Design Guide
Capacity controller with
cascade control
AK-PC 783A
ADAP-KOOL® Refrigeration control systems
Contents
1. Introduction .............................................................................3
Application .................................................................................................. 3
Principles...................................................................................................... 4
2. Design of a controller ..............................................................7
Module survey ........................................................................................... 8
Common data for modules .................................................................10
Controller ...........................................................................................12
Extension module AK-XM 101A .................................................14
Extension module AK-XM 102A / AK-XM 102B .....................16
Extension module AK-XM 103A .................................................18
Extension module AK-XM 204A / AK-XM 204B .....................20
Extension module AK-XM 205A / AK-XM 205B .....................22
Extension module AK-XM 208C ................................................24
Extension module AK-OB 110 ....................................................26
Extension module EKA 163B / EKA 164B ............................... 27
Graphic display MMIGRS2 ............................................................27
Power supply module AK-PS 075 / 150 / 250 ........................28
Communication module AK-CM 102 .......................................29
Preface to design ....................................................................................30
Functions ............................................................................................30
Connections ...................................................................................... 31
Limitations ......................................................................................... 31
Design of a compressor and condenser control .........................32
Procedure: ..........................................................................................32
Sketch .................................................................................................. 32
Compressor and condenser functions ....................................32
Connections ...................................................................................... 33
Planning table .................................................................................. 35
Length .................................................................................................36
Linking of modules ......................................................................... 36
Determine the connection points ............................................37
Connection diagram ...................................................................... 38
Supply voltage ................................................................................ 40
Ordering ..................................................................................................... 41
3. Mounting and wiring .............................................................43
Mounting ................................................................................................... 44
Mounting of analog output module ........................................ 44
Mounting of extension module on the basic module ....... 45
Wiring .......................................................................................................... 46
4. Configuration and operation ................................................49
Configuration ...........................................................................................50
Connect PC ........................................................................................ 50
Authorization .................................................................................... 52
Unlock the configuration of the controllers ..........................53
System setup ....................................................................................54
Set plant type ................................................................................... 55
Set control of suction group MT ................................................56
Set control of suction group LT .................................................. 60
Set oil management ....................................................................... 63
Setup control of condenser fans ...............................................65
Set control of cascade heat exchanger ..................................67
Setup control of heat recovery.................................................. 68
Setup control of pump function ............................................... 68
Setup Display .................................................................................... 69
Setup Functions for General purpose ......................................70
Separate thermostats ............................................................. 71
Separate pressostats ..............................................................71
Separate voltage signals .......................................................72
Separate alarm inputs ............................................................ 72
Separate PI functions ............................................................. 73
Configuration of inputs and outputs .......................................74
Set alarm priorities..........................................................................76
Lock configuration ..........................................................................78
Check configuration .......................................................................79
Check of connections ............................................................................ 81
Check of settings.....................................................................................83
Schedule function .................................................................................. 85
Installation in network .......................................................................... 86
First start of control ................................................................................87
Start the control ...............................................................................88
Manual capacity control ............................................................... 89
5. Regulating functions .............................................................91
Suction group ..........................................................................................92
Controlling sensor selection .......................................................92
Reference ...........................................................................................93
Capacity control of compressors ...............................................94
Capacity distribution methods ........................................... 96
Power pack types – compressor combinations ............97
Compressor timers ................................................................101
The capacity from the digital scroll compressor ........102
Cascade control .....................................................................103
Load shedding ........................................................................104
Injection ON ............................................................................105
Liquid injection in suction line .........................................105
Safety functions .............................................................................106
Oil management............................................................................108
Pump control ..................................................................................110
Condenser ...............................................................................................112
Capacity control of condenser .................................................112
Reference for condensing pressure ........................................112
Capacity distribution ...................................................................114
EC motor ...........................................................................................114
Step regulation ......................................................................................114
Speed regulation ..................................................................................114
Condenser couplings ...................................................................115
Safety functions for condenser ................................................115
General monitoring functions .........................................................116
Miscellaneous ........................................................................................118
Appendix A – Compressor combinations and coupling pat-
terns ...........................................................................................................122
Appendix B - Alarm texts ...................................................................128
2 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
1. Introduction
Application
AK-PC 783A is complete regulating units for capacity control of
compressors and condensers in refrigeration plants with cascade
function.
The controller controls the high-pressure circuit, low-pressure
circuit and cascade circuit.
The controller is with oil management, simple heat recovery function and coordination between the high-pressure control and
low-pressure control.
In addition to capacity control the controllers can give signals to
other controllers about the operating condition, e.g. forced closing of expansion valves, alarm signals and alarm messages.
The controller’s main function is to control compressors and
condensers so that operation all the time takes place at the
energy-optimum pressure conditions. Both suction pressure
and condensing pressure are controlled by signals from pressure
transmitters.
Capacity control is carried out by suction pressure P0 on the two
circuits.
Cascade control is performed in accordance with the two temperature sensors, Scasc2 and Scasc3.
Among the different functions are:
- Capacity control of up to 12 compressors
(Max. 6 on each circuits or 7 MT + 5 LT or 8 MT + 4 LT)
- Up to 3 unloaders for each compressor
- Up to 3 screw compressors
- Digital scroll compressor
- Oil equalisation function on MT circuit
- Oil management. Either shared or individual for all of the compressor's oil valves in the LT circuit. Receiver pressure control.
- Speed control of one or two compressors
- Up to 6 safety inputs for each compressor
- Option for capacity limitation to minimize consumption peaks
- When the compressor does not start, signals can be transmitted
to other controllers so that the electronic expansion valves will
be closed
- Control of liquid injection into suction line
- Control of liquid injection into screw compressor
- Control of liquid injection in heat exchanger (cascade)
- Control of two cascade circuits in parallel
- Safety monitoring of high pressure / low pressure / discharge
temperature
- Capacity control of up to 8 fans on the condenser
- Floating reference with regard to outside temperature
- Heat recovery function
- Step coupling, speed regulation or a combination
- Control of CO2 pump system
- Safety monitoring of fans
- Control of fans with EC motors
- The status of the outputs and inputs is shown by means of lightemitting diodes on the front panel
- Alarm signals can be generated via data communication
- Alarms are shown with texts so that the cause of the alarm is
easy to see.
- Plus some completely separate functions that are totally independent of the regulation – such as alarm, thermostat ,pressure
and PI-regulating functions.
SW = 1.1x
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 3
Principles
The great advantage of this series of controllers is that it can be
extended as the size of the plant is increased. It has been developed for refrigeration control systems, but not for any specific
application – variation is created through the read-in software and
the way you choose to define the connections.
It is the same modules that are used for each regulation and the
composition can be changed, as required. With these modules
(building blocks) it is possible to create a multitude of various
kinds of regulations. But it is you who must help adjusting the
regulation to the actual needs – these instructions will assist you
to find your way through all the questions so that the regulation
can be defined and the connections made.
Controller
Top part
Advantages
• The controller’s size can “grow” as systems grow
• The software can be set for one or more regulations
• Several regulations with the same components
• Extension-friendly when systems requirements are changed
• Flexible concept:
- Controller series with common construction
- One principle – many regulation uses
- modules are selected for the actual connection requirements
- The same modules are used from regulation to regulation
Extension modules
Bottom part
The controller is the cornerstone of the regulation. The module has inputs and
outputs capable of handling small systems.
• The bottom part – and hence the terminals – are the same for all controller types.
• The top part contains the intelligence with software. This unit will vary according
to controller type. But it will always be supplied together with the bottom part.
• In addition to the software the top part is provided with connections for data
communication and address setting.
Examples
A regulation with few connections can
be performed with the controller module
alone
If the system grows and more functions have to be controlled, the regulation can be
extended.
With extra modules more signals can be received and more relays cut in and out –
how many of them – and which – is determined by the relevant application.
If there are many connections one or more extension modules have to be mounted
4 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Direct connection
Setup and operation of an AK controller must be accomplished via
the “AK-Service Tool” software program.
The program is installed on a PC, and setup and operation of
the various functions are carried out via the controller’s menu
displays.
Displays
The menu displays are dynamic, so that different settings in one
menu will result in different setting possibilities in other menus.
A simple application with few connections will give a setup with
few settings.
A corresponding application with many connections will give a
setup with many settings.
From the overview display there is access to further displays for
the compressor regulation and the condenser regulation.
At the bottom of the display there is access to a number of general
functions, such as “time table”, “manual operation”, “log function”,
“alarms”, and “service” (configuration).
Network linking
The controller can be linked up into a network together with other
controllers in an ADAP-KOOL® refrigeration control system. After
the setup operation can be performed at a distance with, say, our
software program type AKM.
Users
The controller comes supplied with several languages, one of
which can be selected and employed by the user. If there are several users, they may each have their choice of language. All users
must be assigned a user profile which either gives access to full
operation or gradually limits the operation to the lowest level that
only allows you “to see”.
Language selection is part of the service tool settings.
If the language selection is not available in the service tool for the
current regulator, English texts will be displayed.
External display
An external display can be fitted in order for P0 (Suction) and Pc
(Condensing) readings to be displayed.
A total of 4 displays can be fitted and with one setting it is possible to choose between the following readings: suction pressure,
suction pressure in temperature, S4, Ss, Sd, condenser pressure,
condenser pressure in temperature, S7 media temperature etc.
A graphical display with control buttons can also be fitted.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 5
Light-emitting diodes
A number of light-emitting diodes makes it possible to follow the
signals that are received and transmitted by the controller.
Log
From the log function you can define the measurements you wish
to be shown.
The collected values can be printed, or you may export them to a
file. You can open the file in Excel.
If you are in a service situation you can show measurements in a
trend function. The measurements are then made real-time and
displayed instantly.
■ Power
■ Comm
■ DO1 ■ Status
■ DO2 ■ Service Tool
■ DO3 ■ LON
■ DO4 ■ I/O Extension
■ DO5 ■ Alarm
■ DO6
■ DO7 ■ Display
■ DO8 ■ Service Pin
Slow flash = OK
Quick flash = answer from gateway
Constantly ON = error
Constantly OFF = error
Flash = active alarm/not cancelled
Constant ON = Active alarm/cancelled
Alarm
The display gives you an overview of all active alarms. If you wish
to confirm that you have seen the alarm you can cross it off in the
acknowledge field.
If you want to know more about a current alarm you can click on it
and obtain an information display on the screen.
A corresponding display exists for all earlier alarms. Here you can
upload information if you need further details about the alarm
history.
Trouble-shooting
The controller contains a function that continuously follows
a number of measurements and deals with them. The result
indicates whether the function is OK or whether an error may be
expected within a given period of time (“the trip down the roller
coaster has started”). At this time an alarm is transmitted about
the situation – no error has appeared as yet, but it will come.
One example may be slow clogging-up of a condenser. When the
alarm comes the capacity has been reduced, but the situation is
not serious. There will be time to plan a service call.
Alarm
Error
6 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
2. Design of a controller
This section describes how the controller is designed.
The controller in the system is based on a uniform connection
platform where any deviations from regulation to regulation is
determined by the used top part with a specific software and
by which input and output signals the relevant application will
require. If it is an application with few connections, the controller
module (top part with belonging bottom part) may be sufficient.
If it is an application with many connections it will be necessary to
use the controller module plus one or more extension modules.
This section will give you a survey of possible connections plus
assistance in selecting the modules required by your actual
application.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 7
Module survey
• Controller module – capable of handling minor plant requirements.
• Extension modules. When the complexity becomes greater
and additional inputs or outputs are required, modules can be
attached to the controller. A plug on the side of the module will
transmit the supply voltage and data communication between
the modules.
• Top part
The upper part of the controller module contains the intelligence. This is the unit where the regulation is defined and where
data communication is connected to other controllers in a bigger network.
• Connection types
There are various types of inputs and outputs. One type may, for
example, receive signals from sensors and switches, another may
receive a voltage signal, and a third type may be outputs with
relays etc. The individual types are shown in the table below.
Extension module with
additional analog inputs
• Optional connection
When a regulation is planned (set up) it will generate a need for
a number of connections distributed on the mentioned types.
This connection must then be made on either the controller
module or an extension module. The only thing to be observed
is that the types must not be mixed (an analog input signal must
for instance not be connected to a digital input).
• Programming of connections
The controller must know where you connect the individual
input and output signals. This takes place in a later configuration where each individual connection is defined based on the
following principle:
- to which module
- at which point (”terminals”)
- what is connected (e.g. pressure transmitter/type/
pressure range)
Extension module with additional
relay outputs and additional
analog inputs.
External display for
suction pressure etc.
Bottom part
Controller with analog inputs and
relay outputs.
Top part
Extension module with
2x analog output signals
The module with additional relay outputs is
also available in a version where the top part
is provided with change-over switches so
that the relays can be overridden.
If the row of modules needs to
be interrupted due to length or
external positioning, a communication module should be used.
8 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
1. Controller
Type Function Application
AK-PC 783A
Controller for capacity control of compressors and condensers
12 compressors with up to 3 unloaders, 8 fans, max. 160 inputs/outputs
Compressor MT and LT/ Condenser MT/Cascade.
Oil management / Heat recovery.
2. Extension modules and survey of inputs and outputs
Type Analog
inputs
For sensors, pressure transmitters
etc.
Controller 11 4 4 - - - -
Extension modules
AK-XM 101A 8
AK-XM 102A 8
AK-XM 102B 8
AK-XM 103A 4 4
AK-XM 204A 8
AK-XM 204B 8 x
AK-XM 205A 8 8
AK-XM 205B 8 8 x
AK-XM 208C 8 4
On/Off outputs On/off supply voltage
Relay
(SPDT)
Solid state Low voltage
(DI signal)
(max. 80 V)
High voltage
(max. 260 V)
Analog
outputs
0-10 V d.c. For valves
Stepper
output
with step
control
Module with
switches
For override of
relay outputs
The following extension module can be placed on the PC board in the controller module.
There is only room for one module.
AK-OB 110 2
3. AK operation and accessories
Type Function Application
Operation
AK-ST 500 Software for operation of AK controllers AK-operation
- Cable between PC and AK controller USB-A — USB-B (standard IT cable)
Accessories Power supply module 230 V / 115 V to 24 V d.c.
AK-PS 075 18 VA
Supply for controllerAK-PS 150 36 VA
AK-PS 250 60 VA
Accessories External display that can be connected to the controller module. For showing, say, the suction pressure
EKA 163B Display
EKA 164B Display with operation buttons
MMIGRS2 Graphic display with operation buttons
-
Accessories Communication modules for controllers where modules cannot be connected continuously
AK-CM 102 Communication module
Cable between EKA display and controller Length = 2 m, 6 m
Cable between graphic display and controller Length = 1.5 m, 3.0 m
Data communication for external extension
modules
On the following pages there is data specific to each module.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 9
Common data for modules
Supply voltage 24 V d.c./a.c. +/- 20%
Power consumption AK-__ (controller) 8 VA
AK-XM 101, 102, 103, 107, AK-CM 102 2 VA
AK-XM 204, 205, 208 5 VA
Analog inputs Pt 1000 ohm /0°C Resolution: 0.1°C
Pressure transmitter type AKS 32R / AKS
2050
AKS 32 (1-5 V)
Other pressure transmitter:
Ratiometric signal
Min. and Max. pressure must be set
Voltage signal 0-10 V
Contact function (On/Off ) On at R < 20 ohm
On/off supply voltage inputs Low voltage
Relay outputs
SPDT
Solid state outputs Can be used for loads that are cut in and
Stepper outputs Used for valves with stepper input 20-500 step/s
Ambient temperature During transport -40 to 70°C
0 / 80 V a.c./d.c.
High voltage
0 / 260 V a.c.
AC-1 (ohmic) 4 A
AC-15 (inductive) 3 A
U Min. 24 V
out frequently, e.g. :
Oil valves, fans and AKV valves
During operation -20 to 55°C ,
Accuracy: +/- 0.5°C
+/- 0,5°C between -50°C and +50°C
+/- 1°C between -100°C and -50°C
+/- 1°C between +50°C and +130°C
Resolution:1 mV
Accuracy +/- 10 mV
Max. connection of 5 pressure transmitters on one module
Off at R > 2K ohm
(Gold -plated contacts not necessary)
Off: U < 2 V
On: U > 10 V
Off: U < 24 V
On: U > 80 V
Max. 230 V
Low and high voltage must not be connected to the same
output group
Max. 240 V a.c. , Min. 48 V a.c.
Max. 0,5 A,
Leak < 1 mA
Max. 1 AKV
Separate supply to stepper outputs : 24 d.c.
0 to 95% RH (non condensing)
No shock influences / vibrations
Enclosure Material PC / ABS
Density IP10 , VBG 4
Mounting For mounting on panel wall or DIN rail
Weight with screw terminals Modules in 100- / 200- / controller-series Ca. 200 g / 500 g / 600 g
Approvals EU low voltage directive and EMC require-
ments are complied with
UL 873,
The mentioned data applies to all modules.
If data is specific, this is mentioned together with the module in question.
LVD tested according to EN 60730
EMC tested
Immunity according to EN 61000-6-2
Emission according to EN 61000-6-3
UL file number: E166834 for XM and CM-modules
UL file number: E31024 for PC-modules
10 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Dimensions
The module dimension is 72 mm.
Modules in the 100-series consist of one
module
Modules in the 200-series consist of two
modules
Controllers consist of three modules
The length of an aggregate unit = n x 72 + 8
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 11
Controller
Function
There are several controllers in the series. The function is determined by the programmed software, but outwardly the controllers are identical – they all have the same connection possibilities:
11 analog inputs for sensors, pressure transmitters, voltage signals
and contact signals.
8 digital outputs, with 4 Solid state outputs and 4 relay outputs
Supply voltage
24 V a.c. or d.c. to be connected to the controller.
The 24 V must not be retransmitted and used by other controllers as it is not galvanically separated from inputs and outputs. In
other words, you must use a transformer for each controller. Class
II is required. The terminals must not be earthed.
The supply voltage to any extension modules is transmitted via
the plug on the right-hand side.
The size of the transformer is determined by the power requirement of the total number of modules.
The supply voltage to a pressure transmitter can be taken either
from the 5 V output or from the 12 V output depending on transmitter type.
PIN
Data communication
If the controller is to be included in a system, communication
must take place via the LON connection.
The installation has to be made as mentioned in the separate
instructions for LON communication.
