Danfoss AK-PC 551 User manual

AK-PC 551 Refrigeration Controller
Technical brochure

2 Technical brochure RC8CF102 © Danfoss 08-2014 AK-PC 551

AK-PC 551 Technical brochure RC8CF102 © Danfoss 08-2014 3
Content
Introduction ������������������������������������������������������������������������������� 4
Applications 4
Compressor combinations 5
Condenser combinations 5
Inputs and outputs 5
Basic Operation������������������������������������������������������������������������� 6
Status 6
Password 6
Logout 6
Setup & service 6
View parameters 8
Change parameters 8
Day / night schedule 8
First time start up ��������������������������������������������������������������������� 9
Conguration 9
Example: Application������������������������������������������������������������ 10
Application: Digital scroll 10
Example: Wiring Diagram���������������������������������������������������� 11
Electrical wiring 11
Connection, lower level 11
Electrical diagram 11
Connection, upper level 11
Example: Wizard���������������������������������������������������������������������� 12
Wizard setup 12
Example: Check IO conguration������������������������������������� 14
Wizard assignment of inputs and outputs (I/0) 14
Assignment of inputs and outputs 14
IO conguration error 15
Example: Add extra I/O ������������������������������������������������������� 16
Example: Check I/O wiring�������������������������������������������������� 17
Initialize the controllers IO conguration 17
Network setup������������������������������������������������������������������������� 18
Example: Quick conguration ������������������������������������������� 19
Quick conguration 19
Application table 20
Frequently asked questions (FAQ)������������������������������������ 22

4 Technical brochure RC8CF102 © Danfoss 08-2014 AK-PC 551
Introduction
This technical brochure will give you a short introduction to
the AK-PC 551 pack controller� With an application example, it
is shown how easy the controller is congured and operated
through the graphical display�
The AK-PC 551 is a pack controller for 1 or 2 suction groups of
compressors and a common condenser�
AK-PC 551 supports a variety of compressor combinations
including variable speed, Digital scroll and Stream 4 cylinder
compressors� Additionally it oers a large number of energy
saving functions and optimization features�
AK-PC 551 can be fully congured through a LCD display� The LCD
display can be built in and/or be a remote connected display�
AK-PC 551 has a compact size of 8 DIN modules� All inputs and
outputs can be congured for a variety of functions making the
controller highly adaptable to any pack application�
AK-PC 551 can be connected into a MODBUS communication
network and is available with 24 Vac or 110-230 Vac power supply�
Applications
AK-PC 551 is used for capacity control of compressors and
condenser fans on small to medium sized refrigeration
systems� It covers the following main applications:
• One compressor group (max� 8 relays) and one condenser
group
• Two compressor groups (max� 4 relays per group) and a
common condenser

AK-PC 551 Technical brochure RC8CF102 © Danfoss 08-2014 5
Introduction
Compressor combinations
The compressor capacity can be controlled according to the
suction pressure Po or a media temperature sensor S4�
AK-PC 551 covers a variety of compressor combinations�
Inputs and outputs
All in- and outputs of an AK-PC 551 controller can be congured
for various functions and signal types:
• 8 analogue inputs for pressure transmitters and temperature
sensors�
• 6 digital relay outputs for compressors, fans, alarm�
• 2 digital solid state outputs for PWM control of Digital scroll
or Stream compressor� If not used for this purpose they can
be used as normal relay outputs�
• 2 analogue outputs for speed control of compressors and
condenser fans�
Speed control of all fans Step control of all fans
Condenser combinations
The condenser capacity can be controlled according to the
condensing pressure Pc or a media temperature sensor S7
The condenser can be controlled in two ways:
• Speed control of all fans
• Step control of single fans

6 Technical brochure RC8CF102 © Danfoss 08-2014 AK-PC 551
Basic Operation
Suction statusHome Condenser status Active alarms Cleared alarms Controller information
From any status screen press ENTER for
2 sec� to access main menu
Press ESCAPE to
go one level back
Password
Parameters and menus are protected by a
password that gives access on 3 dierent
user levels�
Level 0: See parameters (000)
Level 1: Change weekly schedule (100)
Level 2: Change control setpoints (200)
Level 3: Change conguration setpoints (300)
The password cannot be reset, so please
remember the (level 3) password�
Logout
Go to the "Home" screen and hold down the
X key for 5 seconds to logout�
Setup & service
In the main menu you will nd all control
parameters divided into sub menus�
Press ESCAPE to go back to status
Press UP to decrease digit
Press DOWN to increase digit
Press ENTER to login
Press LEFT / RIGHT to go to next / previous digit
Conguration and daily operation of AK-PC 551 is done via the
built-in display or via a remote connected display� The display
supports multiple languages and engineering units�
For a full description of the controller parameters please see the
manual RS8GY
Status
Get an overview of how the system is running in the status
screens� Use the LEFT / RIGHT buttons to view the status screens�

