Danfoss VLT - Feedback 1 Conversion; Feedback 1 Source Unit

[104] Sensorless Flow Requires set up by MCT10 with sensorless specific plug in.
[105] Sensorless Pressure Requires set up by MCT10 with sensorless specific plug in.
NB!
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 .
[3] Pressure to flow Pressure to flow is used in applications where the air flow in a duct is to be controlled. The feedback
signal is represented by a dynamic pressure measurement (pitot tube).
Flow = Duct Area × Dynamic Pressure × Air Density Factor
See also parameters 20.34-20.38 for setting of duct area and air density.
[4] Velocity to flow Velocity to flow is used in applications where the air flow in a duct is to be controlled. The feedback
signal is represented by an air velocity measurement.
Flow = Duct Area × Air Velocity
See also parameters 20.34-20.37 for setting of duct area.
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 Con-
troller.
[0] *
[1] %
[5] PPM
[10] 1/min
[11] RPM
[12] Pulse/s
[20] l/s
[21] l/min
[22] l/h
[23] m³/s
[24] m³/min
[25] m³/h
[30] kg/s
[31] kg/min
3 Parameter Description VLT
®
HVAC Drive Programming Guide
176 MG.11.C9.02 - VLT
®
is a registered Danfoss trademark
3