Danfoss AK-PC 781 User guide

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Design Guide

Capacity controller with heat recovery function

AK-PC 781

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 AK-OB 101A..................................................27

Extension module EKA 163B / EKA 164B / EKA 166 ............ 28

Graphic display AK-MMI ...............................................................28

Power supply module AK-PS 075 / 150 / 250 ........................29

Communication module AK-CM 102 .......................................30

Preface to design ....................................................................................32

Functions ............................................................................................32

Connections ...................................................................................... 33

Limitations ......................................................................................... 33

Design of a compressor and condenser control .........................34

Procedure: ..........................................................................................34

Sketch .................................................................................................. 34

Compressor and condenser functions ....................................34

Connections ...................................................................................... 35

Planning table .................................................................................. 37

Length .................................................................................................38

Linking of modules ......................................................................... 38

Determine the connection points ............................................39

Connection diagram ...................................................................... 40

Supply voltage ................................................................................ 42

Ordering ..................................................................................................... 43

3. Mounting and wiring .............................................................45

Mounting ................................................................................................... 46

Mounting of analog output module ........................................ 46

Mounting of extension module on the basic module ....... 47

Wiring .......................................................................................................... 48

4. Conguration and operation ................................................51

Conguration ...........................................................................................52

Connect PC ........................................................................................ 52

Authorization .................................................................................... 54

Unlock the conguration of the controllers ..........................55

System setup ....................................................................................56

Set plant type ................................................................................... 57

Set control of compressors ..........................................................58

Set oil management ....................................................................... 61

Setup control of condenser fans ...............................................63

Setup control of high pressure ...................................................65

Setup control of receiver pressure ............................................66

Setup control of heat recovery..................................................67

Setup Display .................................................................................... 70

Setup Functions for General purpose ......................................71

Separate thermostats ............................................................. 72

Separate pressostats ..............................................................72

Separate voltage signals .......................................................73

Separate alarm inputs ............................................................ 73

Separate PI functions ............................................................. 74

Conguration of inputs and outputs .......................................75

Set alarm priorities..........................................................................77

Lock conguration ..........................................................................79

Check conguration .......................................................................80

Check of connections ............................................................................ 82

Check of settings.....................................................................................84

Schedule function .................................................................................. 86

Installation in network .......................................................................... 87

First start of control ................................................................................88

Start the control ............................................................................... 89

Manual capacity control ............................................................... 90

5. Regulating functions .............................................................91

Suction group ..........................................................................................92

Controlling sensor selection .......................................................92

Reference ...........................................................................................93

Capacity control of compressors ...............................................94

Capacity distribution methods ........................................... 96

Power pack types – compressor combinations ............97

Compressor timers ................................................................101

The capacity from the digital scroll compressor ........101

Load shedding ........................................................................102

Cascade systems – coordination and injection ..........103

Injection ON ............................................................................105

Liquid injection in suction line .........................................106

Safety functions .............................................................................106

Oil management............................................................................108

Condenser ...............................................................................................110

Capacity control of condenser .................................................110

Reference for condensing pressure ........................................110

Capacity distribution ...................................................................112

Step regulation ......................................................................................112

Speed regulation ..................................................................................112

Condenser couplings ...................................................................113

Safety functions for condenser ................................................113

EC motor ...........................................................................................113

CO2 transcritical system and heat recovery ........................114

Circuit for heat recovery or hot tap water ....................115

Circuit for recovery for heating .........................................116

Circuits for control of CO2 gas pressure ........................119

Receiver control .....................................................................121

Parallel compression ............................................................122

General monitoring functions .........................................................124

Miscellaneous ........................................................................................126

Appendix A – Compressor combinations and coupling pat-

terns ...........................................................................................................130

Appendix B - Alarm texts ...................................................................136

Appendix C - Recommended connection - AK-PC 781 ...........138

2 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Application

1. Introduction

SW = 4.5x

AK-PC 781 is complete regulating units for capacity control of compressors and condensers in refrigeration systems. 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 condensers so that operation all the time takes place at the energy-optimum pressure conditions. Both suction pressure and condensing pressure are controlled by signals from pressure transmitters. Capacity control can be carried out by suction pressure P0, media temperature S4 or separate control pressure Pctrl (for cascade).

Among the dierent functions are:

- Capacity control of up to 8 compressors

- Up to 3 unloaders for each compressor

- Oil management. Either shared or individual for all of the compressor's oil valves. Receiver pressure control.

- Speed control of one or two compressors

- Up to 6 safety inputs for each compressor

- Option for capacity limitation to minimize consumption peaks

- When the compressor does not start, signals can be transmitted to other controllers so that the electronic expansion valves will be closed

- Regulation of liquid injection into suction line

- Start/stop of liquid injection in heat exchanger (cascade)

- MT/LT - coordination between controllers in cascade control

- Safety monitoring of high pressure / low pressure / discharge temperature

- Capacity control of up to 8 fans

- Floating 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.

Examples

Traditional capacity control

Booster control with 2 controls

(For pure booster control without MT cooling, the intermediate pressure must be connected to the receiver to prevent Pmin and Pmax cut-outs during the start-up).

Heat recovery functions, controlling the condensing pressure and receiver pressure of a CO2 plant

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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 specic application – variation is created through the read-in software and the way you choose to dene 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 nd your way through all the questions so that the regulation can be dened 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 RS8GG602 © Danfoss 2015-03 AK-PC 781

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 dierent settings in one menu will result in dierent 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” (conguration).

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 prole 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 tted in order for P0 (Suction) and Pc (Condensing) readings to be displayed. A total of 4 displays can be tted and with one setting it is possible to choose between the following readings: suction pressure, suction pressure in temperature, Pctrl, S4, Ss, Sd, condenser pressure, condenser pressure in temperature, S7 gas cooler temperature, hot tap water at heat recovery and heat exchanger temperature at heat recovery. A graphical display with control buttons can also be tted.

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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 dene the measurements you wish to be shown. The collected values can be printed, or you may export them to a le. You can open the le 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

■ DO8 ■ Service Pin

Slow ash = OK Quick ash = 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 conrm that you have seen the alarm you can cross it o in the acknowledge eld. If you want to know more about a current alarm you can click on it and obtain an information display on the screen.

