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
temperature
The feedback signal is a pressure with units
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]
[171]
psi
lb/in2
[172] in WG
[173] ft WG
7-62 Feedback 2 Conversion
Option:
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
.
[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
temperature
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
.
7-63 Feedback 2 Source Unit
Option:
Function:
Select the pressure unit applicable to feedback
source 1 defined in
7-22 Process CL Feedback 2
Resource
.
[70]
mbar
[71]
bar
[72]
Pa
[73]
kPa
[74]
m WG
[170]
[171]
psi
lb/in2
[172] in WG
[173] ft WG
6.8.3 7-7* Pressure to Temperature
Conversion
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.
Parameter Descriptions
Operating Instructions VLT
®
CDS302 and CDS303
MG34M302 - VLT
®
is a registered Danfoss trademark/Commercial Compressor
75
6
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