Danfoss Controller type AKC 24W2 for control of water chillers Installation guide
- Type
- Installation guide
RC.1J.60.02 09-1995
Controller for control of water chillers
AKC 24W2
ADAP-KOOL
®
Functional description
2 Functional description RC.1J.60.02 © Danfoss 09/95 AKC 24W2
Contents Introduction ............................................................................................................... 3
System information................................................................................................... 4
Operation ................................................................................................................... 4
Application ................................................................................................................ 5
Function switch......................................................................................................... 5
Refrigerant ................................................................................................................. 5
Capacity regulation ................................................................................................... 6
Regulation ......................................................................................................... 6
Neutral zone and zone bands ........................................................................... 7
Media temperature sensor ................................................................................ 7
Frost protection ................................................................................................. 7
Compressor groups ........................................................................................... 8
Cut-in and cut-out of capacity steps and compressors ..................................... 8
Signal from safety controls .............................................................................. 10
Hourmeter ....................................................................................................... 10
External displacement of reference temperature............................................. 11
Expansion valve function....................................................................................... 12
Selection of function ........................................................................................ 12
Forced closing ................................................................................................. 12
Pressure transmitter/temperature sensor ........................................................ 12
Superheat ........................................................................................................ 13
MOP control .................................................................................................... 13
Separate pressure transmitter ......................................................................... 13
Service ..................................................................................................................... 14
Measurements ................................................................................................ 14
Forced operation ............................................................................................. 14
Alarms and messages ............................................................................................ 15
Clock function ......................................................................................................... 18
Plant measurements/data ....................................................................................... 19
Capacity regulation.......................................................................................... 19
Expansion valve .............................................................................................. 19
Controller data ................................................................................................. 19
Continuous updating ....................................................................................... 19
List of literature ....................................................................................................... 20
This function description produced in May 1994 and applies to AKC 24W2 units with
software version 1.0x.
Valitidy
Installation
considerations
Accidental damage, poor installation, or site conditions, can give rise to malfunctions
of the control system, and ultimately lead to a plant breakdown.
Every possible safeguard is incorporated into our products to prevent this. However,
a wrong installation, for example, could still present problems. Electronic control is no
substitute for normal, good engineering practice.
Danfoss will not be responsible for any goods, or plant components, damaged as a
result of the above defects. It is the installer's responsibility to check the installation
thoroughly, and to fit the necessary safety devices.
Particular attention is drawn to the need for a “force closing” signal to controllers in
the event of compressor stoppage, and to the requirement for suction line accumula-
tors.
Your local Danfoss agent will be pleased to assist with further advice, etc.
AKC 24W2 Functional description RC.1J.60.02 © Danfoss 09/95 3
Introduction AKC 24W2 is a complete control unit for water chillers or heat pumps. The unit
contains:
• Capacity regulator controlling the compressor’s capacity by media temperature.
• Adaptive refrigerant control with one or two expansion valves. The refrigerant
charge is in this way optimally adapted to the load.
• Frost protection thermostat.
• Monitoring and alarm functions.
• DANBUSS
®
data communication.
• Operation via control panel type AKA 21 and/or PC.
Capacity regulation
The controller’s main function is the electronic step regulator, which based on the
media temperature adjusts the compressor’s capacity, so that it is always adapted to
the actual load.
The step regulator calculates the required capacity on the basis of the actual media
temperature and whether it is falling or rising, to minimize in this way the number of
step changes. In addition to the step regulator function itself, there is a built-in frost
protection thermostat and monitoring of sensor errors.
Evaporator control
Built into the controller are two units that adaptively regulate the supply of refrigerant
to a shell and tube evaporator.
The controller can operate one or two electronic expansion valves type AKV, so that
optimum charging of the evaporator is ensured at all times.
The superheat is controlled by means of one temperature sensor (S2) and one
pressure transmitter for each evaporator.
4 Functional description RC.1J.60.02 © Danfoss 09/95 AKC 24W2
Controller type AKC 24W2 is a unit in the ADAP-KOOL
®
refrigeration control system.
The controller can be linked up with other controllers in the system via a two-core
connection - the DANBUSS
®
Data Communication. Through this connection
information can be transmitted between the units, like settings, measurements,
alarms etc.
