User Guide
Capacity controller
for small CO2 refrigeration system
AK-PC 772A
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 / EKA 166 ............ 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 MT compressors ...................................................56
Set control of LT compressors .....................................................60
Setup control of condenser fans ...............................................61
Setup control of high pressure ...................................................63
Setup control of receiver pressure ............................................64
Setup control of heat recovery..................................................65
Setup Display .................................................................................... 66
Setup Functions for General purpose ......................................67
Separate thermostat...............................................................68
Separate pressostat ................................................................68
Separate voltage signal .........................................................69
Separate alarm inputs ............................................................ 69
Separate PI function ............................................................... 70
Configuration of inputs and outputs .......................................71
Set alarm priorities..........................................................................73
Lock configuration ..........................................................................75
Check configuration .......................................................................76
Check of connections ............................................................................ 78
Check of settings.....................................................................................80
Schedule function .................................................................................. 82
Installation in network .......................................................................... 83
First start of control ................................................................................84
Start the control ...............................................................................85
Manual capacity control ............................................................... 86
5. Regulating functions .............................................................87
Suction groups ........................................................................................88
Controlling sensor...........................................................................88
Reference ...........................................................................................88
Capacity control of compressors ...............................................89
Capacity distribution methods ........................................... 90
Power pack types – compressor combinations ............91
Compressor timers ..................................................................95
Compressor with variable capacity ................................... 96
Load shedding ..........................................................................97
Injection ON .............................................................................. 97
Liquid injection in common suction line ........................ 98
Safety functions ............................................................................... 98
Condenser / Gas cooler ......................................................................100
Capacity control of condenser .................................................100
Reference for condensing pressure ........................................100
Heat recovery .................................................................................102
Capacity distribution ...................................................................104
EC motor ...........................................................................................104
Step regulation .......................................................................104
Speed regulation ...................................................................104
Condenser couplings ...........................................................105
Safety functions for condenser.........................................105
Circuits for control of CO2 gas pressure ................................106
Receiver control .....................................................................107
Parallel compression ............................................................108
General monitoring functions .........................................................109
Miscellaneous ........................................................................................111
Appendix - Alarm texts .......................................................................116
2 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
1. Introduction
Application
AK-PC 772A is complete regulating units for capacity control of
compressors and gas cooler in a small CO2 refrigeration systems.
Either as a compressor and condenser control on MT or as a booster system. There can be regulated with one parallel compressor.
The controller is with oil management, heat recovery function and
CO2 gas 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 gas
cooler so that operation all the time takes place at the energyoptimum pressure conditions. Both suction pressure and gas
pressure are controlled by signals from pressure transmitters and
temperature sensors.
Among the different functions are:
- Capacity control of up to 3 compressors on high pressure
(2 if also regulating with parallel compressor).
- Capacity control of up to 2 compressors on low pressure
- Up to 3 unloaders for each compressor
- 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
- Safety monitoring of high pressure / low pressure / discharge
temperature
- Capacity control of up to 4 fans
- Floating gas cooler reference with regard to outside temperature
- Heat recovery function
- CO2 gas cooler control and receiver control
- Parallel compression on transcritical CO2 system
- Step coupling, speed regulation or a combination
- Safety monitoring of fans
- 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=1.3x
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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, Ss, Sd, condenser pressure, condenser pressure in temperature, gas cooler temperature, etc.
A graphical display with control buttons can also be fitted.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 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.
6 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 ap-
plication.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
1. Controller
Type Function Application
AK-PC 772A
Controller for capacity control of a small CO2 plant with booster.
A maximum of 3 compressors for high pressure, 2 for low pressure,
4 fans and a maximum of 120 inputs/outputs
Transcritical CO2 Booster control. Parallel compression /Heat recovery / CO2 gas pressure
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-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
EKA 166 Display with operation buttons and LED for function cut in
MMIGRS2 Graphic display with operation
-
Accessories Communication modules for controllers where modules cannot be connected continuously
AK-CM 102 Communication module
Cable between display and controller Length = 2 m, 6 m
Cable between graphic display and controller Length = 1.5 m, 3 m
Data communication for external extension
modules
On the following pages there is data specific to each module.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 9
Common data for modules
Supply voltage 24 V d.c./a.c. +/- 20%
Power consumption AK-__ (controller) 8 VA
AK-XM 101, 102, 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
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. :
Fans and AKV valves
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
Stepper outputs Used for valves with stepper input 20-500 step/s
Ambient temperature During transport -40 to 70°C
During operation -20 to 55°C ,
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.
Separate supply to stepper outputs : 24 a.c./d.c. / xx VA
0 to 95% RH (non condensing)
No shock influences / vibrations
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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 USB-B 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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
Ss
Sd
Shr
Sgc
Sc3
Saux_
P
AKS 32R
3: Brown
2: Blue
1: Black
P0
Pc
Pgc
Prec
AKS 32
3: Brown
2: Black
1: Red
Paux
U
...
On/Off Ext.
Main
switch
Day/
Night
Door
Level
switch
DO
AKV
AKV
Comp
Fan
Alarm
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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
Ss
Sd
Shr
Pt 1000
Sgc
Sc3
Saux_
AKS 32R /
P0
Pc
Pgc
Prec
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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
Ss
Sd
Shr
Pt 1000
Sgc
Sc3
Saux_
AKS 32R /
P0
Pc
Pgc
Prec
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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
20 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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.
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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
Point
S
Pt 1000 ohm/0°C
Signal Signal
type
Ss
Sd
Shr
Pt 1000
Sgc
Sc3
Saux_
Point 1 2 3 4 5 6 7 8
Type AI1 AI2 AI3 AI4 AI5 AI6 AI7 AI8
Terminal 9: 12 V
Terminal 10: 5 V
Terminal 21: 12 V
Terminal 22: 5 V
Terminal 11, 12, 23, 24 :
(Cable screen)
Point 9 10 11 12 13 14 15 16
Type DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8
P
AKS 32R
AKS 32
U
On/Off
DO
3: Brown
2: Blue
1: Black
3: Brown
2: Black
1: Red
P0
Pc
Pgc
Prec
Paux
...
Ext. Main
switch
Day/
Night
Door
Level
switch
Comp
Fan
Alarm
Solenoid
valve
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
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) 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
Terminal
Signal type /
Active at
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 supply 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.
24V d.c. +/-20%
(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.
Separate voltage
supply is required
24 V a.c./d.c. / fx 13 VA
max. 10 V
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
Valve data
Type P
ETS 12.5 - ETS 400
KVS 15 - KVS 42
CCMT 2 - CCMT 8
CCM 10 - CCM 40
CCMT 16 - CCMT 40 5.1 VA
1.3 VA
Output:
24 V d.c.
20-500 step/s
Phase current = 800 mA RMS
∑ P
= 21 VA
max.
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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
Point
CCM
CCMT
Step /
Terminal
ETS
CCM / CCMT
KVS 15
KVS 42-54
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
White Black Green Red
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
Extension module EKA 163B / EKA 164B / EKA 166
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.
Termination
The display must be terminated. Mount a connection between the
terminals H and R.
(AK-PC 772A is terminated internally.)
Placing
The display can be placed at a distance of up to 3 m from the
controller.