A corresponding display exists for all earlier alarms. Here you can upload information if you need further details about the alarm history.

Trouble-shooting

The controller contains a function that continuously follows a number of measurements and deals with them. The result indicates whether the function is OK or whether an error may be expected within a given period of time (“the trip down the roller coaster has started”). At this time an alarm is transmitted about the situation – no error has appeared as yet, but it will come. One example may be slow clogging-up of a condenser. When the alarm comes the capacity has been reduced, but the situation is not serious. There will be time to plan a service call.

Alarm

Error

6 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

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 specic 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 sucient. 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.

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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 dened 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 conguration where each individual connection is dened 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.

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1. Controller

Type Function Application

AK-PC 781

Controller for capacity control of compressors and condensers 8 compressors with up to 3 unloaders, 8 fans, max. 120 inputs/outputs

Compressor / Condenser / Both/ Oil management / 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/O outputs On/o 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 AK - Com port

- Cable between PC and AK controller AK - USB

Accessories Power supply module 230 V / 115 V to 24 V d.c.

AK-PS 075 18 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

AK-MMI Graphic display with operation

Cable between zero modem cable and AK controller / Cable between PDA cable and AK controller

Cable between display and controller Length = 2 m, 6 m

Cable between graphic display and controller Length = 1.5 m, 3.0 m

AK - RS 232

Supply for controllerAK-PS 150 36 VA

Accessories Real time clock for use in controllers that require a clock function, but are not wired with data communication.

AK-OB 101A Real time clock with battery backup. To be mounted in an AK controller

Accessories Communication modules for controllers where modules cannot be connected continuously

AK-CM 102 Communication module

Data communication for external extension modules

On the following pages there is data specic to each module.

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Common data for modules

Supply voltage 24 V d.c./a.c. +/- 20%

Power consumption AK-__ (controller) 8 VA

AK-XM 101, 102, 103, 107, AK-CM 102 2 VA

AK-XM 204, 205, 208 5 VA

Analog inputs Pt 1000 ohm /0°C Resolution: 0.1°C

Pressure transmitter type AKS 32R / AKS 2050 AKS 32 (1-5 V)

Other pressure transmitter: Ratiometric signal Min. and Max. pressure must be set

Voltage signal 0-10 V

Contact function (On/O ) On at R < 20 ohm

On/o supply voltage inputs Low voltage

Relay outputs SPDT

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

Accuracy: +/- 0.5°C

Resolution:1 mV Accuracy +/- 10 mV Max. connection of 5 pressure transmitters on one module

O at R > 2K ohm (Gold -plated contacts not necessary)

O: U < 2 V On: U > 10 V

O: U < 24 V On: U > 80 V

Max. 230 V Low and high voltage must not be connected to the same output group

Solid state outputs Can be used for loads that are cut in and

out frequently, e.g. : Oil valves, fans and AKV valves

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 specic, this is mentioned together with the module in question.

Max. 240 V a.c. , Min. 48 V a.c. Max. 0,5 A, Leak < 1 mA Max. 1 AKV

Separate supply to stepper outputs : 24 a.c./d.c. / 13 VA

0 to 95% RH (non condensing) No shock inuences / vibrations

LVD tested according to EN 60730 EMC tested Immunity according to EN 61000-6-2 Emission according to EN 61000-6-3

UL le number: E166834 for XM and CM-modules UL le number: E31024 for PC-modules

10 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

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 781 Capacity controller RS8GG602 © Danfoss 2015-03 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.

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 ash when the gateway sends an acceptance message.

Operation

The conguration operation of the controller must take place from the software program “Service Tool”. The program must be installed on a PC, and the PC must be connected to the controller via the network plug on the front of the unit.

Light-emitting diodes

There are two rows with LED’s. They mean: Left row:

• Voltage supply to the controller

• Communication active with the bottom PC board (red = error)

• Status of outputs DO1 to DO8

Right row:

• Software status (slow ash = OK)

• Communication with Service Tool

• Communication on LON

• Communication with AK-CM 102

• Alarm when LED ashes

- 2 LED’s that are not used

• “Service Pin” switch has been activated

Address

■ Power

■ Comm

■ DO1 ■ Status

■ DO2 ■ Service Tool

■ DO3 ■ LON

■ DO4 ■ I/O Extension

■ DO5 ■ Alarm

■ DO6

■ DO7

■ DO8 ■ Service Pin

Slow ash = OK Quick ash = 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 RS8GG602 © Danfoss 2015-03 AK-PC 781

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

S1 S2

Pt 1000 ohm/0°C

Saux_ SsA SdA Shr Stw Sgc

AKS 32R

3: Brown

2: Blue

1: Black

P0A P0B PcA PcB

AKS 32

3: Brown

2: Black

1: Red

Paux Pgc Prec

...

On/O Ext.

Main switch Day/ Night Door Level switch

AKV

Comp 1 Comp 2 Fan 1 Alarm Light Rail heat Defrost Solenoid valve

Option Board

Please see the signal on the page with the module.

24 and 25 used only when "Option board tted"

type

Pt 1000

AKS 32R / AKS 2050

-1 - xx bar

AKS 32

-1 - zz bar

0 - 5 V 0 - 10 V

Active at:

Closed

Open

Active at:

O

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

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 781 Capacity controller RS8GG602 © Danfoss 2015-03 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 RS8GG602 © Danfoss 2015-03 AK-PC 781

Point

Point 1 2 3 4

Type AI1 AI2 AI3 AI4

Terminal 9: 12 V Terminal 10: 5 V

Pt 1000 ohm/0°C

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

S1 S2 Saux SsA

Pt 1000

SdA Shr Stw Sgc

P0A P0B PcA PcB Paux Pgc Prec

AKS 32R / AKS 2050

-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

On/O

...

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 781 Capacity controller RS8GG602 © Danfoss 2015-03 15

Extension module AK-XM 102A / AK-XM 102B

Function

The module contains 8 inputs for on/o 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/O: On: DI > 10 V a.c. O: DI < 2 V a.c.

AK-XM 102B

Max. 230 V

On/O: On: DI > 80 V a.c. O: DI < 24 V a.c.