Remote service
The different messages and alarms can, via the telephone network, be transmitted by
modems to, say, a service company.
Address coding
An address code must be set by means of a number of switches on the controller’s
front plate. There are seven switches for the coding. How coding is performed is
explained in the installation instructions for the data communication cable (literature
No. RC.0X.A).
Connection of control panel type AKA 21
If control panel type AKA 21 is to be used, a terminal box will have to be installed. (cf.
the installation instructions for the data communication cable, literature No.
RC.0X.A).)
Data communication
To obtain correct data communication it is important that the installation instructions
for the data communication cable be adhered to (literature No. RC.0X.A).
The controller can be operated in two different ways. Either by using control panel
type AKA 21 or by means of a PC with system software type AKM.
AKA 21 operation
Setting of the different functions is performed via a menu system. The menu system
is built up on several levels where you change around between the different menus
by means of arrow keys.
The complete list of menus is contained in the document “Menu operation via AKA
21”. (Cf. list of literature).
PC operation
Operation takes place from a PC where Microsoft-Windows and System Software
type AKM have been installed. (The PC is connected to the system via Gateway type
AKA 24).
Setting of the different functions is performed by means of rolling menus and dialogue
boxes. Settings can either be made via the keyboard or by using a mouse.
For users of AKM system software the complete list of menus is found in the
document “Menu operation via AKM”. (Cf. list of literature).
System information
Operation
AKC 24W2 Functional description RC.1J.60.02 © Danfoss 09/95 5
Application The controller may be used for the control of either heat pumps or water chillers. The
control function is in principle the same for the two types of regulation. The only
differences are the step regulator’s function and the location of temperature sensor
S3 that registers the media temperature.
Water chiller control: S3 registers the water chiller’s outlet temperature. Capacity
steps are cut in at rising S3 temperature.
Heat pump control: S3 registers the condenser’s outlet temperature. Capacity
steps are cut in at falling S3 temperature.
Main Function Cooling (1) / Heating (2) Cool / Heat
1 / 2
The function switch is used for stopping and starting the control function.
- Normal control state (Setting = +1)
- Control stopped (Setting = 0)
- Service function (Setting = -1)
Main Function Main Switch Main Switch
-1 / 0 / 1
If the function switch is set at “stopped control” or “service” (0 or -1), all the control-
ler’s functions will be inactive.
External function switch
The control can be started and stopped via an external contact function connected to
input DI3 (terminals H3 and H4).
If the connection is interrupted, all control functions will be stopped.
The registered control parameters are preserved if the controller’s supply voltage is
maintained.
The external function switch is only active, if the internal function switch is in position
+1 (normal control function).
Function switch
Refrigerant Before regulation can be commenced, the refrigerant must be defined. You can
choose between the following refrigerants:
1 R12 8 R23 15 R227
2 R22 9 R500 16 R401A
3 R134a 10 R503 17 AZ50
4 R502 11 R114 18 R402A
5 R717 12 R142b 19 R404A
6 R13 13 User-defined
7 R13b1 14 R32
The refrigerant is selected by keying a figure between 1 and 19. At 0 no refrigerant is
selected.
Warning: Wrong choice of refrigerant may cause damage to the compressor.
Main function Rfg. type 1..19 Rfg. type
___
Rfg. Fac. a1
___
Rfg. Fac. a2
___
Rfg. Fac. a3
___
A later change of refrigerant can only be made in the following way:
- Select new type
- Controller indicates error
6 Functional description RC.1J.60.02 © Danfoss 09/95 AKC 24W2
- Interrupt supply voltage to controller
- Wait five seconds
- Connect supply voltage again
- Regulation can now be started
Other refrigerants?
The function has been prepared for the definition of a refrigerant that differs from the
above mentioned types. This definition can be made by keying the figure “13” plus a
number of subsequent parameters. This setting can only be made with assistance
from Danfoss.
Capacity regulation The step regulator in the controller can control up to eight capacity steps that may be
distributed on one or two compressors. (The capacity distribution for compressors is
related to the input signals for the safety controls (DI 1 and DI 2)).
ON/OFF capacity regulation is selected.
Capacity Ctrl. Cap. Settings Cap. Ctrl.
OFF / ON
In position OFF, all outputs to the capacity regulation are OFF.