EKA 166
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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
Supply to a controller
AK-PS 075
AK-PS 150
AK-PS 250
28 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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, including any high-pressure
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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 / 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 120 (AK-PC 772A).
✔ 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).
✔ 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)
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 31
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 group MT x
Regulation of a condenser group LT x
Regulation of a parallel compression IT x
Regulation of a gas cooler x
Regulation of CO2 receiver pressure x
Regulation of compressor capacity
Regulation sensor = P0 x
PI-regulation x
Max. number of compressor steps on MT + IT 3
Max. number of compressor steps on LT 2
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
AK-PC
772A
External start/stop of compressors x
Oil management
Oil equalisation x
Suction pressure reference
Override via P0 optimization x
Override via “night setback” x
Override via "0 -10 V signal" x
Regulation of gas cooler
Regulation sensor = Sgc x
Step regulation x
Max. number of steps 4
Speed regulation x
Step and speed regulation x
Speed regulation first step x
Limitation of speed during night operation x
Heat recovery function for domestic water or room x
Gas cooler pressure reference
Floating pressure reference x
Setting of references for heat recovery functions x
32 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
High pressure control
If needed, offset for greater compressor capacity x
Offset when there are requirements for heat recovery x
Safety functions
Min. suction pressure x
Max. suction pressure x
Max. condensing pressure x
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
Inject On function x
Option for connection of separate display 4 +1
Separate thermostat function 1
Separate pressostat function 1
Separate voltage measurement 1
PI regulation 1
Max. input and output 120
A bit more about the functions
Compressor
Regulation of up to 3 compressors on MT and 2 on LT
Up to 3 unloaders per compressor.
Compressor No. 1 or 2 can be speed-regulated.
P0 - Suction pressure is used as a regulation sensor.
When regulating with parallel compression (IT circuit),
2 compressors can be used to regulate MT, one on IT and along
with 2 on LT.
If regulating on MT only, 3 compressors can be used to regulate.
Gas cooler
Regulation of up to 4 fans.
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.
An Sgc temperature sensor is used as a regulation sensor at the
gas cooler discharge.
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.
Pulse wide modulating unloading
When using a compressor with PWM-unloading, the unloading
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 measurement
A voltage measurement 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.
Heat recovery
There are adjustment options for hot water containers for domestic hot water or for heating.
If you want to know more about the functions, go to
chapter 5.
Connections
3
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
• 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 regulation is performed with floating condenser reference.
• Saux (extra temperature sensor)
For monitoring, data collection or separate thermostat function.
• Shr (temperature sensors for heat recovery)
Must be used when adjusting the heat tank.
• Sgc (temperature sensor for gas cooling controls)
Shall be placed within one metre after the gas cooler.
• Shp (temperature sensor, the refrigerant may be bypassed gas cooler)
Pressure transmitters
• P0 Suction Pressure
Must always be used
• Pc Condensing Pressure
Must always be used
• Pgc Gas cooler pressure.
Must always be used
• Prec. Pressure i CO2 reciever
Must always be used
• Paux
One extra pressure transmitters can be connected for monitoring and
data collection.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 33
Voltage signal
• Ext. Ref
Used if a reference override signal is received from another control.
• Voltage input
One extra voltage signal can be connected for monitoring and data
collection
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
• External start/stop of regulation
• 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 suction line
• Start/stop of valve and circulation pump for heat recovery
• ON/OFF signal for start/stop of speed regulation
• Alarm relay. I'm alive relay.
• On/off signals from general thermostat (1), pressure switch (1) or voltage
input function (1).
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).
• Should be used if controlled using a digital scroll compressor.
Analog output
• Speed regulation of the condenser’s fans.
• Speed regulation of the compressor
• Stepper signal for high pressure valve
• Stepper signal for hot gas by-pass valve
Example
Compressor group:
MT circuit
• 3 x compressors with “Cyclical”. One speed-controlled
• Safety monitoring of each compressor
• Common high pressure monitoring
• P0 setting –10°C, P0 optimisation
LT circuit
• 2 x compressors with “Cyclical”. One speed-controlled
• Safety monitoring of each compressor
• Common high pressure monitoring
• P0 setting –30°C, P0 optimisation
Gas cooling control:
• Fans, speed controlled
• Pressure regulation Pgc with reference from Sc3 and Sgc
• Pressure increase for heat recovery
Containers:
• Control of pressure in CO2 receiver
• Controlling the tank temperature for domestic water, 55°C
Safety functions:
• Monitoring of Po, Pc, Sd and superheat in suction line
• MT-Po max = -5°C, Po min = -35°C
• MT-Pc max = 110 bar
• MT-Sd max = 120°C
• LT-Po max = -5°C, Po min = -45°C
• LT-Pc max = 40 bar
• LT-Sd max = 120°C
• SH min = 5°C, SH max = 35°C
Data from this example is used on the
next page.
The result is that the following modules
should be used:
• AK-PC 772A controller
• AK-XM 208C stepper output module
• AK-XM 103A analog input and output
module
34 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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, Sgc 6
Extra temperature sensor / separate thermostats /PI-regulation
Pressure transmitters, P0, Pc, Prec / separate pressostat 5 P = Max. 5 / module
Voltage signal from other regulation, separate signals
Heat recovery via thermostat Shr 1
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 5
Safety circuits, condenser fans, frequency converter Max. 1/ fan
External start/stop
Night setback of suction pressure
Separate alarm functions via DI
Load shedding
Start of Heat recovery
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
7
Limitations
On/off outputs
Compressors, motors 5
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 1 Max.1
Liquid injection in suction line Max.1
Hot gas dump 1
Analog control signal, 0-10 V
Frequency converter, Compressor, fans, valves etc. 3
Valves with stepper motor. Parallel valves, if applicable 2
Sum of connections for the regulation 19 0 0 8 3+2 Sum = max. 120
Number of connections on a controller module 11 11 0 0 0 0 8 8 0 0 0
Missing connections, if applicable 8 - 0 0 3+2
5
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) ___ 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) ___ 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
Max. 1+1+1
Sum of power
1 pcs. á 8 VA = 8
Sum =
Sum = max. 32 VA
The example:
None of the limitations are exceeded => OK
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 35
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 + 1 extension module in 200-series + 1 extension
module in 100 series =
224 + 144 + 72 = 440 mm.
