Danfoss AK-CC 550 User guide

User Guide

Controller for appliance control

AK-CC 550

ADAP-KOOL® Refrigeration control systems

Contents

Introduction ....................................................................................................... 2

Operation ............................................................................................................ 4

Applications .....................................................................................................12

Survey of functions ........................................................................................ 15

Introduction

Application

Complete refrigeration appliance control with great exibility to
adapt to all types of refrigeration appliances and cold storage
rooms.

Advantages

• Energy optimisation of the whole refrigeration appliance

• One controller for several dierent refrigeration appliances

• Integrated display at the front of the controller

• Quick set-up with predened settings

• Built-in data communication

• Built-in clock function with power reserve

Principle

The temperature in the appliance is registered by one or two
temperature sensors which are located in the air ow before the
evaporator (S3) or after the evaporator (S4) respectively. A setting
for thermostat, alarm thermostat and display reading determines
the inuence the two sensor values should have for each indi­vidual function.
In addition product sensor S6, which can be optionally placed in
the appliance, can be used to register the temperature near the
required product in a certain place within the appliance.
The temperature of the evaporator is registered with the S5 sensor
which can be used as a defrosting sensor.
In addition to the outlet to the electronic injection valve of the
type AKV, the controller has 5 relay outputs which are dened by
the use selected – the individual usage options are described in
detail on page 12.

Operation .......................................................................................................... 26

Menu survey .....................................................................................................28

Connections ..................................................................................................... 32

Data ..................................................................................................................... 34

Ordering ............................................................................................................35

Functions

• Day/night thermostat with ON/OFF or modulating principle

• Product sensor S6 with separate alarm limits

• Switch between thermostat settings via digital input

• Adaptive control of superheat

• Adaptive defrosting based on evaporator performance

• Start of defrost via schedule, digital input or network

• Natural, electric or hot gas defrost

• Stop of defrost on time and/or temperature

• Coordination of defrosting among several controls

• Pulsing of fans when thermostat is satised

• Case cleaning function for documentation of HACCP procedure

• Rail heat control via day/night load or dew point

• Door function

• Control of two compressors

• Control of night blinds

• Light control

• Heat thermostat

• Factory calibration that will guarantee a better measuring accu-

racy than stated in the standard EN 441-13 without subsequent
calibration (Pt 1000 ohm sensor)

• Integrated MODBUS communication with the option of mount­ing a LonWorks or DANBUSS communication card

2 Manual RS8EN702 © Danfoss 2016-03 AK-CC 550

Appliance examples

Applications

Here is an overview of the controller’s usage options.
A setting will congure input and outputs so that the controller’s
operation interface is directed at the selected application.
The current settings for the respective uses can be found on page

28.

Application 1-8

These uses are applied to standard appliances or cold storage
rooms with one valve, one evaporator and one refrigeration sec­tion.
The sensors are used according to standard principles.
The output functions change depending on the selected applica­tion.

Application 9

This use is for refrigeration appliances with one valve, two evapo­rators and two refrigeration sections.
Here the temperature and alarm monitoring are always controlled
using the S4 sensor.
The S3 sensor is used for display readings.
The product sensor is replaced by an extra defrosting sensor S5B
for the second evaporator.

Application 10

This use is for refrigeration appliances with one valve, one evapo­rator and two refrigeration sections.
Here temperature is always controlled using the S4 temperature.
The S6 sensor is placed in the S3B position. The S3B sensor uses
alarm limits, etc which are normally used for the S6 sensor.
The two S3 temperatures are used for alarm monitoring and
display readings for each refrigeration section. There are separate
alarm limits for each refrigeration section.

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Operation

Liquid injection

Liquid injection in the evaporator is controlled by an electronic
injection valve of the type AKV. The valve functions as both expan­sion valve and solenoid valve. The valve opens and closes using
signals from the controller.
The function contains an adaptive algorithm which independently
adjusts the valve’s opening so that the evaporator constantly sup­plies optimum refrigeration.

Superheat can be measured via one of the two following princi­ples:

• Pressure sensor P0 and temperature sensor S2
For this use a correct measurement of superheat is achieved
under all conditions which ensures a very robust and precise
control.
The signal from one pressure transmitter can be used by several
controllers, but only if there is no signicant pressure dierence
between the evaporators in question.