Regulation
The cut-in compressor capacity is controlled by the actual value of the media tempera-
ture, and whether the temperature is rising or falling.
- In the neutral zone there is no cut-in or cut-out of capacity steps.
- In the +zone and -zone band cut-in and cut-out depend on whether the media tem-
perature is rising or falling. Cut-in/cut-out takes place with the selected time delays.
- In the ++zone and --Zone band cut-in/cut-out takes place with the selected time
delays.
- Refrigeration will be stopped when temperatures are reached that are lower than the
set limit values.
The control function is based on the set value and the temperature measured with the
media sensor.
Capacity Ctrl. Cap. Settings Media
°
C ___
When the media temperature is too high, an alarm message is sent. It is transmitted if
AKC 24W2 Functional description RC.1J.60.02 © Danfoss 09/95 7
the set temperature value is exceeded.
Capacity Ctrl. Cap. Settings Media Al
°
C ___
Neutral zone and zone bands
The neutral zone is set.
The +zone and -zone band is set.
The time delay of the +zone and -zone band is set.
The time delay of the ++zone and --zone band is set.
Capacity Ctrl. Cap. Settings NZ K ___
+zone K ___
-zone K ___
Capacity Ctrl. Adv. Capacity Settings +zone s ___
-zone s ___
+ +zone s ___
- -zone s ___
Media temperature sensor
Measurement of the media temperature can freely take place with one of the following
sensors:
1: S3 Media temperature (temperature sensor, from -100 to 150°C)
2: S4 Media temperature (temperature sensor, from -100 to 150°C)
3: P0 A Suction pressure (pressure transmitter type AKS 32, from -1 to 12 bar,
1-5 V)
4: P0 B Suction pressure (pressure transmitter type AKS 32, from -1 to 12 bar,
1-5 V)
5: P AUX Condensing pressure (pressure transmitter type AKS 32,
from -1 to 34 bar, 1-5 V)
Sensor input and type are selected by keying a figure between 1 and 5.
Capacity Ctrl. Adv. Capacity Settings Media Sens
1...5
Frost protection
The controller has a built-in thermostat function that provides protection against too
low-temperature. A temperature sensor or a pressure sensor is placed where the
temperature has to be monitored. Measuring can be done with one of the following
sensors:
0: Function is not used
1: S3 Media temperature (temperature sensor, from -100 to 150°C)
2: S4 Media temperature (temperature sensor, from -100 to 150°C)
3: P0 A Suction pressure (pressure transmitter type AKS 32, from -1 to 12 bar,
1-5 V)
4: P0 B Suction pressure (pressure transmitter type AKS 32, from -1 to 12 bar,
1-5 V)
5: P AUX Condensing pressure (pressure transmitter type AKS 32,
from -1 to 34 bar, 1-5 V)
6: P0 A og P0 B Lower of the two pressure transmitter values is followed
Sensor input and type are selected by keying a figure between 0 and 6.
Capacity Ctrl. Adv. Capacity Settings Limit Sens
0...6
The temperature value is set (select a value outside of the neutral zone).
Capacity Ctrl. Cap. Settings Limit.
°
C ___
8 Functional description RC.1J.60.02 © Danfoss 09/95 AKC 24W2
The controller will automatically convert a pressure signal to a temperature value. If a
temperature lower than the set one is registered, one compressor step will be cut out
after one second. If the temperature is still too low, the next capacity step will be cut-
out after one second, etc. Renewed cut-in will automatically be commenced when the
temperature again exceeds the set value plus a temperature differential plus the time
delay “Del. ( )” (see later).
The cut-out time of one second and the temperature differential for renewed cut-in can
be changed by using Danfoss’ system software type AKM. The cut-out time can be set
between 1 and 300 seconds, and the temperature differential between 1 and 5 K.
Compressor groups
The controller can operate up to eight compressor steps distributed on one or two
compressors. The compressor steps must be defined in two groups, so that the con-
troller will know which steps belong to compressor A and which to compressor B.
Define first the number of steps for compressor A. After that, the total number of steps
to be regulated by the controller.
The value in “Max. step A” will determine the outputs that belong to compressor A (DO
1 - DO x).