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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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
1 (AI 1) 1 - 2
Shr Receiver temperature 2 (AI 2) 3 - 4 Pt 1000
3 (AI 3) 5 - 6
Suction gas temperature - Ss MT 4 (AI 4) 7 - 8 Pt 1000
Discharge temperature - Sd MT 5 (AI 5) 9 - 10 Pt 1000
Suction pressure - P0 MT 6 (AI 6) 11 - 12 AKS 2050-59
Condensing pressure - Pc MT 7 (AI 7) 13 - 14 AKS 2050-159
8 (AI 8) 19 - 20
Suction gas temperature - Ss LT 9 (AI 9) 21 - 22 Pt 1000
Discharge temperature - Sd LT 10 (AI 10) 23 - 24 Pt 1000
Suction pressure - P0 LT 11 (AI 11) 25 - 26 AKS 2050-59
Compressor 1 MT 12 (DO 1) 31 - 32 ON
Compressor 2 MT 13 (DO 2) 33 - 34 ON
Compressor 3 MT 14 (DO 3) 35 - 36 ON
Compressor 1 LT 15 (DO 4) 37 - 38 ON
Compressor 2 LT 16 (DO 5) 39 - 40 - 41 ON
Valve and circulation pump HR 17 (DO6) 42 - 43 - 44 ON
Fan motors 18 (DO7) 45 - 46 - 47 ON
Hot gas dump 19 (DO8) 48 - 49 - 50 ON
1
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/Step Terminal Signal type
Compressor 1 MT Gen. Safety
Compressor 2 MT Gen. Safety 2 (AI 2) 3 - 4 Open
Compressor 3 MT Gen. Safety 3 (AI 3) 5 - 6 Open
All compressors common safety
MT
Compressor 1 LT Gen. Safety 5 (AI 5) 9 - 10 Open
Compressor 2 LT Gen. Safety 6 (AI 6) 11 - 12 Open
All compressors common safety LT 7 (AI 7) 13 - 14 Open
Stepper signal to by-pass valve,
CCM
Stepper signal to high pressure
valve, CCMT
Signal Module Point Terminal Signal type
Outdoor temperature Sc3
Temp. gas cooler outlet Sgc 2 (AI 2) 3 - 4 Pt 1000
Gas cooler pressure Pgc 3 (AI 3) 5 - 6 AKS 2050-159
Receiver pressure Prec 4 (AI 4) 7 - 8 AKS 2050-159
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, compressor, EC 7 (AO 3) 13 - 14 0 - 10 V
1 (AI 1) 1 - 2 Open
4 (AI 4) 7 - 8 Open
2
8 (AI 8) 15 - 16
9 (step 1)
10 (step 2) 29 - 30 - 31 - 32
11 (step 3) 33 - 34 - 35 - 36 CC MT
12 (step 4) 37 - 38 - 39 - 40
1 (AI 1) 1 - 2 Pt 1000
3
8 (AO 4) 15 - 16
25 - 26 - 27 - 28
CCM (ETS)
Continued next page
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 37
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.
38 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Example continued:
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 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.
CO2 regulation makes it necessary to safeguard the voltage to the
controller and valves using UPS.
Example continued:
Controller module 8 VA
+ 1 extension modules in 200 series 5 VA
+ 1 extension modules in 100 series 2 VA
-----Power supply size (least) 15 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)
+ Separate power supply for the module with the stepper motors:
Modules valve control 7.8 VA
CCM valve 1.3 VA
CCMT valve fx. 5.1 VA
------Power supply size (least) 14.2 VA
40 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Ordering
1. Controller
Type Function Application Language Code no.
AK-PC 772A
Controller for capacity control of compressors and condensers. With high pressure
control and parallel compressor (optional)
A small CO2 plant with
booster
English, German, French, Dutch, Italian 080Z0201
continued
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
AK-XM 103A 4 4 080Z0032 x
AK-XM 204A 8 080Z0011
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. 260
V)
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
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 USB A-B (standard IT cable) - 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
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
EKA 166 Display with operation buttons and LED's 084B8578
MMIGRS2 Graphic display with operation 080G0294
- Cable between EKA display and controller
-
Accessories Communication modules for controllers where modules cannot be connected continuously
AK-CM 102 Communication module Data communication for external extension modules 080Z0064
Cable between graphic display type MMIGRS2 and
controller (controller with RJ11 plug)
Supply for controller
Length = 2 m 084B7298
Length = 6 m 084B7299
Length = 1.5 m 080G0075
Length = 3 m 080G0076
080Z0053 x x
Example
continued
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 41
42 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 772A controller module
• AK-XM 208C analog input module + stepper output module
• AK-XM 103A analog input and output module
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 displayed for information purposes 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 two extension modules are to be fitted to the basic
module. We have chosen to fit the module with stepper output directly
on the basic module and then the following module. The sequence is
thus:
All the subsequent settings that affect the two 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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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:
Signal Module Point
1 (AI 1) 1 - 2
Shr container temperature 2 (AI 2) 3 - 4 Pt 1000
3 (AI 3) 5 - 6
Suction gas temperature - Ss MT 4 (AI 4) 7 - 8 Pt 1000
Discharge temperature - Sd MT 5 (AI 5) 9 - 10 Pt 1000
Suction pressure - P0 MT 6 (AI 6) 11 - 12 AKS 2050-59
Condensing pressure - Pc MT 7 (AI 7) 13 - 14 AKS 2050-159
8 (AI 8) 19 - 20
Suction gas temperature - Ss LT 9 (AI 9) 21 - 22 Pt 1000
Discharge temperature - Sd LT 10 (AI 10) 23 - 24 Pt 1000
Suction pressure - P0 LT 11 (AI 11) 25 - 26 AKS 2050-59
Compressor 1 MT 12 (DO 1) 31 - 32 ON
Compressor 2 MT 13 (DO 2) 33 - 34 ON
Compressor 3 MT 14 (DO 3) 35 - 36 ON
Compressor 1 LT 15 (DO 4) 37 - 38 ON
Compressor 2 LT 16 (DO 5) 39 - 40 - 41 ON
Valve and circulation pump HR 17 (DO6) 42 - 43 - 44 ON
Fan motors 18 (DO7) 45 - 46 - 47 ON
Hot gas dump 19 (DO8) 48 - 49 - 50 ON
1
24 -
25 -
Terminal
Signal type /
Active at
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.
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 two different ones. One up to 59 bar and two up to 159
bar.
Signal Module Point/Step Terminal Signal type
Compressor 1 MT Gen. Safety
Compressor 2 MT Gen. Safety 2 (AI 2) 3 - 4 Open
Compressor 3 MT Gen. Safety 3 (AI 3) 5 - 6 Open
All compressors common safety
MT
Compressor 1 LT Gen. Safety 5 (AI 5) 9 - 10 Open
Compressor 2 LT Gen. Safety 6 (AI 6) 11 - 12 Open
All compressors common safety LT 7 (AI 7) 13 - 14 Open
Stepper signal to by-pass valve,
CCM
Stepper signal to high pressure
valve, CCMT
Signal Module Point Terminal Signal type
Outdoor temperature Sc3
Temp. gas cooler outlet Sgc 2 (AI 2) 3 - 4 Pt 1000
Gas cooler pressure Pgc 3 (AI 3) 5 - 6 AKS 2050-159
Receiver pressure Prec 4 (AI 4) 7 - 8 AKS 2050-159
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, compressor, EC 7 (AO 3) 13 - 14 0 - 10 V
1 (AI 1) 1 - 2 Open
4 (AI 4) 7 - 8 Open
2
8 (AI 8) 15 - 16
9 (step 1)
10 (step 2) 29 - 30 - 31 - 32
11 (step 3) 33 - 34 - 35 - 36 CC MT
12 (step 4) 37 - 38 - 39 - 40
3
8 (AO 4) 15 - 16
25 - 26 - 27 - 28
1 (AI 1) 1 - 2 Pt 1000
CCM (ETS)
46 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 47
Mounting and wiring - continued
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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 3 compressors for
MT and 2 compressors for LT and high pressure control using heat
recovery and gas cooler.
The example is shown two pages in.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 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.
For connecting and operating the "AK service tool" software,
please see the manual for the software.
Start Service Tool programme
Login with user name SUPV
Select the name SUPV and key in the access code.
