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Configuration - continued
Set control of suction group MT
1. Go to Configuration menu
2. Select Suction group
3. Set values for the reference
Press the +-button to go on to the
next page
4. Set values for capacity control
Press the +-button to go on to the
next page
58
The configuration menu in the
Service Tool has changed now.
It shows the possible settings for
the selected plant type.
In our example we select the
settings:
- Set point = -10°C
The settings are shown here in the
display.
There are several pages, one after
the other.
The black bar in this field tells you
which of the pages is currently
displayed.
Move between the pages using
the + and - buttons.
If a screw compressor is chosen
in the first line, its type must be
determined in the next line.
In our example we select:
- External compressor stop
- VSD + single step
- 4 compressors
- P0 as signal to the regulation
- Best fit
Capacity controller RS8GN202 © Danfoss 11-2013
3 - Reference mode
Displacement of suction pressure as a function of external
signals
0: Reference = set reference + night offset + offset from external
0-10 V signal
1: Reference = set reference + offset from P0 optimization
Setpoint ( -80 to +30°C)
Setting of required suction pressure in °C
Offset via Ext. Ref
Select whether a 0-10V external reference override signal is
required
Offset at max input (-100 to +100 °C)
Displacement value at max. signal (10)
Offset at min input (-100 to +100 °C)
Displacement value at min. signal (0 V)
Offset filter (10 - 1800 Sec)
Here you can set how quickly the reference must become ef-
fective.
Night Offset via DI
Select whether a digital input is required for activation of night
operation. Night operation can alternatively be controlled via
internal weekly schedule or via a network signal
Night Offset (-25 to +25 K)
Displacement value for suction pressure in connection with an
active night setback signal (set in Kelvin)
Max reference (-50 to +80 °C)
Max. permissible suction pressure reference
Min reference (-80 to +25 °C)
Min. permissible suction pressure reference
4 - Compressor application
Select one of the available compressor configuration here
Screw compressorer
The following options are available for screw compressors
No. of compressors
Set total number of compressors
No. of unloaders
Set number of unloader valves
Ext. compressor stop
An external switch can be connected which will start and stop
the compressor control.
Variable compessor type
Choose between speed control or digital scroll.
Control sensor
Po: Suction pressure Po is used for control
S4: Media temperature S4 is used for control
Step control mode
Select coupling pattern for compressors
Cyclic: Runtime equalisation between compressors (FIFO)
Best fit: Compressors are cut in/out in order to make the best
possible fit to actual load
Injection heat exchanger
Selects whether an output signal is to be sent for start/stop of
liquid injection in a cascade heat exchanger
Pump down
Select whether a pump down function is required on the last
running compressor
Pump down limit Po (-80 to +30 °C)
Set the actual pump down limit
VSD min speed (0.5 – 60.0 Hz)
Min. speed where the compressor must cutout
VSD start speed (20.0 – 60.0 Hz)
Minimum speed for start of Variable speed drive (Must be set
higher than "VSD Min. Speed Hz")
VSD max speed (40.0 – 120.0 Hz)
Highest permissible speed for the compressor motor
AK-PC 783
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