Danfoss VLT FC 100 Operating Instructions Manual page 123

6 How to Programme
[2] * Analog input 54
[3] Pulse input 29
[4] Pulse input 33
[7] Analog input X30/11
[8] Analog input X30/12
[9] Analog Input X42/1
[10] Analog Input X42/3
[11] Analog Input X42/5
[15] Analog Input X48/2
[100] Bus feedback 1
[101] Bus feedback 2
[102] Bus feedback 3
[104] Sensorless Flow
[105] Sensorless Pressure
6
If a feedback is not used, its source must be set to
No Function [0]. Par. 20-20 Feedback Function deter-
mines how the three possible feedbacks will be used
by the PID Controller.
20-01 Feedback 1 Conversion
Option:
[0] * Linear
[1] Square root
[2] Pressure to temperature
[3] Pressure to flow
[4] Velocity to flow
122
Requires set up by MCT 10 Set-up Software with sensorless specific plug in.
Requires set up by MCT 10 Set-up Software with sensorless specific plug in.
Function:
This meter 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 feedback
flow ∝ pressure )).
((
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:
A 2
Temperature =
( ln ( Pe + 1 ) − A 1 )
where A1, A2 and A3 are refrigerant-specific constants. 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
Pressure to flow is used in applications where the air flow in a duct is to be controlled. The feed-
back signal is represented by a dynamic pressure measurement (pitot tube).
Flow = Duct Area × Dynamic Pressure
Air Density Factor
×
See also par. 20-34 Duct 1 Area [m2] through par. 20-38 Air Density Factor [%] for setting of
duct area and air density.
Velocity to flow is used in applications where the air flow in a duct is to be controlled. The feed-
back signal is represented by an air velocity measurement.
Flow = Duct Area × Air Velocity
Duct 1 Area [m2] through par. 20-37 Duct 2 Area [in2] for setting of duct
See also par. 20-34
area.
MG.11.F3.02 - VLT ® is a registered Danfoss trademark
VLT HVAC Drive High Power Operating In-
− A 3,
structions
Refrigerant .