AK-PC 551 Technical brochure RC8CF102 © Danfoss 08-2014 7
Suction reference
Condenser reference
Condenser reference
Condenser control sensor readout
Number of fans running
(1 of 2 fans is running)
Suction reference
Suction control sensor readout
Number of compressors running
(1 of 2 compressors is running)
The number of status screens and the presented data depends
upon the congured application�
Running compressor capacity
Condenser control sensor
Condenser reference
Suction control sensor
Basic Operation
Suction status
Home
Active alarms
Controller information
Cleared alarms
Press ENTER to see
alarm details
Press ENTER to see
cleared alarm details
Running fan capacity
? temperature
Condenser control sensor
Condenser status
Alarm priority Alarm priority
Alarm text
Alarm text
Active alarm Cleared alarm
Alarm activated at Alarm activated at
Alarm cleared at
Technical controller information
like code number and software
version etc�
To clear an alarm press ESC (X) for 2 sec�

8 Technical brochure RC8CF102 © Danfoss 08-2014 AK-PC 551
Press ESCAPE to go one level back
Press UP to increace the time
Press DOWN to decrease the time
Press ENTER to save the setting
Basic Operation
Day / night schedule
View parameters
The display will only present parameters that are valid for the
congured application e�g� if 4 compressors are selected only 4 are
showed�
A partly highlighted row indicates that a parameter can be viewed
and not changed�
Change parameters
A full highlighted row indicates that a parameter can be changed�
A changable parameter has a frame around the setting�
Control status menu
Control settings menu
Control status readout
Setpoint readout
Setpoint selected
Press ESCAPE to go one level back
Press ESCAPE to go back one level
Press ESCAPE to go one level back
Press UP to increace the setpoint
Press DOWN to see next parameter
Press DOWN to see next parameter
Press DOWN to decrease the setpoint
Press ENTER to edit a parameterPress ENTER
to select
setpoint
Press ENTER
to select
control
status
Press ENTER to save the setpoint
Press LEFT / RIGHT to go to hour / minute
Press ENTER to select day
System menu
Press ENTER
to select
weekly
schedule
Weekly schedule
Monday open time

AK-PC 551 Technical brochure RC8CF102 © Danfoss 08-2014 9
Conguration
After installation the controller must be congured for an
application� Once power is applied to the controller, the "Power
on" screen will appear�
Use one of the three options to congure the controller:
• Setup wizard
• Quick configuration
• Parametric setup
Setup wizard
Setup wizard is a step by step up and running guideline, setting
up inputs and outputs automatically�
Quick conguration
Quick conguration is a series of precongured applications,
setting up inputs and outputs automatically�
Parametric setup
Parametric setup is for the expert user, who wants to set each
parameter individually, adjust or netune settings�
First time start up
Quick start
Power on screen
Press ENTER for 2 sec�
and enter password (300)
to access quick start

10 Technical brochure RC8CF102 © Danfoss 08-2014 AK-PC 551
Example: Application
Application: Digital scroll
The conguration and daily operation of the AK-PC 551 will be
explained via an application example:
AK-PC 551 controls a refrigeration system with two suction
groups of compressors and a common air cooled condenser�
Refrigerant: R404A
Suction group MT:
1 digital scroll compressor
2 single step scroll compressors
Control according to suction pressure Po
Set point -15 °C
Monitoring of discharge temperature of digital scroll
Suction group LT:
2 single step scroll compressors
Control according to suction pressure Po
Set point -30°C
Condenser:
Speed control of 4 fans
Common safety monitoring of fans
Relay output for start/stop of VSD
Control according to condensing pressure Pc
Floating reference according to Sc3 outdoor temp�

