NB!
If a feedback is not used, its source must be set to
No Function
[0]. Parameter 20-10 determines how the three possible feedbacks
will be used by the PID Controller.
20-01 Feedback 1 Conversion
Option:
Function:
This parameter allows a conversion function to be applied to Feedback 1.
[0]
*
Linear
Linear
[0] has no effect on the feedback.
[1]
Square root
Square root
[1] is commonly used when a pressure sensor is used to provide flow feedback
(
( flow
∝
pressure)
).
[2]
Pressure to tempera-
ture
Pressure to temperature
[2] is used in compressor applications to provide temperature feedback using a pressure
sensor. The temperature of the refrigerant is calculated using the following formula:
Temperature =
A2
(ln(Pe + 1)
−
A1)
−
A3
, where A1, A2 and A3 are refrigerant-specific constants. The
refrigerant must be selected in parameter 20-30. 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 20-30.
20-02 Feedback 1 Source Unit
Option:
Function:
This parameter determines the unit that is used for this Feedback Source, prior to applying the feedback con-
version of
par. 20-01, Feedback 1 Conversion
. This unit is not used by the PID Controller. It is used only for
display and monitoring purposes.
[0]
None
[1]
*
%
[5]
PPM
[10]
1/min
[11]
RPM
[12]
Pulse/s
[20]
l/s
[21]
l/min
[22]
l/h
[23]
m
3
/s
[24]
m
3
/min
[25]
m
3
/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
3. Parameter Description
VLT
®
HVAC Drive Programming Guide
154
MG.11.C5.02 - VLT
®
is a registered Danfoss trademark
3