• Two temperature sensors S1 and S2
Use of the S1 sensor means that location is particularly impor­tant. The sensor must be located so as to read the evaporating
temperature during injection without the presence of too much
pressure drop. Danfoss recommends that the S1 sensor be
located on the rst pipe bend on the evaporator.

Placement of the S1 sensor is crucial for a safety signal
and with this a satisfactory control.

Temperature control

The temperature in the appliance is registered by one or two
temperature sensors which are located in the air ow before the
evaporator (S3) or after the evaporator (S4) respectively. A setting
for the thermostat, alarm thermostat and display reading deter­mines how much the two sensor values should inuence each
individual function, e.g. 50% will produce an equal value from
both sensors.

The actual temperature control can take place in two ways: as an
ordinary ON/OFF regulation with a dierential, or as a modulat­ing control there the temperature variation will not be nearly as
great as in ON/OFF control. There is however a limit to the use of
a modulating control as it can only be used in central plant. In a
decentralised plant the thermostat function with ON/OFF control
should be selected.
In a central plant the thermostat function may either be selected
for ON/OFF control or modulating control.

Temperature monitoring

Just as is possible for the thermostat, the alarm monitoring can be
set with a weighting between S3 and S4 so that you can decide
how much the two sensor values should inuence the alarm
monitoring. Minimum and maximum limits can be set for alarm
temperature and time delays. A longer time delay can be set for
high temperature alarms. This time delay is applicable during
defrosting, appliance cleaning and start-up.

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Thermostat bands

Thermostat bands can be used benecially for appliances where
dierent product types are stored which require dierent tem­perature conditions. It is possible to change between the two
dierent thermostat bands via a contact signal on a digital input.
Separate thermostat and alarm limits can be set for each thermo­stat band – also for the product sensor.

Night setback of thermostat value

In refrigeration appliances there may be big load dierences
between the shop’s opening and closing hours, especially if night
lids/blinds are used. The thermostat reference may be raised here
without it having any eect on the product temperature.
Change-over between day and night operation can take place, as
follows:

• via an external switch signal.

• via a signal from the data communication system.

Product sensor

A separate optional product sensor S6, which may be placed
in the appliance, can also be used and which can register and
monitor the temperature in the warmest part of the appliance.
There are separate alarm limits and time delays for the product
sensor.

Appliance cleaning

This function makes it easy for the shop’s sta to carry out a
cleaning of the appliance according to a standard procedure.
Appliance cleaning is activated via a signal – as a rule via a key
switch placed on the appliance.
Appliance cleaning is carried out via three phases:
1 - at the rst activation the refrigeration is stopped, but the fans

keep on operating in order to defrost the evaporators. ”Fan” is
shown on the display.

2 - at the second activation the fans are also stopped and the

appliance can now be cleaned. ”OFF” is shown on the display.

3 - At the third activation refrigeration is recommenced. The

display will show the actual appliance temperature, (o97
setting).

When appliance cleaning is activated a cleaning alarm is trans­mitted to the normal alarm recipient. A later processing of these
alarms will document that the appliance has been cleaned as
often as planned.

Alarm monitoring
There are no temperature alarms during appliance cleaning.

- + + °C

1 ÷ + Fan

2 ÷ ÷ O

3 + + °C

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Defrost

Depending on the application you may choose between the fol­lowing defrost methods:
Natural: Here the fans are kept operating during the defrost
Electric: The heating element is activated
Hotgas: Here the solenoid valves are controlled so that the
hotgas can ow through the evaporator

Defrost sequence

1) Pump down

2) Defrost

3) Waiting position after defrost

4) Draining (drain delay. Hotgas only)

5) Drip o

6) Delay of fan

Hot gas defrost (application 6 only)

This type of connection can be used on systems with hotgas
defrost, but only in small systems in, say, supermarkets – the
functional content has not been adapted to systems with large
charges
Relay 2 is used for suction valve
Relay 4’s change-over function can be used by the bypass valve
and/or the hotgas valve.
Must not be used together with PMLX and GPLX valves, unless a
time delay relay is installed, which ensures that the PMLX/GPLX
valve is closed completely before the hotgas is turned on.