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Connection, lower level
Electrical wiring
The electrical wiring is laid out according to the wizard rules for
assigning functions to the inputs and outputs
Electrical diagram
Connection, upper level
Example: Wiring Diagram
DO Function DI Function AO Function AI Function
DO1 Com� 1A DI1 Comp� 1A safety AO3 Fan VSD AI1 PoA suction pressure
DO2 Comp� 2A DI2 Comp� 2A safety AO4 AI2 PoB suction pressure
DO3 Comp� 3A DI3 Comp� 3A safety AI3 Pc condensing pressure
DO4 Comp� 1B DI4 Comp� 1B safety AI4 Sc3 outdoor temp�
DO5 Comp� 1A PWM DI5 Comp� 2B safety AI5 Sd Comp� 1A
DO6 Comp� 2B DI6 Fan safety AI6
DO7 Fan VSD DI7 AI7
DO8 DI8 AI8
DO8 DI8 AI8

12 Technical brochure RC8CF102 © Danfoss 08-2014 AK-PC 551
Example: Wizard
Press ENTER to
start the wizard
Press ENTER
to select the
wizard
Press ENTER for 2 sec�
and enter password (300)
to access quick start
Wizard setup
In this example we will use the wizard to congure the controller�
General
In the rst general screens you must select
how data are presented in the display�
Please note that the“Control setup unit”
decides whether the control set points are
presented in pressure units or temperature
units (saturated temperature)�
Language: English
Control setup unit: Sat. temp
Temperature units: °C
Pressure units: Bar
Wizard screens: Settings:
Plant type
Select the overall application of the
controller and the refrigerant type�
Select plant type: 2 comp + 1 cond
Refrigerant type: R404A
Suction A and B
Set the compressor combination as well
as the compressor sizes, control sensor
and set point� The pressure range of the
pressure transmitter can be set�
Suction A
Po sensor max� range: 12.0 bar
Po sensor min� range: -1.0 bar
Setpoint: -15 °C
Compressor mode: Digital scroll
No� of compressors: 3
Lead compressor size: 5 kW
Comp� size: 5 kW
Suction B
Po sensor max� range: 12 bar
Po sensor min� range: -1.0 bar
Setpoint: -30 °C
Compressor mode: Single step
No� of compressors: 2
Comp� size: 3 kW
Press ESCAPE to
leave the wizard

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Example: Wizard
Condenser
Set the condenser control as well as control
sensor and reference settings� The pressure
range of the pressure transmitter can be
set�
Pc sensor max� range: 34.0 bar
Pc sensor min� range: -1.0 bar
Reference mode: Floating
Setpoint: 30 °C
Min� reference: 15 °C
Max� reference: 45 °C
Capacity ctrl� mode: Speed
No� of fans: 1
VSD Start via DO: Yes
Monitor fan safety: Common
Extra
Select whether to use an alarm relay and
Modbus network address�
Alarm output: No relay
Modbus address: 100
Summary
Get an overview of the inputs and outputs
generated by the wizard�
Next step
Select which main menu to go to� Press
DOWN to go to the selected menu�
It is recommended to check the IO (input /
output) conguration before starting the
controller�
Apply wizard settings
Press ENTER to apply the wizard settings
to the controller including automatic
assignment requested inputs and outputs�
Press DOWN to go to the selected menu and nish the
wizard

14 Technical brochure RC8CF102 © Danfoss 08-2014 AK-PC 551
Press ENTER to select
digital and analog I/O
Press ENTER to select
I/O conguration
Main menu IO conguration menu
Digital outputs Digital inputs Analog outputs Analog inputs
Example: Check IO conguration
Wizard assignment of inputs and outputs (I/0)
Once the wizard is applied, the IO functions are automatically
assigned to hardware inputs and outputs�
The screens below shows how the IO functions are assigned
according to the example�
Assignment of inputs and outputs
The table indicates rules for assignment of inputs and outputs via the wizard�
* Special features to be enabled through conguration screens. Not part of the wizard setup.
Digital outputs (DO1-DO8) Digital inputs (DI1-DI8) Analog outputs (AO3 – AO4) Analog inputs(AI1-AI8)
PWM outputs for capacity
control of Digital scroll or
Stream 4 compressor are placed
on the solid state relays DO5
and DO6
Compressor safety inputs for
respectively suction group A
and B
Speed control of compressor
for respectively suction group A
and B
PoA og PoB suctionpressure are
placed on AI1 and AI2
Starting from DO1: Fan safety inputs Speed control of condenser Pc condensing pressure is
placed on AI3
Compressor start relays
followed by unloading valves
for respectively suction group
A and B
External Main switch (ON/
OFF) *
Sc3 outdoor temperature is
placed on AI4
Condenser fan HP safety switch* S4A and S4B suction media
temperature sensors *
Injection ON for A/B * LP safety switch * S7 condenser media
temperature sensor *
Alarm relay Night setback * Sd komp� 1 discharge temp�
sensor for digital scroll/Stream
compressor for suction A and B
Heat recovery * Ss suction gas temperature for
suction group A and B *
Load shedding * Sd discharge temperature for
suction A and B *
General alarm inputs 1-3 * Saux for general thermostat *