Examples:
gnitteS
tuptuO
A.pmoCB.pmoC
spetseerhthtiwrosserpmocenO
3=Apets.xaM
3=pets.xaM
3,2,1-
spetsowthtiwsrosserpmocowT
2=Apets.xaM
4=pets.xaM
2,14,3
spets4dnaowthtiwsrosserpmocowT
2=Apets.xaM
6=pets.xaM
2,16,5,4,3
Capacity Ctrl. Adv. Capacity Settings Max. step A ___
Max. step ___
Cut-in and cut-out of capacity steps and compressors
Time delays
1. Capacity steps
Please refer to the section “Regulation”.
2. Compressors
To protect the compressor against frequent start-ups, a time delay can be
included. The compressor cannot start again until this time has elapsed.
Capacity Ctrl. Adv. Capacity Settings Del A min. ___
Del B min. ___
Sequence for cut-out of capacity steps
When capacity steps are cut out, the sequence can be selected in one of the
following ways:
1. A linear cut-out is performed. I.e., the cut-in and cutout sequence is not
changed (last cut-in step will be cut-out first when the required capacity again
drops).
2. A re-allocation is made of the steps on the border between compressor A and
compressor B. This function will ensure that compressor B will not stop before
the control unit cuts-out the last step of compressor A.
AKC 24W2 Functional description RC.1J.60.02 © Danfoss 09/95 9
Example:
Setting = 1 Setting = 2
Capacity Ctrl. Adv. Capacity Settings Step mode 1 / 2
Operating time of the compressors
The sequence of the compresssors’ operating time can be defined.
1. Compressor A to start first, then B will be allowed.
2. Compressor B to start first, then A will be allowed.
3. Automatic equalisation of operating time between compressors A and B. At
the different start-ups the compressor with the lowest number of operating
hours will start first. The factory has put in a time differential of 25 hours.
(With Danfoss’ system software type AKM this time differential can be
changed to anywhere between 0 and 100 hours).
The function is selected by keying a number between 1 and 3.
Capacity Ctrl. Adv. Capacity Settings Time share
1 / 2 / 3
More capacity
When the last capacity step had been cut in (“Max. step” setting) and there is still a
need for more capacity, the DO 9 output will be activated. The output may for instance
be used for start-up of a spare water chiller, or, in connection with cascade coupling, of
several controllers. The output must not be used for controlling a ninth compressor
step, as it is not interrupted when safety inputs DI 1 and DI 2 are cut-out.
You may choose between two criteria causing the DO9 output to be activated.
Setting = 1: (Capacity requirements)
- When all valid steps have been cut-in, and more capacity is required
- If there has been a safety cut-out in one or both circuits, and additional capac-
ity is required
Setting = 2: (Thermostat function)
- When the signal from the media sensor exceeds the value set in the menu
10 Functional description RC.1J.60.02 © Danfoss 09/95 AKC 24W2
“DO9 set °C”. (The relay outputs will fall again when the signal has come down
to the set value minus a set differential).
NB! This thermostat function depends on whether the “Cap. Ctrl.” setting
is in position ON or OFF, or whether the “Main Switch” setting is +1 or
0.1 eller 0.
Capacity Ctrl. Adv. Capacity Settings DO9 mode
1 / 2
DO9 set
°
C ___
DO9 diff K ___
Signal from safety controls
The controller has two inputs receiving signals about the status of the safety circuit.
The inputs are connected to an extra set of NC relays in the safety circuit.
(The safety
circuit must stop the compressor without involving AKC 24W2).
If the safety circuit is
cut-out, the controller will cut-out the capacity steps for the compressor concerned (A
or B) and stop its injection function. Regulation will continue with the other compressor.
Input DI 1 is connected to the safety circuit for compressor A.
Input DI 2 is connected to the safety circuit for compressor B.
(Interrupted connection (DI 1, DI 2) will stop the regulation.
K1 and K2 must have gold-plated contacts.
Hourmeter
The compressors’ operating time is registered by a timer. This registration can be used
in two ways:
1. Display of operating time.
The number of operating hours divided by 10 is shown. In other words, a total
operating time of, say, 700 hours will be indicated with the figure 70.
Capacity Ctrl. Cap. Measurements Run A h/10
Run B h/10
2. Service message.
The controller can transmit a message stating when the next service is due.