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.
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 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
Refrigerating plant example
We have decided to describe the setup by means of an example
comprising a MT & LT compressor group and a high pressure
control.
The example is the same as the one given in the "Design" section,
i.e. the controller is an AK-PC 772A + extension modules.
Example
Compressor Group
MT circuit
• 3 x compressors with “Cyclical”. One speed-controlled
• Safety monitoring of each compressor
• Common high pressure monitoring
• P0 setting –10°C, P0 optimisation
LT circuit
• 2 x compressors with “Cyclical”. One speed-controlled
• Safety monitoring of each compressor
• Common high pressure monitoring
• P0 setting –30°C, P0 optimisation
Gas cooling control:
• Fans, speed-controlled
• Pressure regulation Pgc with reference from Sc3 and Sgc
• Pressure increase for heat recovery
Containers:
• Control of pressure in CO2 receiver
• Controlling the tank temperature for domestic water, 55°C
Safety functions:
• Monitoring of Po, Pc, Sd and superheat in suction line
• MT-Po max = -5°C, Po min = -35°C
• MT-Pc max = 110 bar
• MT-Sd max = 120°C
• LT-Po max = -5°C, Po min = -45°C
• LT-Pc max = 40 bar
• LT-Sd max = 120°C
• SH min = 5 °C, SH max = 35 °C
Warning
Here, only the internal main switch is used to initiate regulation.
If disconnected during operation, it will stop all regulation, including
high pressure regulation.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 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 RS8HF102 © Danfoss 2017-07 AK-PC 772A
Configuration - continued
Set plant type
1. Go to Configuration menu
2. Select plant type
Press the line Select plant type.
3. Set plant type
Press the +-button to go on to the
next page
4. Set Common functions
Our example
The comments for the example are shown on the
following pages, in the middle column.
In our example, the controller must
regulate a Booster System, High Pressure Control
Subsequent settings will then be
available.
There are several pages, one after the
other.
The black bar in this field tells you which
of the pages is currently displayed.
Move between the pages using the + and
- buttons.
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 one of the four controls
Refrigerant
The refrigerant is always CO2
Condenser fan control
Select whether the controller should control
the condenser component / gas cooler. To be
set later.
No of fans
Set the number of relay outputs that will be
used.
Heat recovery
Heat recovery enabled. To be adjusted later on.
Quick setup
Not used
4- Plant type continued
Select compressor application and no. of
comp. MT
Press the +-button to go on to the
next page
5. Quick basis setup
Adjust only the lines with "Smart"
Here you must adjust the overall pressure
values for the system
- Regulation Pgc max
- Regulation Receiver reference.
The controller will then suggest values for all
settings connected with this.
The values can be seen in this display, but
also later in the relevant setup.
Fine adjustments can be made if necessary.
Select compressor application and no. of
comp. LT
Select compressor application for IT
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.
Show advanced settings
This function opens the advanced settings in
the various menus.
5 – Quick relative setup
Easy Pgc max. provides a group setting for the
overall pressure values.
Easy Prec ref. provides a group setting for the
receiver controller..
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 55
Configuration - continued
Set control of MT compressors
1. Go to Configuration menu
2. Select Suction group MT
3. Set values for the reference
The configuration menu in the
Service Tool has changed now.
It shows the possible settings for
the selected plant type.
In our example we select the
settings:
- P0 optimisation
- Suction pressure = -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 via DI
Select whether a digital input is required for activation of night
operation. Night operation can alternatively be controlled via
internal weekly schedule or via a network signal
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 the compressor application required
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
In our example we select:
-VSD + single step
- 3 compressors
- P0 as signal to the regulation
- Cyclic
Lead compressor type (For LT only)
• Variable
The following options are available for variable:
No. of compressors
Set number of compressors (Total)
(max. 2 if parallel compressor is also selected)
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 is used for control
Step control mode
Select coupling pattern for compressors
Cyclic: Runtime equalisation between compressors (FIFO)
Best fit: Best possible adaptation of capacity (minimum capacity jump)
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
No: There will be two analog outputs available.
Yes: There will be one analog output.
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
56 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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
The compressor capacity is set in
displaced volume per hour. m3/h.
See compressor data.
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 = 103.0 bar
- Safety limit for low suction
pressure = -40°C
than “VSD Min. Speed Hz”)
VSD max speed (40.0 – 120.0 Hz)
Highest permissible speed for the compressor motor
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 (must be
set to a higher value than "PWM Min. capacity")
Load shed limits
Select which signal is to be used for load limitation
(only via network, a DI + network or two DI + network)
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 T0
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 T0 (0.1 – 10.0)
Amplifications factor for PI regulation
Tn T0
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
Select whether the advanced capacity control settings should
be visible
T0 filter
Reduce changes in the Po reference
Pc filter
Reduce changes in the Pc reference
Minimize cycling
The control zone may vary for connections and disconnections. See Section 5.
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
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 (0.0 – 1000,0 m3/h)
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
Press the +-button to go on to the
til næste side.
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%.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 57
Configuration - continued
8. Set monitoring of compressor
Press the +-button to go on to the
next page
9. Set operation time for compressor
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.
Unload
Readout of the capacity on every unloading 0-100%.
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 bar
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.
Tc max. limit
Limit value read in °C
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 "T0 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.
Press the +-button to go on to the
next page .
10. Set Misc. functions
In our example we do not use
these functions.
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.
Individuel Sd pr. compressor
Select whether an Sd measurement should be made for each
compressor.
Max discharge temp.
Cutout temperature.
Sd compressor alarm delay
Delay time for the alarm
Sd compressor safety cutout
Set whether safety cut-out should be enabled
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.
Safety timer
- 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.
58 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 com-
munication.
Compressor start delay
Delay time for compessor start
Injection Off delay
Delay time for "Injection off"
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.
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
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 59
Configuration - continued
Set control of LT compressors
1. Go to Configuration menu
2. Select Suction group LT
In principle, the functions are the same as for MT.
In principle, the same settings are carried out, but in the LT
group it will be possible to select compressors with variable
capacity.
For the IT group the compressors must be speed controlled.
60 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 Sgc 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
Sgc: The temperature at the outlet of the gas cooler
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 temperature
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 2-3 K at CO2).
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 voltage min
Voltage value in % at 0% capacity
EC voltage max
Voltage value in % at 100% capacity
EC Voltage abs. max
Permissible live voltage for EC motor in % (overcapacity)
Absolut max Sgc
Max value for temperature at Sgc. If the value is exceeded,
the EC voltage will be raised to the value in “EC Voltage abs.
max.”
Continues
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 61
Configuration - continued
Continued
Control type
Choice of control strategy
P-band: The fan capacity is regulated via P-band control. The
P band is "100/Kp"
PI-Control: The fan capacity is regulated by the PI controller.
Kp
Amplification factor for 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.
62 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Configuration - continued
Setup control of high pressure
1. Go to Configuration menu
2. Select HP control
3. Set regulation values
The settings are shown here in the
display
(The read outs "Pgc HR min" and
"Pgc HR offset" are visible when
Heat recovery is selected ON)
3 - HP control
Vhp output type
Select the signal type for controlling the high pressure
valve.
