mines how the three possible
feedbacks will be used by the
PID controller.
20-01
Feedback 1 Conversion
Value:
Linear
[0]
Square root
[1]
Pressure to temperature
[2]
Function:
This parameter allows a conversion function
to be applied to Feedback 1.
Linear
[0] has no effect on the feedback.
Square root
[1] is commonly used when a
pressure sensor is used to provide flow feed-
back
(
flow
∝
pressure
)
).
Pressure to temperature
24 is used in com-
pressor applications to provide temperature
feedback using a pressure sensor. The tem-
perature of the refrigerant is calculated using
the following formula:
Temperature
=
A
2
- where A1, A2 and A3
are refrigerant-specific constants. The refrig-
erant must be selected in parameter 20-20.
Parameters 20-21 through 20-23 allow the
values of A1, A2 and A3 to be entered for a
refrigerant that is not listed in parameter
20-20.
20-03
Feedback 2 Source
Function:
See
Feedback 1 Source
, par. 20-00 for details.
20-04
Feedback 2 Conversion
Function:
See
Feedback 1 Conversion
par. 20-01 for de-
tails.
20-06
Feedback 3 Source
Function:
See
Feedback 1 Source
, par. 20-00 for details.
20-07
Feedback 3 Conversion
Function:
See
Feedback 1 Conversion
, par. 20-01 for
details.
20-20
Feedback Function
Value:
Sum
[0]
Difference
[1]
Average
[2]
Minimum
[3]
Maximum
[4]
Multi-setpoint min
[5]
Multi-setpoint max
[6]
Function:
This parameter determines how the three
possible feedbacks will be used to control the
output frequency of the adjustable frequency
drive.
NOTE
Any unused feedback must be
set to “No function” in its Feed-
back Source parameter: 20-00,
20-03 or 20-06.
The feedback resulting from the function se-
lected in par. 20-20 will be used by the PID
Controller to control the output frequency of
the adjustable frequency drive. This feedback
can also: be shown on the adjustable frequen-
cy drive’s display, be used to control an ad-
justable frequency drive's analog output, and
be transmitted over various serial communi-
cation protocols.
The adjustable frequency drive can be config-
ured to handle multi-zone applications. Two
different multi-zone applications are suppor-
ted:
6. How to program the adjustable frequency
drive
VLT
®
HVAC Drive Instruction Manual
90
MG.11.A4.22
-
VLT
®
is a registered Danfoss trademark
6