Address setting
When the controller is connected to a gateway type AKA 245,
the controller’s address must be set between 1 and 119. (If it is a
system manager AK-SM .., then 1-999).
Service PIN
When the controller is connected to the data communication
cable the gateway must have knowledge of the new controller.
This is obtained by pushing the key PIN. The LED “Status” will flash
when the gateway sends an acceptance message.
Operation
The configuration operation of the controller must take place
from the software program “Service Tool”. The program must be
installed on a PC, and the PC must be connected to the controller
via the network plug on the front of the unit.
Light-emitting diodes
There are two rows with LED’s. They mean:
Left row:
• Voltage supply to the controller
• Communication active with the bottom PC board (red = error)
• Status of outputs DO1 to DO8
Right row:
• Software status (slow flash = OK)
• Communication with Service Tool
• Communication on LON
• Communication with AK-CM 102
• Alarm when LED flashes
- 1 LED that is not used
• Communication with display on RJ11 plug
• “Service Pin” switch has been activated
Address
■ Power
■ Comm
■ DO1 ■ Status
■ DO2 ■ Service Tool
■ DO3 ■ LON
■ DO4 ■ I/O Extension
■ DO5 ■ Alarm
■ DO6
■ DO7 ■ Display
■ DO8 ■ Service Pin
Slow flash = OK
Quick flash = answer from gateway
Constantly ON = error
Constantly OFF = error
Flash = active alarm/not cancelled
Constant ON = Active alarm/cancelled
Keep the safety
distance!
Low and high
voltage must not
be connected to
the same output
group
A small module (option board) can be placed on the bottom part
of the controller. The module is described later in the document.
12 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Point
Point 1 2 3 4 5 6 7 8 9 10 11
Type AI1 AI2 AI3 AI4 AI5 AI6 AI7 AI8 AI9 AI10 AI11
Terminal 15: 12 V
Terminal 16: 5 V
Terminal 27: 12 V
Terminal 28: 5 V
Analog
inputs
on 1 - 11
Solid state outputs
on 12 - 15
Relay or AKV coil
fx 230 V a.c.
Signal Signal
S
Pt 1000 ohm/0°C
S2
Saux_
SsLT
SdMT
Shr
Stw
Scasc
P
AKS 32R
3: Brown
2: Blue
1: Black
P0LT
P0MT
Pc LT
AKS 32
3: Brown
2: Black
1: Red
PcMT
Paux
U
...
On/Off Ext.
Main
switch
Day/
Night
Door
Level
switch
DO
AKV
AKV
PWM
Comp 1
Comp 2
Fan 1
Alarm
Light
Solenoid
valve
Option Board
Please see the signal
on the page with the
module.
24 and 25 used
only when "Option board fitted"
type
Pt 1000
AKS 32R /
AKS 2050 /
MBS 8250
-1 - xx bar
AKS 32
-1 - zz bar
0 - 5 V
0 - 10 V
Active at:
Closed
/
Open
Active at:
On
/
Off
Point 12 13 14 15 16 17 18 19
Type DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8
Signal Module Point
1 (AI 1) 1 - 2
2 (AI 2) 3 - 4
3 (AI 3) 5 - 6
4 (AI 4) 7 - 8
5 (AI 5) 9 - 10
6 (AI 6) 11 - 12
7 (AI 7) 13 - 14
8 (AI 8) 19 - 20
9 (AI 9) 21 - 22
10 (AI 10) 23 - 24
11 (AI 11) 25 - 26
1
12 (DO 1) 31 - 32
13 (DO 2) 33 - 34
14 (DO 3) 35 - 36
15 (DO 4) 37 - 38
16 (DO 5) 39 - 40- 41
17 (DO6) 42 - 43 - 44
18 (DO7) 45 - 46 - 47
19 (DO8) 48 - 49 - 50
24 -
25 -
Terminal
17, 18, 29, 30:
(Cable screen)
Relay outputs on
16 - 19
Terminal
Signal type /
Active at
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 13
Extension module AK-XM 101A
Function
The module contains 8 analog inputs for sensors, pressure transmitters, voltage signals and contact signals.
Supply voltage
The supply voltage to the module comes from the previous module in the row.
Supply voltage to a pressure transmitter can be taken from either
the 5 V output or the 12 V output depending on transmitter type.
Light-emitting diodes
Only the two top LED’s are used. They indicate the following:
• Voltage supply to the module
• Communication with the controller is active (red = error)
14 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Point
Point 1 2 3 4
Type AI1 AI2 AI3 AI4
Terminal 9: 12 V
Terminal 10: 5 V
S
Pt 1000 ohm/0°C
P
AKS 32R
AKS 32
At the top the
signal input is
the left of the
two terminals.
At the bottom
the signal input
is the right of the
two terminals.
3: Brown
2: Blue
1: Black
3: Brown
2: Black
1: Red
Signal Signal
type
S2
Saux
SsLT
Pt 1000
SdMT
Shr
Stw
Sscac
AKS 32R /
P0LT
P0MT
Pc LT
PcMT
Paux
AKS 2050 /
MBS 8250
-1 - xx bar
AKS 32
-1 - zz bar
Terminal 15: 5 V
Terminal 16: 12 V
Terminal
11, 12, 13, 14:
(Cable screen)
Point 5 6 7 8
Type AI5 AI6 AI7 AI8
U
On/Off
...
Ext.
Main
switch
Day/
Night
Door
Level
switch
0 - 5 V
0 - 10 V
Active at:
Closed
/
Open
Signal Module Point
1 (AI 1) 1 - 2
2 (AI 2) 3 - 4
3 (AI 3) 5 - 6
4 (AI 4) 7 - 8
5 (AI 5) 17 - 18
6 (AI 6) 19 - 20
7 (AI 7) 21 - 22
8 (AI 8) 23 - 24
Terminal
Signal type /
Active at
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 15
Extension module AK-XM 102A / AK-XM 102B
Function
The module contains 8 inputs for on/off voltage signals.
Signal
AK-XM 102A is for low voltage signals.
AK-XM 102B is for high voltage signals.
Supply voltage
The supply voltage to the module comes from the previous
module in the row.
Light-emitting diodes
They indicate:
• Voltage supply to the module
• Communication with the controller is active (red = error)
• Status of the individual inputs 1 to 8 (when lit = voltage)
AK-XM 102A
Max. 24 V
On/Off:
On: DI > 10 V a.c.
Off: DI < 2 V a.c.
AK-XM 102B
Max. 230 V
On/Off:
On: DI > 80 V a.c.
Off: DI < 24 V a.c.
16 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Point
DI
AK-XM 102A: Max. 24 V
AK-XM 102B: Max. 230 V
Signal Active at
Ext.
Main
switch
Day/
Night
Comp.
safety 1
Comp.
safety 2
Level
switch
Closed
(voltage on)
/
Open
(voltage off)
Point 1 2 3 4
Type DI1 DI2 DI3 DI4
Point 5 6 7 8
Type DI5 DI6 DI7 DI8
(The module can not register a pulse signal from
e.g. a reset function.)
Signal Module Point Terminal Active at
1 (DI 1) 1 - 2
2 (DI 2) 3 - 4
3 (DI 3) 5 - 6
4 (DI 4) 7 - 8
5 (DI 5) 9 - 10
6 (DI 6) 11 - 12
7 (DI 7) 13 - 14
8 (DI 8) 15 - 16
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 17
Extension module AK-XM 103A
Function
The module contains :
4 analog inputs for sensors, pressure transmitters, voltage signals
and contact signals.
4 analog voltage outputs of 0 - 10 V
Supply voltage
The supply voltage to the module comes from the previous
module in the row.
Supply voltage to a pressure transmitter can be taken from either
the 5 V output or the 12 V output depending on transmitter type.
Galvanic isolation
The inputs are galvanically separated from the outlets.
The outlets AO1 and AO2 are galvanically separated from AO3 and
AO4.
Light-emitting diodes
Only the two top LED’s are used. They indicate the following:
• Voltage supply to the module
• Communication with the controller is active (red = error)
Max. load
I < 2.5 mA
R > 4 kΩ
18 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Point
Point 1 2 3 4
Type AI1 AI2 AI3 AI4
Terminal 9: 12 V
Terminal 10: 5 V
S
Pt 1000 ohm/0°C
P
AKS 32R
AKS 32
At the top the
signal input is
the left of the
two terminals.
At the bottom
the signal input
is the right of the
two terminals.
3: Brown
2: Blue
1: Black
3: Brown
2: Black
1: Red
Signal Signal
type
S2
Saux
Ss
Pt 1000
Sd
Shr
Stw
Scasc
AKS 32R /
P0LT
P0MT
Pc LT
PcMT
Paux
AKS 2050 /
MBS 8250
-1 - xx bar
AKS 32
-1 - zz bar
Terminal
11, 12:
(Cable screen)
Galvanic isolation:
AI 1-4 ≠ AO 1-2 ≠ AO 3-4
Point 5 6 7 8
Type AO1 AO2 AO3 AO4
U
...
On/Off Ext.
Main
switch
Day/
Night
Door
Level
switch
AO
0 - 5 V
0 - 10 V
Active at:
Closed
/
Open
0-10 V
Signal Module Point Terminal Signal type /Active at
1 (AI 1) 1 - 2
2 (AI 2) 3 - 4
3 (AI 3) 5 - 6
4 (AI 4) 7 - 8
5 (AO 1) 17 - 18
6 (AO 2) 19 - 20
7 (AO 3) 21 - 22
8 (AO 4) 23 - 24
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 19
Extension module AK-XM 204A / AK-XM 204B
Function
The module contains 8 relay outputs.
Supply voltage
The supply voltage to the module comes from the previous module in the row.
AK-XM 204B only
Override of relay
Eight change-over switches at the front make it possible to override the relay’s function.
Either to position OFF or ON.
In position Auto the controller carries out the control.
Light-emitting diodes
There are two rows with LED’s. They mean:
Left row:
• Voltage supply to the controller
• Communication active with the bottom PC board (red = error)
• Status of outputs DO1 to DO8
Right row: (AK-XM 204B only):
• Override of relays
ON = override
OFF = no override
Fuses
Behind the upper part there is a fuse for each output.
AK-XM 204A AK-XM 204B
Max. 230 V
AC-1: max. 4 A (ohmic)
AC-15: max. 3 A (Inductive)
Keep the safety distance!
Low and high voltage
must not be connected to
the same output group
AK-XM 204B
Override of relay
Note
If the changeovers are used to override the compressor operation,
it is necessary to wire a safety relay into the circuit for oil management. Without this safety relay, the controller will fail to stop the
compressor if it should run out of oil. See Regulating functions.
20 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Point
DO
Signal Active at
Comp. 1
Comp. 2
Fan 1
Alarm
Solenoid
valve
On
/
Off
Point 1 2 3 4 5 6 7 8
Type DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8
Signal Module Point Terminal Active at
1 (DO 1) 25 - 27
2 (DO 2) 28 - 30
3 (DO 3) 31 - 33
4 (DO 4) 34 -36
5 (DO 5) 37 - 39
6 (DO 6) 40 - 41 - 42
7 (DO 7) 43 - 44 - 45
8 (DO 8) 46 - 47 - 48
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 21
Extension module AK-XM 205A / AK-XM 205B
Function
The module contains:
8 analog inputs for sensors, pressure transmitters, voltage signals
and contact signals.
8 relay outputs.
Supply voltage
The supply voltage to the module comes from the previous module in the row.
AK-XM 205B only
Override of relay
Eight change-over switches at the front make it possible to override the relay’s function.
Either to position OFF or ON.
In position Auto the controller carries out the control.
Light-emitting diodes
There are two rows with LED’s. They mean:
Left row:
• Voltage supply to the controller
• Communication active with the bottom PC board (red = error)
• Status of outputs DO1 to DO8
Right row: (AK-XM 205B only):
• Override of relays
ON = override
OFF = no override
AK-XM 205A AK-XM 205B
max. 10 V
Fuses
Behind the upper part there is a fuse for each output.
Note
If the changeovers are used to override the compressor operation,
it is necessary to wire a safety relay into the circuit for oil management. Without this safety relay, the controller will fail to stop the
compressor if it should run out of oil. See Regulating functions.
Max. 230 V
AC-1: max. 4 A (ohmic)
AC-15: max. 3 A (Inductive)
AK-XM 205B
Override of relay
Keep the safety distance!
Low and high voltage
must not be connected to
the same output group
22 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Point
S
Pt 1000 ohm/0°C
P
AKS 32R
AKS 32
U
On/Off
DO
3: Brown
2: Blue
1: Black
3: Brown
2: Black
1: Red
Signal Signal
type
S2
Saux
Ss
Pt 1000
Sd
Shr
Stw
Scasc
AKS 32R /
P0MT
P0LT
PcMT
Pc LT
Paux
Prec
AKS 2050 /
MBS 8250
-1 - xx bar
AKS 32
-1 - zz bar
0 - 5 V
...
Ext. Main
switch
Day/
Night
Door
0 - 10 V
Active at:
Closed
Open
Level
switch
Active at:
Comp 1
Comp 2
on
Fan 1
Alarm
Light
Off
Solenoid
valve
Point 1 2 3 4 5 6 7 8
Type AI1 AI2 AI3 AI4 AI5 AI6 AI7 AI8
Point 9 10 11 12 13 14 15 16
Type DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8
Signal Module Point
/
/
Terminal 9: 12 V
Terminal 10: 5 V
Terminal 21: 12 V
Terminal 22: 5 V
Terminal 11, 12, 23, 24 :
(Cable screen)
Terminal
1 (AI 1) 1 - 2
2 (AI 2) 3 - 4
3 (AI 3) 5 - 6
4 (AI 4) 7 - 8
5 (AI 5) 13 - 14
6 (AI 6) 15 - 16
7 (AI 7) 17 - 18
8 (AI 8) 19 -20
9 (DO 1) 25 - 26 - 27
10 (DO 2) 28 - 29 - 30
11 (DO 3) 31 - 30 - 33
12 (DO 4) 34 - 35 - 36
13 (DO 5) 37 - 36 - 39
14 (DO6) 40 - 41 - 42
15 (DO7) 43 - 44 - 45
16 (DO8) 46 - 47 - 48
Signal type /
Active at
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 23
Extension module AK-XM 208C
Function
The module contains:
8 analog inputs for sensors, pressure transmitters, voltage signals
and contact signals.
4 outputs for stepper motors.
Supply voltage
The supply voltage to the module comes from the previous module in the row. Here supplied with 5 VA.
The supply voltage to the valves must be from a separate supply,
which must be galvanically separated from the supply for the
control range.
(Power requirements: 7.8 VA for controller + xx VA per valve).
A UPS may be necessary if the valves need to open/close during a
power failure.
Light-emitting diodes
There is one row with LED’s. It indicate the following:
• Voltage supply to the module
• Communication active with the bottom PC board (red = error)
• Step1 to step4 OPEN: Green = Open
• Step1 to step4 CLOSE: Green = Close
• Red flash = Error on motor or connection
Separate voltage supply is
required
24 V a.c./d.c. / fx. 13 VA
max. 10 V
Valve data
Type P
ETS 12.5 - ETS 400
KVS 15 - KVS 42
CCMT 2 - CCMT 8
CCM 10 - CCM 40
CTR 20
CCMT 16 - CCMT 42 5.1 VA
1.3 VA
Output:
24 V d.c.
20-500 step/s
Max phase current = 800 mA RMS
∑ P
= max. 21 VA
out
Power supply to AK-XM 208C:
Fx: 7.8 + (4 x 1.3) = 13 VA AK-PS 075
Fx: 7.8 + (4 x 5.1) = 28.2 VA AK-PS 150
24 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Point
CCMT
Step /
Terminal
ETS
CCM / CCMT
CTR
KVS
Point 1 2 3 4 5 6 7 8
Type AI1 AI2 AI3 AI4 AI5 AI6 AI7 AI8
Terminal 17: 12 V
Terminal 18: 5 V
Terminal 19, 20:
(Cable screen)
Point 9 10 11 12
Step 1 2 3 4
Type AO
1 25 26 27 28
2 29 30 31 32
3 33 34 35 36
4 37 38 39 40
White Black Red Green
Valve Module Step Terminal
1 (point 9) 25 - 28
2 (point 10) 29 - 32
3 (point 11) 33 - 36
4 (point 12) 37 - 40
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 25
Extension module AK-OB 110
Function
The module contains two analog voltage outputs of 0 – 10 V.
Supply voltage
The supply voltage to the module comes from the controller
module.
Placing
The module is placed on the PC board in the controller module.
Point
The two outputs have points 24 and 25. They are shown on the
earlier page where the controller is also mentioned.
Max. load
I < 2.5 mA
R > 4 kohm
AO
AO 0 - 10 V
Module
Point 24 25
Type AO1 AO2
1
AO2
AO1
26 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Extension module EKA 163B / EKA 164B
Function
Display of important measurements from the controller, e.g. ap-
pliance temperature, suction pressure or condensing pressure.
Setting of the individual functions can be performed by using the
display with control buttons.
It is the controller used that determines the measurements and
settings that can occur.
Connection
The extension module is connected to the controller module via
a cable with plug connections. You have to use one cable per
module. The cable is supplied in various lengths.
Both types of display (with or without control buttons) can be
connected to either display output A, B, C and D.
Ex.
A: P0. Suction pressure in °C.
B: Pc. Condensing pressure in °C.
When the controller starts up, the display will show the output
that is connected.
- - 1 = output A
- - 2 = output B
etc.
EKA 163B EKA 164B
Placing
The extension module can be placed at a distance of up to 15 m
from the controller module.
Point
No point has to be defined for a display module – you simply connect it.
Graphic display MMIGRS2
Function
Setting and display of values in the controller.
Connection
The display connects to the controller via a cable with RJ11 plug
connections.
Supply voltage
Received from the controller via cable and RJ11 connector.
Termination
The display must be terminated. Mount a connection between the
terminals H and R.
(AK-PC 783A is terminated internally.)
Placing
The display can be placed at a distance of up to 3 m from the
controller.
Point / Address
No point has to be defined for a display – you simply connect it.
