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Configuration - continued
5. Set values for capacity of the
compressors
Press the +-button to go on to the
next page
6. Set values for main step and any
unloaders
Press the +-button to go on to the
next page
7. Set values for safe operation
Press the +-button to go on to the
til næste side.
AK-PC 772A
The compressor capacity is set in
displaced volume per hour. m
See compressor data.
In our example there are no
unloaders and hence no changes.
In our example we select:
- Safety limit for discharge
temperature = 120°C
- Safety limit for high condensing
pressure = 103.0 bar
- Safety limit for low suction
pressure = -40°C
Capacity controller RS8HF102 © Danfoss 2017-07
than "VSD Min. Speed Hz")
VSD max speed (40.0 – 120.0 Hz)
Highest permissible speed for the compressor motor
VSD safety monitoring
Select this if input for monitoring of the frequency converter is
required
PWM period time
Period time for bypass valve (on time + off time)
PWM Min. capacity
3
/h.
Minimum capacity in the period time (without a minimum capa-
city the compressor will not be cooled)
PWM Start capacity
Minimum capacity at which the compressor will start (must be
set to a higher value than "PWM Min. capacity")
Load shed limits
Select which signal is to be used for load limitation
(only via network, a DI + network or two DI + network)
Load shed limit 1
Set max capacity limit for load shed input 1
Load shed limit 2
Set max capacity limit for load shed input 2
Override limit T0
Any load below the limit value is freely permitted. If the T0 ex-
ceeds the value, a time delay is started. If the time delay runs out,
the load limit is cancelled
Override delay 1
Max. time for capacity limit, if P0 is too high
Override delay 2
Max. time for capacity limit, if P0 is too high
Easy PI Selection
Group setting for the 4 control parameters: Kp, Tn, + acceleration
and - acceleration. If the setting is set to "user defined" the 4
control parameters can be fine-tuned.
Kp T0 (0.1 – 10.0)
Amplifications factor for PI regulation
Tn T0
Integration time for PI-regulation
+ Zone acceleration (A
Higher values result in a faster regulation
- Zone acceleration (A
Higher values result in a faster adjustment
Advanced settings
Select whether the advanced capacity control settings should
be visible
T0 filter
Reduce changes in the Po reference
Pc filter
Reduce changes in the Pc reference
Minimize cycling
The control zone may vary for connections and disconnec-
tions. See Section 5.
Initial start time (15 – 900 s)
The time after start-up where the cut-in capacity is limited to
the first compressor step.
Unloading mode
Select whether one or two capacity controlled compressors
are allowed to be unloaded at the same time at decreasing
capacity
AO filter
Absorber changes at the analog output
AO max. limit
Limit the voltage on the analog output.
5 - Compressors
In this screen the capacity distribution between the com-
pressors is defined.
Capacities that need to be set depend upon the "compressor
application" and "Step control mode" that has been selected.
Nominal capacity (0.0 – 1000,0 m
Set the nominal capacity for the compressor in question.
For compressors with variable speed drive the nominal
capacity must be set for the mains frequency (50/60 Hz)
Unloader
Number of unload valves for each compressor (0-3)
6 - Capacity distribution
The installation is dependent on the combination of com-
pressors and coupling pattern.
Main step
Set the nominal capacity of the main step (Set the percent-
age of the relevant compressor's nominal capacity) 0 -
100%.
)
+
-
)
3
/h)
57
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