- Voltage signal (ICMTS must have 0-10 V signal)
- Stepper motor signal via AK-XM 208C
- 2 Stepper motor signals for parallel valves
Extra capacity offset
Adjust how much the pressure shall be increased by when
the function "Extra capacity offset" is activated.
Pgc min.
Min. acceptable pressure in the gas cooler
Pgc max.
Max. acceptable pressure in the gas cooler
Advanced settings
Vhp min. OD
Restriction of the valve's degree of closing
Vhp max. OD
Restriction of the valve's degree of opening
Pgc max. limit P-band
P-band under "Pgc max" where the valve's degree of
opening is increased
dT Subcool
Desired subcooling temperature
Kp
Amplification factor
Tn
Integration time
Pgc HR min.
Read the min. acceptable pressure in the high pressure
circuit during heat recovery
Pgc HR offset
Set the pressure increase during heat recovery
Ramp down bar/min.
Here you may select how quickly the reference must be
changed after a completed heat recovery
Temp. at 100 bar
Temperature at 100 bar. Here you may define the
regulation curve during transcritical operation. Set the
required temperature value.
Warning
If the regulation is stopped during high-pressure regulation, the
pressure will rise.
The system must be dimensioned to the higher pressure;
otherwise, there will be a loss of
charge.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 63
Configuration - continued
Setup control of receiver pressure
1. Go to Configuration menu
2. Select Receiver control
3. Set regulation values
The settings are shown here in
the display
3 - Receiver control
Vrec output type
Select the signal type for controlling the gas bypass valve:
- Voltage signal
- Stepper motor signal via AK-XM 208C
- 2 stepper motor signal for parallel valves
Vrec min. OD
Limitation of the Vrec valve's degree of closing
Vrec max. OD
Limitation of the Vrec valve's degree of opening.
Show Trec
Set whether Trec should be shown in overview display 1.
Prec set point
Select the set point for the pressure in the receiver when IT
compressor is stopped
Kp
Amplification factor
Tn
Integration time
Prec min.
Min. permissible pressure in the receiver
Prec max.
Max. permissible pressure in the receiver
(Also becomes regulation reference if the compressors are
stopped with the "External compressor stop" function)
Prec min. limit P-band
P-band under "Prec min" where the ICMTS valve's degree of
opening is increased
Prec max. limit P-band
P-band over "Prec max" where the ICMTS valve's degree of
opening is decreased
Monitor liquid level
Choose whether liquid level should be monitored
Liquid alarm delay
Time delay for the alarm
Use hot gas dump
Select whether hot gas should be supplied if the receiver
pressure falls too low
Prec hot gas dump
Receiver pressure at which hot gas is turned on
Prec gas dump diff.
Difference at which hot gas is turned off again.
Show advanced settings
IT Comp. start
Opening degree for the Vrec valve when the IT compressor
is to start.
IT Comp. delay
The opening degree of the Vrec must be higher during the
entire delay time before the relay pulls, thereby sending a
signal to the IT controller.
IT End delay
The duration the IT compressor must have been stopped
before regulation is transferred to Vrec
IT Comp. Sgc min.
The temperature limit for operation with IT compressor. Will
not start when a lower value is detected, regardless of the
opening degree of the Vrec valve.
64 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Configuration - continued
Setup control of heat recovery
1. Go to Configuration menu
2. Select heat recovery
3. Set regulation values
The settings are shown here in the
display
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 cutout
Temperature value where the thermostat cuts-out the heat
recovery.
Heat recovery cutin
Temperature value where the thermostat cuts-out the heat
recovery.
Use extern HR offset
Here you define how the condensing pressure (HP) shall be
regulated when the recovery circuit for heating requires
heat:
- No. No HP offset (simple control)
- Yes. Here the controller must receive a voltage signal or
a temperature signal from an external source. The offset
values that apply to the max. value must be defined.
Input type select
- Temperature control
A signal from a temperature sensor must be received.
Set the reference temperature.
- Consumer
A 0-10 V or 0.5 V signal must be received.
Control type
Regulation with external offset: select P or PI control
Temperature reference
Reference settings at temperature control
Kp
Ampflication factor
Tn consumer filter
Averaging the consumer signal
Fan HR min.
Set point for fan control in the condenser when heat recovery is called for
Fan HR offset
Temperature increase from 50% to 100% in consumer
signal
Pgc HR min.
Pressure value when heat recovery is called for
Pgc HR offset
Pressure increase from 0 to 50% in consumer signal.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 65
Configuration - continued
Setup Display
1. Go to Configuration menu
2. Select Display setup
3 - Display setup
Display
The following can be read for the four outputs..
Comp. control sensor
P0 in temperature
P0 in barSs
Sd
Cond. control sensor
Tc
Pc bar
Sgc
Pgc bar
Prec bar
Trec
Speed Compressor
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.
Unit readout
Choose whether readings are to be in SI units (°C and bar) or
(US-units °F and psi)
66 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Configuration - continued
Setup Functions for General purpose
1. Go to Configuration menu
2. Select General purpose
3. Define number of required
functions
In our example, we do not use
functions for general purposes,
so the picture is included for
orientation.
Each function is described on the
following pages.
The following number of different functions can be
defined:
1 thermostat
1 pressostat
1 voltage signal
10 alarm signals
1 PI-regulation
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 67
Configuration - continued
Separate thermostat
1. Select thermostat
2. Select actual thermostat
3. Define the required thermostat
functions
In our example, separate
thermostat functions are not
used.
3 - Thermostats
The general thermostat can be used to monitor a temperature. The thermostat has a separate outlet to control external
automation.
Settings
• 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 pressostat
1. Select pressostat
In our example, separate
pressostat functions are not used.
2. Select actual pressostat
3. Define the required pressostat
functions
68 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
3 - Pressostat
Settings as the thermostat
Configuration - continued
Separate voltage signal
1. Select Voltage input
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).
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 input
The general volt inlet can be used to monitor a external
voltage signal. The function has a separate outlet to control
external automatic controls.
Settings:
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
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 69
In our example we do not use
this function, so the display
has been included for your
information 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 function
1. Select PI function
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
• Quick settings
Here is a list of suggestions for PI regulations:
• PI Name
• 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.
70 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Configuration - continued
Conguration of inputs
and outputs
1. Go to Configuration menu
2. Select I/O configuration
3. Configuration of Digital outputs
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
Compressor 1 MT DO1 1 12 ON
Compressor 2 MT DO2 1 13 ON
Compressor 3 MT DO3 1 14 ON
Compressor 1 LT DO4 1 15 ON
Compressor 2 LT DO5 1 16 ON
Valve and circulation pump hr D06 1 17 ON
Fan DO7 1 18 ON
Hot gas dump DO8 1 19 ON
3 - Outputs
The possible functions are
the following:
Comp. 1
Unloader 1-1
Unloader 1-2
Unloader 1-3
Do for Compressor. 2 and 3
Compressor run
IT compressor release
Injection suction line
Injection ON
Fan 1 / VSD
Fan 2 - 4
HP Control
Hot gas dump
Heat recovery
Alarm
I'm alive relay
Thermostat 1
Pressostat 1
Volt input 1
PI 1-PWM
Press the +-button to go on to the
next page
4. Setup On/off inputs
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
Compressor 1 MT Safety AI1 2 1 Open
Compressor 2 MT Safety AI2 2 2 Open
Compressor 3 MT Safety AI3 2 3 Open
All compressors common safety MT AI4 2 4 Open
Compressor 1 LT Safety AI5 2 5 Open
Compressor 2 LT Safety AI6 2 6 Open
All compressors common safety LT AI7 2 7 Open
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.
