Danfoss VLT CDS302 - Page 76

Illustration 6.10
The parameters in this group allow selection of a
refrigerant, which implicitly determines the constants A1,
A2 and A3. Alternatively, user defined constants can be
programmed explicitly.
7-70 Refrigerant
Option: Function:
[0] R22
[1] R134a
[2] * R404A
[3] R407C
[4] R410A
[5] R502
[6] R744
[7] User defined
7-71 User Defined Refrigerant A1
Range: Function:
[8.0000 –
12.0000]
Selects the value used for the constant A1
in the pressure to temperature conversion
formula (see parameter group 7-7* Pressure
to Temperature Conversion).
7-72 User Defined Refrigerant A2
Range: Function:
[-3000.00 –
-1500.00]
Selects the value used for the constant A2
in the pressure to temperature conversion
formula (see parameter group 7-7* Pressure
to Temperature Conversion).
7-73 User Defined Refrigerant A3
Range: Function:
[200.000 –
300.000]
Selects the value used for the constant A3
in the pressure to temperature conversion
formula (see parameter group 7-7* Pressure
to Temperature Conversion).
6.8.4 7-8* Thermostat/Pressostat Function
The Thermostat-Pressostat Function (TPF) can be used to
stop and start the compressor when running in closed
loop. The TPF monitors and compares the resulting
feedback with the Cut-out value in 7-81 Cut-out Value.
When the resulting feedback gets below 7-81 Cut-out Value
a stop signal is generated and the compressor stops. When
the resulting feedback gets above the Cut-in value in
7-82 Cut-in Value the stop signal is removed and the
compressor starts again.
The Set-point should be set to a value in between Cut-in
and Cut-out.
Illustration 6.11
Point A: At start-up the temperature will be higher than
wanted in the evaporator and therefore a higher pressure
than the Cut-in level and the compressor must run.
Another situation could be that the start situation is where
the feedback is between Cut-out and Cut-in. In that case,
no STOP is initiated.
Parameter Descriptions
Operating Instructions VLT
®
CDS302 and CDS303
76 MG34M302 - VLT
®
is a registered Danfoss trademark/Commercial Compressor
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