16 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Point

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 o)

Point 1 2 3 4

Type DI1 DI2 DI3 DI4

Point 5 6 7 8

Type DI5 DI6 DI7 DI8

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

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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)

18 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Point

Point 1 2 3 4

Type AI1 AI2 AI3 AI4

Terminal 9: 12 V Terminal 10: 5 V

Pt 1000 ohm/0°C

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

S1 S2 Saux SsA

Pt 1000

SdA Shr Stw Sgc

P0A P0B PcA

AKS 32R / AKS 2050

-1 - xx bar PcB Paux Pgc

AKS 32

-1 - zz bar Prec

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

...

On/O Ext.

Main switch Day/ Night

Door Level switch

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 781 Capacity controller RS8GG602 © Danfoss 2015-03 19

Extension module AK-XM 204A / AK-XM 204B

Function

The module contains 8 relay outputs.

Supply voltage

The supply voltage to the module comes from the previous module in the row.

AK-XM 204B only Override of relay

Eight change-over switches at the front make it possible to override the relay’s function. Either to position OFF or ON. In position Auto the controller carries out the control.

Light-emitting diodes

There are two rows with LED’s. They mean: Left row:

• Voltage supply to the controller

• Communication active with the bottom PC board (red = error)

• Status of outputs DO1 to DO8

Right row: (AK-XM 204B only):

• Override of relays ON = override OFF = no override

Fuses

Behind the upper part there is a fuse for each output.

AK-XM 204A AK-XM 204B

Max. 230 V

AC-1: max. 4 A (ohmic) AC-15: max. 3 A (Inductive)

Keep the safety distance!

Low and high voltage must not be connected to the same output group

AK-XM 204B Override of relay

Note

If the changeovers are used to override the compressor operation, it is necessary to wire a safety relay into the circuit for oil management. Without this safety relay, the controller will fail to stop the compressor if it should run out of oil. See Regulating functions.

20 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Point

Signal Active at

Comp. 1

Comp. 2

Fan 1

Alarm

Solenoid valve

O

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 781 Capacity controller RS8GG602 © Danfoss 2015-03 21

Extension module AK-XM 205A / AK-XM 205B

Function

The module contains: 8 analog inputs for sensors, pressure transmitters, voltage signals

and contact signals.

8 relay outputs.

Supply voltage

The supply voltage to the module comes from the previous module in the row.

AK-XM 205B only Override of relay

Eight change-over switches at the front make it possible to override the relay’s function. Either to position OFF or ON. In position Auto the controller carries out the control.

Light-emitting diodes

There are two rows with LED’s. They mean: Left row:

• Voltage supply to the controller

• Communication active with the bottom PC board (red = error)

• Status of outputs DO1 to DO8

Right row: (AK-XM 205B only):

• Override of relays ON = override OFF = no override

AK-XM 205A AK-XM 205B

max. 10 V

Fuses

Behind the upper part there is a fuse for each output.

Note

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 RS8GG602 © Danfoss 2015-03 AK-PC 781

Point

Pt 1000 ohm/0°C

AKS 32R

AKS 32

On/O

3: Brown

2: Blue

1: Black

3: Brown

2: Black

1: Red

Signal Signal

type

S1 S2 Saux SsA

Pt 1000

SdA Shr Stw Sgc

P0A P0B PcA PcB Paux Pgc

AKS 32R / AKS 2050

-1 - xx bar

AKS 32

-1 - zz bar

Prec

0 - 5 V

...

Ext. Main switch Day/ Night Door

0 - 10 V

Active at:

Closed

Open

Level switch

Comp 1

Active at:

Comp 2 Fan 1

on Alarm Light Rail heat

O

Defrost Solenoid valve

Point 1 2 3 4 5 6 7 8

Type AI1 AI2 AI3 AI4 AI5 AI6 AI7 AI8

Point 9 10 11 12 13 14 15 16

Type DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8

Signal Module Point

Terminal 9: 12 V Terminal 10: 5 V

Terminal 21: 12 V Terminal 22: 5 V

Terminal 11, 12, 23, 24 :

(Cable screen)

Terminal

1 (AI 1) 1 - 2

2 (AI 2) 3 - 4

3 (AI 3) 5 - 6

4 (AI 4) 7 - 8

5 (AI 5) 13 - 14

6 (AI 6) 15 - 16

7 (AI 7) 17 - 18

8 (AI 8) 19 -20

9 (DO 1) 25 - 26 - 27

10 (DO 2) 28 - 29 - 30

11 (DO 3) 31 - 30 - 33

12 (DO 4) 34 - 35 - 36

13 (DO 5) 37 - 36 - 39

14 (DO6) 40 - 41 - 42

15 (DO7) 43 - 44 - 45

16 (DO8) 46 - 47 - 48

Signal type /

Active at

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 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. The supply voltage to the valves must be from a separate supply, which must be galvanically separated from the supply for the control range. 24 V d.c. +/-20%. (Power requirements: 7.8 VA for controller + 1.3 VA per valve).

A UPS may be necessary if the valves need to open/close during a power failure.

Light-emitting diodes

There is one row with LED’s. It indicate the following:

• Voltage supply to the module

• Communication active with the bottom PC board (red = error)

• Status of outputs step1 to step4

Separate voltage supply is required 24 V d.c. 13 VA

max. 10 V

Output:

24 V d.c.

= 500 m A / coil

max.

20-500 step/s

24 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Point

CCM

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 781 Capacity controller RS8GG602 © Danfoss 2015-03 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 0 - 10 V

Module

Point 24 25

Type AO1 AO2

AO2

AO1

26 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Extension module AK-OB 101A

Function

The module is a real time clock module with battery backup.

The module can be used in controllers that are not linked up in a data communication unit together with other controllers. The module is used here if the controller needs battery backup for the following functions

• Clock function

• Fixed times for day/night change-over

• Fixed defrost times

• Saving of alarm log in case of power failure

• Saving of temperature log in case of power failure

Connection

The module is provided with plug connection.

Placing

The module is placed on the PC board inside the top part.

Point

No point for a clock module to be dened – just connect it.