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 and 3
Fan 1 safety
Do for fan 2-4
VSD cond safety
AC limit
Rec. low liquid level
Rec. high liquid level
Heat recovery
DI 1 Alarm input
DI 2-10 ...
PI-1 Di ref
External DI PI-1
Press the +-button to go on to the
til næste side.
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Configuration - continued
5. Configuration of Analog
outputs
Press the +-button to go on to
videre til næste side.
6. Configuration of Analog
Input signals
Function Output Module Point Type
Stepper signal for by-pass valve, CCM Step 1 2 9 CCM
Stepper signal for high pressure
valve, CCMT
Speed control, compressor MT AO1 3 5 0 - 10 V
Speed control, compressor LT AO2 3 6 0 - 10 V
Speed control, EC AO3 3 7 0 - 10 V
Sensor Input Module Point Type
Heat reclaim temperature Shr AI2 1 2 Pt 1000
Suction gas temperature - Ss MT AI4 1 4 Pt 1000
Disch. gas temperature - Sd MT AI5 1 5 Pt 1000
Suction pressure - P0 MT AI6 1 6 AKS 2050-59
Condenser pressure - Pc MT AI7 1 7 AKS 2050-159
Suction gas temperature - Ss LT AI9 1 9 Pt 1000
Disch. gas temperature - Sd LT AI10 1 10 Pt 1000
Suction pressure - P0 LT AI11 1 11 AKS 2050-59
Outdoor temp. Sc3 AI1 3 1 P t 1000
Temp. gas cooler outlet Sgc AI2 3 2 Pt 1000
Gas cooler pressure Pgc
Receiver pressure Prec
Step 3 2 11 CCMT
AI3 3 3
AI4 3 4
AKS 2050-159
AKS 2050-159
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
Stepper user defined: See
section "Miscellaneous"
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)
Po suction pres.
Ss suction gas
Sd disch. temp.
Pc Cond. Pres.
Sc3 air on
Ext. Ref. Signal
• 0 – 5 V,
• 0 -10 V
HP control
Pgc
Prec
Sgc
Shr
Saux 1
Paux 1
Voltage input 1
• 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.
72 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Configuration - continued
Set alarm priorities
1. Go to Configuration menu
2. Select Alarm priorities
3. Set priorities for Suction group
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.
Setting
High X X X X 1
Medium X X X 2
Low X X X 3
Log only X 4
Disconnected
See also alarm text at the end of the manual.
Log Alarm relay selection Net-
Non High Low - High
work
AKM dest.
In our example we select the settings shown here in the display
Press the +-button to go on to the next page
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
74 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 75
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
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.
76 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Configuration - continued
Press the +-button to go on to the next page
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.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 77
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
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.
78 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 79
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. Check the individual pages
The last page contains control data
5. Go back to the overview. Repeat for LT
80 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Check of settings - continued
6. Select condenser group
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.
10. General functions
When all the functions in overview display 1 have been reviewed, it is time to look at the "General functions" in overview
display 2. Press the + button to access.
The first is the thermostat group
Check the settings.
11. Then the pressure switch group
Check the settings.
12. Proceed with the remaining functions.
13. The controller setup has been completed.
All the defined general functions are shown in overview display 2.
In addition to always being shown in display 2, functions can be
selected to be shown in display 1. Individual functions can be selected
for display in display 1 via the "Show in overview display" setting.
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Schedule function
1. Go to Configuration menu
2. Select schedule
3. Setup schedule
Before regulation is started we will set the schedule function for the
night setback of the suction pressure.
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.
82 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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 network 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.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 83
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 red 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.
84 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 85
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.
86 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
5. Regulating functions
This section describes how the different functions work
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 87
Suction groups
Controlling sensor
The capacity distributor can regulate according to the suction
pressure P0.
The IT compressors are also regulated according to the suction
pressure, but the signal is received from the receiver - Prec. See
page 108 for IT description
An error in the controlling sensor will mean that regulation continues with fx. 50% cutin in daily operation and fx. 25% cut-in at
night, but for a minimum of one step.
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.
P0 ref
Max.
Reference
The reference for the regulation can be defined in 2 ways:
Either
P0Ref = P0 setting + P0 optimization
or
P0Ref = P0 setting + night displacement + Ext. Ref
P0 setting
A basic value for the suction pressure is set.
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
• From a master gateway’s override function
• Internal time schedule
Min.
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.
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.
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).
88 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Capacity control of compressors
Capacity control
AK-PC 772A can control up to 3 compressors on MT and 2 on LT.
(For parallel compressor operation, however, the system can only
control 2 on MT and 2 on LT.) 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/temperature sensor 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:
3 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.
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.
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.
Note that the configured pump down limit should be set higher
than the configured safety limit for low suction pressure "Min Po".
For the IT compressor, pump down will be controlled by the receiver and MT temperature.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 89
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.
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.
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.
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
- 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.
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.
90 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Power pack types – compressor combinations
The controller is able to control power packs with compressors of
various types:
- One or two speed controlled compressor
- Capacity controlled piston compressors with up to 3 unloader
valves
- Single step compressors – piston
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 Coupling
One-step compressors. *1 x x
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
pattern
Cyclical
x
x
x
Best fit
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.
• 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.
*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 compressor should also be the same
size.
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
x x
x
x x
The following is a description of some general rules for handling
capacity-regulated compressors, speed-regulated compressors
and also for two speed-regulated compressors.
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.
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 91
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:
92 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
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.
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
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
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 772A Capacity controller RS8HF102 © Danfoss 2017-07 93
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.
94 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Two independent speed-regulated compressors
If the two speed-regulated compressors need to be controlled
asynchronously, they must each have their own analogue voltage
signal.
The controller first starts one of the speed-regulated compressors.
If more capacity is required, the other speed-regulated compressor is started, and then the single compressors.
Analogue outputs
Max. speed
Nominal
Start speed
Min. speed
The first is run up to maximum speed. Number two is then activated and run up to nominal speed – and kept there. The speed
of number one is reduced at the same time, so the capacity is balanced. All variations are now handled by number one. If number
one reaches maximum speed, number two will also be raised.
If number one reaches minimum speed, it will be kept there while
number two takes over the variation below its nominal speed.
When engaging and disengaging, the total hours of operation for
the compressors is compared, so they are run an equal number of
hours.
Compressor timers
Time delays for cutins and cutouts
To protect the compressor against frequent restarts three time
delays can be put in.
- A minimum time to run from a compressor’s startup and until it
may be restarted.
- A minimum time (ON-time) for the compressor to operate before
it may be stopped again.
- A minimum OFF time to run from a compressor stops and until it
may be restarted
When unloaders are cut in and out, the time delays will not be
used.
Timer
The operating time of a compressor motor is registered continuously. You can read out:
- operating time for the previous 24-hour period
- total operating time since the timer was last set to zero-set.
Equalizing operating hours
Operating hours are also summed in the "Equalization time" field.
During cyclical operation, this field is used for equalizing operating hours.
Coupling counter
The number of relay cutins and cutouts is registered continuously.
