Danfoss AK-PC 551

10 User Guide RS8GY302 © Danfoss 2015-06 AK-PC 551
Pump down Pump-down function
To avoid too many compressor starts/stops at a low load, it is possible to dene a pump-
down function for the last compressor. In this case, the compressor will be cut out when the
current suction pressure is down at the set “Pump-down limit Po”.
(The setting must be greater than the safety limit for low suction pressure “PoA Min Limit”.)
Yes /No
Fac: No
Min: -80°C (-1.0 bar)
Max: 30°C (50.0 bar)
Facb: -40°C (0.3 bar)
Load shed limit Capacity limitation at “low shed signal”
Set how much compressor capacity can be cut in when a signal is received from either a DI
input or a system device via data communication.
Min: 0 %
Max: 100%
Fac: 100%
Emergency cap. day Emergency capacity in the event of a malfunction of the regulation sensor (suction pressure
sensor)
Set the desired capacity that will apply during daytime operation.
(If the S4 media temperature sensor becomes damaged/defective, use Po for regulation.)
Min: 0 %
Max: 100%
Fac: 50%
Emergency cap. night Emergency capacity in the event of a malfunction of the regulation sensor (suction pressure
sensor)
Set the desired capacity that will apply during night operation.
(If the S4 media temperature sensor becomes damaged/defective, use Po for regulation.)
Min: 0 %
Max: 100%
Fac: 25%
Comp. start delay Delay of compressor start after forced closing of expansion valves (at the end of a forced
close signal)
The delay will result in the system device receiving a start signal for all the evaporator con-
trols involved before the rst compressor is started.
Min: 0 s
Max: 180 s
Fac: 30 s
Injection OFF delay Delay of the forced closing of expansion valves, if the controller calls for cut in of compres-
sors, but the compressors are in a locked situation and therefore cannot start.
Min: 0 s
Max: 300 s
Fac: 120 s
Conguration Conguration
Control sensor Select the regulating sensor for the suction circuit:
• Pressure transmitter Po
• Media temperature sensor S4 (brine regulation). (Po is used for safety)
AI-demand
Po / S4
Fac: Po
Compressor mode Set the type of compressor to be used for regulation:
• Multi all:****
)
All compressors have unloaders
• Multi + Single:****
)
First compressor has unloaders. The remaining ones are one-step units
• Speed+Multi: ***
)
First compressor is speed-controlled. The remaining ones are with unload-
ers.
• Speed+Single: ***
)
First compressor is speed-controlled. The remaining ones are
one-step units
• CRII4+Multi **
)
First compressor is CRII4 compressor. The remaining ones are with unloaders
• CRII4+Single **
)
First compressor is CRII4 compressor. The remaining ones are
one-step units
• Stream 4+Multi: **
)
First compressor is a stream compressor. The remaining ones are with
unloaders
• Stream 4+Single: **
)
First compressor is a stream compressor. The remaining ones are
one-step units
• Digital scroll: *
)
First compressor is a digital scroll. The remaining ones are one-step units
• Single-step only: All are one-step compressors
• None:
DO-demand /
AO-demand
Fac:
Single step only
No. of compressors Set the number of compressors on the suction circuit
This is a total amount.
(If both suction groups are selected, the max. number will be 4 for A and 4 for B.)
DO-demand
Min: 1
Max: 8
Fac: 0
Lead comp. size Set the nominal compressor capacity for the rst compressor (it is dened under
“Compressor mode”)
That is, the capacity of either a “Digital scroll”, “Stream”, “Variable speed CRII” or
“First compressor with unloaders”
Min: 1 kW
Max: 100 kW
Fac: 1 kW
Comp. size Set the nominal compressor capacity of the other compressors
For single-step only: All are of the same size, including the rst.
For unloader all: All are of the same size, including the rst.
Min: 1 kW
Max: 100 kW
Fac: 1 kW
VSD Min. speed ***: For speed
Min. speed at which the compressor will cut out
Min: 10 Hz
Max: 60 Hz
Fac: 30 Hz
VSD Start speed ***: For speed
Minimum speed at which the compressor will start (must be set to a higher value than
“VSD Min. speed”)
Min: 20 Hz
Max: 60 Hz
Fac: 45 Hz
VSD Max speed ***: For speed
Highest permitted speed for compressor
Min: 40 Hz
Max: 120 Hz
Fac: 60 Hz
PWM period time *, **: For “Scroll” and “Stream”
Set the period time for the unloader valve (on time + o time)
Min: 10 s
Max: 20 s
Fac: 20 s
CRII Period time **: For CRII
Set the period time for the unloader valve (on time + o time)
Min: 10 s
Max: 20 s
Fac: 60 s