However, the address must be verified. See the instructions accompanying the controller.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 27
Power supply module AK-PS 075 / 150 / 250
Function
24 V supply for controller.
Supply voltage
230 V a.c or 115 V a.c. (from 100 V a.c. to 240 V a.c.)
Placing
On DIN-rail
Effect
Type Output tension Output current Power
AK-PS 075 24 V d.c. 0.75 A 18 VA
AK-PS 150 24 V d.c. (adjustable) 1.5 A 36 VA
AK-PS 250 24 V d.c. (adjustable) 2.5 A 60 VA
Dimension
Type High Width
AK-PS 075 90 mm 36 mm
AK-PS 150 90 mm 54 mm
AK-PS 250 90 mm 72 mm
Connections
Class II
Supply to a controller
AK-PS 075
AK-PS 150
AK-PS 250
28 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Communication module AK-CM 102
Function
The module is a new communication module, meaning the row of
extension modules can be interrupted.
The module communicates with the regulator via data communication and forwards information between the controller and the
connected extension modules.
Connection
Communication module and controller fitted with RJ 45 plug connectors.
Nothing else should be connected to this data communication; a
maximum of 5 communication modules can be connected to one
controller.
Communication cable
One metre of the following is enclosed:
ANSI/TIA 568 B/C CAT5 UTP cable w/ RJ45 connectors.
Positioning
Max. 30 m from the controller
(The total length of the communication cables is 30 m)
Max. 32 VA
Supply voltage
24 volt AC or DC should be connected to the communication
module.
The 24 V can be sourced from the same supply that supplies the
controller. (The supply for the communication module is galvanically separated from the connected extension modules).
The terminals must not be earthed.
The power consumption is determined by the power consumption of the total number of modules.
The controller strand load must not exceed 32 VA.
Each AK-CM 102 strand load must not exceed 20 VA.
Point
Connection points on the I/O modules should be defined as if the
modules were an extension of each other.
Address
The address for the first communication module should be set to
1. Any second module should be set to 2. A maximum of 5 modules can be addressed.
Termination
The termination switch on the final communication module
should be set to ON.
The controller should permanently be set to = ON.
Warning
Additional modules may only be installed following the installation of the final module. (Here following module no. 11; see the
sketch.)
After configuration, the address must not be changed.
Max. 20 VA
Max. 20 VA
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 29
Preface to design
Be aware of the following when the number of extension modules
is being planned. A signal may have to be changed, so that an additional module may be avoided.
• An ON/OFF signal can be received in two ways. Either as a
contact signal on an analog input or as voltage on a low or highvoltage module.
• An ON/OFF output signal can be given in two ways. Either with a
relay switch or with solid state. The primary difference is the permitted load and that the relay switch contains a cutout switch.
Mentioned below are a number of functions and connections that
may have to be considered when a regulation has to be planned.
There are more functions in the controller than the ones mentioned here, but those mentioned have been included in order
that the need for connections can be established.
Functions
Clock function
Clock function and change-over between summer time and winter time are contained in the controller.
The clock setting is maintained for at least 12 hours at a power
failure.
The clock setting is kept updated if the controller is linked up in a
network with a system manager.
Start/stop of regulation
Regulation can be started and stopped via the software. External
start/stop can also be connected.
Warning
The function stops all regulation.
Excess pressure can lead to a loss of charge.
Start/stop of compressors
External start/stop can be connected.
Alarm function
If the alarm is to be sent to a signal transmitter, a relay output will
have to be used.
I'm alive function
A relay can be reserved which is pulled during normal regulation.
The relay will be released if the regulation stops with the main
switch or if the controller fails.
Extra temperature sensors and pressure sensors
If additional measurements have to be carried out beyond the
regulation, sensors can be connected to the analog inputs.
Forced control
The software contains a forced control option. If an extension
module with relay outputs is used, the module’s top part can be
with change-over switches – switches that can override the individual relays into either OFF or ON position.
Wiring should be done with a safety relay. See Regulating functions.
Data communication
The controller module has terminals for LON data communication.
The requirements to the installation are described in a separate
document.
30 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Connections
In principle there are the following types of connections:
Analog inputs ”AI”
This signal must be connected to two
terminals.
Signals can be received from the following
sources:
• Temperature signal from Pt 1000 ohm
temperature sensor
• Contact signal where the input is shortcircuited or ”opened”, respectively
• Voltage signal from 0 to 10 V
• Signal from pressure transmitter AKS 32,
AKS 32R, AKS 2050 or MBS 8250.
The supply voltage is supplied from the
module’s terminal board where there is
both a 5 V supply and a 12 V supply.
When programming the pressure transmitter’s pressure range must be set.
ON/OFF voltage inputs ”DI”
This signal must be connected to two
terminals.
• The signal must have two levels, either 0 V
or ”voltage” on the input.
There are two different extension
modules for this signal type:
- low-voltage signals, e.g. 24 V
- high-voltage signals, e.g. 230 V
When programming the function must be set:
• Active when the input is without voltage
• Active when voltage is applied to the
input.
ON/OFF output signals ”DO”
There are two types, as follows:
• Relay outputs
All relay outputs are with change-over
relay so that the required function can be
obtained when the controller is without
voltage.
• Solid state outputs
Reserved for AKV valves, but output can
cut an external relay in and out, as with a
relay output.
The output is only found on the
controller module.
When programming the function must be set:
• Active when the output is activated
• Active when the output is not activated.
Analog output signal ”AO”
This signal is to be used if a control signal is
to be transmitted to an external unit, e.g. a
frequency converter.
When programming the signal range must
be defined: 0-5 V, 1-5 V, 0-10 V or 2-10 V.
Pulse signal for the stepper motors.
This signal is used by valve motors of the
type ETS, KVS, CCM and CCMT.
The valve type should be set during programming.
Limitations
As the system is very flexible regarding the number of connected
units you must check whether your selection complies with the
few limitations there are.
The complexity of the controller is determined by the software,
the size of the processor, and the size of the memory. It provides
the controller with a certain number of connections from which
data can be downloaded, and others where coupling with relays
can be performed.
✔ The sum of connections cannot exceed 160 (AK-PC 783A).
✔ The number of extension modules must be limited so that the
total power in a row will not exceed 32 VA (including controller).
If the AK-CM 102 communication module is used, each row of
AK-CM 102 must not exceed 20 VA (incl. AK-CM 102).
There must not be more than a total of 12 modules (controller
+ 11 modules).
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 31
✔ No more than 5 pressure transmitters may be connected to one
controller module.
✔ No more than 5 pressure transmitters may be connected to one
extension module.
Common pressure transmitter
If several controllers receive a signal from the same pressure transmitter, the supply to the affected controllers must be wired so that
it is not possible to switch off one of the controllers without also
switching off the others. (If one controller is switched off, the signal will be pulled down, and all the other controllers will receive a
signal which is too low)
Design of a compressor and condenser control
Procedure:
1. Make a sketch of the system in question
2. Check that the controller’s functions cover the required
application
3. Consider the connections to be made
4. Use the planning table. / Note down the number of connections
./ add up
5. Are there enough connections on the controller module? – If
not, can they be obtained by changing an ON/OFF input signal
from voltage signal to contact signal, or will an extension
module be required?
6. Decide which extension modules are to be used
7. Check that the limitations are observed
8. Calculate the total length of modules
9. The modules are linked together
10. The connection sites are established
11. Draw a connection diagram or a key diagram
12. Size of supply voltage/transformer
1
Follow these 12
steps
Sketch
Make a sketch of the system in question.
2
Compressor and condenser functions
Application
Regulation of a compressor groups on MT and LT x
Regulation of a condenser groups on MT x
Regulation of up to 2 cascade heat exchangers x
Regulation of compressor capacity
Control sensor = P0 x
PI-regulation x
Max. number of compressors
Max. number of unloaders each compressor 3
Identical compressor capacities x
Different compressor capacities x
Speed regulation of 1 or 2 compressors x
Run time equalisation x
Min. restart time x
Min. On-time x
Liquid injection in suction line x
Liquid injection in cascade heat exchanger x
Liquid injection in screw compressor x
External start/stop of compressors x
AK-PC 783A
6 MT + 6 LT /
7 MT + 5 LT /
8 MT + 4 LT
Oil management
Oil injection in compressor. Shared or individual x
Receiver pressure control x
Monitoring of oil level in receiver x
Management of oil level in oil separator x
Reset of oil management x
Cutout of compressors at oil failure x
Safety relays during forced compressor control x
Suction pressure reference
Override via P0 optimization x
Override via “night setback” x
Override via "0 -10 V signal" x
Regulation of condenser capacity
Control sensor = PcMT x
Step regulation x
Max. number of steps 8
Speed regulation x
Step and speed regulation x
Speed regulation first step x
32 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Limitation of speed during night operation x
Heat recovery function x
Trouble-shooting function FDD on condenser x
Condenser pressure reference
Floating condensing pressure reference x
Setting of references for heat recovery functions x
Cascade regulation
Control sensor =Scasc2 and Scasc3 (app. SdLT) x
Expansion valve = ETS, CCMT or AKV. Parallel valve can be mounted x
Regulation of two cascade exchangers in parallel x
Safety functions
Min. suction pressure x
Max. suction pressure x
Max. condensing pressure x
A bit more about the functions
Max. discharge gas temperature x
Min. / Max. superheat x
Safety monitoring of compressors x
Common high pressure monitoring of compressors x
Safety monitoring of condenser fans x
General alarm functions with time delay 10
Miscellaneous
Extra sensors 7
Inject On function x
Option for connection of separate display 2
Separate thermostat functions 3
Separate pressostat functions 3
Separate voltage measurements 3
PI regulation 3
Max. input and output 160
Compressor
Regulation of up to 12 compressors and up to 3 unloaders each
compressor.
Compressor No. 1 or 2 can be speed-regulated.
The following can be used as control sensor:
1) P0 - Suction pressure
2) S4 - Cold brine temperature
(P0-LT is also used for 2, but for low-pressure safety.)
Condenser
Regulation of up to 8 condenser steps.
Fans can be speed-regulated. Either all on one signal or only the first
fan of several. EC motor can be used.
Relay outputs and solid state outputs may be used, as desired.
The following can be used as control sensor:
1) Pc - Condensing pressure
2) S7 - Warm brine temperature (Pc is used here for high-pressure
safety.)
Connection between high-pressure and low-pressure circuits (MT
and LT circuits)
All control between the MT and LT circuit must be performed internally in the controller.
Speed regulation of condenser fans
The function requires an analog output module.
A relay output may be used for start/stop of the speed regulation.
The fans may also be cut in and out by relay outputs.
Heat recovery
A thermostat function can be selected that will engage when desired
for heating.
Digital scroll
When using a digital scroll, the unloading of the compressor should
be connected to one of the four solid state outputs in the controller.
Safety circuit
If signals are to be received from one or more parts of a safety circuit,
each signal must be connected to an ON/OFF input.
Day/night signal for raising the suction pressure
The clock function can be used, but an external ON/OFF signal may be
used instead.
If the “P0 optimization” function is used, no signal will be given concerning the raising of the suction pressure. The P0 optimization will
see to this.
“Inject ON” override function
The function closes expansion valves on evaporator controls when all
compressors are prevented from starting.
The function can take place via the data communication, or it may be
wired via a relay output.
Separate thermostat and pressure control functions
A number of thermostats can be used according to your wishes. The
function requires a sensor signal and a relay output. In the controller
there are settings for cutin and cutout values. An associated alarm
function may also be used.
Separate voltage measurements
A number of voltage measurements can be used according to your
wishes. The signal can for example be 0-10 V. The function requires a
voltage signal and a relay output. In the controller there are settings
for cutin and cutout values. An associated alarm function may also be
used.
Separate PI regulations
A series of PI regulations can be set up as desired.
If you want to know more about the functions, go to chapter 5.
3
Connections
Here is a survey of the possible connections. The texts can be read in
context with the table on the following page.
Analog inputs
Temperature sensors
• S4 (Cold brine temperature)
Must be used when the control sensor for compressor control has been
selected as S4.
• Ss (suction gas temperature)
Must always be used in connection with compressor regulation.
• Sd (discharge gas temperature)
Must always be used in connection with compressor regulation.
• Sc3 (outdoor temperature)
To be used when monitoring function FDD is used.
To be used when regulation is performed with floating condenser reference.
• S7 (warm brine return temperature)
Must be used when the control sensor for condenser has been selected
as S7.
• Saux (1-4), any extra temperature sensors
Up to four additional sensors for monitoring and data collection may be
connected. These sensors can be used for general thermostat functions.
• Scasc2, Scasc3
Control sensors for cascade
(The SdLT signal can be used instead of the Scasc3 signal, but only if
nothing else is mounted in the pressure pipe).
• Shrec
Temperature sensor for heat recovery
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 33
Pressure transmitters
• P0 Suction Pressure
Must always be used in connection with compressor regulation
(frost protection).
• Pc Condensing Pressure
Must always be used in connection with compressor or condenser
regulation
• Prec. Oil receiver pressure. Must be used for receiver pressure regulation.
• Paux (1-3)
Up to 3 extra pressure transmitters can be connected for monitoring and
data collection.
These sensors can be used for general pressure switch functions.
Note. A pressure transmitter type AKS 32 or AKS 32R can supply signals to
a maximum of five controllers.
Voltage signal
• Ext. Ref
Used if a reference override signal is received from another control.
• Voltage inputs (1-3)
Up to 3 extra voltage signals can be connected for monitoring and data
collection. These signals are used for general voltage input functions.
On/Off-inputs
Contact function (on an analog input) or
voltage signal (on an extension module)
• Common safety input for all compressors (e.g. common high-pressure/
low-pressure pressure switch)
• Up to 6 signals from the safety circuit of each compressor
• Signal from the condenser fans safety circuit
• Any signal from the frequency converter’s safety circuit
• External start/stop of regulation
• External stop of cascade heat exchanger regulation (1 input for each
cascade)
• External day/night signal (raise/lower the suction pressure reference). The
function is not used if the “P0 optimization” function is used.
• DI alarm (1-10) inputs
Up to 10 no. extra on/off signals for general alarm for monitoring and
data collection can be connected.
• Level contacts
On/off-outputs
Relay outputs
• Compressors
• Unloaders
• Fan motor
• Injection On function (signal for evaporator controls. One per suction
group).
• Start/stop of liquid injection in heat exchanger
• Start/stop of liquid injection in suction line
• Start/stop of 3-way valves at heat recovery
• ON/OFF signal for start/stop of speed regulation
• Alarm relay. I'm alive relay.
• On/off signals from general thermostats (1-3), pressure switches (1-3) or
voltage input functions (1-3).
• Oil valves
• Safety relays for cutouts of compressors at oil failure
Solid state outputs
The solid state outputs on the controller module may be used for the
same functions as those mentioned under “relay outputs”. (The output will
always be “OFF” when the controller has a power failure).
Analog output
• Speed regulation of the condenser’s fans.
• Speed regulation of the compressor
• Stepper signal for expansion valve on cascade heat exchanger
Example
Compressor group:
• MT circuits and LT circuits
• Refrigerant MT=134a LT=CO2 (R744)
• 4 and 2 compressors with "cyclic" operation.
• Speed control of first compressor
• Safety monitoring of each compressor
• Common high-pressure monitoring in each circuit
• ToMT Setpoint =-10°C, ToLT = -30°C
• P0 optimisation
• Oil management of each LT compressor
• Pulse reset for stopped compressor (lack of oil)
Condenser:
• Fans with EC motors, speed controlled
• Pc-MT regulates flooating based on temperature sensor
Sc3
Cascade exchanger
• Control sensor =Scasc3
• Valves = Stepper valve ETS and Solenoid valve EVR
Receivers:
• Control of pressure in oil receiver
Safety functions:
• Monitoring of Po, Pc, Sd and superheat in suction line
• Monitoring of low and high level in oil receiver
Data from this example is used on the next page.
The result is that the following modules should be used:
• AK-PC 783 controller
• AK-XM 204A input and output module
• AK-XM 208C stepper output module
• AK-XM 102B digital input module
• AK-XM 103A analog input and output module
34 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
4
Planning table
The table helps you establish whether there are enough
inputs and outputs on the basic controller.
If there are not enough of them, the controller must be
extended by one or more of the mentioned extension
modules.
Note down the connections you will require and add
them up
Analog inputs
Temperature sensors, Ss, Sd, Sc3, S4, S7, Stw.., Shr.., 7
Extra temperature sensor / separate thermostats /PI-regulation 0
Pressure transmitters, P0, Pc, Prec / separate pressostats 5 P = Max. 5 / module
Voltage signal from other regulation, separate signals
Heat recovery via thermostat
On/off inputs Contact 24 V 230 V
Safety circuits, common for all compressors 2 Max.2
Safety circuits, Oil pressure Max. 1/ Comp.
Safety circuits, comp. Motor protection
Safety circuits, comp. Motor temp.
Safety circuits, comp. High pres. thermostat
Safety circuits, comp. High pres. pressostat
Safety circuits, general for each compressor 6
Safety circuits, condenser fans, frequency converter Max. 1/ fan
Safety circuits, flow switch
External start/stop
External start/stop of each cascade heat exchanger regulation
Night setback of suction pressure
Separate alarm functions via DI
Load shedding
Start of Heat recovery
Liquid level, Oil level 5
Impulse pressure, Pulse reset of oil management 1
On/off outputs
Compressors, motors 6
Unloaders
Fan motors, circulation pumps 1
Alarm relay, I'm alive relay
Inject ON Max. 2
Separate thermostat and pressostat functions and voltage measurements
Heat recovery function via thermostat Max.1
Liquid injection in suction line / heat exchanger 1
Signal for external cascade control
Solenoid valve for Oil. 3
3-way valve
Analog control signal, 0-10 V
Frequency converter, Compressor, fans, pumps, valves etc. 3
Valves with stepper motor. Parallel valves, if applicable 1
Sum of connections for the regulation 18 0 8 11 3+1 Sum = max. 160
Number of connections on a controller module 11 11 0 0 0 0 8 8 0 0 0
Missing connections, if applicable 7 - 8 3 3+1
5
Analog input signal
Example
On/off voltage signal
Example
On/off voltage signal
Example
On/Off output signal
Example
Analog output signal 0-10 V
Stepper output
Example
Max. 5+5+5
7
Limitations
The example:
None of the 3 limitations are exceeded => OK
The missing connections to be supplied by one or more extension modules:
6
AK-XM 101A (8 analog inputs) ___ pcs. á 2 VA = __
AK-XM 102A (8 digital low voltage inputs) ___ pcs. á 2 VA = __
AK-XM 102B (8 digital high voltage outputs) 1 ___ pcs. á 2 VA = __
AK-XM 103A (4 analog inputs, 4 analog outputs) 1 1 ___ pcs. á 2 VA = __
AK-XM 204A / B (8 relay outputs) ___ pcs. á 5 VA = __
AK-XM 205A / B (8 analog inputs. + 8 relay output) 1 ___ pcs. á 5 VA = __
AK-XM 208C (8 analog inputs + 4 stepper outputs) 1 1 ___ pcs. á 5 VA = __
AK_OB 110 (2 analog outputs) ___ pcs. á 0 VA = 0
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 35
Sum of power
1 pcs. á 8 VA = 8
Sum =
Sum = max. 32 VA
8
Length
If you use many extension modules the controller’s length will
grow accordingly. The row of modules is a complete unit which
cannot be broken.