Hot gas application

Drip tray heating element

It is possible to control a heating element in the drip tray for
hot gas defrosting. When defrosting is commenced, the heating
element is activated. The heating element remains activated until
a set time after defrosting has ended by time or temperature.

Start of defrost

A defrost can be started in dierent ways
Interval: Defrost is started at xed time intervals, say, every

eighth hour. An interval must ALWAYS be set to
a "higher" value than the period set between two
defrostings when a schedule or network signal is used.

Refrigeration time: Defrost is started at xed refrigeration time

intervals, in other words, a low need for refrigeration will
”postpone” the defrost

Schedule: Here defrost can be started at xed times of the

day and night. However, max. 6 times
Contact: Defrost is started with a contact signal on a digital input
Network: The signal for defrost is received from a system unit
via the data communication
Adaptive defrost: Here defrosting is started based on intelligent

registering of evaporator performance.
Manual: An extra defrost can be activated from the controller’s

lower-most button
All the mentioned methods can be used at random – if just of
them is activated a defrost will be started.

Stop of defrost

Defrosting can be stopped by either:

• Time

• Temperature (with time as safety).

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Coordinated defrost

There are two ways in which coordinated defrost can be arranged.
Either with wire connections between the controllers or via data
communication

Wire connections
The digital input DI2 is connected between the current controllers.
When one controller starts a defrost all the other controllers will
follow suit and likewise start a defrost. After the defrost the indi­vidual controllers will move into waiting position. When all are in
waiting position there will be a change-over to refrigeration.

Coordination via data communication
Here the system unit handles the coordination.
The controllers are gathered in defrosting groups and the system
unit ensures that defrosting is started in the group according to a
weekly schedule.
When a controller has completed defrosting, it sends a message
to the system unit and then goes into a waiting position. When
every controller in the group is in a waiting position, refrigeration
is again permitted in all the individual controllers.

Max. 10

System manager

Defrost on demand

1 Based on refrigeration time

When the aggregate refrigeration time has passed a xed time,
a defrost will be started.

2 Adaptive defrosting based on monitoring of evaporator per-

formance

This function is based on a registration of the air ow through

the evaporator. By using the AKV valve as mass owmeter for the

refrigerant ow it is possible to compare the energy input on the

refrigerant side with the energy output on the air side. Via this

comparison the air ow through the evaporator can be deter-

mined and hence also the amount of ice/frost build-up on the

evaporator surface. If the ice/frost build-up reduces the capac-

ity of the evaporator the function will carry out an additional

defrost.

Enter in the weekly defrost schedule the number of defrosts
corresponding to the basic load. If the load of the evaporator is
increased beyond this, defrost on demand will add the required
additional defrosts.
The function requires the following connections:

- Expansion valve type AKV

- Temperature signal from both S3 and S4

- Temperature signal from the condensing pressure Tc which is to
be distributed via the network from the system manager. If the
controller can not load the Tc signal, the measurement is repla­ced by a constant.

NOTE. The S3 and S4 sensors must be placed in the air ow/chan­nel immediately before/after the evaporator.
Min. time between defrosts

There is a 2 hours minimum time between defrosts.
This avoids that planned defrosts in accordance with the weekly
schedule are carried out immediately after a defrost on demand
has been carried out. The time applies from when a defrost on
demand has been completed to when a planned defrost is again
permitted. The defrost on demand will not start defrosting with a
shorter interval than the 2 hours either.

Reset
If the adaptive defrost function registers problems with the
defrost, it will show an error message and the function will no
longer carry out extra defrosts. In this event a manual reset of the
function via d22 should be carried out.
When the reset function is activated it will start a defrost so that
the subsequent tuning will take place on an evaporator with no
ice/frost build-up.

Note
The function "Adaptive defrost” should only be activated when the
evaporator runs under normal operational conditions.

Melting function

This function will stop the air ow in the evaporator from being re­duced by frost created by uninterrupted operation for a long time.
The function is activated if the thermostat temperature has
remained in the range between -5°C and +10°C for a longer

Real-time clock

The controller has a built-in real-time clock which can be used to
start defrosts. This clock has a power reserve of four hours.
If the controller is equipped with data communication, the clock

will automatically be updated from the system unit.
period than the set melting interval. The refrigeration will then be
stopped during the set melting period. The frost will be melted
so that the air ow and hence the evaporator’s capacity will be
greatly improved.