AK-PC 551 Technical brochure RC8CF102 © Danfoss 08-2014 15
Example: Check IO conguration
I/O summary
Alarm:
IO conguration error
IO conguration error
If you get an “IO conguration error” alarm after setting main
switch in ON position, the reasons can be:
• Not all enabled IO functions have been assigned to a
hardware input or output
• The number of enabled IO functions exceeds the number of
available inputs or outputs of the controller
IO summary
Go to Main menu -> IO Status -> IO summary
If the number of enabled IO functions exceeds the maximum
number supported by the hardware, an exclamation mark“!” will
be shown at the IO type in question� This means that you will have
to disable some of the IO functions via the conguration menus
of the suction groups and condenser in order not to exceed the
maximum available inputs or outputs�
If no exclamation mark is shown it means that at least one IO
function has not been assigned to a hardware input or output�
This means that you will have to go into the IO conguration
menu of each IO type, select a free input/output and select the
missing function (if a function is selectable this is the reason for
the IO conguration error alarm)�
An exclamation mark is shown
when max. number of IO is
exceeded !

16 Technical brochure RC8CF102 © Danfoss 08-2014 AK-PC 551
Conguration menu
Sd discharge temp.
Analog inputs menu
Analog input (AI) no. 6
AI no. 6 function
Analog inputs
Example: Add extra I/O
Add extra I/O
The wizard covers all basic functions of the AK-PC 551
pack controller� Additional features can be set through the
conguration screens of the suction group or the condenser�
In this example we will add a Sd discharge temperature
monitoring of both suction groups�
1. Enable Sd temperature monitoring in suction group A and B
Go to Main menu -> Suction A ->Conguration
If a function has been assigned to an input or output and the
same function has been deselected in the suction/condenser
conguration afterwards, the IO conguration will show an
exclamation mark at the function� This is done in order to show
that an IO point is occupied by a function which is not used by the
controller�
In this situation you should either enable the function again in the
suction/condenser conguration menus or deselect the function
in the IO conguration�
2. Assign the two Sd discharge temperature sensors to free
analog inputs
Go to Main menu -> IO conguration of analog inputs (AI)
3. Select the Sd A and Sd B discharge sensors for respectively
AI6 and AI7
Please notice that it is only functions that are enabled in the
suction/condenser conguration menus that are selectable in the
IO conguration�
PWM outputs for Digital scroll or Stream compressors can only be
selected on the solid state relays DO5 and DO6�
Pressure transmitters with current signals of 0-20mA or 4-20mA
are only supported on AI1-AI4�
An exclamation mark is shown
when an IO point is occupied by
a function which is not used by
the controller.

AK-PC 551 Technical brochure RC8CF102 © Danfoss 08-2014 17
Example: Check I/O wiring
Initialize the controllers IO conguration
1. Set main switch in ON position
Go to Main menu -> Start/Stop
Set main switch ON
2. Check correct reading of inputs and outputs in the IO status
menus
Go to Main menu -> IO Conguration -> Analog/Digital inputs
Check correct status of all inputs�
3. Check correct wiring of the outputs via the IO manual
control menus
Go to Main menu -> IO Conguration -> Analog/Digital outputs
Check correct electrical wiring by manually overriding the
outputs�
Analog inputs Digital inputs
Digital output 1 ON
Digital outputs
Main switch menu
The stars "****" indicates that
sensor error is detected or not
intialized (main switch ON).

