Danfoss VLT Refrigeration Drive FC 103 Programming Manual page 134

Parameter Description
Example 2 – Multi-zone, multi-setpoint
The previous example illustrates the use of multi-zone,
single-setpoint control. If the zones require different
pressures for each VAV box, each setpoint may be specified
in
3 3 •
Parameter 20-21 Setpoint 1.
•
Parameter 20-22 Setpoint 2.
•
Parameter 20-23 Setpoint 3.
By selecting [5] Multi-setpoint minimum in
parameter 20-20 Feedback Function, the PID controller
increases the compressor speed if any one of the
feedbacks is below its setpoint. If all feedbacks are above
their individual setpoints, the PID controller decreases the
compressor speed.
20-21 Setpoint 1
Range:
0
ProcessCtrlUnit
20-22 Setpoint 2
Range:
0
ProcessCtrlUnit
132
Function:
[-999999.999 - Setpoint 1 is used in closed-
999999.999 loop mode to enter a setpoint
*
ProcessCtrlUnit] reference that is used by the
frequency converter's PID
controller. See the description
of parameter 20-20 Feedback
Function.
NOTICE
The setpoint reference
entered here is added to
any other references that
are enabled (see
parameter group 3-1*
References).
Function:
[-999999.999 - Setpoint 2 is used in closed-
999999.999 loop mode to enter a
*
ProcessCtrlUnit] setpoint reference for the PID
controller. See the description
of parameter 20-20 Feedback
Function.
NOTICE
The setpoint reference
entered here is added to
any other references that
are enabled (see
parameter group 3-1*
References).
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®
VLT Refrigeration Drive FC 103
20-23 Setpoint 3
Range:
0
ProcessCtrlUnit
20-25 Setpoint Type
Select the setpoint type.
Option:
[0] Fixed
[1] Fixed with Night Setback
[2] Floating
[3] Fixed with Night Speed
3.16.3 20-3* Feedback Adv. Conversion
In air conditioning compressor applications it is often
useful to control the system based on the temperature of
the refrigerant. However, it is generally more convenient to
directly measure its pressure. This parameter group allows
the frequency converter's PID controller to convert
refrigerant pressure measurements into temperature values.
20-30 Refrigerant
Option:
[0] User defined
[1] R12
[2] R22
[3] R134a
Function:
[-999999.999 - Setpoint 3 is used in closed-
999999.999 loop mode to enter a setpoint
*
ProcessCtrlUnit] reference that may be used
by the frequency converter's
PID controller. See the
description of
parameter 20-20 Feedback
Function.
NOTICE
The setpoint reference
entered here is added to
any other references that
are enabled (see
parameter group 3-1*
References).
Function:
Select the refrigerant used in the
compressor application. This parameter
must be specified correctly for the pressure
to temperature conversion to be accurate. If
the refrigerant used is not listed in options
[0]–[6], select [7] User defined. Then, use
parameter 20-31 User Defined Refrigerant A1,
parameter 20-32 User Defined Refrigerant A2,
and parameter 20-33 User Defined Refrigerant
A3 to provide A1, A2, and A3 for the
equation below:
A2
Temperature =
ln Pe + 1 − A1
Function:
− A3
MG16H202