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Control of two compressors

The two compressors must be of the same size. When the control­ler demands refrigeration it will rst cut in the compressor with
the shortest operating time. After the time delay the second
compressor will be cut in.

When the temperature has dropped to ”the middle of the dieren­tial”, the compressor with the longest operation time will be cut
out.
The running compressor will continue until the temperature has
reached the cutout value. Then it will cut out. When the tempera­ture again reaches the middle of the dierential, a compressor will
again be started.
If one compressor cannot maintain the temperature within the
dierential, the second compressor will also be started.
If one of the compressors has run on its own for two hours, the
compressors will be changed over so that operational time is bal­anced.

The two compressors must be of a type that can start up against a
high pressure.
The compressors’s settings for ”Min On time” and ”Min O time”
will always have top priority during normal regulation. But if one
of the override functions is activated, the ”Min On time” will be
disregarded.

Railheat

It is possible to pulse-control the power to the rail heat in order to
save energy. Pulse control can either be controlled according to
day/night load or dew point.

Pulse control according to day and night

Various ON periods can be set for day and night operation.
A period time is set as well as the percentage part of the period in
which the rail heat is ON.

Pulse control according to dew point

In order to use this function a system manager of the type AK-SM
is required which can measure dew point and distribute the cur­rent dew point to the appliance controllers. For this the rail heat’s
ON period is controlled from the current dew point.
Two dew point values are set in the appliance control:

• One where the eect must be max. i.e.100%. (o87)

• One where the eect must be min. (o86).
At a dew point which is equal to or lower than the value in 086,
the eect will be the value indicated in o88.
In the area between the two dew point values the controller will
manage the power to be supplied to the rail heat.

During defrosting

During defrosting the rail heat will always be 100% ON.

Rail heat

Dew point

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Fan

Pulse control

To obtain energy savings it is possible to pulse control the power
supply to the fans at the evaporators.
Pulse control can be accomplished in one of the following ways:

- during the thermostat’s cutout period (cold room)

- during night operation and during the thermostat’s cutout pe-

riod (appliance with night lid)

(This function is not present when r14 = 2, i.e. modulating regula-

tion.)

A period of time is set as well as the percentage of this period of
time where the fans have to be operating.

Cutout of fans during plant breakdowns

If the refrigeration in a breakdown situation stops, the
temperature in the cold room may rise quickly as a result of the
power supply from large fans. In order to prevent this situation the
controller can stop the fans if the temperature at S5 exceeds a set
limit value.

Light function

The function can be used for controlling the light in a refrigeration
appliance or in a cold room. It can also be used for controlling a
motorised night blind.

The light function can be dened in three ways:

- the light is controlled via a signal from a door contact. Together

with this function a time delay can be set so that the light is kept
on for a period of time after the door has been closed.

- the light is controlled via the day/night function

- the light is controlled via the data communication from a system

unit.
Here there are two operational options if data communication
should fail:

- The light can go ON

- The light can stay in its current mode.

The light load must be connected to the NC switch on the relay.
This ensures that the light remains on in the appliance if power to
the controller should fail.
The light is switched o when "r12" (Main switch) is set to o (see
o98).
The light is switched o when the appliance cleaning function is
activated.

Night blind

Motorised night blind can be controlled automatically from the
controller. The night blinds will follow the status of the light
function. When the light is switched on, the night blinds opens
and when the light is switched o, the night blinds close again.
When the night blinds are closed, it is possible to open them using
a switch signal on the digital input. If this input is activated, the
night blinds will open and the refrigeration appliance can be lled
with new products. If the input is activated again, the blinds close
again.
When the night blind function is used, the thermostat function
can control with dierent weighting between the S3 and S4
sensors. A weighting during day operation and another when the
blind is closed.
A night blind is open when the appliance cleaning function is
activated.
A setting can dene that the night blind is open when "r12" (Main
switch) is set to o (see o98).