18 Technical brochure RC8CF102 © Danfoss 08-2014 AK-PC 551
Network setup
AK-PC 551 can be integrated into a Modbus communication
network� It is important that the installation of the communication
cable is done correctly� Also remember correct termination at
both ends of the cable�
Please refer to separate literature no� RC8AC
When AK-PC 551 is integrated into an ADAP-KOOL® network
with a system manager of the types AK-SC 355 or AK-SM 850 it is
important that some settings are set correctly�
1. Set unit of setpoints
Go to Main menu -> Plant type
The "Unit of setpoints" has to be set up before the controller is
scanned on the network� This is required in order for the front
end (AK-SC 355 or AK-SM 850) to present settings/readings in the
correct units (saturated temperature or pressure)�
2. Set network address
Go to Main menu -> System -> Network
3. Set the Modbus address in the range 1-199
- assuring that the selected address is not occupied by another
controller on the network�
4. Make sure that the Baud rate of the controller is set to“384”
(38400 bits per second)
5. Make sure that the serial mode is set“8E1”
When a network scan is carried out the controller will be identied
as:
• "AK-PC 551 - xxxx (MC250000)" - if the control setup unit is
saturated temperature�
• "AK-PC 551 - xxxx (MC250001)" - if the control setup unit is
pressure�
You can check the scanned controller in the front end in the menu
entry:
Conguration -> Network Nodes -> Scan Status
Network
Modbus address and
Baudrate
Scanned controllers shown in the front end
The AK-SM 850/AK-SC 355 must have software version G03�090 or
higher in order to support AK-PC 551� The software version can be
found in menu entry:
Info -> Information -> SW version
Unit of setpoints

AK-PC 551 Technical brochure RC8CF102 © Danfoss 08-2014 19
Example: Quick conguration
Press ENTER to select
the quick settings
Quick Start menu
The Quick setup can
(after rst time setup) be
accessed from the main
menu.
1. Select quick setting
Go to Main menu -> Quick setup or select Quick settings at start
up�
In this example is used the preconguration number 17:
3CDA + 2CB+FS
2. Set language
Go to Main menu -> System -> Display
Quick setting
No plant type selected
Language
Unit of setpoints
Plant type selected
Quick conguration
As an alternative to the wizard, the controller can be set up by
selecting one of the precongurations dened in the controller�
Please refer to the application table (on page 18) for a full
description of all selectable precongurations and the associated
input and output wiring�
A quick conguration is done in ve steps:
1� Select a quick setting
2� Set language
3� Set unit of setpoints
4� Set refrigerant type
5� Set main switch on
3. Set unit of setpoints
Go to Main menu -> Plant type
After pressing ENTER the selection
goes back to "None" and the selected
preconguration is loaded into the
controller.
Default is "English"
Default is "Sat. Temp."

20 Technical brochure RC8CF102 © Danfoss 08-2014 AK-PC 551
Application table
The application table shows the selectable precongurations
number, type of compressors and condensor fans� For more
details see the quick conguration table�
Example: Quick conguration
5. Set main switch ON
Go to Main menu -> Start/Stop -> Main switch
Main switch on
Start/Stop menu
4. Set refrigerant type
Go to Main menu -> Plant type
Refrigerant menu
Refrigerant type R404A
By default the Quick conguration will assign AKS32R type
pressure transmitters for the suction and condensing pressure
with -1 to 12 bar and -1 to 34 bar pressure ranges�
It is recommended to check the IO (input / output) conguration
before starting the controller�
Default is "None"
App. no. Display views Suction group A Suction group B Condenser
Speed Digital
(Scroll / steam)
1-step 1-step Step Speed
17 3CDA + 2CB + FS 1 2 2 x
16 2CDA + 2CB + 3F 1 1 2 3
15 3CSA + 2CB + FS 1 2 2 x
14 2CSA + 2CB + 3F 1 1 2 3
13 4CA + 3CB + FS 4 3 x
12 3CA + 2CB + FS 3 2 x
11 2CA + 2CB + 3F 2 2 3
10 4CDA + FS 1 3 x
9 3CDA + FS 1 2 x
8 3CDA + 3F 1 2 3
7 2CDA + 2F 1 1 2
6 4CSA + FS 1 3 x
5 4CA + FS 4 x
4 4CA + 4F 4 4
3 3CSA + FS 1 2 x
2 3CA + FS 3 x
1 3CA + 3 F 3 3
0 None After selection the setting returns to "None"