Danfoss ADAP-KOOL AK-PC 781 User manual

Capacity controller with
heat recovery
AK-PC 781
User Guide
ADAP-KOOL®Refrigeration control systems

2 Menu operation RC8CE202 © Danfoss 03/2013 AK-PC 781 Version 4.1x
Menu list This menu function can be used together with system software type AKM. The description is divided
up into function groups that can be displayed on the PC screen. Within each group it is now possible
to show the measured values, or settings. Regarding the use of AKM, reference is made to the AKM
Manual.
Measurements The various measurements can be read directly. If a graphic display of the measurements is required,
up to eight of them can be shown. Select the required measurements and push “Trend”.
Settings Settings can only be made for the daily operation. Conguration settings cannot be seen, changed or
written out. They can only be made from the Service Tool programme.
There are four kinds of settings, ON/OFF settings, settings with a variable value, time settings and
“reset alarms”.
Enter the new value or move the sliding scale up or down.
The new value will apply, when“OK” is pushed.
Set the required value and push“OK”
Validity This menu operation (from March 2013) applies to controller type AK-PC 781, code number
080Z0186 / 080Z0187 / 080Z0188 / 080Z0189 / 080Z0190 with programme version 4.1x.
The operation is divided up into several
function groups. When a selection has been
made, push“OK”, and you may continue to
the next display. By way of example,“Suction
capacity control” has been selected here.
From the measure line the dierent val-
ues can be read. The values are constantly
updated.
In the list of settings the set values can be
seen. If a setting has to be changed, select
the parameter and proceed via“OK”.
Function groups

AK-PC 781 Version 4.1x Menu operation RC8CE202 © Danfoss 03/2013 3
Go through the individual functions one by one and make the required settings. When settings have
been made for one controller, the set values may be used as basis in the other controllers of the same
type and with the same software version. Copy the settings by using the copy settings function in the
AKM programme, and adjust subsequently any settings where there are deviations.
NB! If a list is required for noting down the individual settings, a printout can be made of it with a func-
tion in the AKM programme. Read the next section, “Documentation”.
Documentation Documentation of the settings of the individual controllers can be made with the print function in the
AKM programme. Select the controller for which documentation of the settings is required and select
the “Print Settings”function (cf. also the AKM Manual).
Functions Shown below are function groups with corresponding measurements and settings. A printout of the
given settings can be made using the AKM function “Print Settings”(see above).
Note It has been necessary to make selections among the many measurements and settings coming from
the controller.
The operation from the AKM programme cannot contain them all.
If there is a need for access to all measurements and settings, you should make use of Service Tool
type AK-ST 500.

4 Menu operation RC8CE202 © Danfoss 03/2013 AK-PC 781 Version 4.1x
Main settings
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Compr. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc Bar Actual gas cooler pressure
Pgc reference bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
External Main Switch Status of input “Extern Main Switch”. In pos.“OFF”the regulation is stopped by force
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
Conguration lock Lock of conguration.
In order to select quick setup or select refrigerant type, the conguration lock must
be “open”. Note: ”Main switch”must be OFF in order to set conguration lock in “open”
position
0: Open
1: Locked
Refrigerant type Po Select refrigerant type
0= not selected, 1=R12. 2=R22. 3=R134a. 4=R502. 5=R717. 6=R13. 7=R13b1.
8=R23. 9=R500. 10=R503. 11=R114. 12=R142b. 13=User dened 14=R32. 15=R227.
16=R401A. 17=R507. 18=R402A. 19=R404A. 20=R407C. 21=R407A. 22=R407B.
23=R410A. 24=R170. 25=R290. 26=R600. 27=R600a. 28=R744. 29=R1270. 30=R417A.
31=R422A. 32=R413A. 33=R422D. 34=R427A. 35=R438A. 36=XP10. 37=R407F.
Suction capacity control
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Compr. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc Bar Actual gas cooler pressure
Pgc reference Bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
MC dP0 oset K Actual displacement value for the suction pressure in connection with a “P0
Optimiser” function (Master control function in AKA gateway)