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Digital inputs

There are two digital inputs DI1 and DI2 with contact function and
one digital input DI3 with high voltage signal.
They can be used for the following functions:

- Retransmission of contacts position via data communication

- Door contact function with alarm

- Starting a defrost

- Main switch - start/stop of cooling

- Night setback

- Thermostat bands switch

- General alarm monitoring

- Case cleaning

- Forced cooling

- Override of night blinds

- Coordinated defrost (DI2 only)

- Forced closing of valve (DI 3 only)

Forced closing

The AKV valves can be closed with an external signal ( "Forced
closing").
The function must be used in connection with the compressor’s
safety circuit, so that there will be no injection of liquid into the
evaporator when the compressor is stopped by the safety con­trols. (However not at low pressure – LP).
If a defrost cycle is in progress, the forced closing status will not be
re-established until the defrost is completed.
The signal can be received from the DI3-input or via the data com­munication.
During a forced closing the fans can be dened to be stopped or
in operation.

Door contact

The door contact function can via the digital inputs be dened for
two dierent applications:

Alarm monitoring

The controller monitors the door contact and delivers an alarm
message if the door has been opened for a longer period than
the set alarm delay.

Alarm monitoring and stop of refrigeration

When the door is opened the refrigeration is stopped, i.e. the
injection, the compressor and the fan are stopped and light
switch on.
If the door remains open for a longer time than the set restart
time, refrigeration will be resumed. This will ensure that
refrigeration is maintained even if the door is left open or if the
door contact should be defective. If the door remains open for
a longer period than the set alarm delay an alarm will also be
triggered.

Heating function

The heating function is used to prevent the temperature
becoming too low, e.g. in a cutting room, etc. The limit for when
the heating function cuts o is set as an oset value under the
current cutout limit for the refrigeration thermostat. This ensures
that refrigeration and heating do not occur simultaneously.
The dierence for the heating thermostat has the same value
as for the refrigeration thermostat. To prevent that the heating
thermostat cuts in during short-term drops in air temperature a
time delay can be set for when to change from refrigeration to
heating.

Refrigeration

Neutral zone

Heat

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Data communication

The controller has xed built-in MODBUS data communication.

If there is a requirement for a dierent form of data
communication, a Lon RS 485 or DANBUSS module can be
inserted in the controller.
The connection must then be to terminal RS 485.

(To use a Lon RS 485 module and gateway type AKA 245 the
module must be Version 6.20 or higher.)

Display

The controller has one plug for a display. Here display type EKA
163B or EKA 164B (max. length 15m) can be connected.
EKA 163B is a display for readings.
EKA 164B is both for readings and operation.
The connection between display and controller may be with a
cable which has a plug at both ends.

If the distance between display and controller is greater than 15

Address o03 > 0

m, the connection must take another form.
An extra module must also be mounted in the controller if data
communication is used.
The built-in MODBUS data communication is used so that the
display connection and the data communication to the other
controllers must take place via a module. The module can be:
Lon RS 485, DANBUSS or MODBUS.
When a display is to be connected to the built-in MODBUS, the
display can advantageously be changed to one of the same type,
but with Index A (version with screw terminals).
The controllers address must be set higher than 0 in order for the
display to be able to communicate with the controller.
If connection of two displays is required, one must be connected
to the plug (max. 15 m) and the other must then be connected to
the xed data communication.

Important

All connections to the data communication MODBUS, DANBUSS
and RS 485 must comply with the requirements for data
communication cables. See literature: RC8AC.

Override

The controller contains a number of functions which can be used together with the override function in the master gateway/system
manager.

Function via data communication Function in gateway/system manager Used parameters in AK-CC 550

Start of defrosting Defrost control / Time schedule / Defrost group --- Def start

Coordinated defrost Defrost control / Defrost group --- HoldAfterDef / - - - DefrostState

Prevent defrost start --- Disable Def

Day/Night schedule Day/Night control / Time schedule / Light zone --- Night setback

Light control Day/Night control / Time schedule O39 light Remote

Forced closing Forced Close / Injection ON / AKC ON --- Forced cl.

Forced cooling --- Forced cool

Railheat link to dew point / Enhanced railheat --- Dew point

P0 optimization P0 Optimization The controller supports P0 optimization

Adaptive defrost / Adaptive defrost. System manager only - - - Tc TempMean

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