Working life of the battery

The working life of the battery is several years – even if there are frequent power failures. An alarm is generated when the battery has to be replaced. After the alarm there are still several months of operating hours left in the battery.

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 27

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 dened for a display module – you simply connect it.

Graphic display AK-MMI

Function

Setting and display of values in the controller.

Connection

The display connects to the controller via a cable with plug connections. Use plug RJ45 to connect to the controller; the same plug is also used for service tool AK-ST 500.

Supply voltage

24 V a.c. / d.c. 1.5 VA.

Placing

The display can be placed at a distance of up to 3 m from the controller.

EKA 166

Point

No point has to be dened for a display – you simply connect it.

28 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

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

Eect

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

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 29

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 tted 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. The communication module can be used only with controllers of the type AK-PC 781.

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 dened as if the modules were an extension of each other.

Address

The address for the rst 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 nal 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 nal module. (Here following module no. 11; see the sketch.) After conguration, the address must not be changed.

Max. 20 VA

30 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 31

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 dierence 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 is zeroset when there is power failure. The clock’s setting is maintained if the controller is linked up in a network with a gateway, a system manager or a clock module can be mounted in the controller.

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.

32 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

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 or AKS 2050 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 dierent 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 dened: 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 and CCM. The valve type should be set during programming.

Limitations

As the system is very exible 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.

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 33

✔ The sum of connections cannot exceed 120 (AK-PC 781).

✔ 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.

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

Follow these 12 steps

Sketch

Make a sketch of the system in question.

Compressor and condenser functions

Application

Regulation of a compressor group x

Regulation of a condenser group x

Both compressor group and condenser group x

Regulation of compressor capacity

Regulation sensor. Either P0, S4 or Pctrl x

PI-regulation x

Max. number of compressor steps 8

Max. number of unloaders each compressor 3

Identical compressor capacities x

Dierent compressor capacities x

Speed regulation of 1 or 2 compressors x

Run time equalisation x

Min. restart time x

Min. On-time x

Liquid injection in suction line x

Liquid injection in cascade heat exchanger x

External start/stop of compressors x

Oil management

Oil injection in compressor. Shared or individual x

AK-PC 781

Receiver pressure control x

Monitoring of oil level in receiver x

Management of oil level in oil separator x

Reset of oil management x

Cutout of compressors at oil failure x

Safety relays during forced compressor control x

Suction pressure reference

Override via P0 optimization x

Override via “night setback” x

Override via "0 -10 V signal" x

Regulation of condenser capacity

Regulation sensor. Either: Pc, Sgc or S7 x

Step regulation x

Max. number of steps 8

Speed regulation x

Step and speed regulation x

Speed regulation rst step x

Limitation of speed during night operation x

Heat recovery function for tap water control x

Heat recovery function for heating x

Controlling the gas cooler (high pressure valve). parallel valve, if applicable

34 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Trouble-shooting function FDD on condenser x

Condenser pressure reference

Floating condensing pressure reference x

Setting of references for heat recovery functions 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

A bit more about the functions

Compressor

Regulation of up to 8 compressors. And up to 3 unloaders each compressor. Compressor No. 1 or 2 can be speed-regulated. The following can be used as control sensor:

1) P0 - Suction pressure

2) S4 - Cold brine temperature

3) Pctrl - Condensing pressure in the low pressure circuit controls the high-pressure circuit for cascade control.

(P0 is also used for 2 and 3, but for low-pressure safety.)

Condenser

Regulation of up to 8 condenser steps. Fans can be speed-regulated. Either all on one signal or only the rst fan of several. EC motor can be used. Relay outputs and solid state outputs may be used, as desired. The following can be used as control sensor:

1) Pc - Condensing pressure

2) S7 - Warm brine temperature (Pc is used here for high-pressure

safety.)

3) Sgc -Temperature at the gas cooler outlet.

Connection between high-pressure and low-pressure circuits

(MT and LT circuits)

Capacity control of the high-pressure circuit can be adjusted by the condensing pressure in the low-pressure circuit. The controller can give o a signal from a relay output so that the low-pressure circuit can only start when the high-pressure circuit is on. The controller can receive a signal from the low-pressure circuit that there is a need for refrigeration. Coordination is also required for parallel compression.

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.

Connections

Here is a survey of the possible connections. The texts can be read in context with the table on the following page.

Analog inputs

Temperature sensors

• S4 (Cold brine temperature) Must be used when the control sensor for compressor control has been selected as S4.

• Ss (suction gas temperature)

Must always be used in connection with compressor regulation.

• Sd (discharge gas temperature)

Must always be used in connection with compressor regulation.

Common high pressure monitoring of compressors x

Safety monitoring of condenser fans x

General alarm functions with time delay 10

Miscellaneous

Extra sensors 7

Inject On function x

Option for connection of separate display 2

Separate thermostat functions 5

Separate pressostat functions 5

Separate voltage measurements 5

PI regulation 3

Max. input and output 120

Digital scroll

When using a digital scroll, the unloading of the compressor should be connected to one of the four solid state outputs in the controller.

Heat recovery

There are adjustment options for hot water and heat containers for heating. The controller manages, in order of priority: 1 -tap water 2-heating 3-gas cooler, which removes the remaining excess heat.

Safety circuit

If signals are to be received from one or more parts of a safety circuit, each signal must be connected to an ON/OFF input.

Day/night signal for raising the suction pressure

The clock function can be used, but an external ON/OFF signal may be used instead. If the “P0 optimization” function is used, no signal will be given concerning the raising of the suction pressure. The P0 optimization will see to this.

“Inject ON” override function

The function closes expansion valves on evaporator controls when all compressors are prevented from starting. The function can take place via the data communication, or it may be wired via a relay output.

Separate thermostat and pressure control functions

A number of thermostats can be used according to your wishes. The function requires a sensor signal and a relay output. In the controller there are settings for cutin and cutout values. An associated alarm function may also be used.

Separate voltage measurements

A number of voltage measurements can be used according to your wishes. The signal can for example be 0-10 V. The function requires a voltage signal and a relay output. In the controller there are settings for cutin and cutout values. An associated alarm function may also be used.

If you want to know more about the functions, go to chapter 5.

