Danfoss VLT CDS302 Operating Instructions Manual page 75

Parameter Descriptions
7-39 On Reference Bandwidth
Range: Function:
5 % [0 - 200 Enter the On Reference bandwidth. When the
*
%] PID Control Error (the difference between the
reference and the feedback) is less than the
set value of this parameter the On Reference
status bit is high, i.e. =1.
6.8.2 7-6* Feedback Conversion
Select how the signals from the feedback sources must be
converted.
7-60 Feedback 1 Conversion
Option: Function:
Selects the conversion to apply to the
feedback signal measured on the analog
input selected as feedback 1 source in 7-20
Process CL Feedback 1 Resource.
[0] Linear No conversion is applied. The feedback
*
signal is assumed to be in the unit selected
in 3-01 Reference/Feedback Unit and enters
the process controller unchanged.
[1] Square root The square root of the feedback signal is
calculated before passing it to the process
controller.
[2] Pressure to The feedback signal is a pressure with units
temperature as specified in 7-61 Feedback 1 Source Unit.
It is converted to a temperature before
passing it to the process controller. The
pressure to temperature conversion is
based on the refrigerant selected in 7-70
Refrigerant.
7-61 Feedback 1 Source Unit
Option: Function:
Select the pressure unit applicable to feedback
source 1 defined in 7-20 Process CL Feedback 1
Resource.
[70] mbar
[71] bar
[72] Pa
[73] kPa
[74] m WG
[170] psi
[171] lb/in2
[172] in WG
[173] ft WG
MG34M302 - VLT
®
Operating Instructions VLT CDS302 and CDS303
7-62 Feedback 2 Conversion
Option:
[0] Linear
*
[1] Square root
[2] Pressure to
temperature
7-63 Feedback 2 Source Unit
Option:
[70]
[71]
[72]
[73]
[74]
[170]
[171]
[172] in WG
[173] ft WG
6.8.3 7-7* Pressure to Temperature
The conversion of a feedback signal P in units of a
pressure to a temperature T is accomplished via the
formula:
T = A2/(log(P+1)-A1) – A3
where A1, A2 and A3 are refrigerant dependent constants.
®
is a registered Danfoss trademark/Commercial Compressor
Function:
Selects the conversion to apply to the
feedback signal measured on the analog
input selected as feedback 2 source in 7-22
Process CL Feedback 2 Resource.
No conversion is applied. The feedback
signal is assumed to be in the unit selected
in 3-01 Reference/Feedback Unit and enters
the process controller unchanged.
The square root of the feedback signal is
calculated before passing it to the process
controller.
The feedback signal is a pressure with units
as specified in 7-62 Feedback 2 Source Unit.
It is converted to a temperature before
passing it to the process controller. The
pressure to temperature conversion is
based on the refrigerant selected in 7-70
Refrigerant.
Function:
Select the pressure unit applicable to feedback
source 1 defined in 7-22 Process CL Feedback 2
Resource.
mbar
bar
Pa
kPa
m WG
psi
lb/in2
Conversion
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