AK-PC 781 Version 4.1x Menu operation RC8CE202 © Danfoss 03/2013 5
S4 media temp. °C Actual media temperature measured at S4 sensor
(Only used if S4 is selected as control sensor)
Pctrl °C Actual regulation pressure measured with Pctrl pressure transmitter (cascade
pressure)
Suction status 0: Power up Controller has been powered up (power supply re-connected)
1: Stopped Capacity control has been stopped ("Main switch" = OFF or
"Control mode" = OFF)
2: Manual Capacity is controlled manually ("Control mode" = MAN)
3: Alarm Capacity control is in alarm condition (fx. alarm on Po Min
or Pc Max)
4: Restart Capacity control is waiting for elapse of “Restart time”
5: Standby Capacity control is ready to start
6: State o timer
7-10: State on timer
11: Unloaded
12-14: Unload cutin
15: Full loaded All capacity cutin
16: Running Capacity control is running
Actual Zone Actual zone for capacity regulation:
0: P0-error
1: - - Zone
2: - Zone
3: NZ
4: + Zone
5: + + Zone
Suction superheat K Actual superheat
Night Setback Status of night setback function
ON: Night (An increase of the evaporating pressure is permitted)
OFF: Normal situation
Load shed 1 Actual status on Load shed input 1
Load shed 2 Actual status on Load shed input 2
Injection ON Status of the “Injection ON”function (earlier mentioned “AKC ON”)
0: Forced closing of all AKV valves
1: Normal operation of AKC controllers
MT release output Actual status on ”Comp. release”output signal from MT controller
MT request input Actual status on ”Comp. request” input signal on MT controller
LT request output Actual status on ”Comp. request” output signal from LT controller
LT release input Actual status on ”Comp. release”input signal on LT controller
No. of compressors Dened number of compressors
Comp. application Select the compressor application required (see the manual for further details)
0: Single step only
1: 1xComp. w. unloaders + Single step
2: 2xComp. w. unloaders + Single step
3: Comp. w. unloaders only
4: 1xVariable speed + Single step
5: 1xVariable speed + Comp. w. unloaders
6: 2xVariable speed + Single step
Step control mode Selected coupling pattern for compressors
Sequential: Compressors are cut in/out in strict accordance
with compressor number
Cyclic: Runtime equalisation between compressors
Best t: Compressors are cut in/out in order to
make the best possible t to actual load
0: Sequential
2: Cyclic
3: Best t
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
Cap. control mode 0: MAN (The compressor capacity will be controlled manually)
1: OFF (The capacity control will be stopped)
2: AUTO (The capacity is controlled by the PI controller)
Manual capacity % Manual setting of compressor capacity
The value is in % of total capacity controlled by the controller
Reference mode Displacement of suction pressure as a function of external signals
0: Reference = set reference + night oset + oset from external 0-10 V signal
1: Reference = set reference + oset from P0 optimization + night oset

6 Menu operation RC8CE202 © Danfoss 03/2013 AK-PC 781 Version 4.1x
Setpoint °C Setting of required suction pressure in °C
Min.Reference °C Min. permissible suction pressure reference
Max.Reference °C Max. permissible suction pressure reference
Night oset K Displacement value for suction pressure in connection with an active night
setback signal (set in Kelvin)
++Zone delay s Time delay between step cut-ins in the regulation band over the“+Zone band”
Set in seconds
+Zone delay s Time delay between step cut-ins in the regulation band over the neutral zone
Set in seconds
+Zone band K Regulation band over the neutral zone
Neutral zone K Neutral zone for suction pressure
-Zone band K Regulation band under the neutral zone
-Zone delay s Time delay between step cut-outs in the regulation band under the neutral zone
Set in seconds
--Zone delay s Time delay between step cut-outs in the regulation band under the“-Zone band”
Set in seconds.
Kp Po Ampliication factor for P0 regulation
VSD Min. speed Hz Minimum allowed speed before stop of Variable Speed drive (Low load condition)
VSD Start speed Hz Minimum speed for start of Variable speed drive (Must be set higher than
“VSD Min. Speed Hz”)
VSD Max. speed Hz Highest permissible speed for the compressor motor
Sd max. limit °C Alarm at too high Sd
Sd comp. alarm delay Time delay for Sd alarm
P0 min. limit °C Alarm at too low P0
P0 max. alarm °C Alarm at too high P0
P0 max. delay m Time delay for P0 alarm
SH min. alarm K Alarm at too low superheat
SH max. alarm K Alarm at too high superheat
SH alarm delay m Time delay for SH alarm
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
MT release delay s Time delay on output signal ”Comp. release”on MT controller
MT request delay s Time delay on input signal for ”Comp. request” on MT controller
LT request delay s Time delay on output signal ”Comp. request” on LT controller
LT release delay s Time delay on input signal for ”Comp. release”on LT controller
Po pump down Select if a pump down function on the last compressor is requested
Po pump down limit °C Set the actual pump down limit for the last compressor
Initial start time The time after start-up where the cut-in capacity is limited to the rst compressor step.
Safety restart time Time delay before restart of compressors
Suction compressor status
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Comp. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc Bar Actual gas cooler pressure