If the row becomes longer than desired, the row can be broken by
using AK-CM 102.
The module dimension is 72 mm.
Modules in the 100-series consist of one module
Modules in the 200-series consist of two modules
The controller consist of three modules
The length of an aggregate unit = n x 72 + 8
or in an other way:
Module Type Number at Length
Controller module 1 x 224 = 224 mm
Extension module 200-series _ x 144 = ___ mm
Extension module 100-series _ x 72 = ___ mm
Total length = ___ mm
9
Linking of modules
Start with the controller module and then mount the selected
extension modules. The sequence is of no importance.
However, you must not change the sequence, i.e. rearrange the
modules, after you have made the setup where the controller
is told which connections are found on which modules and on
which terminals.
The modules are attached to one another and kept together by a
connection which at the same time transmits the supply voltage
and the internal data communication to the next module.
Example continued:
Controller module + 2 extension modules in 200-series + 2 extension module in 100 series =
224 + 144 + 144 + 72 + 72 = 656 mm.
Example continued
Mounting and removal must always be performed when there is
no voltage.
The protective cap mounted on the controller’s plug connection
must be moved to the last vacant plug connection so that the
plug will be protected against short-circuit and dirt.
When the regulation has started the controller will all the time
check whether there is connection to the connected modules. This
status can be followed by the light-emitting diode.
When the two catches for the DIN rail mounting are in open position the module can be pushed into place on the DIN rail – no
matter where in the row the module is found.
Removal is likewise carried out with the two catches in the open
position.
36 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
10
Determine the connection points
All connections must be programmed with module and point, so
in principle it does not matter where the connections are made, as
long as it takes place on a correct type of input or output.
• The controller is the first module, the next one is 2, etc.
• A point is the two or three terminals belonging to an input or
output (e.g. two terminals for a sensor and three terminals for a
relay).
The preparation of the connection diagram and the subsequent
programming (configuration) should take place at the present
time. It is most easily accomplished by filling in the connection
survey for the relevant modules.
Principle:
Name On module On Point Function
fx Compressor 1 x x Close
fx Compressor 2 x x Close
fx Alarm relay x x NC
fx Main switch x x Close
fx P0 x x AKS 32R 1-6 bar
The connection survey from the controller and any extension
modules are uploaded from the paragraph "Module survey. E.g.
controller module:
Module Point
Mind the numbering.
The right-hand part of the
controller module may look like
a separate module. But it isn’t.
Note
The safety relays should not be fitted onto a module
with override changeovers, as they can be put out of
operation by an incorrect setting.
Example continued
Signal Module Point
Discharge temperature - Sd - MT
Suction gas temperature- Ss - MT 2 (AI 2) 3 - 4 Pt 1000
Outdoor temperature - Sc3 3 (AI 3) 5 - 6 Pt 1000
Discharge temperature - Sd - LT 4 (AI 4) 7 - 8 Pt 1000
Suction gas temperature- Ss - MT 5 (AI 5) 9 - 10 Pt 1000
Suction pressure - P0-MT 6 (AI 6) 11 - 12 AKS 32R-12
Condensing pressure - Pc-MT 7 (AI 7) 13 - 14 AKS 32R-34
Level switch, oil, comp.1 LT 8 (AI 8) 19 - 20 Closed
Level switch, oil, comp.2 LT 9 (AI 9) 21 - 22 Closed
Solenoid valve, oil , comp. 1 LT 12 (DO 1) 31 - 32 ON
Solenoid valve, oil , comp. 2 LT 13 (DO 2) 33 - 34 ON
Solenoid valve, oil, Separator 16 (DO 5) 39 - 40 - 41 ON
Solenoid valve, oil, ccascade 17 (DO6) 42 - 43 - 44 ON
EC-motor on/off signal 18 (DO7) 45 - 46 - 47 ON
1 (AI 1) 1 - 2 Pt 1000
10 (AI 10) 23 - 24
1
11 (AI 11) 25 - 26
14 (DO 3) 35 - 36
15 (DO 4) 37 - 38
19 (DO8) 48 - 49 - 50
24 -
25 -
Terminal
Signal type /
Active at
- Columns 1, 2, 3 and 5 are used for the programming.
- Columns 2 and 4 are used for the connection diagram.
Signal Module Point
Compressor 1 MT
Compressor 2 MT 2 (DO 2) 28 - 29 - 30 ON
Compressor 3 MT 3 (DO 3) 31 - 32 - 33 ON
Compressor 4 MT 4 (DO 4) 34 - 35 - 36 ON
Compressor 1 LT 5 (DO 5) 37 - 38 - 39 ON
Compressor 2 LT 6 (DO6) 40 - 41 - 42 ON
Signal Module Point/Step Terminal Signal type
Level switch, oil, receiver High
Level switch, oil, receiver Low 2 (AI 2) 3 - 4 Closed
Level switch, oil, Separator, High 3 (AI 3) 5 - 6 Closed
Pulse reset of stopped compressor 6 (AI 6) 11 - 12 Pulse
Suctioon pressure - P0-LT 7 (AI 7) 13 - 14 AKS 2050-59
Condenser pressure - Pc-LT 8 (AI 8) 15 - 16 AKS 2050-59
Stepper signal til ETS valve 1 (AO 1)
1 (DO 1) 25 - 26 - 27 ON
2
7 (DO7) 43 - 44 - 45
8 (DO8) 46 - 47 - 48
1 (AI 1) 1 - 2 Closed
4 (AI 4) 7 - 8
5 (AI 5) 9 - 10
3
2 (AO 2)
3 (AO 3) 33 - 34 - 35 - 36
4 (AO 4) 37 - 38 - 39 - 40
Terminal
25 - 26 - 27 - 28
29 - 30 - 31 - 32
Signal type /
Active at
ETS
Continued next page
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 37
Signal Module Point Terminal Active at
Compressor 1 Gen. Safety MT
Compressor 2 Gen. Safety MT 2 (DI 2) 3 - 4 Open
Compressor 3 Gen. Safety MT 3 (DI 3) 5 - 6 Open
Compressor 4 Gen. Safety MT 4 (DI 4) 7 - 8 Open
All compressors common safety MT 5 (DI 5) 9 - 10 Open
All compressors common safety LT 6 (DI 6) 11 - 12 Open
Compressor 1 Gen. Safety LT 7 (DI 7) 13 - 14 Open
Compressor 2 Gen. Safety LT 8 (DI 8) 15 - 16 Open
Signal Module Point Terminal Signal type
Temp. heat exchanger Scasc2
Temp. heat exchanger Scasc3 2 (AI 2) 3 - 4 P t 1000
Oil receiver, Prec Oil
Speed control, compressor MT 5 (AO 1) 9 - 10
Speed control, compressor LT 6 (AO 2) 11 - 12 0 - 10 V
Speed control, EC motor 7 (AO 3) 13 - 14 0 - 10 V
1 (DI 1) 1 - 2 Open
4
1 (AI 1) 1 - 2 Pt 1000
3 (AI 3) 5 - 6
4 (AI 4) 7 - 8
5
8 (AO 4) 15 - 16
AKS 2050-59
0 - 10 V
11
Connection diagram
Drawings of the individual modules may be
ordered from Danfoss.
Format = dwg and dxf.
You may then yourself write the module
number in the circle and draw the individual
connections.
The supply voltage for the pressure
transmitter should be taken from
the same module that receives the
pressure signal.
GND connection to a sensor signal
must be made on the same module
receiving the temperature signal.
38 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Example continued:
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 39
12
Supply voltage
Supply voltage is only connected to the controller module. The
supply to the other modules is transmitted via the plug between
the modules.
The supply must be 24 V +/-20%. One power supply must be used
for each controller. The power supply must be a class II.
The 24 V must not be shared by other controllers or units. The
analog inputs and outputs are not galvanically separated from the
supply.
The + and – 24V input must not be earthed.
If using stepper motor valves, the supply for these must be provided from a separate power supply.
For CO2 facilities, it will also be necessary to safeguard the voltage
to the controller and valves using UPS.
Example continued:
Controller module 8 VA
+ 2 extension modules in 200 series 10 VA
+ 2 extension modules in 100 series 4 VA
-----Power supply size (least) 22 VA
+ Separate power supply for the module with the stepper motors: 13 VA.
Power supply size
The power consumption grows with the number of modules used:
Module Type Number á Effect
Controller 1 x 8 = 8 VA
Extension module 200 series _ x 5 = __ VA
Extension module 100 series _ x 2 = __ VA
Total ___ VA
Common pressure transmitter
If several controllers receive a signal from the same pressure transmitter, the supply to the affected controllers must be wired so that
it is not possible to switch off one of the controllers without also
switching off the others. (If one controller is switched off, the signal will be pulled down, and all the other controllers will receive a
signal which is too low)
40 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Ordering
1. Controller
Type Function Application Language Code no.
Controller for capacity control of MT com-
AK-PC 783A
pressors, condensers, LT compressors and
cascade heat exchangers.
With oil management
Capacity control on
cascade plant
English, German, French, Dutch, Italian,
Spanish, Portuguese
080Z0193
2. Extension modules and survey for inputs and outputs
Type Analog
inputs
For sensors,
pressure
transmitters
etc.
Controller 11 4 4 - - - - -
Extension modules
AK-XM 101A 8 080Z0007
AK-XM 102A 8 080Z0008
AK-XM 102B 8 080Z0013 x
AK-XM 103A 4 4 080Z0032 x
AK-XM 204A 8 080Z0011 x
AK-XM 204B 8 x 080Z0018
AK-XM 205A 8 8 080Z0010
AK-XM 205B 8 8 x 080Z0017
AK-XM 208C 8 4 080Z0023 x
The following extension module can be placed on the PC board in the controller module.
There is only room for one module.
AK-OB 110 2 080Z0251
On/Off outputs On/off supply voltage
Relay
(SPDT)
Solid state Low volt-
(DI signal)
age
(max. 80 V)
High voltage
(max. 260V)
Analog
outputs
0-10 V d.c. For valves
Stepper
outputs
with step
control
Module
with
switches
For override
of relay
outputs
Code no.
With screw
terminals
continued
continued
Example
X
Example
3. AK operation and accessories
Type Function Application Code no.
Operation
AK-ST 500 Software for operation of AK controllers AK-operation 080Z0161 x
- Cable between PC and AK controller USBA - USBB (standard IT cable) 080Z0264 x
Accessories Power supply module 230 V / 115 V to 24 V d.c.
AK-PS 075 18 VA
AK-PS 150 36 VA 080Z0054 x
AK-PS 250 60 VA 080Z0055
Accessories External display that can be connected to the controller module. For showing, say, the suction pressure
EKA 163B Display 084B8574
EKA 164B Display with operation buttons 084B8575
MMIGRS2 Graphic display with operation 080G0294
- Cable between EKA display and controller
Cable between graphic display type MMIGRS2 and
controller (controller with RJ11 plug)
Accessories Communication modules for controllers where modules cannot be connected continuously
AK-CM 102 Communication module Data communication for external extension modules 080Z0064
Supply for controller
Length = 2 m 084B7298
Length = 6 m 084B7299
Length = 1.5 m 080G0075
Length = 3 m 080G0076
080Z0053 x
Example
continued
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 41
42 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
3. Mounting and wiring
This section describes how the controller:
• Is fitted
• Is connected
We have decided to work on the basis of the example we went
through previously, i.e. the following modules:
• AK-PC 783A controller module
• AK-XM 204A output module
• AK-XM 208C analog input module + stepper output module
• AK-XM 102B digital input module
• AK-XM 103B analog input and output module
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 43
Mounting
Mounting of analog output module
1. Lift the top part off the basic module
The basic module must not be connected to voltage.
Press in the plate on the left-hand side of the light-emitting
diodes and the plate on the right-hand side for the red address
changers.
Lift the top part off the basic module.
The analogue extension module used for mounting inside the control
module is shown for guidance only. This is not used in the example.
2. Mount the extension module in the basic module
3. Put the top part back on the basic module
There are two outputs.
44 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Mounting and wiring - continued
Mounting of extension module on the basic module
1. Move the protective cap
Remove the protective cap from the connection plug on the
right-hand side of the basic module.
Place the cap on the connection plug to the right of the extension module that is to be mounted on the extreme right-hand
side of the AK assembly.
In our example four extension modules are to be fitted to the basic
module. We have chosen to fit the module with relays directly on the
basic module and then the following module. The sequence is thus:
All the subsequent settings that affect the four extension modules are
determined by this sequence.
2. Assemble the extension module and the basic
module
The basic module must not be connected to voltage.
When the two snap catches for the DIN rail mounting are in the open
position, the module can be pushed into place on the DIN rail – regardless of where the module is on the row.
Disassembly is thus done with the two snap catches in the open position.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 45
Mounting and wiring - continued
Wiring
Decide during planning which function is to be connected and
where this will be.
1. Connect inputs and outputs
Here are the tables for the example:
Remember the isolation amplifier
If signals are received from different controls, e.g. heat recovery for one of the inputs, a galvanically insulated module
should be inserted.
Signal Module Point
Discharge gas temperature - Sd-MT
Suction gas temperature - Ss-MT 2 (AI 2) 3 - 4 Pt 1000
Outdoor temperature - Sc3 3 (AI 3) 5 - 6 Pt 1000
Discharge gas temperature - Sd-LT 4 (AI 4) 7 - 8 Pt 1000
Suction gas temperature - Ss-LT 5 (AI 5) 9 - 10 Pt 1000
Suction pressure - P0-MT 6 (AI 6) 11 - 12 AKS 32R-12
Condenser pressure - Pc-MT 7 (AI 7) 13 - 14 AKS 32R-34
Level switch, oil, comp. 1 LT 8 (AI 8) 19 - 20 closed
Level switch, oil, comp..2 LT 9 (AI 9) 21 - 22 closed
Solenoid valve, oil, Comp. 1 LT 12 (DO 1) 31 - 32 ON
Solenoid valve, oil, Comp. 2 LT 13 (DO 2) 33 - 34 ON
Solenoid valve , oil, Separator 16 (DO 5) 39 - 40 - 41 ON
Solenoid valve, cascade 17 (DO6) 42 - 43 - 44 ON
EC motor on/off signal 18 (DO7) 45 - 46 - 47 ON
Signal Module Point
Compressor 1 MT
Compressor 2 MT 2 (DO 2) 28 - 29 - 30 ON
Compressor 3 MT 3 (DO 3) 31 - 32 - 33 ON
Compressor 4 MT 4 (DO 4) 34 - 35 - 36 ON
Compressor 1 LT 5 (DO 5) 37 - 38 - 39 ON
Compressor 2 LT 6 (DO6) 40 - 41 - 42 ON
1 (AI 1) 1 - 2 Pt 1000
10 (AI 10) 23 - 24
1
11 (AI 11) 25 - 26
14 (DO 3) 35 - 36
15 (DO 4) 37 - 38
19 (DO8) 48 - 49 - 50
24 -
25 -
1 (DO 1) 25 - 26 - 27 ON
2
7 (DO7) 43 - 44 - 45
8 (DO8) 46 - 47 - 48
Terminal
Terminal
Signal type /
Active at
Signal type /
Active at
The function of the switch functions can be seen in the last column.
There are pressure transmitters AKS 32R and AKS 2050 available for
several pressure ranges.
Here there are three different ones. One up to 12 bar, 34 bar and 59 bar.
Signal Module Point Terminal Active at
Compressor 1 Gen. Safety MT
Compressor 2 Gen. Safety MT 2 (DI 2) 3 - 4 Open
Compressor 3 Gen. Safety MT 3 (DI 3) 5 - 6 Open
Compressor 4 Gen. Safety MT 4 (DI 4) 7 - 8 Open
All compressors common safety MT 5 (DI 5) 9 - 10 Open
All compressors common safety LT 6 (DI 6) 11 - 12 Open
Compressor 1 Gen. Safety LT 7 (DI 7) 13 - 14
Compressor 2 Gen. Safety LT 8 (DI 8) 15 - 16
1 (DI 1) 1 - 2 Open
4
Open
Open
Signal Module Point/Step Terminal Signal type
Level switch, oil, receiver High
Level switch, oil, receiver Low 2 (AI 2) 3 - 4 Closed
Level switch, oil, Separator, High 3 (AI 3) 5 - 6 Closed
Pulse reset of stopped compressor 6 (AI 6) 11 - 12 Pulse
Suctioon pressure - P0-LT 7 (AI 7) 13 - 14 AKS 2050-59
Condenser pressure - Pc-LT 8 (AI 8) 15 - 16 AKS 2050-59
Stepper signal til ETS valve 1 (AO 1)
1 (AI 1) 1 - 2 Closed
4 (AI 4) 7 - 8
5 (AI 5) 9 - 10
3
25 - 26 - 27 - 28
2 (AO 2) 29 - 30 - 31 - 32
3 (AO 3) 33 - 34 - 35 - 36
4 (AO 4) 37 - 38 - 39 - 40
ETS
Temp. heat exchanger Scasc2
Temp. heat exchanger Scasc3 2 (AI 2) 3 - 4 P t 1000
Oil receiver, Prec Oil 4 (AI 4) 7 - 8 AKS 2050-59
Speed control, compressor MT 5 (AO 1) 9 - 10 0 - 10 V
Speed control, compressor LT 6 (AO 2) 11 - 12 0 - 10 V
Speed control, EC motor 7 (AO 3) 13 - 14 0 - 10 V
Signal Module Point Terminal Signal type
1 (AI 1) 1 - 2 Pt 1000
3 (AI 3) 5 - 6
5
8 (AO 4) 15 - 16
46 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Mounting and wiring - continued
The connections for the example can be seen here.
