Danfoss AK-CC 525A User guide
User Guide
Controller for appliance control
AK-CC 525A
ADAP-KOOL® Refrigeration control systems
Introduction
Application
Complete refrigeration appliance control.
Advantages
• Energy optimisation of the whole refrigeration appliance
• Quick set-up with predefined 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 flow before the
evaporator (S3) or after the evaporator (S4) respectively. A setting
for thermostat, alarm thermostat and display reading determines
the influence the two sensor values should have for each individual function.
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.
Functions
• Day/night thermostat with ON/OFF or modulating principle
• Switch between thermostat settings via digital input
• Adaptive control of superheat
• Start of defrost via schedule, digital input or network
• Natural or electric defrost
• Stop of defrost on time and/or temperature
• Coordination of defrosting among several controls
• Pulsing of fans when thermostat is satisfied
• Door function
• Light control
• Factory calibration that will guarantee a better measuring accuracy than stated in the standard EN 13485 without subsequent
calibration (Pt 1000 ohm sensor)
• Integrated MODBUS communication with the option of mounting a LonWorks communication card.
Appliance examples
Application
The controller can be set so that relay DO3 is used for one of the
following functions:
• Cooling
Here the relay is active when cooling is necessary.
• Rail heat
Here the relay controls the effect to the rail heat.
DO3
Contents
Introduction ....................................................................................................... 2
Regulating functions ....................................................................................... 3
Survey of functions .......................................................................................... 9
Operation .......................................................................................................... 19
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Menu survey .....................................................................................................20
Connections ..................................................................................................... 24
Data ..................................................................................................................... 26
Ordering ............................................................................................................27
Regulating functions
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:
• Pressure sensor Po 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 significant pressure difference
between the evaporators in question.
Temperature control
The temperature in the appliance is registered by one or two
temperature sensors which are located in the air flow 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 influence 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 differential, 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 influence 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 alarm. This time delay is active after defrosting
and start-up.
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Thermostat displacement
Thermostat displacement can be used beneficially for appliances
where different product types are stored which require different
temperature conditions. It is possible to change between two different thermostat settings via a contact signal on a digital input.
During a thermostat displacement, the alarm limits will be displaced accordingly.
Night setback of thermostat value
In refrigeration appliances there may be big load differences
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 effect 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.
• Alarm limits are not displaced during night operation.
Appliance shut-down
The function closes the AKV valve and all outputs are switched off.
The cooling appliance is stopped like the “Main switch”, but this
happens without an “A45 standby alarm”.
The function can be enabled by a switch on the DI input or via a
setting through data communication.
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
Gas: Simple hotgas defrost where compressor is running
during defrost.
Defrost sequence
1) Pump down
2) Defrost
3) Waiting position after defrost (coordinated defrost only)
4) Drip off
5) Delay of fan
Start of defrost
A defrost can be started in different ways
Interval: Defrost is started at fixed 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 fixed refrigeration time
intervals, in other words, a low need for refrigeration will
”postpone” the defrost
Schedule: Here defrost can be started at fixed 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
Manual: An extra defrost can be activated from the display lower-
most button or via parameter setting
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.
Defrost on demand
1 Based on refrigeration time
When the aggregate refrigeration time has passed a fixed time,
a defrost will be started.
Max. 10
System manager
Melting function
This function will stop the air flow 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
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 flow and hence the evaporator’s capacity will be
greatly improved.
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.
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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 period (appliance with night lid)
(The function is not actual when r14=2, i.e. modulating
regulation).
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.
Period time
The light function can be defined 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 off when "r12" (Main switch) is set to off (see
o98).
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 displacement
- General alarm monitoring
- Case shut down
- Coordinated defrost (DI2 only)
- Forced closing of valve (DI 3 only)
Function Input/Settings menu Setting
DI1 DI2 DI3
o02 o37 o84
Not used + + + 0
Follows DI’s status + + + 1
Door contact function + + + 2
Door alarm + + + 3
Start defrost + + + 4
Main switch + + + 5
Nighttime operation + + + 6
Thermostat displacement + + + 7
DI alarm when closed + + 8
DI alarm when open + + 9
Coordinated defrost + 13
Forced close + 14
Case shutdown + + + 15
Example
If DI1 is used to start a defrost cycle, o02 must be set to 4.