The number of starts can be read out here:
- Number during the previous 24-hour period
- Total number since the counter was last set to zero-set.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 95
Compressor with variable capacity
Digital scroll compressor
The capacity is divided into period times as "PWM per". 100% capacity is delivered when cooling takes place for the whole period.
An off time is required by the by-pass valve within the period and
an on time is also permitted. There is "no cooling" when the valve
is on.
The controller itself calculates the capacity needed and will then
vary it according to the cut-in time of the by-pass valve.
A limit is introduced if low capacity is needed so that the cooling
does not go below 10%. This is because the compressor can cool
itself. This value can be increased if necessary.
Refrigeration
No refrigeration
Period time
Individual Sd monitoring
When regulating with Sd monitoring, one of the three compressor
types will increase capacity if the temperature nears the Sd limit.
This will result in better cooling of the unloaded compressor.
Min. capacity
Copeland Stream compressor
The PWM signal can also be used to control one stream compressor with one unloader valve (Stream 4) or one with two unloaders
(Stream 6).
Stream 4: The compressor capacity is distributed by up to 50% for
one relay and the remaining 50-100% for the unloader.
Stream 6: The compressor capacity is distributed by up to 33% for
one relay and the remaining 33-100% for the unloader.
Bitzer CRII Ecoline
CRII 4: The pulse signal can also be used to control one CRII with
two unloaders (4-cylinder version).
The compressor capacity can be controlled from 10 to
100%, depending on the pulsation of the unloaders. The
compressor start signal is connected to a relay output, and
the unloaders are connected to fx DO1 and DO2.
Unloader 1
Extra refrigeration capacity (“extra compressor”)
This function improves the system’s refrigeration capacity by
increasing the pressure in the gas cooler. The function will start
when the compressor capacity has been at 100% for 5 minutes.
The cooling performance increases to Q0+dh0.
The function also increases the load on the compressor motor as
pressure increases. Power consumption increases to Qm+dQm.
Unloader 2
Unloader 2 follows unloader 1,
but it remains displaced by a
half period.
CRII 6: The pulse signal can also be used to control one CRII with
three unloaders (6-cylinder version).
The compressor signal is connected to one relay output.
The two unloaders are connected to fx DO1 and DO2. The
third is connected to a relay output.
The compressor capacity can be controlled from 10 to 67%,
depending on the pulse of the unloaders.
The relay is then connected to the third unloader. When
this relay is on, the capacity will be controlled between 33
and 100%.
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Load shedding
On some installations there is the desire to limit the cut-in compressor capacity so that one can limit the total electrical load in
the store for periods. (The IT circuit is not directly affected)
This limitation can be activated in the following way:
• Via signal from the network
• Via signal on one DI input + signal via the network
• Via signal on two DI inputs + signal via the network
The signal via the network will result in the same function as if the
signal were received on DI 1.
For each digital inlet a limit value is attached for the maximum
allowable cut-in compressor capacity so that one can carry out the
capacity limitation in 2 steps.
Injection ON
The electronic expansion valves in the refrigeration appliances
must be closed when all the compressors are prevented from
starting. In this way the evaporators will not be filled with liquid
which is subsequently passed on to a compressor when regulation
is restarted.
One of the compressor control relays may be used for this function, or the function can be obtained via data communication.
When a digital inlet is activated, the maximum allowable compressor capacity is limited to the set limit. This means that if the actual
compressor capacity upon activation of the digital inlet is higher
than this limit, then so much compressor capacity is cut-out that
it will then be on or under the set maximum limit value for this
digital inlet.
The threshold value may not be set lower than the compressor's
lowest capacity step/"Start speed".
When both load-shedding signals are active, the lowest limit value
for the capacity will be the one that is applicable.
Definition of load shedding:
The function is defined in the MT group. Once defined, it will open
up the settings of max. capacity of the MT group and the max.
capacity of the LT group.
Overriding of load shedding:
To avoid load shedding leading to temperature problems for the
chilled products, an overriding function is fitted.
with relay
with data communication
The function is described based on the sequence of events below:
T1) The last compressor is cut-out
T2) The suction pressure has increased to a value corresponding to
Po Ref + ½ NZ + 2 K but no compressor can start due to re-start
timers or safety cut-out
T3) The time delay “Injection OFF delay” elapses and the injection
valves are forced to close via relay signal or via network signal.
T4) The first compressor is now ready to start. The forced closure
signal via the network is now cancelled.
T5) The time delay “Comp. Start delay” expires and the forced
closure signal via the relay switch is cancelled simultaneously
with the first compressor being allowed to start.
The reason why the forced closure signal via the network is
cancelled before the first compressor starts, is that it will take
some time to distribute the signal to all appliance controllers via
the network.
A overriding limit is set for the suction pressure as well as a delay
time for each digital inlet.
If the suction pressure during load shedding exceeds the set
overriding limit and the attached delay times for the two digital
inlets expire then load shedding overrides the signals so that the
compressor capacity can be increased until the suction pressure
is again under the normal reference value. The load shedding can
then be activated again.
Alarm:
When a load shedding digital inlet is activated, an alarm will be
activated to inform that the normal control has been bypassed.
This alarm can however be suppressed if so desired.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 97
Liquid injection in common suction line
Safety functions
The discharge pressure gas temperature can be kept down by
means of liquid injection into the suction line. (Not IT circuit).
• With a thermostatic expansion valve in series with a solenoid
valve. The solenoid valve is connected to the controller.
Control can be carried out in two ways:
1. The liquid injection is exclusively controlled on the basis of the
superheat in the suction line. Two values are set – a starting
value and a differential where the injection is stopped again.
2. The liquid injection is both controlled by the superheat (as
described above) and by discharge temperature Sd. Four
values are set – two as mentioned above and two for the Sd
function, a starting value and a differential. The liquid injection
is started when both starting values have been passed, and is
stopped again when just one of the two functions cuts out.
• Direct using an electrically operated expansion valve of the type
AKV
Signal from the compressor’s safety controls
The controller can monitor the status of each compressor’s safety
circuit. The signal is taken directly from the safety circuit and
connected to an input.
(The safety circuit must stop the compressor without involving the
controller).
If the safety circuit is cut out the controller will cut out all
output relays for the compressor in question and give an alarm.
Regulation will continue with the other compressors.
General safety circuit
If a low-pressure switch is placed in the
safety circuit it must be placed at the end of
the circuit. It must not cut out the DI signals.
(There is a risk that the regulation will become locked and that it will not start again).
This also applies to the example below.
If an alarm is needed which also monitors
the low-pressure thermostat, a “general
alarm” can be defined (an alarm that does
not affect the control).
See the following section “General monitoring functions”.
Extended safety circuit
Instead of a general monitoring of the safety circuit this monitoring function
can be extended. In this way a detailed alarm message is issued which tells you
which part of the safety circuit has dropped out.
The sequence of the safety circuit must be established as shown, but not all of
them need necessarily be used.
Oil pressure safety
Over current safety
Motor protect. safety
Discharge temp. safety
Four values are adjusted -- a start value for the Sd temperature,
min. and max. values for overheating and a period time for the
AKV valve.
The pulse width modulating signal for the AKV valve shall be
taken from one of the controller's four solid state outputs.