Warning
Keep signal cables separate from
cables with high voltage.
The screen on the pressure
transmitter cables must only
be connected at the end of the
controller.
The supply voltage for the pressure
transmitter should be taken from
the same module that receives the
pressure signal.
Remember separate power supply
for AK-XM 208C.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 47
2. Connect LON communication network
The installation of the data communication must comply with
the requirements set out in document RC8AC.
3. Connect supply voltage
Is 24 V, and the supply must not be used by other controllers or
devices. The terminals must not be earthed.
4. Follow light-emitting diodes
When the supply voltage is connected the controller will go
through an internal check. The controller will be ready in just
under one minute when the light-emitting diode ”Status” starts
flashing slowly.
5. When there is a network
Set the address and activate the Service Pin.
6. The controller is now ready to be configured.
Internal communication
between the modules:
Quick flash = error
Constantly On = error
■ Power
■ Comm
■ DO1 ■ Status
■ DO2 ■ Service Tool
■ DO3 ■ LON
■ DO4 ■ I/O extension
■ DO5 ■ Alarm
■ DO6
■ DO7 ■ Display
■ DO8 ■ Service Pin
Status on output 1-8
Slow flash = OK
Quick flash = answer from gateway
in 10 min. after network
installation
Constantly ON = error
Constantly OFF = error
External communication
Communication to AK-CM 102
Flash = active alarm/not cancelled
Constant ON = Active alarm/cancelled
Network installation
48 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
4. Conguration and operation
This section describes how the controller:
• Is configured
• Is operated
We have decided to work on the basis of the example we went
through previously, i.e. compressor control with 4 MT-compressors, 2 LT-compressors and cascade heat exchangers.
The example is shown two pages in.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 49
Conguration
Connect PC
PC with the program “Service Tool” is connected to the controller.
The controller must be switched on first and the LED “Status” must
flash before the Service Tool program is started.
Start Service Tool programme
For connecting and operating the "AK service tool" software,
please see the manual for the software.
The first time the Service Tool is connected to a new version of a controller the start-up of the Service Tool will take longer than usual while
information is retrieved from the controller.
Time can be followed on the bar at the bottom of the display.
Login with user name SUPV
Select the name SUPV and key in the access code.
When the controller is supplied the SUPV access code is 123.
When you are logged into the controller an overview of it will always
appear.
In this case the overview is empty. This is because the controller has not
yet been set up.
The red alarm bell at the bottom right tells you that there is an active
alarm in the controller. In our case the alarm is due to the fact that the
time in the controller has not yet been set.
50 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Refrigerating plant example
We have decided to describe the setup by means of
an example comprising a MT compressor group, a LT
compressor group and a cascade heat exchanger.
The example is the same as the one given in the
"Design" section, i.e. the controller is an AK-PC 783A
+ extension modules.
Compressor Group
• MT circuit and LT circuit
• Refrigerant MT=134a. LT=CO2 (R744)
• 4 and 2 compressors with "cyclic" operation
• First compressor is speed controlled
• Safety monitoring of each compressor
• Common high-pressure monitoring in each circuit
• T0-MT set point = -10°C, T0-LT = -30°C
• P0 optimisation on MT
• Oil management of each LT compressor
• Pulse reset for stopped compressor (lack of oil)
Condenser:
• Fans with EC motors, speed controlled
• Pc-MT regulates flooating based on temperature
sensor Sc3
Cascade exchanger
• Control sensor =Scasc3, Scacs 2, P0-MT, Pc-LT
• Valves = Stepper valve ETS and Solenoid valve EVR
Receivers:
• Control of pressure in oil receiver
Safety functions:
• Monitoring of Po, Pc, Sd and superheat in suction
line
• Monitoring of low and high level in oil receiver
There can be both an external and internal main switch as a setting. Both must be
“ON” before any adjustment is made.
Warning
The main switch will stop all regulations. In the event of temperature increases,
there is a risk of loss of filling.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 51
Configuration - continued
Authorization
1. Go to Configuration menu
Press the orange setup button with the spanner at the bottom
of the display.
2. Select Authorization
3. Change setting for the user ‘SUPV‘
When the controller is supplied it has been set with standard authorization for different user interfaces. This setting should be changed and
adapted to the plant. The changes can be made now or later.
You will use this button again and again whenever you want to get to
this display.
On the left-hand side are all the functions not shown yet. There will be
more here the further into the setup we go.
Press the line Authorization to get to the user setup display.
4. Select user name and access code
5. Carry out a new login with the user name and the
new access code
Mark the line with the user name SUPV.
Press the button Change
This is where you can select the supervisor for the specific system and a
corresponding access code for this person.
The controller will utilize the same language that is selected in the
service tool but only if the controller contains this language. If the
language is not contained in the controller, the settings and readings
will be shown in English.
To activate the new settings you must carry out a new login to the controller with the new user name and the relevant access code.
You will access the login display by pressing the icon at the top left
corner of the display.
52 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Configuration - continued
Unlock the conguration of the
controllers
1. Go to Configuration menu
2. Select Lock/Unlock configuration
3. Select Configuration lock
Press the blue field with the text Locked
The controller can only be configured when it is unlocked.
The values can be changed when it is locked, but only for those settings
that do not affect the configuration.
4. Select Unlocked
Select Unlocked.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 53
Configuration - continued
System setup
1. Go to Configuration menu
2. Select System setup
3. Set system settings
All settings can be changed by pressing in the
blue field with the setting and then indicating the value of the required setting.
In the first field you enter a name for what
the controller will be controlling. The text
written in this field can be viewed at the top
of all screens, together with the controller's
address.
When the time is set the PC’s time can be
transferred to the controller.
When the controller is connected to a network, date and time will automatically be set
by the system unit in the network. This also
applies to change-over Daylight saving.
Power failure, the clock will be kept running
for at least 12 hours.
54 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Configuration - continued
Set plant type
1. Go to Configuration menu
2. Select plant type
Press the line Select plant type.
3. Set plant type
3. continued
Our example
The comments for the example are shown on the
following pages, in the middle column.
In our example we want the controller
to control an MT group, an LT group,
the condenser group and the cascade
heat exchanger. Therefore, we select
the Cascade plant type.
Subsequent options are then available,
but only those options allowed by the
current selection.
Select the refrigerant type, here R134a
and CO2, further options are made available, etc.
The settings for our example can be
viewed in the display.
General
If you want to know more about the different
configuration options, they are listed in the right
column.
The number refers to the number and picture in
the column on the left.
As the screen only shows the settings and readings
that are required for a given setup, all possible settings have also been included in the right column.
3 - Plant type
Application selection
Select Cascade control
3- after Application selection
Refrigerant
Select refrigerant type
Refrigerant factors K1, K2, K3
Only used if “Po refrigerant type” is set to custom
(contact Danfoss for information)
MT = Medium temperature. LT = Low temperature
Condenser fan control
Select how the controller is to control the
condenser. Set later.
No. of fans
Set no of fans
Cold pump control
Select whether the controller should manage
pump circulated CO2.
Heat recovery
Heat recovery enabled. To be adjusted later on.
Oil management
Oil control enabled. To be adjusted later on.
Select quick setup
You can reset all settings and return to factory
settings here.
4 - Compressor combinations MT
Select between:
There are several underlying
Press the +-button to go on to the
next page
4. Set Common functions
pages.
The black bar in this field tells you
which of the pages is currently
displayed.
Browse the pages using the +
and - buttons.
No of compressors
Set the number of compressor units
Compressor combinations LT
See above, but no screw compressor
No of compressors
Set the number of compressor units
External main switch
A switch may be connected for starting and
stopping the regulation.
Mon. Ext. Power loss (signal from an UPS)
Monitoring of external voltage. When selecting
"yes", a digital input is allocated.
Alarm output
Here you may set whether or not it should be
an alarm relay, and which priorities will activate
it.
I'm alive relay
A relay will "release" if the regulation is stopped.
Night select via DI
Change to night-time operation at the signal
for a DI input.
Comp. cap. out to AO
Select whether the cutin capacities must be
displayed on analogue outputs.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 55
Configuration - continued
Set control of suction group MT
1. Go to Configuration menu
2. Select Suction group
The configuration menu in the
Service Tool has changed now.
It shows the possible settings for
the selected plant type.
3. Set values for the reference
In our example we select the
settings:
- Set point = -10°C
The settings are shown here in the
display.
3 - Reference mode
Displacement of suction pressure as a function of external
signals
0: Reference = set reference + night offset + offset from external
0-10 V signal
1: Reference = set reference + offset from P0 optimization
Setpoint ( -80 to +30°C)
Setting of required suction pressure in °C
Offset via Ext. Ref
Select whether a 0-10V external reference override signal is
required
Offset at max input (-100 to +100 °C)
Displacement value at max. signal (10)
Offset at min input (-100 to +100 °C)
Displacement value at min. signal (0 V)
Offset filter (10 - 1800 Sec)
Here you can set how quickly the reference must become effective.
Night Offset (-25 to +25 K)
Displacement value for suction pressure in connection with an
active night setback signal (set in Kelvin)
Max reference (-50 to +80 °C)
Max. permissible suction pressure reference
Min reference (-80 to +25 °C)
Min. permissible suction pressure reference
4 - Compressor application
Select one of the available compressor configuration here
Press the +-button to go on to the
next page
4. Set values for capacity control
Press the +-button to go on to the
next page
If a variable or screw compressor
is chosen in the first line, its type
must be determined in the next
line.
In our example we select:
- External compressor stop
- VSD + single step
- 4 compressors
- P0 as signal to the regulation
- Cyclic
Lead compressors
The following options are available for variable:
The following options are available for screw compressors:
No. of compressors
Set total number of compressors
No. of unloaders
Set number of unloader valves
Ext. compressor stop
An external switch can be connected which will start and stop
the compressor control.
Control sensor
Po: Suction pressure Po is used for control
S4: Media temperature S4 is used for control
Step control mode
Select coupling pattern for compressors
Cyclic: Runtime equalisation between compressors (FIFO)
Best fit: Compressors are cut in/out in order to make the best
possible fit to actual load
Pump down
Select whether a pump down function is required on the last
running compressor
Pump down limit To (-80 to +30 °C)
Set the actual pump down limit
Synchronous speed.
Select whether the two compressors must operate synchronously.
VSD min speed (0.5 – 60.0 Hz)
Min. speed where the compressor must cutout
VSD start speed (20.0 – 60.0 Hz)
Minimum speed for start of Variable speed drive (Must be set
higher than “VSD Min. Speed Hz”)
VSD max speed (40.0 – 120.0 Hz)
Highest permissible speed for the compressor motor
56 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Configuration - continued
5. Set values for capacity of the
compressors
Press the +-button to go on to the
next page
6. Set values for main step and any
unloaders
Press the +-button to go on to the
next page
7. Set values for safe operation
Press the +-button to go on to the
next page
In our example there are no
unloaders and hence no changes.
In our example we select:
- Safety limit for discharge
temperature = 120°C
- Safety limit for high condensing
pressure = 103.5 bar
- Safety limit for low suction
pressure = -40°C
- Alarm limit for high suction
pressure = -5°C
- Alarm limit for min. and max.
superheat, respectively = 5 and
35 K.
VSD safety monitoring
Select this if input for monitoring of the frequency converter
is required
PWM period time
Period time for bypass valve (on time + off time)
PWM Min. capacity
Minimum capacity in the period time (without a minimum
capacity the compressor will not be cooled)
PWM Start capacity
Minimum capacity at which the compressor will start
Load shed limits
Select how many load shedding inputs are required
Load limitation period
Set the maximum time permitted for load limitation
Load shed limit 1
Set max capacity limit for load shed input 1
Load shed limit 2
Set max capacity limit for load shed input 2
Override limit To
Any load below the limit value is freely permitted. If the T0
exceeds the value, a time delay is started. If the time delay
runs out, the load limit is cancelled
Override delay 1
Max. time for capacity limit, if P0 is too high
Override delay 2
Max. time for capacity limit, if P0 is too high
Easy PI Selection
Group setting for the 4 control parameters: Kp, Tn, + acceleration
and - acceleration. If the setting is set to “user defined” the 4
control parameters can be fine-tuned.
Kp To (0.1 – 10.0)
Amplifications factor for PI regulation
Tn To
Integration time for PI-regulation
+ Zone acceleration (A+)
Higher values result in a faster regulation
- Zone acceleration (A-)
Higher values result in a faster adjustment
Advanced settings
To filter
Reduce changes in the To reference
Pc filter
Reduce changes in the Pc reference
Initial start time (15 – 900 s)
The time after start-up where the cut-in capacity is limited to
the first compressor step.
Unloading mode
Select whether one or two capacity controlled compressors
are allowed to be unloaded at the same time at decreasing
capacity
Compressor Run signal DO
By "Yes" is reserved an outlet which shows whether the
compressors are running
AO filter
Absorber changes at the analog output
AO max. limit
Limit the voltage on the analog output.
5 - Compressors
In this screen the capacity distribution between the compressors is defined.
Capacities that need to be set depend upon the “compressor
application” and “Step control mode” that has been selected.
Nominal capacity (1.0 – 1000.0 m
Set the nominal capacity for the compressor in question.
For compressors with variable speed drive the nominal
capacity must be set for the mains frequency (50/60 Hz)
Unloader
Number of unload valves for each compressor (0-3)
6 - Capacity distribution
The installation is dependent on the combination of compressors and coupling pattern.
Main step
Set the nominal capacity of the main step (Set the percentage of the relevant compressor’s nominal capacity) 0 100%.
Unload
Readout of the capacity on every unloading 0-100%.
3
/h)
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 57
Configuration - continued
8. Set monitoring of compressor
Press the +-button to go on to the
next page
9. Set operation time for compressor
Press the +-button to go on to the
next page.
10. Set Misc. functions
In our example we use:
- Common high-pressure pressure
control for all compressors
- One general safety monitoring
unit for each compressor
(The remaining options could have
been selected if specific safety
controls for each compressor had
been required).
Set min. OFF-time for the compressor relay
Set min. ON-time for the compressor relay
Set how often the compressor is
allowed to start
The settings only apply to the
relay that cuts the compressor
motor in and out.
They do not apply to unloaders.
If the restrictions overlap, the
controller will use the longest
restriction time.
7 - Safety
Emergency cap. day
The desired cut-in capacity for daily use in the case of emergency operations resulting from error in the suction pressure
sensor/ media temperature sensor.
Emergency cap. night
The desired cut-in capacity for night operations in the case
of emergency operations resulting from error in the suction
pressure sensor/ media temperature sensor.
Sd max limit
Max. value for discharge gas temperature
10 K below the limit, the compressor capacity should be
reduced and the entire condenser capacity will be cutin.
If the limit is exceeded, the entire compressor capacity will
be cutout
Pc Max limit
Maximum value for the condenser pressure in °C
3 K below the limit, the entire condenser capacity will be
cutin and the compressor capacity reduced.
If the limit is exceeded, the entire compressor capacity will
be cutout.
Pc Max delay
Time delay for the alarm Pc max
T0 Min limit
Minimum value for the suction pressure in °C
If the limit is reduced, the entire compressor capacity will be
cutout.
T0 Max alarm
Alarm limit for high suction pressure P0
T0 Max delay
Time delay before alarm for high suction pressure P0.
Safety restart time
Common time delay before restarting the compressor.
(Applicable to the functions: "Sd max. limit", Pc max. limit"
and "P0 min. limit).
SH Min alarm
Alarm limit for min. superheat in suction line.
SH Max alarm
Alarm limit for max. superheat in suction line.
SH alarm delay
Time delay before alarm for min./max. superheat in suction line.
8 - Compressor safety
Common safety
Choose whether an overall, common safety input for all
compressors is desired. If the alarm is activated, all compressors will be cutout.
Oil pressure etc
Define here whether this type of protection should be connected.
For "General", there is a signal from each compressor.
Sd sensor pr. compressor
One shared Sd reading or one Sd sensor for each compressor.
In our example we do not use
these functions.
9 - Minimum operation times
Configure the operation times here so "unnecessary operation" can be avoided.
Restart time is the time interval between two consecutive
starts.
Cutout delay
The time delay resulting from drop-out of automated safety
measures and until the compressor-error is reported. This
setting is common for all safety inputs for the relevant
compressor.
Restart delay
Minimum time that a compressor should be OK after a safety
cut-out. After this interval it can start again.
10 - Misc. functions
Injection On
Select this function if a relay must be reserved for the function. (The function must be wired to controllers with expansion valves in order to close liquid injection for the safety
cut-out of the last compressor.)
Network: The signal is sent to the controllers via data
communication.
Liq. inj suction line
Select the function if a liquid injection is required in the suction line in order to keep the discharge gas temperature down.
Regulation can be done either using a solenoid valve and a
TEV, or using an AKV valve.
58 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
AKV OD suction line
Opening degree of the valve in %
Inject start SH
Superheat value where the liquid injection starts
Inject diff SH
Differential when adjusted for superheat
Inject start Sd temp.
Start temperature for liquid injection in suction line
Inject diff. Sd temp.
Differential when adjusted on Sd
SH Min suction line
Minimum superheat in suction line
SH Max suction line
Maximum superheat in suction line
AKV period time
Periode time for AKV valve
Inject delay at start up
Delay time for liquid injection at start-up
Screw compresssor:
Special settings for screw compressors
Use Economizer
Select whether the controller should control an EVR for an
ECO function.
Use Liq. Injection (individual Sd)
Select whether there should be liquid injection to the
compressor in the event of high Sd. Must be stopped
again 20 K below “Max discharge”.
Output type: Select the valve signal for the stepper or
analogue signa here.
Max liquid injection OD
Set the maximum degree of opening of the valve as a %.
Max discharge
Maximum Sd temperature in the event of any individual
Sd readings.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 59
Configuration - continued
Set control of suction group LT
1. Go to Configuration menu
2. Select Suction group
3. Set values for the reference
All setting options are identical to those for an MT group.
However, it is not possible to choose screw compressors.
Please refer to the previous pages.
Press the +-button to go on to the
next page.
4. Set values for capacity control
Press the +-button to go on to the
next page.
60 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Configuration - continued
5. Set values for capacity of the
compressors
Press the +-button to go on to the
next page.
6. Set values for main step and any
unloaders
Press the +-button to go on to the
next page.
