VLT is a registered Danfoss trademark
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Multi zone, single setpoint
•
Multi zone, multi setpoint
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