• Sc3 (outdoor temperature) To be used when monitoring function FDD is used. To be used when regulation is performed with oating condenser reference.

• S7 (warm brine return temperature) Must be used when the control sensor for condenser has been selected as S7.

• Saux (1-4), any extra temperature sensors

Up to four additional sensors for monitoring and data collection may be connected. These sensors can be used for general thermostat functions.

• Stw2, 3, 4 and 8 (temperature sensors for heat recovery)

Must be used when adjusting hot tap water.

Shr2, 3, 4 and 8 (temperature sensors for heat recovery)

Must be used when adjusting the heat receiver for heating.

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 35

• Sgc (temperature sensor for gas cooling controls) Shall be placed within one metre after the gas cooler.

• Shp (temperature sensor, if the refrigerant can be routed outside of the gas cooler)

Pressure transmitters

• P0 Suction Pressure

Must always be used in connection with compressor regulation (frost protection).

• Pctrl (control pressure for cascade) Must only be used if the control sensor for compressor control has been selected as Pctrl (cascade)

• Pc Condensing Pressure

Must always be used in connection with compressor or condenser regulation

• Prec. Oil receiver pressure. Must be used for receiver pressure regulation.

• Pgc Gas cooler pressure. Must be used for CO2 transcritical operation.

• Prec.CO2 Pressure reading in the CO2 receiver. Must be used for CO2 transcritical operation.

• Paux (1-5) Up to 5 extra pressure transmitters can be connected for monitoring and data collection. These sensors can be used for general pressure switch functions.

Note. A pressure transmitter type AKS 32 or AKS 32R can supply signals to a maximum of ve controllers.

Voltage signal

• Ext. Ref Used if a reference override signal is received from another control.

• Voltage inputs (1-5) Up to 5 extra voltage signals can be connected for monitoring and data collection. These signals are used for general voltage input functions.

On/O-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

• Compressor release signal on LT controller in cascade

• Compressor requirements signal on MT controller in cascade

Example

Compressor group:

• MT circuits

• Refrigerant CO2 (R744)

• 4 only compressors with "Best t". One speed controlled

• Safety monitoring of each compressor

• Common high-pressure monitoring

• Po setting -15°C, night displacement 5 K

• Oil management of each compressor

• Pulse reset for stopped compressor (lack of oil)

High pressure controls:

• Heat recovery for tap water

• Heat recovery for heating circuit

• Gas cooler

• Fans, speed controlled

• Pc regulates based on temperature sensor Sc3 and Sgc

Receivers:

• Monitoring of CO2 level

• Control of pressure in oil receiver

• Controlling the tap water receiver temperature, 55°C

• Controlling the receiver temperature for the heating circuit, 40°C

Fan in plant room

• Thermostat control of fan in engine room

Safety functions:

• Monitoring of Po, Pc, Sd and superheat in suction line

• Po max = -5°C, Po min = -35°C

• Pc max = 50 °C

• Sd max = 120°C

• SH min = 5 °C, SH max = 35 °C

• Monitoring of low and high level in oil receiver

Other:

• Alarm output used

• External compressor stop used

• Signal from the condenser fans safety circuit

• Any signal from the frequency converter’s 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/o signals for general alarm for monitoring and data collection can be connected.

• Flow switch for heat recovery

• Level contacts

On/o-outputs

Relay outputs

• Compressors

• Unloaders

• Fan motor

• Injection On function (signal for evaporator controls. One per suction group).

• Start/stop of liquid injection in heat exchanger

• Compressor release, output signal from MT controller in cascade

• Compressor request, output signal from LT controller in cascade

• Start/stop of liquid injection in suction line

• Start/stop of 3-way valves at heat recovery

• ON/OFF signal for start/stop of speed regulation

• Alarm relay. I'm alive relay.

• On/o signals from general thermostats (1-5), pressure switches (1-5) or

voltage input functions (1-5).

• Oil valves

• Safety relays for cutouts of compressors at oil failure

Solid state outputs

The solid state outputs on the controller module may be used for the same functions as those mentioned under “relay outputs”. (The output will always be “OFF” when the controller has a power failure).

Analog output

• Speed regulation of the condenser’s fans.

• Speed regulation of the compressor

• Speed control of pumps for heat recovery

• Control signal for high pressure CO2 valve. (stepper signal. if applicable)

• Stepper signal for hot gas by-pass valve

Data from this example is used on the next page. The result is that the following modules should be used:

• AK-PC 781 controller

• AK-XM 205A input and output module

• AK-XM 208C stepper output module

• AK-XM 102B digital input module

• AK-XM 103B analog input and output module

• AK-OB 110 analog output module

36 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Planning table

The table helps you establish whether there are enough inputs and outputs on the basic controller. If there are not enough of them, the controller must be extended by one or more of the mentioned extension modules.

Note down the connections you will require and add them up

Analog inputs

Temperature sensors, Ss, Sd, Sc3, S4, S7, Stw.., Shr.., Sgc 9

Extra temperature sensor / separate thermostats /PI-regulation 1

Pressure transmitters, P0, Pc, Pctrl. Prec / separate pressostats 5 P = Max. 5 / module

Voltage signal from other regulation, separate signals

Heat recovery via thermostat

On/o inputs Contact 24 V 230 V

Safety circuits, common for all compressors 1 Max.1

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 4

Safety circuits, condenser fans, frequency converter Max. 1/ fan

Safety circuits, ow switch 2

External start/stop 1

LT release input / MT request input / IT release input

Night setback of suction pressure

Separate alarm functions via DI 1

Load shedding

Start of Heat recovery 1 1

Liquid level, Oil level, Pulse reset of oil management 9

On/o outputs

Compressors, motors 4

Unloaders

Fan motors, circulation pumps 3

Alarm relay, I'm alive relay

Inject ON Max. 1

Separate thermostat and pressostat functions and voltage measurements

Heat recovery function via thermostat Max.1

Liquid injection in suction line / heat exchanger. Heat gas dump Max.1

MT release output / LT request output / IT on-outp. / IT release outp.