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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. Otherwise, the
defrost cycle is stopped immediately once the signal is received.
The function is defined in o90. The signal can be received from the
DI3-input or via the data communication.
During a forced closing the fans can be defined to be stopped or
in operation.
Door contact
The door contact function can via the digital inputs be defined for
two different 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.
Railheat (o61=2)
It is possible to pulse-control the power to the rail heat in order
to save energy. Pulse control can be controlled according to day/
night load.
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.
During defrosting
During defrosting rail heat will be active, as selected in setting
d27.
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Data communication
The controller has fixed built-in MODBUS data communication.
If there is a requirement for a different 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 AKA
245 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
m, the connection must take another form.
An extra module must also be mounted in the controller if data
! Address
o03 > 0
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 fixed 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 525A
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.
P0 optimization P0 Optimization The controller supports P0 optimization
Case shutdown Day/night control / Time schedule --- Case shutdown
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Survey of functions
Function Para-
meter
Normal display
Normally the temperature value from one of the two thermostat sensors S3 or S4 or a
mixture of the two measurements is displayed.
In o17 the ratio is determined.
Thermostat r- - Thermostat control
Set point
Regulation is based on the set value plus a displacement, if applicable. The value is set
via a push on the centre button.
The set value can be locked or limited to a range with the settings in r02 and r 03.
The reference at any time can be seen in "u91 Cutout temp".
Differential
When the temperature is higher than the reference + the set differential, the compressor relay will be cut in. It will cut out again when the temperature comes down to
the set reference.
Ref. Dif.
Setpoint limitation
The controller’s setting range for the setpoint may be narrowed down, so that much
too high or much too low values are not set accidentally - with resulting damages.
To avoid a too high setting of the setpoint, the max. allowable reference value may be
lowered.
To avoid a too low setting of the setpoint, the min. allowable reference value may be
increased.
Correction of the display’s temperature
If the temperature at the products and the temperature received by the controller are
not identical, an offset adjustment of the display temperature can be carried out.
Temperature unit
Set here if the controller is to show temperature values in °C or in °F.
Correction of signal from S4
Compensation possibility due to long sensor cable
Correction of signal from S3
Compensation possibility due to long sensor cable
Start / stop of refrigeration
With this setting refrigeration can be started, stopped or a manual override of the
outputs can be allowed. (For manual control the value is set at -1. Then the AKV outlet
and the relay outlets can be force-controlled by the respective reading parameters
(u23, u58, etc.). Here the read value can be overwritten.)
Start / stop of refrigeration can also be accomplished with the external switch function connected to a DI input.
Stopped refrigeration will give a ”Standby alarm”.
Night setback value
The thermostat’s reference will be the setpoint plus this value when the controller
changes over to night operation. (Select a negative value if there is to be cold accumulation.)
Thermostat function
Here it is defined how the thermostat is to operate. Either as an ordinary ON/OFF thermostat or as a modulating thermostat.
1: ON/OFF thermostat
2: Modulating
Parameter by operation via data
communication
Display air (u56)
r00 Cutout °C
r01 Differential
r02 Max cutout °C
r03 Min cutout °C
r04 Disp. Adj. K
r05 Temp. unit
°C=0. / °F=1
(Only °C on AKM, whatever the setting)
r09 Adjust S4
r10 Adjust S3
r12 Main Switch
1: Start
0: Stop
-1: Manual control of outputs allowed
r13 Night offset
r14 Therm. mode
When operation is ”modulating” the AKV valve will limit the flow of refrigerant so that
the temperature variation will be less than for the ON/OFF thermostat.
The differential (r01) must not be set lower than 2K for "modulating".
In a decentralised plant you must select the ON/OFF thermostat setting.
Selection of thermostat sensor
Here you define the sensor the thermostat is to use for its control function. S3, S4, or a
combination of them. With the setting 0%, only S3 is used (Sin). With 100%, only S4.
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r15 Ther. S4 %
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