7. Set values for safe operation
Press the +-button to go on to the
next page.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 61
Configuration - continued
8. Set monitoring of compressor
Press the +-button to go on to the
next page.
9. Set operation time for compressor
Press the +-button to go on to the
next page.
10. Set Misc. functions
62 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Configuration - continued
Set oil management
1. Go to Configuration menu
2. Select Oil management
3. Set refrigeration circuit MT
Press the +-button to go on to the
the LT circuit
4. Set refrigeration circuit LT
Press the +-button to go on to the
next page
In our example oil control is not
used on the MT circuit.
(Oil equalisation may be defined
using “Select plant type...” but only
for cyclical compressor operation.)
We do not use safety relays in our
example.
In this example, we want to
control the oil receiver.
This is done with a pressostat.
The pressostat should be set as
follows:
- Select pressure transmitter
When the pressure drops in the
receiver, the valve should open.
- Set the pressure level at which
the valve should open. Set at 18
bar, here.
- Set the pressure level, at
which the valve should close
completely again. Set at 22 bar,
here.
In the example, we have two level
switches in the receiver. Both one
high and one low.
3
Oil equalisation MT
Use oil equalisation
(Only possible with cyclic operation and compressors
without unloader)
Interval time
Set how often a compressor must pause during full
operation.
Equalisation time
Set the duration of the oil equalisation (the pause).
4
Use oil equalisation
(Only possible with cyclic operation and compressors
without unloader)
Interval time
Set how often a compressor must pause during full
operation.
Equalisation time
Set the duration of the oil equalisation (the pause).
Oil control safety relay
If this setting is set to YES, the controller will reserve a safety
relay for each compressor. The relay terminal is connected
in series to the compressor relay. The relay can hereby
stop the compressor, if a lack of oil is registered when the
compressor is force controlled. (Forced controlled to ON
with the setting "Manual" or with the "changeover" on an
extension module.)
Danfoss recommends this function to avoid any compressor damages due to lack of care.
(In order to keep things simple, this function is not used as
an example.)
Oil receiver
Select whether you wish to activate pressure regulation in
one of the oil receivers.
Level switch receiver
Define the desired level sensors. Only High / High and low
Level alarm delay
Delay time tor level alarm
Input for pressure build
Select whether the pressure is controlled by a pressostat or
signal from the pulse counter.
Comp. per. to start seq.
(For pulse counter): Percentage value of total pulses of the
different compressors
Pressure buildup seq.
(For pulse counter) Select between:
Only pulses from the HP circuit. Pulses from both HP and
LP are included
Actual pressure
Measured value
Actual state
Status of oil separation
Cut out pressure
Receiver pressure for shutting off oil
Cut in pressure
Receiver pressure for turning on oil
High alarm limit
An alarm is given if a higher pressure is registered
High alarm delay
Time delay for alarm
High alarm text
Write an alarm text
Low alarm limit
An alarm is given if a lower pressure is registered
Low alarm delay
Time delay for alarm
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 63
Configuration - continued
5. Set oil management for the
compressors
Press the +-button to go on to the
next page.
6. Set oil separator
In our example, the oil supply is
controlled separately for each
individual compressor.
The settings are shown here in
the diagram.
The process is as follows:
20 seconds after the signal from
the level switch is given, the oil
injection starts. This pulsates
three times with one minute
intervals. Each pulse lasts one
second. Then there is a pause for
20 seconds. If the level switch
has not registered any oil at this
point, the compressor is stopped.
In our example, there is only one
single separator that has just one
level switch.
The settings are shown here in
the diagram.
The process is as follows:
When a signal is given from the
level switch, the discharging
process to the receiver
commences. This pulsates three
times with one minute intervals.
Each pulse lasts one second. If
the level switch does not register
an oil drop at this point, an alarm
is given when the delay time has
expired.
Low alarm text
Write an alarm text
5
Compressor oil setup
Select whether the oil supply to all the compressors is to
be shared at the same time or whether each compressor is
to be controlled separately.
Advanced stop control
'Yes' means pulses will be allowed following compressor
stop
Oil cycle pre delay
Delay time before oil pulses commence
Oil cycle post delay
Delay time for signal that will stop oil pulses
High oil alarm delay
If an activation of the level switch is not registered
before the time has expired, an alarm will be given. (the
compressor not use the oil).
No of periods
No. of pulses that are to be enabled in a oil filling sequence
No of periods before stop (Advanced stop control =
yes)
If oil is still missing after this number of pulses, the
compressor is stopped. The remaining number of pulses
will then be permitted.
Period time
Time between pulses
Oil valve open time
The valve's opening time for each pulse.
6
Separator
Select whether there should be one shared separator for
all the compressors or one separator for each compressor.
Level switch
Select whether the separator is to be controlled by "one in
which all pulses are carried out", "one in which the pulse
sequence is stopped by the switch-level " or one in which
the level is held between "High" and "Low".
Level alarm delay
Alarm given when using a level switch for low level.
Repeat oil return cycle
Time period between repeat emptying processes from the
separator if the level switch stays at high level.
No oil sep. alarm delay
Alarm delay when a signal is given that oil is not being
separated ("high" level contact not activated)
No of periods
No. of times the valve should open in emptying sequence
Period time
Time between valve openings.
Open time
The open time of the valve
64 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Configuration - continued
Setup control of condenser fans
1. Go to Configuration menu
2. Select Condenser fan control
3. Set control mode and reference
Press the +-button to go on to the
next page
4. Set values for capacity regulation
In our example the condenser
pressure is controlled on the basis
of the Pc and from Sc3 (floating
reference).
The settings shown here in the
display.
In our example we use a number of
fans that are all speed-controlled
in parallel.
The settings shown here in the
display.
For your information the function
”Monitor fan safety” will require
an input signal from each fan.
3 - PC reference
Control sensor
Pc: The condensing pressure PC is used for regulation
S7: Media temperature is used for regulation
Reference Mode
Choice of condenser pressure reference
Fixed setting: Used if a permanent reference is required =
“Setting”
Floating: Used if the reference is changed as a function
of Sc3 the external temperature signal, the configured
"Dimensioning tm K"/"Minimum tm K" and the actual cut in
compressor capacity. (Liquid is recommended for CO2 and
heat recovery.)
Setpoint
Setting of desired condensing pressure in bar
Min. tm
Minimum average temperature difference between Sc3 air
and Pc condensing temperature with no load.
Dimensioning tm
Dimensioning average temperature differential between Sc3
air and Pc condensing temperature at maximum load (tm
difference at max load, typically 8-15 K).
Min reference
Min. permitted condenser pressure reference
Max reference
Max. permitted condenser pressure reference
Show Tc
Set whether Tc should be displayed.
4 - Capacity control
Capacity control mode
Select control mode for condenser
Step: Fans are step-connected via relay outputs
Step/speed: The fan capacity is controlled via a combination
of speed control and step coupling
Speed: The fan capacity is controlled via speed control
(frequency converter)
Speed 1.step: First fan speed controlled, rest step coupling
No of fans
Set number of fans.
Monitoring fan safety
Safety monitoring of fans. A digital input is used to monitor
each fan.
Fan speed type
VSD (and normal AC motors)
EC motor = DC controlled fan motors
VSD start speed
Minimum speed for start of speed control (Must be configured higher than "VSD Min. Speed %")
VSD min Speed
Minimum speed whereby speed control is cut-out (low
load).
VSD safety monit.
Choice of safety monitoring of frequency converter. A digital
inlet is used for monitoring the frequency converter.
EC Start capacity
The regulation awaits this need to arise before supplying
voltage to the EC motor
EC min
Voltage value at 0% capacity (20% = 2V @ 0-10V)
EC max
Voltage value at 100% capacity (80% = 8V @ 0-10V)
EC abs. max
Permissible live voltage for EC motor (over capacity)
Absolut max Tc
Max value for Tc
Control type
Choice of control strategy
P-band: The fan capacity is regulated via P-band control. The
P band is configured as "Proportional band Xp"
PI-Control: The fan capacity is regulated by the PI controller.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 65
Configuration - continued
Continues
Continued
Kp
Amplification factor for P/PI controller
Tn
Integration time for PI controller
Capacity limit at night
Setting of maximum capacity limit during night operations.
Can be used to limit fan speed at night in order to limit the
noise level.
Monitor Air flow
Choose whether monitoring is required of the condenser's
air flow via an intelligent error-detection method.
Monitoring requires the use of a Sc3 outer temperature sensor, which must be fitted by the condenser's air inlet.
If "yes", the following settings will become visible:
FDD setting
Set error-detection function
Tuning: Will initiate a routine with a duration of 72
hours, where the controller makes an adjustment to the
condenser concerned. Note that tuning should only be
done when the condenser is operating under normal
operating conditions.
ON: (RUN) is completed and monitoring has commenced.
OFF: Monitoring is cut out.
FDD sensitivity
Set the sensitivity of error-detection on the condenser’s
air flow. Must only be changed by trained staff.
Air flow tuning value
Actual tuning values for air flow.
66 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Configuration - continued
Set control of cascade heat exchanger
1. Go to Configuration menu
2. Select Cascade control
3. Set values for the control
3
Parallel cascade
Select whether the controller should control one cascade or two cascades
in parallel.
Sensor
Selection of control sensor: Scasc3 is normally used, but if the Sd-LT temperature is representative, this sensor can be selected.
Output type
Selection of signal for control of expansion valve:
Step valve; possibly two in parallel.
Voltage signal
AKV valve; possibly two in parallel (AKV is not recommended near the
plate heat exchangers).
EVR in liquid line
If a signal is required for a magnet valve in the liquid line.
Injection start signal
No signal
Signal from LT control
The signal must be mounted on a DI input.
Signal to ext. cascade
The controller can send a signal to an external cascade control.
DI for manual control
Select whether to reserve an input for manual start/stop of control of each
of the cascaded
SH close, SH min, SH max
Values for control of superheat.
MOP-MT
MOP-temperature for MT circuit.
Tc-LT min
Minimum temperature for Tc in LT circuit
Tc-LT max
Maximum temperature for Tc in LT circuit
Advanced settings
Choose whether the technical control settings are to be visible.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 67
Configuration - continued
Setup control of heat
recovery
1. Go to Configuration menu
2. Select heat recovery
3. Define heat recovery circuits
We have not used this function
in our example. It is included for
guidance only.
(This function will only display
in the configuration menu if it is
enabled in the "Select plant type"
menu.)
3 -Heat recovery
Heat recovery mode
Thermostat: Heat recovery operated from thermostat
Digital input: Heat recovery operated from signal on a
digital input.
Heat recovery relay
Choose whether an output is required that should be
activated during heat recovery.
Heat recovery ref
Reference for the condensing pressure, when heat
recovery is activated.
Heat recovery ramp down
Configure how quickly the reference for the condenser
pressure should be ramped down to normal level after
heat recovery. Configure in Kelvin per minute.
Heat recovery cutout
Temperature value where the thermostat cuts-out the
heat recovery.
Heat recovery cutin
Temperature value where the thermostat cuts-out the
heat recovery.
Setup control of pump function
1. Go to Configuration menu
2. Select cold pump control
3. Define pump control
We have not used this function
in our example. It is included for
guidance only.
(This function will only display
in the configuration menu if it is
enabled in the "Select plant type"
menu.)
3 - Pumps
No of pumps (0, 1 or 2)
Cold pump control
Pump operation is defined here:
0: No pumps in operation
1: Only pump 1 in operation
2: Only pump 2 in operation
3: Both in operation
4: Operating time equalisation. Start before stop
5: Operating time equalisation. Stop before start
Pump cycle time
Operating time before changeover to the second pump
(1-500h)
Pump switch time
Overlapping time, where both pumps are in operation
with "start before stop" or break time with "stop before
start" (0-600 sec)
Monitor pump flow
Choose whether to have monitoring using a flow switch.
Pump alarm delay
Delay from drop out of flow switch to alarm.
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Configuration - continued
Setup Display
1. Go to Configuration menu
2. Select Display setup
3. Define which readings are to be
shown for the individual outputs
In our example, separate displays
are not used. The setting is
included here for information.
3 - Display setup
Display
The following can be read for the four outputs..
Comp. control sensor
P0 in temperature MT and LT
P0 i bar-absolute MT and LT
S4 MT
Ss MT
Sd MT
Sd LT
Cond. control sensor
Tc M T
Pc MT bar-absolute
TC LT
PC LT bar absolute
S7
Scasc2
Scasc3
Sc3
Compressor speed MT
Compressor speed LT
Unit readout
Choose whether readings are to be in SI units (°C and bar) or
(US-units °F and psi)
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Configuration - continued
Setup Functions for General purpose
1. Go to Configuration menu
2. Select General purpose
3. Define number of required
functions
3
The following number of different functions can be
defined:
3 thermostats
3 pressostats
3 voltage signal
10 alarm signals
3 PI-regulations
We have not used the general
purpose functions in our
example. The images are included
for guidance only.
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Configuration - continued
Separate thermostats
1. Select thermostats
2. Select actual thermostat
3. Define the required thermostat
functions
We have not used this function
in our example. The image is
included for guidance only.
3 - Thermostats
The general thermostats can be used to monitor the temperature sensors that are used, as well as 4 extra temperature
sensors. Each thermostat has a separate outlet to control
external automation.
For each thermostat adjust
• Whether the thermostat should also be shown in overview
display 1.
(The function is always shown in overview display 2)
• Name
• Which of the sensors is used
Actual temp.
Temperature measurement on the sensor that is attached to
the thermostat
Actual state
Actual status on the thermostat outlet
Cut out temp.
Cut-out value for the thermostat
Cut in temp.
Cut-in value for the thermostat
High alarm limit
High alarm limit
Alarm delay high
Time delay for high alarm
Alarm text high
Indicate alarm text for the high alarm
Low alarm limit
Low alarm limit
Alarm delay low
Time delay for low alarm
Alarm text low
Indicate alarm text for low alarm
Separate pressostats
1. Select pressostats
2. Select actual pressostat
3. Define the required pressostat
functions
4 - Pressostats
Settings as the thermostats
3 - Pressostats
Settings as the thermostats
In our example, separate
pressostat functions are not used.
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Configuration - continued
Separate voltage signals
1. Select Voltage inputs
2. Select actual voltage signal
3. Define the required names
and values attached to the
signal
In our example we do not use
this function, so the display
has been included for your
information only.
The name of the function may be
xx and further down in the display
the alarm texts may be entered.
The values ”Min. and Max.
Readout” are your settings
representing the lower and upper
values of the voltage range. 2V
and 10V, for example. (The voltage
range is selected during the I/O
setup).
For each voltage input defined
the controller will reserve a
relay output in the I/O setup.
It is not necessary to define
this relay if all you require is
an alarm message via the data
communication.
3 - Voltage inputs
The general volt inlet can be used to monitor external voltage signals. Each volt inlet has a separate outlet to control
external automatic controls.
Set the number of general voltage inputs, specify 1-3:
Show on overview
Name
Select sensor (signal, voltage)
Select the signal which the function should use
Actual value
= read-out of the measurement
Actual state
= read-out of outlet status
Min. readout
State read-out values at minimum voltage signal
Max. readout
State read-out values at maximum voltage signal
Cutout
Cut-out value for outlet (scaled value)
Cutin
Cut-in value for outlet (scaled value)
Cutout delay
Time delay for cut-out
Cut in delay
Time delay for cut-in
High alarm limit
High alarm limit
High alarm delay
Time delay for high alarm
High alarm text
Set alarm text for high alarm
Low alarm limit
Low alarm limit
Low alarm delay
Time delay for low alarm
Low alarm text
Indicate alarm text for low alarm
Separate alarm inputs
1. Select General alarm inputs
2. Select actual alarm signal
3. Define the required names
and values attached to the
signal
72 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
We have not used this function
in our example. It is included for
guidance only.
3 - General alarm input
This function can be used to monitor all kinds of digital
signals.
No. of inputs
Set the number of digital alarm inputs
Adjust for each input
• Show on overview
• Name
• Delay time for DI alarm (common value for all)
• Alarm text
Configuration - continued
Separate PI functions
1. Select PI functions
2. Select actual PI-function
3. Define the required names
and values attached to the
function
In our example we do not use
this function, so the display
has been included for your
information only.
3 - General PI Control
The function can be used for optional regulation.
Adjust for each regulation
• Show on overview
• Name
• Quick settings
Here is a list of suggestions for PI regulations:
• Control mode: Off, Manual or Auto
• Control type: P or PI
• External DI ctrl: Adjusted to On if there is an external switch
that can start/stop the regulation.
• Input type: Choose which signal the regulation shall receive:
Temperature, pressure, pressure converted to temperature,
, voltage signal, Tc, Pc, Ss, Sd etc.
• Reference: Either fixed or signal for the variable reference::
Choose between: : Non, temperature, pressure, pressure
converted to temperature, voltage signal, Tc, Pc, Ss, DI etc..
• Setpoint: If fixed reference is choosen
• Reading the total reference
• Output. Here you select the outlet function (PWM = pulse
width modulated (fx AKV valve)), Stepper signal for a stepper motor or voltage signal.
• Alarm mode: Choose whether an alarm shall be attached to
the function. If it is set to ON, alarm texts and alarm limits
can be entered.
• Advanced ctrl. settings:
• Ref. X1, Y1 and X2,Y2: Points that define and limit the
variable reference
• PWM period time: Period during which the signal has
been on and off.
• Kp: Amplification factor
• Tn: Integration time
• Filter for reference: Duration for smooth changes to the
reference
• Max. error: Maximum permissible fault signal at which the
integrator remains in the regulation
• Min. control output: Lowest permitted output signal
• Max. control output: Maximum permitted output signal
• Start up time: Time at startup at which the output signal is
force-controlled
• Startup output: The output signal size at the startup time.
• Stop output signal. Size of the output signal when regula-
tion is off.
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Configuration - continued
Conguration of inputs
and outputs
1. Go to Configuration menu
2. Select I/O configuration
3. Configuration of Digital outputs
Press the +-button to go on to the
next page
4. Setup On/off inputs
Press the +-button to go on to
the next page.
The following displays will depend on the earlier definitions. The displays will show which connections the earlier settings will require. The
tables are the same as shown earlier.