Solenoid valve for Oil. 5

3-way valve 3

Analog control signal, 0-10 V

Frequency converter, Compressor, fans, pumps, valves etc. 5

Valves with stepper motor. Parallel valves, if applicable 1

Sum of connections for the regulation 27 0 8 16 5+1 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 16 - 8 8 5+1

Analog input signal

Example

On/o voltage signal

Example

On/o voltage signal

Example

On/O output signal

1 Max. 5+5+5

Example

Analog output signal 0-10 V

Stepper output

Example

Limitations

The example:

None of the 3 limitations are exceeded => OK

The missing connections to be supplied by one or more extension modules:

AK-XM 101A (8 analog inputs) ___ pcs. á 2 VA = __

AK-XM 102A (8 digital low voltage inputs) ___ pcs. á 2 VA = __

AK-XM 102B (8 digital high voltage outputs) 1 ___ pcs. á 2 VA = __

AK-XM 103A (4 analog inputs, 4 analog outputs) 1 1 ___ pcs. á 2 VA = __

AK-XM 204A / B (8 relay outputs) ___ pcs. á 5 VA = __

AK-XM 205A / B (8 analog inputs. + 8 relay output) 1 1 ___ pcs. á 5 VA = __

AK-XM 208C (8 analog inputs + 4 stepper outputs) 1 1 ___ pcs. á 5 VA = __

AK_OB 110 (2 analog outputs) 1 ___ pcs. á 0 VA = 0

Sum of power

1 pcs. á 8 VA = 8

Sum =

Sum = max. 32 VA

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 37

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

Linking of modules

Start with the controller module and then mount the selected extension modules. The sequence is of no importance.

However, you must not change the sequence, i.e. rearrange the modules, after you have made the setup where the controller is told which connections are found on which modules and on which terminals.

The modules are attached to one another and kept together by a connection which at the same time transmits the supply voltage and the internal data communication to the next module.

Example continued: Controller module + 2 extension modules in 200-series + 2 extension module in 100 series = 224 + 144 + 144 + 72 + 72 = 656 mm.

Example continued

Mounting and removal must always be performed when there is no voltage.

The protective cap mounted on the controller’s plug connection must be moved to the last vacant plug connection so that the plug will be protected against short-circuit and dirt.

When the regulation has started the controller will all the time check whether there is connection to the connected modules. This status can be followed by the light-emitting diode.

When the two catches for the DIN rail mounting are in open position the module can be pushed into place on the DIN rail – no matter where in the row the module is found. Removal is likewise carried out with the two catches in the open position.

38 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

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 rst 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 (conguration) should take place at the present time. It is most easily accomplished by lling 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 tted onto a module with override changeovers, as they can be put out of operation by an incorrect setting.

Example continued

Signal Module Point

Discharge temperature - Sd

Suction gas temperature- Ss 2 (AI 2) 3 - 4 Pt 1000

Outdoor temperature - Sc3 3 (AI 3) 5 - 6 Pt 1000

External compressor stop 4 (AI 4) 7 - 8 Closed

Thermostat sensor in plant room

- Saux1

Suction pressure - Po 6 (AI 6) 11 - 12 AKS 2050-59

Condensing pressure - Pc 7 (AI 7) 13 - 14 AKS 2050-159

Level switch, oil, comp.1 8 (AI 8) 19 - 20 Closed

Level switch, oil, comp.2 9 (AI 9) 21 - 22 Closed

Level switch, oil, comp.3 10 (AI 10) 23 - 24 Closed

Level switch, oil, comp.4 11 (AI 11) 25 - 26 Closed

Solenoid valve, oil , comp. 1 12 (DO 1) 31 - 32 ON

Solenoid valve, oil , comp. 2 13 (DO 2) 33 - 34 ON

Solenoid valve, oil , comp. 3 14 (DO 3) 35 - 36 ON

Solenoid valve, oil , comp. 4 15 (DO 4) 37 - 38 ON

Solenoid valve, oil, Separator 16 (DO 5) 39 - 40 - 41 ON

Circulation pump tw 17 (DO6) 42 - 43 - 44 ON

Circulation pump hr 18 (DO7) 45 - 46 - 47 ON

Room fan 19 (DO8) 48 - 49 - 50 ON

Voltage signal to high pressure valve, ICMTS

1 (AI 1) 1 - 2 Pt 1000

5 (AI 5) 9 - 10 Pt 1000

24 - 0-10 V

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

Level switch, oil, receiver High

Level switch, oil, receiver Low 2 (AI 2) 3 - 4 Closed

Level switch, oil, Separator 3 (AI 3) 5 - 6 Closed

Level switch, CO2 receiver 4 (AI 4) 7 - 8 Open

Pulse reset of stopped compressor 5 (AI 5) 13 - 14 Pulse

Refrigerant receiver, Prec CO2 7 (AI 7) 17 - 18 AKS 2050-159

Oil receiver, Prec Oil 8 (AI 8) 19 - 20 AKS 2050-159

Compressor 1 9 (DO 1) 25 - 26 - 27 ON

Compressor 2 10 (DO 2) 28 - 29 - 30 ON

Compressor 3 11 (DO 3) 31 - 32 - 33 ON

Compressor 4 12 (DO 4) 34 - 35 - 36 ON

Start /stop of VLT for fans 13 (DO 5) 37 - 38 - 39 ON

3-way valve, tap water, V3tw 14 (DO6) 40 - 41 - 42 ON

3-way valve, heat circuit, V3hr 15 (DO7) 43 - 44 - 45 ON

3-way valve, gas cooler, V3gc 16 (DO8) 46 - 47 - 48 ON

Signal Module Point/Step Terminal Signal type

Tap water temperature - Stw2

Tap water temperature - Stw3 2 (AI 2) 3 - 4 Pt 1000

Tap water temperature - Stw4 3 (AI 3) 5 - 6 Pt 1000

Tap water temperature - Stw8 4 (AI 4) 7 - 8 Pt 1000

Heat reclaim temperature Shr2 5 (AI 5) 9 - 10 Pt 1000

Heat reclaim temperature Shr3 6 (AI 6) 11 - 12 Pt 1000

Heat reclaim temperature Shr4 7 (AI 7) 13 - 14 Pt 1000

Heat reclaim temperature Shr8 8 (AI 8) 15 - 16 Pt 1000

Stepper signal to by-pass valve,

CCM

1 (AI 1) 1 - 2 Closed

6 (AI 6) 15 - 16

1 (AI 1) 1 - 2 Pt 1000

9 (step1)