The function is used, as follows:
Read the timer as described earlier. Add a value to the value read, and enter
the new figure in the controller. When the timer reaches this figure, the “Time
for compr A(B) inspection” message will be sent.
Note that the displayed value must be the number of hours divided by 10.
Example: Display = 70 and service is required in 1000 hours. The display 70
corresponds to 700 hours. Add the 1000 hours, and you obtain 1700 hours.
This value is entered in the menu with the figure 170.
AKC 24W2 Functional description RC.1J.60.02 © Danfoss 09/95 11
Capacity Ctrl. Adv. Capacity Settings Max A h/10 ___
Max B h/10 ___
NB! When operation is based on system software type AKM, the actual
number of hours is shown
The timer’s range is from 0 to 320,000 hours.
External displacement of reference temperature
The reference temperature can be displaced by sending an external voltage signal to
terminal “REF”. The voltage must be either 0 - 10 V or 2 - 10 V.
With this signal the reference can be displaced by up to 50 K in positive or negative
direction. 10 V gives max. displacement.
The change of reference is damped with a time constant of approx. 30 seconds.
The function is set to one of the following values:
0: No displacement.
1: Displacement with 0 - 10 V signal
New reference = set ref. + voltage signal x “Ext.Max K”/10
2: Displacement with 2 - 10 V signal
New reference = set ref. + (voltage signal minus 2) x 1.25 x “Ext.Max K”/10
Capacity Ctrl. Adv. Capacity Settings Ext. Ref.
0 / 1 / 2
Ext. Max K ___
If displacement of the reference temperature is performed with a potentiometer, the
voltage to the potentiometer may be taken from the controller. Below is an example
where the setting must be 2.
12 Functional description RC.1J.60.02 © Danfoss 09/95 AKC 24W2
Expansion valve
function
The controller has two separate injection mechanisms that can regulate the injection
into a shell and tube evaporator.
The adjustment possibilities are the same for the two regulations. Below, () will
indicate that the setting applies to both the A and B regulations.
AKV 10 or AKV 20 valves are used as expansion valve. The required capacity deter-
mines which.
Selection of function
The injection function may be selected ON or OFF.
Injection Ctrl. ( ) Inj. Settings Inj.Ctrl. ( )
OFF / ON
Forced closing
The injection function can be stopped with an external signal. The signal makes the
AKV valve shut off the liquid supply to the evaporator.
The closing can be performed in two ways:
1: Short-circuit of the S2 ( ) sensor.
This signal will not influence the controller’s step regulator.
2: Input signal to DI 1 (DI 2) can be interrupted.
The signal will also cut out all capacity steps belonging to the regulation (A or B).
Pressure transmitter/temperature sensor
Each of the two expansion valve functions is controlled by signals from a temperature
measurement (S2) and a pressure measurement (P0).
If the two evaporators operate with the same evaporating pressure, you need only
use one pressure transmitter.
At the same evaporating pressure with one pressure transmitter the signal is con-
nected to regulator B, as follows:
AKC 24W2 Functional description RC.1J.60.02 © Danfoss 09/95 13
Superheat
AKC 24W controls the expansion valve, so that the evaporator has optimum super-
heat at any time (S2-P0).
The superheat is limited by settings for minimum and maximum superheat. At low
loads an even smaller superheat is allowed (set in the "SH close" menu).
Injection Ctrl. ( ) Adv. Inj. Settings SH close K
___
SH min K: ___
SH max K: ___
AKV max %:
___
Warning! Due to the danger of liquid flow, “SH min.” should not be set lower than 3-
4 K.
At loads under 10%, a drop in the superheat to less than " SH min" value is allowed,
but never to values lower than the one set under "SH close".
If the selected valve has an over-capacity in relation to the evaporator, it is possible
to limit the valve’s opening degree. The “AKV max.” setting is used for this. At setting
“100%” the valve’s opening and closing periods will be adapted to a normal regulating
situation. If the setting is lower, the opening period will be correspondingly reduced
and result in a limitation of the capacity. At the same time the “10%” break point will
be similarly lower.
At setting “AKV max. = 100%”, regulation will take place with the “SH close” value at
loads between 0 and 10%, and with the “SH max” value at 100% load. If setting “AKV
max. = 50%”, for example, regulation will be carried out with the “SH close” value at
loads between 0 and 5%, and with the “SH max” value at full capacity.
