Danfoss VLT HVAC Series, Programming Manual, Page: 190 / 338

[11] Analog Input X42/5
[100] Bus feedback 1
[101] Bus feedback 2
[102] Bus feedback 3
NOTE!
If a feedback is not used, its source must be set to
No Function
[0]. par.20-20
Feedback Function
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 temperature
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 for-
mula:
Temperature =
A
2
( ln ( Pe
+ 1) −
A
1)
− A 3
, where A1, A2 and A3 are refrigerant-specific con-
stants. The refrigerant must be selected in par.20-30
Refrigerant
. par.20-21
Setpoint 1
through par.
20-23
Setpoint 3
allow the values of A1, A2 and A3 to be entered for a refrigerant that is not listed
in par.20-30
Refrigerant
.
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 conversion of par.20-01
Feedback 1 Conversion . This unit is not used by the PID controller.
[0] *
[1] %
[5] PPM
[10] min
[11] RPM
[12] PULSE/s
[20] liter / sec.
[21] liter / min
[22] liter / hr.
[23] m³ / sec.
[24] m³/min
[25] m³ / hr.
[30] kg / sec.
[31] kg/min
[32] kg / hr.
[33] ton / min
[34] ton / hr.
3 Parameter Description VLT ® HVAC Drive Programming Guide
3-166
MG.11.C6.22 - VLT ® is a registered Danfoss trademark
3