10 (step 2) 29 - 30 - 31 - 32

11 (step 3) 33 - 34 - 35 - 36

12 (step 4) 37 - 38 - 39 - 40

Terminal

25 - 26 - 27 - 28

Signal type /

Active at

CCM (ETS)

Continued next page

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 39

Signal Module Point Terminal Active at

Compressor 1 Gen. Safety

Compressor 2 Gen. Safety 2 (DI 2) 3 - 4 Open

Compressor 3 Gen. Safety 3 (DI 3) 5 - 6 Open

Compressor 4 Gen. Safety 4 (DI 4) 7 - 8 Open

Start/stop heat recovery hr 5 (DI 5) 9 - 10 Closed

All compressors common safety 6 (DI 6) 11 - 12 Open

Flow switch FStw 7 (DI 7) 13 - 14 Open

Flow switch FShr 8 (DI 8) 15 - 16 Open

Signal Module Point Terminal Signal type

Temp. gas cooler outlet Sgc

Temp. by-pased gas Shp 2 (AI 2) 3 - 4 Pt 1000

Start/stop heat recovery tw

Gas cooler pressure Pgc

Speed control, compressor 5 (AO 1) 9 - 10

Speed control, gas cooler fan 6 (AO 2) 11 - 12 0 - 10 V

Speed control, pump - tw 7 (AO 3) 13 - 14 0 - 10 V

Speed control, pump - hr 8 (AO 4) 15 - 16 0 - 10 V

1 (DI 1) 1 - 2 Open

1 (AI 1) 1 - 2 Pt 1000

3 (AI 3) 5 - 6

4 (AI 4) 7 - 8

Closed

AKS 2050-159

0 - 10 V

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.

40 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Example continued:

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 41

Supply voltage

Supply voltage is only connected to the controller module. The supply to the other modules is transmitted via the plug between the modules. The supply must be 24 V +/-20%. One power supply must be used for each controller. The power supply must be a class II. The 24 V must not be shared by other controllers or units. The analog inputs and outputs are not galvanically separated from the supply.

The + and – 24V input must not be earthed.

If using stepper motor valves, the supply for these must be provided from a separate power supply.

For CO2 facilities, it will also be necessary to safeguard the voltage to the controller and valves using UPS.

Example continued:

Controller module 8 VA + 2 extension modules in 200 series 10 VA + 2 extension modules in 100 series 4 VA

-----Power supply size (least) 22 VA

Power supply size

The power consumption grows with the number of modules used:

Module Type Number á Eect

Controller 1 x 8 = 8 VA Extension module 200 series _ x 5 = __ VA Extension module 100 series _ x 2 = __ VA Total ___ VA

42 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Ordering

1. Controller

Type Function Application Language Code no.

AK-PC 781

Controller for capacity control of compressors and condensers. With oil management

Compressor / condenser / both

English, German, French, Dutch, Italian, Spanish, Portuguese, Danish, Finnish, Russian, Czech, Polish, Chinese

080Z0186

2. Extension modules and survey for inputs and outputs

Type Analog

inputs

For sensors, pressure transmitters etc.

Controller 11 4 4 - - - - -

Extension modules

AK-XM 101A 8 080Z0007

AK-XM 102A 8 080Z0008

AK-XM 102B 8 080Z0013 x

AK-XM 103A 4 4 080Z0032 x

AK-XM 204A 8 080Z0011

AK-XM 204B 8 x 080Z0018

AK-XM 205A 8 8 080Z0010 x

AK-XM 205B 8 8 x 080Z0017

AK-XM 208C 8 4 080Z0023

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 x

On/O outputs On/o 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

Example

continued

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 AK - Com port 080Z0262 x

- Cable between PC and AK controller AK - USB 080Z0264

Accessories Power supply module 230 V / 115 V to 24 V d.c.

AK-PS 075 18 VA

AK-PS 150 36 VA 080Z0054 x

AK-PS 250 60 VA 080Z0055

Accessories External display that can be connected to the controller module. For showing, say, the suction pressure

EKA 163B Display 084B8574

EKA 164B Display with operation buttons 084B8575

EKA 166 Display with operation buttons and LED's 084B8578

AK-MMI Graphic display with operation 080G0311

- Cable between display and controller

- Cable between graphic display and controller

Accessories Real time clock for use in controllers that require a clock function, but are not wired with data communication.

AK-OB 101A Real time clock with battery backup. To be mounted in an AK controller 080Z0252

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 zero modem cable and AK controller / Cable between PDA cable and AK controller

AK - RS 232 080Z0261

080Z0053

Supply for controller

Length = 2 m 084B7298

Length = 6 m 084B7299

Length = 1.5 m 080G0075

Length = 3 m 080G0076

Example

continued

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 43

44 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

3. Mounting and wiring

This section describes how the controller:

• Is tted

• Is connected

We have decided to work on the basis of the example we went through previously, i.e. the following modules:

• AK-PC 781 controller module

• AK-XM 205A input and output module

• AK-XM 208C analog input module + stepper output module

• AK-XM 102B digital input module

• AK-XM 103B analog input and output module

• AK-OB 110 analog output module

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 45

Mounting

Mounting of analog output module

1. Lift the top part o 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 o the basic module.

The analog extension module will supply a signal to the ICMTS valve

2. Mount the extension module in the basic module

3. Put the top part back on the basic module

There are two outputs.

46 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Mounting and wiring - continued

Mounting of extension module on the basic module

1. Move the protective cap

Remove the protective cap from the connection plug on the right-hand side of the basic module. Place the cap on the connection plug to the right of the extension module that is to be mounted on the extreme right-hand side of the AK assembly.

In our example four extension modules are to be tted to the basic module. We have chosen to t the module with relays directly on the basic module and then the following module. The sequence is thus:

All the subsequent settings that aect the four extension modules are determined by this sequence.

2. Assemble the extension module and the basic

module

The basic module must not be connected to voltage.