MOP control
(MOP = Maximum Operating Pressure)
The MOP function enters into operation when the set MOP temperature is reached.
The valve’s opening degree will subsequently be reduced.
Injection Ctrl. ( ) Inj. Settings MOP
OFF / ON
The MOP temperature is set in °C.
Injection Ctrl. ( ) Inj. Settings MOP
°
C
___
Separate pressure transmitter
It is possible to connect a pressure transmitter which can monitor a required pres-
sure. The signal is not used in the controller, but can be shown on the control panel’s
display or on a connected PC.
The pressure transmitter is connected to input “P aux”.
The pressure transmitter must be of type AKS 32 with a pressure range from -1 to 34
bar (1-5 V).
14 Functional description RC.1J.60.02 © Danfoss 09/95 AKC 24W2
Service Before regulation is started, the connected functions should be checked. E.g., expan-
sion valve, sensors, compressor steps and alarm output.
Measurements
All sensor temperatures and values from pressure transmitters can be read and
controlled here.
It is furthermore possible to read the status of the digital input signals.
Service mode Measurement P0 A bar
P0 B bar
P aux bar
S2 A
°
C
S2 B
°
C
S3
°
C
S4
°
C
Ext. Ref. V
DI 3
Safety A
Safety B
Forced operation
The components connected to the AKC 24W outputs can be controlled.
Warning! There is no regulation when the outputs are forced to operate.
The compressor should be stopped!
Admission requirements
To use the service function, two settings have to be made:
1. The function switch must be put in position Service
Main Function Main Switch Main Switch
-1
2. “Manual control” is put in position ON
Service mode Manual Control Man. Ctrl.
ON
The individual outputs can now be forced.
Expansion valve
Forced control of the TQ (PHTQ) valve’s degree of opening.
The setting value is the valve’s opening degree in %.
This function is for instance used when the system has to be evacuated
(setting = 100%).
Warning! Liquid flow in the evaporator may damage the compressor.
Service mode Manual Control AKV A %
___
AKV B %
___
Capacity steps
ON/OFF setting of the individual capacity steps.
Service mode Manual Control Step 1
OFF / ON
Step 2
OFF / ON
Step 3
OFF / ON
Step 4
OFF / ON
Step 5
OFF / ON
Step 6
OFF / ON
Step 7
OFF / ON
Step 8
OFF / ON
More capacity
ON/OFF setting of the “more capacity” output.
Service mode Manual Control More Cap
OFF / ON
AKC 24W2 Functional description RC.1J.60.02 © Danfoss 09/95 15
Alarm
ON/OFF setting of the alarm output.
Service mode Manual Control Alarm Out
OFF / ON
The “OFF” setting will activate the alarm.
When forced operation is concluded, the “Man.Ctrl.” setting must be put in position
OFF before you abandon the service function. The status of the outputs will then
return to the factory-set values.
In connection with the controller’s functions there are a number of alarms and
messages which become visible in case of a fault or incorrect operation.
Distinction is made between important information and not so important information.
The degree of importance is fixed for some, whilst others can be changed if required.
(This change can only be made when a PC is connected to the system and settings
have to be made in each of the relevant controllers).
The importance is indicated by means of the following:
1. "Alarms"
This is important information from the controller.
- The controller’s alarm output is activated.
- Information is transmitted on the DANBUSS
®
network together with status value 1.
- If a gateway type AKA 24 is connected and it is defined as master, its relay output
DO2 will be activated for two minutes (AKA 24 with software version 2.0 or later).
- Later, when the alarm is discontinued, the same information will be repeated, but
this time with status value 0.
2. "Messages"
This is less important information from the controller.
- The information is transmitted on the DANBUSS
®
network together with status
value 2.
- Later, when the “message” is discontinued, the same information will be repeated
but this time with status value 0.
0. “Suppressed information”
This information stops at the controller. It is not transmitted anywhere.