Time delay
A time delay can be set which ensures that the injection is delayed
during start up.
Discharge pressure safety
Common safety circuit
A common safety signal can also be received from the whole suction group. All
compressors will be cut out when the safety signal cuts out.
The function may not be connected to an external main switch.
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Time delays with safety cut-out:
In connection with safety monitoring of a compressor it is possible
to define two delay times:
Cut-out delay time: Delay time from alarm signal from the
safety circuit until the compressor outlet cuts out (note that the
delay time is common to all security inlets for the compressor
concerned)
Safety re-start time: The minimum time a compressor must be OK
after a safety cut-out until it may start again.
Monitoring of superheat
This function is an alarm function which continuously receives
measured data from suction pressure P0 and suction gas Ss.
If superheat is registered which is lower or higher than the set limit values, an alarm will be given when the time delay has passed.
Monitoring of min. suction pressure (P0)
The function promptly cuts out all compressor steps if the suction
pressure becomes lower than the permitted value.
The cutout limit can be defined in the range from -120 to +30°C.
The suction is measured with pressure transmitter P0.
At cutout the alarm function is activated:
The alarm is cancelled and renewed cutin of compressor steps is
permitted when the following conditions are met:
- the pressure (temperature) is above the cutout limit
- the time delay has elapsed (see later).
Monitoring of max. condensing pressure (Pc)
The function cuts in all condenser steps and cuts out compressor
steps one by one if the condensing pressure becomes higher than
permitted. The cutout limit is set in bar. The condensing pressure
is measured with pressure transmitter Pc_.
Monitoring of max. discharge gas temperature (Sd)
The function gradually cuts out compressor steps if the discharge
temperature becomes higher than permitted. The cutout limit can
be defined in the range from 0 to +195°C.
The function is started at a value that is 10 K below the set value.
At this point the entire condenser capacity is cut in at the same
time as 25% of the compressor capacity is cut out (but minimum
one step). This is repeated every 30 seconds. The alarm function is
activated.
If the temperature rises to the set limit value all compressor steps
are immediately cut out.
The alarm is cancelled and renewed cutin of compressor steps is
permitted when the following conditions are met:
- the temperature has dropped to 10 K below the limit value
- the time delay prior to restart has been passed. (see later)
Normal condenser control is permitted again when the temperature has dropped to 10 K below the limit value.
Individual Sd monitoring
The affected compressor will be disconnected here when the
temperature exceeds the threshold value.
- The piston compressor will be reconnected when the temperature has dropped 10 K.
- The capacity of compressors with variable capacity is increased
if the temperature is approaching the limit. Once it has been
cut out, it will only be connected when the temperature has
dropped 10 K.
If signals are also obtained from the embedded NTC sensor,
the disconnect value for this temperature will always remain at
130°C and the reconnect value at 120°C.
The function takes effect at a value which is 3 K below the set
value. At this time the entire condenser capacity is cut in at the
same time as 33% of the compressor capacity is cut out (but min.
one step). This is repeated every 30 seconds. The alarm function is
activated.
If the temperature (pressure) rises to the set limit value, the following will happen:
- all compressor steps will immediately be cut out
- the condenser capacity will remain cut in
The alarm will be cancelled and renewed cutin of compressor
steps is permitted when the following conditions are met:
- the temperature (pressure) falls to 3 K below the limit value
- the time delay for restart has been passed.
Delay of Pc max alarms
It is possible to delay the “Pc max alarm" message.
The controller will still disconnect the compressors, but the sending of the alarm itself is delayed.
The delay is useful on cascade systems where the max. Pc limit is
used to disconnect compressors in the low-pressure circuit if the
high-pressure compressors have not started.
Time delay
There is a joint time delay for “Monitoring of max. discharge gas
temperature” and “Min. suction pressure”.
After a cutout, regulation cannot be recommenced until the time
delay has been passed.
The time delay starts when the Sd temperature has again dropped
to 10 K below the limit value or P0 has risen above the P0 min.
value.
Alarm for too high suction pressure
An alarm limit can be set which will become effective when the
suction pressure becomes too high. An alarm will be transmitted
when the set time delay has been passed. The regulation
continues unchanged.
AK-PC 772A Capacity controller RS8HF102 © Danfoss 2017-07 99
Condenser / Gas cooler
Principle
The condenser in a transcritical CO2 system is also called a gascooler. Unlike in an HFC system, subcooling is not controlled by a
condenser, but by the high-pressure valve Vhp.
The gas-cooler control must regulate the temperature in the gascooler’s discharge, so that it has the lowest possible value and the
energy consumption of the fans is minimal. However, this should
not be so low as to prevent the receiver pressure from being
maintained.
Capacity control of the condenser (gas cooler) can be accomplished via step regulation or speed control of the fans.
• EC motors
An analogue output signal is used here, which controls the fans
from 0 to maximum capacity.
• Step regulation
The controller can control up to 4 condenser steps that are cut in
and out sequentially.
• Speed control
The analog output voltage is connected to a speed control. All
fans will now be controlled from 0 to max. capacity. If an ON/
OFF signal is required it can be obtained from a relay output.
Regulation can be carried out based on one of the following
principles:
- all fans operate at the same speed
- Only the necessary number of fans is cut in.
• Combination with one fan speed regulated and the rest step
regulated.
Reference for condensing pressure
The reference for the regulation can be defined in two ways. Either
as a fixed reference or as a reference that varies according to the
outdoor temperature.
Fixed reference
The reference for the condensing pressure is set in °C.
Floating reference (recommended)
This function allows the condensing pressure’s reference value to
vary according to the outdoor temperature within a defined area.
The reference is based on:
- the outdoor temperature measured with Sc3 sensor
- The minimum temperature difference between the air
temperature and the condensing temperature at 0% compressor
capacity.
- the condenser’s dimensioned temperature difference between
the air temperature and the condensing temperature at 100%
compressor capacity (Dim tmK)
- how large a part of the compressor capacity has been cut in.
The minimum temperature difference (min tm) at low load should
be set at approximately 2 K as this will eliminate the risk that all
fans will be running when no compressors are running.
Set the dimensioned difference (dim tm) at max. load (e.g. 3 K).
The controller will now contribute with a value to the reference
which depends on how large a part of the compressor capacity
has been cut in.
Capacity control of condenser
The cut-in condenser capacity is controlled by the condenser pressure’s actual value and depends on whether the pressure is rising
or falling. Regulation is performed by a PI controller.
The controller cuts in capacity in such a way that the deviation
between the actual condensing pressure and the reference value
becomes as small as possible.
Regulating sensor selection
The capacity distributor regulates from the temperature sensor
Sgc, located at the outlet for the gas cooler.
Cap. Ctrl sensor = Sgc
Pc is used as the safety function for high condenser pressure and
will therefore ensure cut-out of the compressor capacity when
condenser pressure is too high.
Handling sensor errors:
In the event of Sgc failure the controller switches over to an
"emergency cooler sequence" that attempts to maintain regulation.
100 Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A
Heat recovery
The condensing pressure may be increased during heat recovery.
This is mentioned in the “Heat recovery” section.
Limitation of the reference
To safeguard yourself against a too high or too low regulation
reference, a limitation of the reference must be set.
PcRef
Max
Min
(The maximum value can be overridden by the heat recovery
function).
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