• Digital outputs
• Digital inputs
• Analog outputs
• Analog inputs
Load Output Module Point Active at
Solenoid valve, oil, Comp. 1 LT DO1 1 12 ON
Solenoid valve, oil, Comp. 2 LT DO2 1 13 ON
Solenoid valve, oil separator DO5 1 16 ON
Solenoid valve, cascade D06 1 17 ON
EC motor ON/OFF signal DO7 1 18 ON
Compressor 1, MT DO1 2 1 ON
Compressor 2, MT DO2 2 2 ON
Compressor 3. MT DO3 2 3 ON
Compressor 4, MT DO4 2 4 ON
Compressor 1, LT DO5 2 5 ON
Compressor 2, LT DO6 2 6 ON
We set up the controller’s digital outputs by keying in which module
and point on this module each one of these has been connected to.
We furthermore select for each output whether the load is to be active
when the output is in pos. ON or OFF.
Function Input Module Point Active at
Level switch, oil, comp.1 LT AI8 1 8 Closed
Level switch, oil, comp.2 LT AI9 1 9 Closed
Level switch, oil, receiver High AI1 3 1 Closed
Level switch, oil, receiver Low AI2 3 2 Closed
Level switch, oil, Separator High AI3 3 3 Closed
Reset of compressor stop AI5 3 5
Compressor 1 Gen. Safety MT DI1 4 1 Open
Compressor 2 Gen. Safety MT DI2 4 2 Open
Compressor 3 Gen. Safety MT DI3 4 3 Open
Compressor 4 Gen. Safety MT DI4 4 4 Open
All compressors common safety MT DI5 4 5 Open
All compressors common safety LT DI6 4 6 Open
Compressor 1 Gen. Safety LT DI7 4 7 Open
Compressor 2 Gen. Safety LT DI8 4 8 Open
Pulse pressure
We set up the controller’s digital input functions by keying in which
module and point on this module each one of these has been connected
to.
We furthermore select for each output whether the function is to be active when the output is in pos. Closed or Open.
Open has been selected here for all the safety circuits. This means that
the controller will receive signal under normal operation and register it
as a fault if the signal is interrupted.
3 - Outputs
The possible functions are
the following:
Comp. 1
Unloader 1-1
Unloader 1-2
Unloader 1-3
Do for Compressor. 2-4
Oil valve comp. 1-4
Lp comp. oil pulse
Oil valve 1-4
Oil valve separat. 1-4
MT Comp. release
LT Comp. request
Injection heat exchanger
Injection suction line
Injection ON
Fan 1 / VSD
Fan 2 - 8
Heat recovery
Valve tap water V3tw
Pump tap water tw
Valve heat recov. V3hr
Pump heat recov. hr
Alarm
I'm alive relay
Thermostat 1 - 3
Pressostat 1 - 3
Volt input 1 - 3
PI 1-3
4 - Digital inputs
The possible functions are
the following:
Ext. Main switch
Ext. compr. stop
Ext. power loss
Night setback
Load shed 1
Load shed 2
All compressors:
Common safety
Comp. 1
Oil pressure safety
Over current safety
Motor protect. safety
Disch. temp. safety
Disch. press. safety
General safety
VSD comp. 1 Fault
Do for Comp. 2-6
Fan 1 safety
Do for fan 2-8
VSD cond safety
Reset comp. lockout
LP comp.oil counter
Oil receiver low
Oil receiver high
Oil level comp.1-6
Oil separator low 1-6
Oil separator high 1-6
Heat recovery
Stop cascade ctrl
Cold pump flow sw.
Flow switch tw
Flow switch hr
DI 1 Alarm input
DI 2-10 ...
PI-1 Di ref
External DI PI-1
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Configuration - continued
5. Configuration of Analog
outputs
Press the +-button to go on to
the next page
6. Configuration of Analog
Input signals
Function Output Module Point Type
Stepper signal for ETS-valve Step 1 3 9 Steppes
Speed control, compressor, MT AO1 5 5 0 - 10 V
Speed control, compressor, LT AO2 5 6 0 - 10 V
Speed control, EC motor AO3 5 7 0 - 10 V
Sensor Input Module Point Type
Disch. gas temperature - Sd-MT AI1 1 1 Pt 1000
Suction gas temperature - Ss-MT AI2 1 2 Pt 1000
Outdoor temp - Sc3 AI3 1 3 Pt 1000
Disch. gas temperature - Sd-LT AI4 1 4 Pt 1000
Suction gas temperature - Ss-LT AI5 1 5 Pt 1000
Suction pressure - P0-MT AI6 1 6 AKS 32R-12
Condenser pressure - Pc-MT AI7 1 7 AKS 32R-34
Suction pressure - P0-LT AI7 3 7 AKS 2050-59
Condenser pressure - Pc-LT AI8 3 8 AKS 2050-59
Temp. heat exchanger Scasc2 AI1 5 1 Pt 1000
Temp. heat exchanger Scasc3 AI2 5 2 Pt 1000
Oil receiver, Prec Oil AI4 5 4 AKS 2050-59
5 - Analog outputs
The possible signals are
the following:
0 -10 V
2 – 10 V
0 -5 V
1 – 5V
Stepper output
Stepper output 2
6 - Analog inputs
The possible signals are
the following:
Temperature sensors:
• Pt1000
• PTC 1000
Pressure transmitters:
• AKS 32, -1 – 6 bar
• AKS 32R, -1 – 6 bar
• AKS 32, - 1 – 9 bar
• AKS 32R, -1 – 9 bar
• AKS 32, - 1 – 12 bar
• AKS 32R, -1 – 12 bar
• AKS 32, - 1 – 20 bar
• AKS 32R, -1 – 20 bar
• AKS 32, - 1 – 34 bar
• AKS 32R, -1 – 34 bar
• AKS 32, - 1 – 50 bar
• AKS 32R, -1 – 50 bar
• AKS 2050, -1 – 59 bar
• AKS 2050, -1 – 99 bar
• AKS 2050, -1 – 159 bar
• MBS 8250, -1 – 159 bar
• User defined (only
ratiometric, min. and max
value of the pressure
range must be set)
S4 Cold brine
Pctrl
Po suction pres.
Ss suction gas
Sd disch. temp.
Pc Cond. Pres.
S7 Warm brine
Sc3 air on
Ext. Ref. Signal
• 0 – 5 V,
• 0 -10 V
Olie receiver
Prec
Stw2,3,4,8
Shr2,3,4,8
HC 1-5
Heat recovery
Saux 1 - 4
Paux 1 - 3
Voltage input 1 - 5
• 0 -5 V,
• 0 -10 V,
• 1 – 5 V,
• 2 – 10 V
PI-in temp
PI-ref temp
PI- in voltage
PI-in pres.
PI-ref pres.
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Configuration - continued
Set alarm priorities
1. Go to Configuration menu
2. Select Alarm priorities
Very many functions have an alarm connected.
Your choice of functions and settings has connected all the relevant
alarms that are current. They will be shown with text in the three
pictures.
All alarms that can occur can be set for a given order of priority:
• ”High” is the most important one
• ”Log only” has lowest priority
• ”Disconnected” gives no action
The interdependence between setting and action can be seen in the
table.
3. Set priorities for Suction group
Setting
High X X X X 1
Medium X X X 2
Low X X X 3
Log only X 4
Disconnected
Se also alarm text page 128.
Log Alarm relay selection Net-
Non High Low - High
work
AKM dest.
Press the +-button to go on to the next page
In our example we select the settings shown here in the display
4. Set alarm priorities for condenser
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Configuration - continued
Press the +-button to go on to the next page
5. Set alarm priorities for thermostat and extra digital
signals
In our example we select the settings shown here in the display
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Configuration - continued
Lock conguration
1. Go to Configuration menu
2. Select Lock/Unlock configuration
3. Lock Configuration
Press in the field against Configuration lock.
Select Locked.
The setup of the controller has now been locked. If you subsequently
want to make any changes in the controller’s setup, remember first to
unlock the configuration.
The controller will now make a comparison of selected functions and define inputs and outputs. The result can be seen in
the next section where the setup is controlled.
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Configuration - continued
Check conguration
1. Go to Configuration menu
2. Select I/O configuration
3. Check configuration of Digital Outputs
This control requires that the setup is locked
(Only when the setup is locked are all settings for in- and outputs activated.)
An error has occurred, if you see the following:
The setup of the digital
outputs appears as it is supposed to according to the
wiring made.
A 0 – 0 next to a defined function.
If a setting has reverted to 0-0, you must control
the setup again.
This may be due to the following:
• A selection has been made of a combination of
module number and point number that does
not exist.
• The selected point number on the selected module had been set up for something different.
The error is corrected by setting up the output
correctly.
Remember that the setup must be unlocked before you can change module and point numbers..
Press the +-button to go on to the next page
4. Check configuration of Digital Inputs
Press the +-button to go on to the next page
The setup of the digital
inputs appears as it is supposed to according to the
wiring made.
The settings are shown on a RED background.
If a setting has turned red, you must control the
setup again.
This may be due to the following:
• The input or the output has been set up; but the
setup has later been changed so that it should
no longer be applied.
The problem is corrected by setting module
number to 0 and point number to 0.
Remember that the setup must be unlocked before you can change module and point numbers.
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Configuration - continued
5. Check configuration of Analog Outputs
Press the +-button to go on to the next page
6. Check configuration of Analog Inputs
The setup of the analog outputs appears as it is supposed to according
to the wiring made.
The setup of the analog inputs appears as it is supposed to according to
the wiring made.
80 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Check of connections
1. Go to Configuration menu
2. Select I/O status and manual
3. Check Digital Outputs
Before the control is started we check that all inputs and outputs have
been connected as expected.
This controls requires that the setup is locked
By means of the manual control of each output it can be checked
whether the output has been correctly connected.
AUTO The output is controlled by the controller
MAN OFF The output is forced to pos. OFF
MAN ON The output is forced to pos ON
Press the +-button to go on to the next page
4. Check Digital Inputs
Press the +-button to go on to the next page
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Cut out the safety circuit for compressor 1.
Check that LED DI1 on the extension module (module 2) goes out.
Check that the value of the alarm for the safety monitoring of compressor 1 changes to ON.
The remaining digital inputs are checked in the same way.
Check of connections - continued
5. Check Analog outputs
Set Control of output voltage to manual
Press in the Mode field.
Select MAN.
Press in the Value field
Select for example 50%.
Press OK.
On the output you can now measure the expected value: In this
example 5 volts
Example of the connection between a defined output signal
and a manual set value.
Definition Setting
0 % 50 % 100 %
0 - 10 V 0 V 5 V 10 V
1 - 10 V 1 V 5.5 V 10 V
0 - 5 V 0 V 2.5 V 5 V
2 - 5 V 2 V 3.5 V 5 V
6. Put the control of the output voltage back to automatic
Press the +-button to go on to the next page
7. Check Analog inputs
Check that all sensors show sensible values.
In our case we have no values. This may be due to the following:
• The sensor has not been connected.
• The sensor is short-circuited.
• The point or module number has not been set up correctly.
• The configuration is not locked.
82 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Check of settings
1. Go to the overview
2. Select suction group
Before the control starts, we check that all the settings are as they should
be.
The overview display will now show one line for each of the general
functions. Behind each icon there is a number of displays with the
different settings. It is all these settings that have to be checked.
3. Move on through all the individual displays for the
suction group
Change displays with the +- button. Remember the settings at
the bottom of the pages – the ones that can only be seen via
the ”Scroll bar”.
4. Safety limits
5. Go back to the overview. Repeat for LT
The last page contains control data
6. Select condenser group
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Check of settings - continued
7. Move on through all the individual displays for the
condenser group.
Change displays with the +- button. Remember the settings at
the bottom of the pages – the ones that can only be seen via
the ”Scroll bar”.
8. Check the individual pages
The last page contains reference settings.
9. Go back to the overview and move on to the rest of
the functions.
The controller setup has hereafter been completed.
84 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Schedule function
1. Go to Configuration menu
2. Select schedule
3. Setup schedule
We have not used the Schedule function, in which the regulation is
performed via the optimisation of suction pressure, in our example.
Here, the system unit adjusts the suction pressure to the current need —
during both day and night.
Shown on the left is an example of a schedule in which the suction pressure is increased during night-time operation.
In other cases where the controller is installed in a network with one
system unit, this setting may be made in the system unit which will then
transmit a day/night signal to the controller.
Press a weekday and set the time for the day period.
Continue with the other days.
A complete weekly sequence is shown in the display.
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Installation in network
1. Set the address (here, for example 3)
Turn the right-hand address switch so that the arrow will point
at 3.
The arrow of the two other address switches must point at 0.
2. Push the Service Pin
Press down the service pin and keep it down until the Service
Pin LED lights up.
The controller has to be remote-monitored via a network. In this net-
work we assign address number 3 to the controller.
The same address must not be used by more than one controller in the
same network.
Requirement to the system unit
The system unit must be a gateway type AKA 245 with software version
6.0 or higher. It is capable of handling up to 119 AK controllers.
3. Wait for answer from the system unit
Depending on the size of the network it may be up to one
minute before the controller receives an answer as to whether
it has been installed in the network.
When it has been installed the Status LED will start to flash
faster than normal (once every half second). It will continue
with this for about 10 minutes
4. Carry out new login via Service Tool
If the Service Tool was connected to the controller while you
installed it in the network, you must carry out a new login to
the controller via the Service Tool.
Alternatively, it can be an AK-SM 720
or alternatively one form the AK-SM 800 serie.
If there is no answer from the system unit
If the Status LED does not start flashing faster than normal, the controller has not been installed in the network. The reason for this may be
one of the following:
The controller has been assigned an address out of range
Address 0 cannot be used.
If the system unit in the network is an AKA 243B Gateway only the addresses between 1 and 10 can be used.
The selected address is already being used by another controller or
unit in the network:
The address setting must be changed to another (vacant) address.
The wiring has not been carried out correctly.
The termination has not been carried out correctly.
The data communication requirements are described in the document:
”Data communication connections to ADAP-KOOL® Refrigeration Controls” RC8AC.
86 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
First start of control
Check alarms
1. Go to the overview
Press the blue overview button with the compressor and condenser at the bottom left of the display.
2. Go to the Alarm list
Press the blue button with the alarm bell at the bottom of the
display.
3. Check active alarms
In our case, we have a series of alarms. We will tidy them up so that we
only have those that are relevant.
4. Remove cancelled alarm from the alarm list
Press the cross to remove cancelled alarms from the alarm list.
5. Check active alarm again
In our case an active alarm remains because the control has stopped.
This alarm must be active when control has not started. We are now
ready for the startup of control.
Please note that active plant alarms are automatically cancelled when the
main switch is in pos. OFF.
If active alarms appear when the control is started the reason for these
should be found and remedied.
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First start of control - continued
Start the control
1. Go to Start/Stop display
Press the blue manual control button at the bottom of the
display.
2. Start control
Press in the field against Main switch.
Select ON.
The controller will now start controlling the compressors and the fans.
Note:
Control does not start until both the internal and external switch are
“ ON ”.
Any external compressor stop breaker must be ON for the compressors
to start.
88 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Manual capacity control
1. Go to overview
2. Select suction group
Press the suction group button for the suction group that is to
be controlled manually.
Press the +-button to go on to the next page
3. Set capacity control to manual
If you need to manually adjust the capacity of the compressors, you can
use the following procedure:
WARNING!
If you force control the compressors, the oil management will be shut
down. This could cause compressor damages.
(If the wiring of the compressors includes safety relays, monitoring
will continue. See Regulating functions.)
4. Set capacity in percent
Press in the blue field against Manual capacity.
Press the blue field against Control mode
Select MAN.
Set the capacity to the required percentage.
Press OK.
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90 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
5. Regulating functions
This section describes how the different functions work
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Suction group
Controlling sensor selection
Depending on use, the capacity distributor can regulate according
to the suction pressure P0 or a media temperature S4.
Cap. Ctrl sensor = P0 / S4
Example 1 – P0
Example 2 – S4 media sensor
Handling of sensor error
Cap. Ctrl. Sensor = P0
When P0 is used as the regulating sensor, an error in the signal will
mean that regulation continues with fx. 50% cutin in daily operation and 25% cut-in at night, but for a minimum of one step.
Cap. Ctrl. Sensor = S4
Provided that S4 is used as a regulating sensor, an error in this sensor will mean that regulation continues from the P0 signal, but in
accordance with a reference that lies 5K under the real reference.
If there is an error on both S4 and P0, regulation will continue with
fx. 50% cut-in in daily operations and fx. 25% of cut-in in night
operations, but for a minimum of one step.
Used in brine systems in which the MT fittings are cooled by a
brine, and the LT provides condenser heat to the brine.
When the controlling sensor is selected as S4, P0 is used as a safety
function for low suction pressure and will ensure disconnection of
compressor capacity (frost protection).
92 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Reference
The reference for the regulation can be defined in 2 ways:
Either
Reference = Set point + P0 optimization
or
Reference = Set point + night displacement + Ext. Ref
Set point
A basic value for the suction pressure is set.
Forced operation of the compressor capacity in the suction
group
A forced operation of the capacity can be carried out which
disregards the normal regulation.
Depending on the selected form of forced operation, the safety
functions will be cancelled.
Forced operation via overload of requested capacity
The control is set to manual and the desired capacity is set in % of
the possible compressor capacity.
P0 optimization
This function displaces the reference so that regulation will not
take place with a lower suction pressure than required.
The function cooperates with controllers on the individual
refrigeration appliances and a system manager. The system
manager obtains data from the individual regulations and adapts
the suction pressure to the optimum energy level. The function is
described in the manual for the System manager.
With this function you can read which appliance is most heavily
loaded at the moment as well as the displacement allowed for the
suction pressure reference.
Night displacement
The function is used to change the suction pressure reference for
night time operation as an energy saving function.
With this function the reference can be displaced by up to 25 K
in positive or negative direction. (When you displace to a higher
suction pressure, a positive value is set).
Displacement can be activated in three ways:
• Signal on an input
• Signal from a system unit
• Internal time schedule
The “night displacement” function should not be used when
regulation with the override function “P0-optimisation” is performed.
(Here the override function will itself adapt the suction pressure to the
max. permissible).
Forced operation via overload of digital outlets
The individual outputs can be set to MAN ON or MAN OFF in the
software. The control function disregards this but an alarm is sent
out that the outlet is being overridden.
Forced operation via change-over switches
If the forced operation is done with the switch-over on the front of
an expansion model, this is not registered by the control function and no alarm is sounded. The controller continues to run and
couples with the other relays.
