![background image](http://html1.mh-extra.com/html/danfoss/vlt-series/vlt-series_programming-manual_3460644135.webp)
20-23 Setpoint 3
Range:
Function:
0.000
ProcessCtrlUnit
*
[-999999.999 -
999999.999
ProcessCtrlUnit]
Setpoint 3 is used in Closed
Loop Mode to enter a
setpoint reference that may
be used by the frequency
converter’s PID Controller.
See the description of
.
NOTE
The setpoint reference
entered here is added to
any other references
that are enabled (see
meter group 3-1*).
3.18.3 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 meter group allows the
frequency converter’s PID Controller to convert refrigerant
pressure measurements into temperature values.
20-30 Refrigerant
Option:
Function:
Select the refrigerant used in the compressor
application. This meter must be specified
correctly for the pressure to temperature
conversion to be accurate. If the refrigerant
used is not listed in choices [0] through [6],
select
User defined
[7]. Then, use
,
and
20-33 User Defined Refrigerant
to provide A1, A2 and A3 for the equation
below:
Temperature =
A2
(ln(Pe + 1) − A1) − A3
[0]
*
R22
[1]
R134a
[2]
R404A
[3]
R407C
[4]
R410A
[5]
R502
[6]
R744
[7]
User
defined
20-31 User Defined Refrigerant A1
Range:
Function:
10.0000
*
[8.0000 -
12.0000 ]
Use this meter to enter the value of
coefficient A1 when
is set to
User
defined
[7].
20-32 User Defined Refrigerant A2
Range:
Function:
-2250.00
*
[-3000.00 -
-1500.00 ]
Use this meter to enter the value
of coefficient A2 when
is set to
User
defined
[7].
20-33 User Defined Refrigerant A3
Range:
Function:
250.000
*
[200.000 -
300.000 ]
Use this meter to enter the value of
coefficient A3 when
is set to
User
defined
[7].
20-34 Fan 1 Area [m2]
Range:
Function:
0.500
m2
*
[0.000 -
10.000
m2]
Used for setting the area of the air ducts in
connection with feedback conversion
pressure/velocity to flow. The unit (m
2
) is
determined by the setting of
. Fan 1 is used with feedback 1. In
case of flow difference control, set
to [1] Difference, if
flow fan 1 – flow fan 2 is to be controlled.
20-35 Fan 1 Area [in2]
Range:
Function:
Used for setting the area of the air ducts in
connection with feedback conversion
pressure/velocity to flow. The unit (in
2
) is
determined by the setting of
. Fan 1 is used with feedback 1. In
case of flow difference control, set
to [1] Difference, if
flow fan 1 – flow fan 2 is to be controlled.
750
in2
*
[0 -
15000 in2]
Parameter Description
VLT
®
HVAC Drive Programming Guide
134
MG.11.CC.02 - VLT
®
is a registered Danfoss trademark
3
3