AK-PC 781 Version 4.1x Menu operation RC8CE202 © Danfoss 03/2013 7
Pgc reference Bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
VSD 1 safety Status on safety input for variable speed controller on compressor 1
ON: Alarm
OFF: No alarm
VSD 2 safety Status on safety input for variable speed controller on compressor 2
ON: Alarm
OFF: No alarm
VSD Speed % The present speed of the compressor motor controlled by the frequency converter
Comp. 1 Status 0: Power up Controller has been powered up/Compressor is not used
1: Stopped Compressor hat been stopped
2: Manual Compressor capacity is controlled manually
3: Alarm Compressor is in alarm condition (cut out on safety)
4: Restart Compressor is waiting for elapse of “Recycle time”
5: Standby Compressor is ready to start
6-10: Status_RUN_Timer
11: unloaded
12-14: Unloads cutin
15: Full loaded All capacity cutin
16: Running Capacity control is running
Comp 2 … Status As above for compressor no. 2 to 8
Comp 1 capacity % Actual cut-in capacity on this compressor
Comp 2 …capacity % As above for compressor no. 2 to 8
Comp 1 Cycles / 24 h Number of compressor starts during the past 24 hours
Comp 2 …Cycles / 24 h As above for compressor no. 2 to 8
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
1 Min. ON-time m Minimum duration of ON period
2 …Min. ON-time m As above for compressor no. 2 to 8
1 Min. OFF-time m Minimum duration of OFF period
2 …Min. OFF-time m As above for compressor no. 2 to 8
1 Recycle time m Minimum period of time between two successive starts.
2 …Recycle time m As above for compressor no. 2 to 8
1 runtime h Compressor’s total run time in hours
2 …runtime h As above for compressor no. 2 to 8
High pressure control
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Comp. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc Bar Actual gas cooler pressure
Pgc reference Bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
Shp °C Read temperature at high pressure valve
Vhp OD% Read opening degree of high pressure valve

8 Menu operation RC8CE202 © Danfoss 03/2013 AK-PC 781 Version 4.1x
Rec. Status 0: O
1: Standby
2: Normal
3: Emergency operation
4: Manual
Prec Bar Read pressure of receiver
Vrec OD% Read opening degree of receiver valve
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
HP control ManAut Control of high pressure valve: 1=automatic, 2=manual override
Vhp manual OD% Manual setting of opening degree of high pressure valve
Pgc min. Bar Setting of gas coolers min. pressure
Pgc max. Bar Setting of gas coolers max. pressure
Extra capacity os Set requested pressure increase if the "extra cooling capacity" is activated
dT Subcool K Set requested sub cooling in the sub critical range
Rec. Control ManAut Control of receiver valve: 1=automatic, 2=manual override
Rec. Manual OD% Manual setting of opening degree of the receiver valve
Prec setpoint Bar Set requested receiver pressure
Oil management
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Comp. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc Bar Actual gas cooler pressure
Pgc reference Bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
Rec. pressure Actual pressure in receiver
Rec. pres. buildup Status of oil separator
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
Interval time Time between breaks. (Simple oil equalisation)
Equalisation time Duration of oil equalisation (Simple oil equalisation)
Rec. pres. cutin Bar Reciever pressure, which to cutin for the oil
Rec.pres.cutout Bar Receiver pressure, which to cutout for the oil
High alarm limit Bar Alarm limit high
Low alarm limit Bar Alarm limit low
High alarm delay m Delay time for high pressure alarm
Low alarm delay m Delay time for low pressure alarm
Lvl. alarm delay s Delay time for Level alarm
Condenser capacity control
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)