If a short change in the suction pressure is needed (for example,
up to 15 minutes in connection with defrosting) the functions can
be applied. Here the PO-optimisation will not have time to compensate for the change.
Override with a 0 - 10 V signal
When a voltage signal is connected to the controller the reference
can be displaced. In the setup it is defined how big a displacement
is to take place at max. signal (10 V) and at min. signal.
Limitation of reference
To safeguard yourself against a too high or too low regulation
reference, a limitation of the reference must be set.
Reference
Max.
Min.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 93
Capacity control of compressors
PI-control and control zones
AK-PC 783A can control up to 12 compressors. Max. 6MT + 6LT or
7MT + 5LT or 8MT + 4LT. Each compressor can have up to 3 unloaders. One or two of the compressors can be equipped with speed
regulation.
The cut-in capacity is controlled by signals from the connected
pressure transmitter and the set reference.
Set a neutral zone around the reference .
In the neutral zone, the regulating compressor controls the
capacity so that pressure can be maintained. When it can no
longer maintain the pressure within the neutral zone, the controller will cut out or cut in the next compressor in the sequence.
When further capacity is either cut out or cut in, the capacity
from the regulating compressor will be modified accordingly
to maintain the pressure within the neutral zone (only where
the compressor has variable capacity).
– When the pressure is higher than the “reference + a half neutral
zone”, cut-in of the next compressor (arrow up) is permitted.
– When the pressure is lower than the “reference - a half neutral
zone”, cut-out of a compressor (arrow down) is permitted.
– When the pressure is within the neutral zone, the process
will continue with the currently activated compressors. Unload
valves (if present) will activate, depending on whether suction
pressure is above or below the reference value.
Suction pressure P0
Example:
4 compressor of equal size - The capacity curve will look like this
Cut-out of the last compressor stage:
Normally, the last compressor step will only be cut-out when the
required capacity is 0% and the suction pressure is below the
neutral zone.
Operation time first step
At start-up the refrigeration system must have time to be stable
before the PI controller takes over the control. For this purpose at
start-up of a plant a limitation is made of the capacity so that only
the first capacity step will cutin after a set period (to be set via
"runtime first step").
Pump down function:
To avoid too many compressor starts/stops with low load, it is possible to define a pump down function for the last compressor.
Change capacity
The controller will cutin or cutout capacity based on these basic
rules:
Increase capacity:
The capacity distributor will start extra compressor capacity as
soon as the requested capacity has increased to a value, which
allows the next compressor step to start. Referring to below
example - a compressor step is added as soon as there is “Room”
for this compressor step below the requested capacity curve.
Decrease capacity:
The capacity distributor will stop compressor capacity as soon
as the requested capacity has decreased to a value, which allows
the next compressor to stop. Referring to below example - a
compressor step is stopped as soon as there is no more “Room” for
this compressor step above the requested capacity curve.
If the pump down function is used, the compressors will be cutout when the actual suction pressure is down to the configured
pump down limit.
Note that the configured pump down limit should be set higher
than the configured safety limit for low suction pressure "Min Po".
94 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Variable integration time
There are two parameters, so Tn can be made variable. This allows
control to be more rapid, the further pressure deviates from the
reference.
The A+ setting will lower Tn when the pressure is above the reference, and the A- setting will lower Tn when the pressure is below
the reference.
Tn has been set to 120 s in the graph below, and falls to 60 s if the
pressure is above the reference and to 40 s if the pressure is below
the reference.
Above the reference: Set Tn divided by the A+ value.
Below the reference: Set Tn divided by the A- value.
The controller calculates the curve, such that regulation is smooth.
Regulation parameters
To make it easier to start up the system, we have grouped regulation parameters into sets of commonly used values, called "Easysettings". Use these to choose between sets of settings appropriate for a system which responds slowly or quickly. The factory
setting is 5.
If you need to fine tune the control, select the "User defined" setting. All parameters can then be freely adjusted.
Easy-
Settings
1 = Slowest 1.0 200 3.5 5.0
2 1.3 185 3.5 4.8
3 = Slower 1.7 170 3.5 4.7
4 2.1 155 3.5 4.6
5 = Default 2.8 140 3.5 4.4
6 3.6 125 3.5 4.2
7 = Faster 4.6 110 3.5 4.1
8 5.9 95 3.5 4.0
9 7.7 80 3.5 3.8
10= Fastest 9.9 65 3.5 3.5
User defined 1.0 - 10.0 10 - 900 1.0 - 10.0 1.0-10.0
Kp Tn A+ A-
Regulation parameters
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 95
Capacity distribution methods
The capacity distributor can work based on 2 distribution
principles.
Coupling pattern – Cyclical operation:
This principle is used if all compressors are of the same type and
size. (though not speed-controlled).
The compressor cuts-in and cuts-out in accordance with the "First
In First Out" principle (FIFO) to equalise operating hours between
the compressors.
Speed-regulated compressors will always be cut in first, and the
variable capacity is used to fill capacity gaps between the subsequent steps.
Timer restrictions and safety cut outs
If a compressor is prevented from starting because it is “hanging”
on the restart timer or is safety cut out, this step is replaced by
another compressor.
Operating time equalisation
The operating hour equalizing is carried out between compressors
of the same type with the same total capacity.
-At the different startups the compressor with the lowest number
of operating hours will be started first.
- At the different stops the compressor with the highest number of
operating hours will be stopped first.
- For compressors with several steps, the operating time equalizing
is carried out between the compressors’ main steps.
Coupling pattern – Best fit operation
This principle is used if the compressors are of different sizes.
The capacity distributor will cut-in or cut-out the compressor
capacity in order to ensure the least possible capacity jump.
Speed-regulated compressors will always be cut in first, and the
variable capacity will be used to fill capacity gaps between the
subsequent steps.
Timer restrictions and safety cut outs
If a compressor is prevented from starting because it is “hanging”
on the restart timer or is safety-cut out, this step is replaced by
another compressor or another combination.
- The left column shows the operating hours, according to which
the controller equalises.
- The middle column shows (as a percentage) to what extent
the individual compressor has been activated within the last
24 hours.
- The right column shows the compressor's current operating time.
The value should be reset when the compressor is replaced.
96 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
Power pack types – compressor combinations
The controller is able to control power packs with up to 12
compressors of various types:
- One or two speed controlled compressor
- Capacity controlled piston compressors with up to 3 unloader
valves
- Single step compressors - piston or scroll
- One digital scroll compressor
The chart below shows the compressor combination which the
controller is capable of controlling. The chart also shows which
coupling pattern can be set for the individual compressor combinations.
Combination Description Cou-
One-step compressors. *1 x x
pling
pattern
Cyclical
Best fit
In appendix A there is a more detailed description of the coupling
patterns for the individual compressor applications with associated examples.
The following is a description of some general rules for handling
capacity-regulated compressors, speed-regulated compressors
and also for two speed-regulated compressors.
Capacity-regulated compressors with unload valves
"Unloader control mode" determines how the capacity distributor
should handle these compressors.
Unloader control mode = 1
Here the capacity distributor allows only one of the compressors
to be unloaded at a time. The advantage of this setting is that it
avoids operating with several compressors unloaded , which is not
energy efficient.
For example:
Two capacity-regulated compressors of 20 kW, each with 2 unload
valves, cyclical coupling pattern.
The following types of screw compressor may be used for regulations
A compressor with an unload
valve, combined with one-step
compressors. *2
Two compressors with unload
valves, combined with one-step
compressors. *2
All compressors with unload
valves. *2
A speed-regulated compressor combined with one-step
compressors. *1 and *3
A speed-regulated compressor combined with several
compressors with unload valves.
*2 and *3
Two speed-regulated compressors combined with one-step
compressors *4
Screw compressor combined
with one-step compressors
Two screw compressors combined with one-step compressors
Three screw compressors
combined with one-step compressors
x
x
x
x x
x
x x
x
x
x
• For decreasing capacity, the compressor with the most operating
hours is unloaded (C1).
• When C1 is completely unloaded, it is cut-out before compressor
C2 is unloaded.
Unloader control mode = 2
Here the capacity distributor allows two compressors to be unloaded while capacity is decreasing.
The advantage of this setting is it reduces the number of compressor start/stops.
For example:
Two capacity-regulated compressors of 20 kW, each with 2 unload
valves, cyclical coupling pattern.
• For decreasing capacity, the compressor with the most operating
hours is unloaded (C1).
• When C1 is completely unloaded , compressor C2 with one-step
is unloaded before C1 is cut out.
Screw with unloader
0%, 75%, 100%
*1) For a cyclical coupling pattern, the one-step compressors must be the same size.
*2) For compressors with unload valves, it is generally true that they must have the
same size, the same number of unload valves (max 3) and the same sized main
steps. If compressors with unload valves are combined with one-step compressors, all compressors should be the same size.
*3) Speed-regulated compressors can have different sizes in relation to subsequent
compressors.
*4) When two speed-regulated compressors are used, they must have the same
frequency range.
For cyclical coupling patterns, the two speed-regulated compressors should be
the same size and the subsequent one-step compressors should also be the same
size.
Screw with two unloaders
0, 50%, 75%, 100%
Screw with three unloaders + PWM
0 - 100%
Attention!
Relay outputs must not be inverted at unloader valves. The controller inverts the function itself.
There will be no voltage at the bypass valves when the compressor is not in operation.
Power is connected immediately before the compressor is started.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 97
Speed control compressors:
The controller is able to use speed control on the leading
compressor in different compressor combinations. The variable
part of the speed controlled compressor is used to fill in capacity
gaps of the following compressor steps.
General regarding handling:
One of the defined capacity steps for the compressor regulation
may be connected to a speed control unit that may be a
frequency converter type VLT, for example.
An output is connected to the frequency converter’s ON/OFF
input and at the same time an analog output ”AO” is connected to
the frequency converter’s analog input.
The ON/OFF signal will start and stop the frequency converter and
the analog signal will indicate the speed.
It is only the compressor defined as compressor 1 (1+2) that can
be speed controlled.
When the step is in operation it will consist of a fixed capacity
and a variable capacity. The fixed capacity will be the one that
corresponding to the mentioned min. speed and the variable
one will lie between the min. and max. speed. To obtain the
best regulation the variable capacity must be bigger than the
subsequent capacity steps it has to cover during the regulation.
If there are major short-term variations in the plant’s capacity
requirement it will increase the demand for variable capacity.
This is how you cut the step in and out:
Controlling – increasing capacity
If the need for capacity becomes larger than “Max. Speed” then
the subsequent compressor step will be cut-in. At the same time,
the speed on the capacity step will be reduced so the capacity
is reduced with a size that corresponds to exactly the cut-in
compressor step. Thereby a completely "frictionless" transition is
achieved without capacity holes (refer also to sketch).
Controlling – decreasing capacity
If the capacity requirement becomes less than “Min. speed” then
the subsequent compressor step will be cut-out. At the same
time, the speed on the capacity step is increased so the capacity
is increased with a size that corresponds to exactly the cut-out
compressor step.
Cut-out
The capacity step will be cut-out when the compressor has
reached “Min. Speed” and the requested capacity has dropped to
1%.
Timer restriction on speed controlled compressor
If a speed controlled compressor is not allowed to start due to a
timer restriction, no other compressor is allowed to start. When
the timer restriction has expired the speed controlled compressor
will start.
Cutin
The speed-controlled compressor will always be the first to start
and the last to stop. The frequency converter will be started when
a capacity requirement corresponding to the mentioned ”Start
speed” arises (the relay output changes to ON and the analog
output is supplied with a voltage corresponding to this speed).
It is now up to the frequency converter to bring the speed up to
”Start speed”.
The capacity step will now be cut in and the required capacity
determined by the controller.
The start speed always ought to be set so high that a fast
lubrication of the compressor is obtained during the start.
Safety cutout on speed controlled compressor
If the speed controlled compressor is cutout on safety other
compressors are allowed to start. As soon as the speed controlled
compressor is ready to start it will be the first compressor to start.
As mentioned before the variable part of the speed capacity
should be bigger than the capacity of the following compressor
steps in order to achieve a capacity curve without “holes”. In order
to illustrate how the speed control will react at different pack
combinations a couple of examples will be given here:
98 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
a) Variable capacity bigger than following compressor steps:
When the variable part of the speed controlled compressor is
bigger than the following compressors there will be no “holes” in
the capacity curve.
Example:
1 speed controlled compressor with a nominal capacity at 50Hz of
10kw - Variable speed range 30 – 90Hz
2 one step compressors of 10 kW
Fixed capacity = 30 HZ / 50 HZ x 10 kW = 6 kW
Variable capacity = 60 HZ / 50Hz x 10 kW = 12 kW
The capacity curve will look like this:
As the variable part of the speed controlled compressor is bigger
than the following compressor steps, the capacity curve will be
without holes.
1) The speed controlled compressor will be cutin when the
requested capacity has reached the start speed capacity.
2) The speed controlled compressor will increase speed until it
reaches max speed at a capacity of 18 kW.
3) The one step compressor C2 of 10 kW is cut in and the speed on
C1 is reduced too so that it corresponds to 8kW (40Hz)
4) The speed controlled compressor will increase speed until the
total capacity reaches 28 kw at max speed
5) The one step compressor C3 of 10 kW is cut in and the speed on
C1 is reduced too so that it corresponds to 8kW (40Hz)
6) The speed controlled compressor will increase speed until the
total capacity reaches 38 kw at max speed
7) When reducing capacity the one step compressors will be cut
out when the speed on C1 is at minimum
b) Variable part smaller than following compressor steps:
If the variable part of the speed controlled compressor is smaller
than the following compressors there will be “holes” in the
capacity curve.
Example:
1 speed controlled compressor with a nominal capacity at 50Hz of
20kw - Variable speed range 25 – 50Hz
2 one step compressors of 20 kW
Fixed capacity = 25 HZ / 50 HZ x 20 kW = 10 kW
Variable capacity = 25 HZ / 50Hz x 20 kW = 10 kW
The capacity curve will look like this:
As the variable part of the speed controlled compressor is smaller
than the following compressor steps the capacity curve will have
some holes that can not be filled out by the variable capacity.
1) The speed controlled compressor will be cutin when the
requested capacity has reached the start speed capacity.
2) The speed controlled compressor will increase speed until it
reaches max speed at a capacity of 20 kw.
3) The speed controlled compressor will stay at max speed until
the requested capacity has increased to 30 kW.
4) The one step compressor C2 of 20 kW is cut in and the speed
on C1 is reduced to min. so that it corresponds to 10kW (25Hz).
Total capacity = 30 kW.
5) The speed controlled compressor will increase speed until the
total capacity reaches 40 kW at max speed
6) The speed controlled compressor will stay at max speed until
the requested capacity has increased to 50 kW.
7) The one step compressor C3 of 20kW is cut in and the speed
on C1 is reduced to min. so that it corresponds to 10kW (25Hz).
Total capacity = 50 kW
8) The speed controlled compressor will increase speed until the
total capacity reaches 60 kw at max speed
9) When reducing capacity the one step compressors will be cut
out when the speed on C1 is at minimum speed.
AK-PC 783A Capacity controller RS8HN102 © Danfoss 2017-11 99
Two speed-regulated compressors
The controller is capable of regulating the speed of two compressors of the same or different sizes. The compressors can be combined with one-step compressors of the same or different sizes,
depending on the choice of coupling pattern.
General regarding handling:
Generally, the two speed-regulated compressors are managed
according to the same principle as for one speed-regulated compressor. The advantage of using two speed-regulated compressors is that it allows for a very low capacity, which is an advantage
for low loads. At the same time, it produces a very large, variable
regulating area.
Compressor 1 and 2 both have their own relay outlets to start/
stop separate frequency converters, for example of type VLT.
Both frequency converters use the same analog output signal AO
which is connected to the frequency converters’ analog signal
input (they can, however, be configured to run individual signals).
The relay outputs will start and stop the frequency converter and
the analog signal will indicate the speed.
The precondition for using this regulating method is that both
compressors have the same frequency range.
The speed-regulated compressors will always be the first to start
and the last to stop.
Controlling – decreasing capacity
The speed-regulated compressors will always be the last compressors running.
When the capacity requirement during cyclical operations becomes less than "Min. speed" for both compressors, the speedregulated compressor with the most operating hours will be
cut-out. At the same time, the speed of the last speed-regulated
compressor increases so that the capacity is increased to the level
that matches the cut-out compressor’s step.
Cutout
The last speed-regulated compressor will be cut-out when the
compressor has reached ”Min. speed” and the capacity requirement (desired capacity) has decreased to under 1% (see however
the section on the pump down function).
Cut-in
The first speed-regulated compressor will be started when there is
a capacity requirement which matches the setting.
The "Start speed" (relay outlet changes to on and the analog outlet is supplied with a voltage that matches this speed). It is now
up to the frequency converter to bring the speed up to the "Start
speed".
The capacity step will now be cut in and the desired capacity
determined by the controller.
The start speed should always be set so high that a good lubrication of the compressor is quickly reached during start-up.
For a cyclical coupling pattern, the subsequent speed-regulated
compressor will be cut in when the first compressor runs at max.
speed and the desired capacity has reached a value that allows
the cut-in of the next speed-regulated compressor at start speed.
Afterwards, both compressors will be cut in together and will run
in parallel. The following one-step compressors will be cut in and
out in accordance with the selected coupling pattern.
Timer restriction and safety cut-outs
Timer limits and safety cut-outs on speed-regulated compressors should be managed in accordance with the general rules for
individual coupling patterns.
Short descriptions and examples are given below of the handling
of two speed-regulated compressors for the individual coupling
patterns. For a more detailed description, refer to the appendix at
the end of the chapter.
Cyclical operation
For cyclical operations, both speed-regulated compressors will
have the same size and operating hours will be equalized between the compressors in accordance with the First-in-First-Out
Principle (FIFO). The compressor with the least operating hours
will be the first to start. The following speed-regulated compressor
will be cut in when the first compressor runs at max. speed and
the desired capacity has reached a value that allows the cut-in of
the next speed-regulated compressor at start speed. Afterwards,
both compressors will be cut in together and they will run in
parallel. The following one-step compressors will be cut in and out
in accordance with First-In-First-Out principle in order to equalise
operating hours.
100 Capacity controller RS8HN102 © Danfoss 2017-11 AK-PC 783A
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