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

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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�

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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

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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