Technical information

20-23 Setpoint 3
Range: Function:
0.000
ProcessCtrlUnit*
[ par. 20-13 -
par. 20-14
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
20-20 Feedback Function.
NOTE
The setpoint reference
entered here is added
to any other references
that are enabled (see
parameter 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 parameter 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 parameter 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 20-31 User
Defined Refrigerant A1, 20-32 User Defined
Refrigerant A2 and 20-33 User Defined Refrigerant
A3 to provide A1, A2 and A3 for the equation
below:
Temperature =
A 2
(
ln
(
Pe + 1
)
− A 1
)
− A 3
[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 parameter to enter the
value of coefficient A1 when
20-30 Refrigerant is set to User
defined [7].
20-32 User Defined Refrigerant A2
Range: Function:
-2250.00 * [-3000.00 -
-1500.00 ]
Use this parameter to enter the
value of coefficient A2 when
20-30 Refrigerant is set to User
defined [7].
20-33 User Defined Refrigerant A3
Range: Function:
250.000 * [200.000 -
300.000 ]
Use this parameter to enter the
value of coefficient A3 when
20-30 Refrigerant is set to User
defined [7].
20-34 Duct 1 Area [m2]
Range: Function:
0.500
m2*
[0.001 -
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 0-03 Regional
Settings. Fan 1 is used with feedback 1. In
case of flow difference control, set
20-20 Feedback Function 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 0-03 Regional
Settings. Fan 1 is used with feedback 1. In
case of flow difference control, set
20-20 Feedback Function to [1] Difference, if
flow fan 1 – flow fan 2 is to be controlled.
750
in2*
[0 -
15000 in2]
20-36 Fan 2 Area [m2]
Range: Function:
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 0-03 Regional
Settings. Fan 2 is used with feedback 2. In
case of flow difference control, set
20-20 Feedback Function to [1] Difference, if
flow fan 1 – flow fan 2 is to be controlled.
Parameter Description
VLT
®
HVAC Drive Programming Guide
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®
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