AK-PC 781 Version 4.1x Menu operation RC8CE202 © Danfoss 03/2013 9
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Comp. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc Bar Actual gas cooler pressure
Pgc reference Bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
Tc max. limit °C Readout limit value for max condenser pressure
S7 brine temp °C Actual media temperature measured at S7 sensor
(Only used if S7 is selected as control sensor)
Condenser status 0: Power up Controller has been powered up (power supply re-connected)
1: Stopped Capacity control has been stopped (“Main switch”= OFF or
“Control mode” = OFF)
2: Manual Capacity is controlled manually (“Control mode”= MAN)
3: Alarm Capacity control is in alarm condition (f.ex. Pc Max or Sd Max)
4: Restart Capacity control is waiting for elapse of “Restart time”
5: Standby Capacity control is ready to start
6: Unloaded
7-9 Part loaded
10: Full loaded All capacity cutin
11: Running Capacity control is running
Air ow status 0: No RFG. selectNo refrigerant has been selected (monitoring of air
ow can not start)
1: Tuning Monitoring function adapts to the condenser in question
2: OFF Monitoring function is switched OFF
3: OK Air ow is OK
4: Little dirt The amount of dirt decreases the performance of the condenser,
clean when possible
5: Dirty The amount of dirt leads to considerable air ow problems, clean
as soon as possible
6: Blocking The amount of dirt might lead to high pressure problems, clean
now
Sc3 Air on °C Outdoor temperature in °C measured with Sc3 temperature sensor
No. of fans Dened number of fans
VSD Speed % Status of analogue output signal “AO”for variable speed drive (in percent of
full scale f.ex. 0 -10 V d.c.)
VSD safety Status of safety monitoring input for Variable Speed Drive
ON: Alarm on VSD A safety monitoring input
OFF: No alarm on VSD A safety monitoring input
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
Condenser ctrl mode 0: MAN (The condenser capacity will be controlled manually)
1: OFF (The capacity control will be stopped)
2: AUTO (The capacity is controlled by the PI controller)
Manual capacity % Manual setting of condenser capacity
The value is in % of total capacity controlled by the controller
Pc Ref. mode 0: Set point Reference =“PcA setpoint °C”
1: Floating Reference is changed as a function of the outdoor temperature
measured by the“Sc3 air on” sensor, the set “Dimensioning tm K”
and the actual compressor load.
Cond. Setpoint °C Setting of required discharge pressure in °C
Dimensioning tm K Dimensioning mean temperature dierential between air- and condensing
temperature at full load for the condenser in question (Typical 8 – 15K).

10 Menu operation RC8CE202 © Danfoss 03/2013 AK-PC 781 Version 4.1x
Min. tm k tm value at minimum load.
Min. Reference °C Min. permissible condensing pressure reference
Max. Reference °C Max. permissible condensing pressure reference
Capacity Lim. night % Capacity limitation during night operation
Kp Amplication factor P/PI controller
Tn s Integration time for PI controller
VSD Min. speed % Minimum allowed speed before stop of Variable Speed drive (Low load condition)
VSD Start speed % Minimum speed for start of Variable speed drive (Must be set higher than
“VSD Min. Speed %”)
Pc max limit Bar Max. limit for condensing pressure
Pc max alarm delay m Time delay for "Pc max alarm"
Condenser fan status
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Compr. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc bar Actual gas cooler pressure
Pgc reference bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
Fan1/VSD status Status of the Fan 1
ON: Fan is running
OFF: Fan is not running
Fan2.... status As above for fan 2 to 8
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
Heat recovery
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Compr. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.