List of alarm activities
mralA
ecnatropmi
snemralA
sutats
2W42CKA
yalermrala
2W42CKA
DELmrala
12AKA
DEL
42AKA
yaler2OD
1
mralAFFOSEHSALFSEHSALF.nim2FFO
mralaoNNOFFOFFONO
2
mralANOSEHSALFSEHSALFNO
mralaoNNOFFOFFONO
0
mralANOFFOFFONO
mralaoNNOFFOFFONO
Alarms and messages
16 Functional description RC.1J.60.02 © Danfoss 09/95 AKC 24W2
Information from the controller
Below, the information is shown together with the importance of it. The information is
shown in brackets “[ ]”. If there are several figures in the bracket, the setting can be
changed (the factory setting is shown in bold type).
Sx Error ( ) [ 1 ]
Sx may be the S2 (in regulation A or B), S3 or S4 sensor. The sensor may be
cut out, short-circuited or not mounted. When there are errors in S2, the control-
ler will stop the regulation in question and cut out the group of capacity steps.
(This does not apply to short-circuits of S2 sensors. When there are errors in S3
or S4, both the A and the B regulation will be stopped, and all capacity steps will
be cut out.
P0 Error ( ) [
1 ]
P0 can be P0A, P0B or Paux.
The transmitter may be cut-out, short-circuited or not mounted. When there are
errors in P0A or P0B, the controller will stop the regulation in question and cut-
out the group of capacity steps.
Safety ( ) Cut out [ 1,2,0 ]
The respective safety circuit is cut-out. When there is an error the controller will
stop the regulation in question and cut-out the group of capacity steps.
Cut off below Limit temp [ 1, 2,0 ]
The temperature at the selected limit sensor is lower than the limit temperature.
When there is an error, both the A and the B regulation will be stopped, and all
capacity steps will be cut-out at intervals. Regulation will recommence when the
temperature again exceeds the limit temperature and when the time delay “--
zone” and “Del ( )” has elapsed.
Max step A > Max step [ 1, 2,0 ]
Wrong values have been set in the “Max step A” and/or “Max step” menus.
Rfg. type not selected [ 1, 2,0 ]
No refrigerant has been selected. Before regulation can be started, the controller
must have its type of refrigerant set.
Rfg. type change after power up [ 1, 2,0 ]
Refrigerant type changed after start-up of controller.
Warning! Change of refrigerant type may cause damage to the compressor.
See section on choice of refrigerant.
Standby Mode [ 1, 2,0 ]
Regulation is manually stopped/started via the “Main switch” menu. When the
regulation has been stopped, there will be a few messages that cannot be
transmitted.
Time for Compr.( ) inspection [ 1, 2,0 ]
The set operating time for the compressor has been reached. Send for service.
Set the “Max ( ) h/10” menu to the time for the next message.
Too high Media temperature [ 1, 2,0 ]
A media temperature is registered which is higher than the set alarm value
("Media AL °C).
AKC 24W2 Functional description RC.1J.60.02 © Danfoss 09/95 17
This is how the various messages are transmitted:
Information is in principle sent twice.
1) An alarm message when the error is discovered.
2) A message about cancellation of the alarm situation, when the error disappears
again.
(In connection with a sensor alarm, there may be 10 minutes between the two mes-
sages).
This procedure has a different influence on the below-mentioned systems:
Single systems (systems with control panel type AKA 21)
Information can be shown on the screen, when an “E” (error) is observed.
The error message cannot be removed from AKA 21, as long as the cause of
the error has not been removed. When the cause of the error message has been
removed, the error message will remain visible in AKA 21 until it is
acknowledged by pushing “Enter”.
Network (Systems with PC or AKA 24 with printer and control panel type AKA 21)
Here the information can be transmitted to the PC or the printer. Accompanying
this message is indication whether it is a new error or an earlier error that has
been transmitted. On control panel type AKA 21 only “new” alarms can be seen
in this situation. Old errors that are transmitted cannot be seen.
To use this function, you have to make a setting in the controller. This setting
can only be made from a PC.
The "Auto reset" setting is put in position "ON".
The individual messages will now be sent to the printer or the PC along with a
status which is either 1, 2 or 0.
1 means that it is new and important information (information defined with
setting = 1)
2 means that it is new, but not quite so important information (information
defined with setting = 2)
0 means that the error has been deleted.
Who are the alarm receivers?
Single systems
Control panel type AKA 21 will here be the receiver of alarms from the
connected units.
- Each controller is given an address, so that the unit is defined in the system.
Setting of the address is performed directly in each controller via a number of
switches (cf. instructions).