AK-PC 781 Version 4.1x Menu operation RC8CE202 © Danfoss 03/2013 11
Pgc Bar Actual gas cooler pressure
Pgc reference Bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
Shr2 °C (ONLY at CO2). Temperature at sensor Shr2
Stw2 °C (ONLY at CO2). Temperature at sensor Stw2
Status heat circuit (ONLY at CO2). 0=o. 1=waiting. 2=started. 3=standard. 4=variable oset
5=max recovery. 6=stopped. 7=error.
Tw Stw8 °C (ONLY at CO2). Temperature at sensor Stw8. Tap water
Tw Status (ONLY at CO2). 0=o. 1=waiting. 2=started. 3=hot tap water. 5=manual.
6= stopped. 7=error. 8=Flow error. 9=sensor error. 10=boiling.
Tw enable (ONLY at CO2). Readout about tap water circuit can be activated automatically
Hr Shr8 °C (ONLY at CO2).Temperature at sensor Shr8. Heat circuit
Hr Status (ONLY at CO2). 0=o. 1=waiting. 2=started. 3=heat circuit. 5=manual.
6= stopped. 7=error. 8=Flow error. 9=sensor error. 10=boiling.
Hr enable (ONLY at CO2). Readout about heat circuit can be activated automatically
HR thermostat temp°C (Not at CO2). Actual temperature at sensor for heat recovery function
Heat recovery status (Not at CO2). Status on heat recovery function (on/o )
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
Tw setpoint °C (ONLY at CO2). Set point for tap water temperature
Hr setpoint °C (ONLY at CO2). Set point for heat circuit temperature
Pgc HR max. oset (ONLY at CO2). Displacement pressure of max. signal
Pgc HR min. Bar (ONLY at CO2). Set point at min. signal
Heat recovery SP °C (Not at CO2). Reference for condenser pressure when heat recovery is on
HR temp. cutin °C (Not at CO2). Temperature value when thermostat switch to heat recovery
HR temp. cutout °C (Not at CO2). Temperature value when thermostat switch o the heat recovery
Alarm priorities
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Comp. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc Bar Actual gas cooler pressure
Pgc reference Bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
The alarm priority of the following alarms can be changed:
High priority is dened with setting = 1
Medium priority is dened with setting = 2
Low priority is dened with setting = 3
Log only = 4
Overriding the alarms is dened with setting = 0
Main Switch 0/1/2/3/4
Low P0 0/1/2/3/4

12 Menu operation RC8CE202 © Danfoss 03/2013 AK-PC 781 Version 4.1x
High P0 0/1/2/3/4
High Pc/Sd 0/1/2/3/4
Hpcontrol / Receive 0/1/2/3/4
Superheat Min/Max 0/1/2/3/4
Load shedding 0/1/2/3/4
P0/S4/Pctrl error 0/1/2/3/4
Misc. sensors 0/1/2/3/4
Comp. common safety 0/1/2/3/4
Comp. VSD safety 0/1/2/3/4
Comp. 1 safety 0/1/2/3/4
Comp. 2 safety 0/1/2/3/4
Comp. 3 safety 0/1/2/3/4
Comp. 4 safety 0/1/2/3/4
Comp. 5 safety 0/1/2/3/4
Comp. 6 safety 0/1/2/3/4
Comp. 7 safety 0/1/2/3/4
Comp. 8 safety 0/1/2/3/4
Pc/S7 sensor error 0/1/2/3/4
Blocked air ow 0/1/2/3/4
Fan safety 0/1/2/3/4
Comp. Low Oil lvl 0/1/2/3/4
Comp. High Oil lvl 0/1/2/3/4
Oil Separator alarm 0/1/2/3/4
Oil Receiver alarm 0/1/2/3/4
Oil Recv High press 0/1/2/3/4
Oil Recv. Low press 0/1/2/3/4
Tw boiling alarm 0/1/2/3/4
Hr boiling alarm 0/1/2/3/4
General alarm inputs
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Compr. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc Bar Actual gas cooler pressure
Pgc reference Bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
DI 1 input Alarm status on the function dened as a DI1 alarm
ON: Alarm is activ
OFF: No alarm, normal situation
DI 2.... Input As above, but for the alarm functions 2 to 6
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
DI 1 Alarm delay m Time delay for the alarm "DI 1 Alarm"
DI 2.... Alarm delay m As above, but for the alarm functions 2 to 6

AK-PC 781 Version 4.1x Menu operation RC8CE202 © Danfoss 03/2013 13
Thermostat/pressostats
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Comp. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity
Pc Bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc Bar Actual gas cooler pressure
Pgc reference Bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
Thermostat 1 °C Temperature measurement of function dened in Thermostat 1.
Thermostat 2 °C Temperature measurement of function dened in Thermostat 2.
Thermostat 3 °C Temperature measurement of function dened in Thermostat 3.
Pressostat 1 Bar Pressure measurement of function dened in Pressostat 1
Pressostat 2 Bar As above but for Pressostat 2
Pressostat 3 Bar As above but for Pressostat 3
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
T1 Cutin °C Cutin value for function dened in ”Thermostat 1”.
T1 Cutout °C Cutout value for function dened in ”Thermostat 1”.
T1 High Alarm °C High alarm limit "Thermostat 1"
T1 Low Alarm °C Low alarm limit "Thermostat 1"
T1 High Al delay m Time delay for high alarm "Thermostat 1"
T1 Low Al delay m Time delay for low alarm "Thermostat 1"
P1 Cutin press Bar Cutin value for function dened in ” Pressostat 1”.
P1 Cutout press Bar Cutout value for function dened in ”Pressostat 1”.
P1 High Al limit Bar High alarm limit "Pressostat 1"
P1 Low Al limit Bar Low alarm limit "Pressostat 1"
P1 High Al delay m Time delay for high alarm "Pressostat 1"
P1 Low Al delay m Time delay for low alarm "Pressostat 1"
(Use Service Tool if data concerning thermostats 2 to 5 or from Pressostat 2 to 5 have to be downloaded).
Voltage and PI inputs
Measurements AK error When “ON”, the controller is in alarm condition.
Comp. ctrl. temp °C Actual temperature for control sensor (Po or S4)
Comp. ctrl. ref. °C Actual reference temp. for compressor capacity
(incl. external reference signal, if any)
Compressor cap. % Cut-in compressor capacity in % (of total capacity)
Request Comp. Cap % Reference for compressor capacity (deviations may be due to time delays)
P0 °C Suction pressure in °C. (Measured with the pressure transmitter)
Ss Suction gas °C Actual suction gas temperature
Cond. ctrl. temp °C Actual temperature for control sensor (Pc or S7)
Cond. ctrl. ref. °C Actual reference temp. for condenser capacity
(incl. external contributions, if any)
Cond. cap. % Cut-in condenser capacity in % (of total capacity)
Request Cond. cap % Reference for condenser capacity

14 Menu operation RC8CE202 © Danfoss 03/2013 AK-PC 781 Version 4.1x
Pc bar Condensing pressure (measured with the pressure transmitter)
Tc °C Condensing pressure in °C. (measured with the pressure transmitter)
Gc status Actual gas cooler operation:
0=O. 1=Standby. 2=Max COP operation. 3=Heat recovery. 4=Extra capacity.
5=Manual control.
Pgc Bar Actual gas cooler pressure
Pgc reference Bar Actual reference for gas cooler pressure
Sd discharge gas °C Actual discharge gas temperature
Sgc °C Actual temperature at outlet from the gas cooler
V1 Actual input Voltage measurement on the function dened in Volt 1.
V2 Actual input Voltage measurement on the function dened in Volt 2.
V3 Actual input Voltage measurement on the function dened in Volt 3.
PI1 State PI function state
PI1 Alarm state PI function alarm condition
PI1 Input Input signal
PI1 Reference Reference
PI1 Output value Output value
PI1 Output type Output type: PWM. Stepper. Voltage
Settings Main switch Main switch: ON: Regulation
OFF: Controller stopped
V1 Cutin The value where the relay is to cut in
V1 Cutout The value where the relay is to cut out
V1 Cutin delay m Time delay for cutin of relay
V1 Cutout delay m Time delay for cutout of relay
V1 High Al Limit The value for the high alarm limit
V1 Low Al Limit The value for the low alarm limit
V1 High Al delay m Time delay for high alarm
V1 Low Al delay m Time delay for low alarm
PI1 O Aut Man Control of PI function. 0: O, 1: Automatic, 2: Manual
PI1 Manual OD Manual setting of opening degree for PI function
(Use Service Tool if data concerning Volt 2, 3, 4, 5 and PI2 /PI3 are to be downloaded).
AKM menu: "For DANFOSS only"
This menu contains data and setting values for special internal controller functions.
Do not change the stated values.
Danfoss can accept no responsibility for possible errors in catalogues, brochures and other printed material. Danfoss reserves the right to alter its products without notice. This also applies to products
already on order provided that such alternations can be made without subsequential changes being necessary in specications already agreed.
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