Network systems
A defined PC or AKA 24 with printer will here be the receiver of alarms for the
connected units.
- Each controller is given an address, so that the unit is defined in the system.
Setting of the address is performed via a number of switches (cf. instructions).
- Each controller is given a system address. A system address consists of a
network number and an address (the address is the same as the one set in in
the controller). The network number must be set via the PC.
- The addresses of the receivers of all alarms must be set on each controller.
There are two kinds of settings which can only be carried out via the PC.
• The system address of the nearest gateway type AKA 24 which has to
retransmit alarms and messages.
• The system address of the final receiver of alarms and messages.
18 Functional description RC.1J.60.02 © Danfoss 09/95 AKC 24W2
Alarm output on AKC 24W2
The output will only be activated when the setting is [ 1 ] (see above). Activation
will take place, as long as the error is active.
The output is a “Cut-out function” where the following applies:
No alarm: Terminals Y7 and Y8 are short circuited.
Alarm: Terminals Y7 and Y8 are cut-out
The controller contains a clock function.
Days, hours and minutes have to be set.
Danfoss AKC 24W2 clock day
___ 1-7 (1=Monday, 7=Sunday)
clock hour
___ 0-23
clock min
___ 0-59
Note:
The clock must be reset after power failures.
This is however not the case, if the controller is linked up with a gateway type AKA 24
with software version 2.00 or higher (March ’92).
Clock function
AKC 24W2 Functional description RC.1J.60.02 © Danfoss 09/95 19
Functions and measurements pertaining to the refrigerating plant can be read on the
control panel’s display. Temperature readings are indicated in °C and functions with
ON or OFF. Measurements of temperatures and pressures will continue, even if the
function is put in position “OFF”. If no sensor is mounted on an input, this is indicated
on the display with “* * * *.x”.
( ) shows A or B, respectively, for the regulation in question.
Capacity regulation
Cap. Ctrl: Capacity regulation status (ON or OFF)
Media: Actual sensor value (water temperature)
Ref: Reference temperature for capacity regulation
Limit: Actual sensor value for sensor defined as “limit sensor”
DI 3: Status of external switch (ON or OFF)
Compr. ( ) %: Actual number of cut-in capacity steps on compressor A / B
DO 9: Status of output DO 9 (extra capacity)
Safety ( ): Status of safety circuit compressors A and B
Run ( ) h/10: Operating time for compressors A and B (the displayed value
must be multiplied by 10 to obtain the actual number of hours)
Expansion valve
Inj. Ctrl ( ): Expansion valve status (ON or OFF)
S2-S1 ( ): Evaporator superheat measured with the P0 and S2 sensors
SH Ref. ( ): Controller’s actual superheat reference (is changed adaptively)
P0/S1 ( ): Evaporating pressure or refrigerant temperature at evaporator inlet
S2 ( ): Actual sensor value (refrigerant temperature at evaporator outlet)
AKV OD% ( ): Expansion valve opening degree in % of the period time
Controller data
Code no: Controller’s code number and software version
System address: Controller’s system address (network number and address
number). Can only be set from PC
Address: Controller’s address (set on the controller’s switches)
Alarm report to: Address of the final receiver of an alarm. Can only be set from PC
Gateway address: Address of nearest gateway which is to handle alarms. Can only
be set from PC
Continuous updating
If constant display of a menu is required, e.g. a temperature showing, the display on
the control panel can be locked to the menu.
Procedure: Show the required menu on the display, push “enter” for three seconds.
The function is cancelled by pushing one of the arrow keys.
Plant measurements/
data
20 Functional description RC.1J.60.02 © Danfoss 09/95 AKC 24W2
List of literature Functional description (this document) .......................................................... RC.1J.6
Installation guide for data communication cablel ............................................ RC.0X.A
Menu operation via AKA 21(based on software) ............................................RC.1J.7
Menu operation via AKM (based on software) ...............................................RC.1J.8
Mounting instructions (packed with unit) ........................................................RI.1J.Y
Table for menu settings (packed with unit) .....................................................RI.1J.2
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 specifications already agreed.
All trademarks in this material are property of the respecitve companies. Danfoss and Danfoss logotype are trademarks of Danfoss A/S. All rights reserved.
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Danfoss Controller type AKC 24W2 for control of water chillers Installation guide
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