When the two snap catches for the DIN rail mounting are in the open position, the module can be pushed into place on the DIN rail – regardless of where the module is on the row. Disassembly is thus done with the two snap catches in the open position.

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 47

Mounting and wiring - continued

Wiring

Decide during planning which function is to be connected and where this will be.

1. Connect inputs and outputs

Here are the tables for the example:

Remember the isolation amplier If signals are received from dierent controls, e.g. heat recovery for one of the inputs, a galvanically insulated module should be inserted.

Signal Module Point

Discharge gas temperature - Sd

Suction gas temperature - Ss 2 (AI 2) 3 - 4 Pt 1000

Outdoor temperature - Sc3 3 (AI 3) 5 - 6 Pt 1000

External compressor stop 4 (AI 4) 7 - 8 closed

Thermostat sensor in plant room

- Saux1

Suction pressure - P0 6 (AI 6) 11 - 12 AKS 2050-59

Condenser pressure - Pc 7 (AI 7) 13 - 14 AKS 2050-159

Level switch, oil, comp. 1 8 (AI 8) 19 - 20 closed

Level switch, oil, comp..2 9 (AI 9) 21 - 22 closed

Level switch, oil, comp..3 10 (AI 10) 23 - 24 closed

Level switch, oil, comp..4 11 (AI 11) 25 - 26 closed

Solenoid valve, oil, Comp. 1 12 (DO 1) 31 - 32 ON

Solenoid valve, oil, Comp. 2 13 (DO 2) 33 - 34 ON

Solenoid valve, oil, Comp. 3 14 (DO 3) 35 - 36 ON

Solenoid valve, oil, Comp. 4 15 (DO 4) 37 - 38 ON

Solenoid valve , oil, Separator 16 (DO 5) 39 - 40 - 41 ON

Circulation pump tw 17 (DO6) 42 - 43 - 44 ON

Circulation pump hr 18 (DO7) 45 - 46 - 47 ON

Room fan 19 (DO8) 48 - 49 - 50 ON

Voltage signal to high pressure valve, ICMTS

Signal Module Point

Level switch, oil, receiver High

Level switch, oil, receiver Low 2 (AI 2) 3 - 4 closed

Level switch, oil, Separator 3 (AI 3) 5 - 6 closed

Level switch, CO2 receiver 4 (AI 4) 7 - 8 Open

Pulse reset of stopped compressor 5 (AI 5) 13 - 14 Pulse

Refrigerant, receiver, Prec CO2 7 (AI 7) 17 - 18 AKS 2050-159

Oil receiver, Prec Oil 8 (AI 8) 19 - 20 AKS 2050-159

Compressor 1 9 (DO 1) 25 - 26 - 27 ON

Compressor 2 10 (DO 2) 28 - 29 - 30 ON

Compressor 3 11 (DO 3) 31 - 32 - 33 ON

Compressor 4 12 (DO 4) 34 - 35 - 36 ON

Start /stop of VLT to fans 13 (DO 5) 37 - 38 - 39 ON

3-way valve, tap water, V3tw 14 (DO6) 40 - 41 - 42 ON

3-way valve, heat circuit, V3hr 15 (DO7) 43 - 44 - 45 ON

3-way valve, gas cooler, V3gc 16 (DO8) 46 - 47 - 48 ON

Signal Module Point/Step Terminal Signal type

Tap water temperature - Stw2

Tap water temperature - Stw3 2 (AI 2) 3 - 4 Pt 1000

Tap water temperature - Stw4 3 (AI 3) 5 - 6 Pt 1000

Tap water temperature - Stw8 4 (AI 4) 7 - 8 Pt 1000

Heat reclaim temperature Shr2 5 (AI 5) 9 - 10 Pt 1000

Heat reclaim temperature Shr3 6 (AI 6) 11 - 12 Pt 1000

Heat reclaim temperature Shr4 7 (AI 7) 13 - 14 Pt 1000

Heat reclaim temperature Shr8 8 (AI 8) 15 - 16 Pt 1000

Stepper signal to by-pass valve,

CCM

1 (AI 1) 1 - 2 Pt 1000

5 (AI 5) 9 - 10 Pt 1000

24 - 0-10 V

25 -

1 (AI 1) 1 - 2 closed

6 (AI 6) 15 - 16

1 (AI 1) 1 - 2 Pt 1000

9 (step 1)

10 (step 2) 29 - 30 - 31 - 32

11 (step 3) 33 - 34 - 35 - 36

12 (step 4) 37 - 38 - 39 - 40

Terminal

25 - 26 - 27 - 28

Signal type /

Active at

Signal type /

Active at

CCM (ETS)

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 dierent ones. One up to 59 bar and two up to 159 bar.

Signal Module Point Terminal Active at

Compressor 1 Gen. safety

Compressor 2 Gen. safety 2 (DI 2) 3 - 4 Open

Compressor 3 Gen. safety 3 (DI 3) 5 - 6 Open

Compressor 4 Gen. safety 4 (DI 4) 7 - 8 Open

Start/stop heat recovery hr 5 (DI 5) 9 - 10 closed

All comp. common safety 6 (DI 6) 11 - 12 Open

Flow switch FStw 7 (DI 7) 13 - 14 Open

Flow switch FShr 8 (DI 8) 15 - 16 Open

Signal Module Point Terminal Signal type

Temp. gas cooler outlet Sgc

Temp. by-passed gas Shp 2 (AI 2) 3 - 4 Pt 1000

Start/stop heat recovery tw 3 (AI 3) 5 - 6 closed

Gas cooler pressure Pgc 4 (AI 4) 7 - 8 AKS 2050-159

Speed control, compressor 5 (AO 1) 9 - 10 0 - 10 V

Speed control, gas cooler fans 6 (AO 2) 11 - 12 0 - 10 V

Speed control, pump - tw 7 (AO 3) 13 - 14 0 - 10 V

Speed control, pump - hr 8 (AO 4) 15 - 16 0 - 10 V

1 (DI 1) 1 - 2 Open

1 (AI 1) 1 - 2 Pt 1000

48 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

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 781 Capacity controller RS8GG602 © Danfoss 2015-03 49

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 ashing slowly.

5. When there is a network

Set the address and activate the Service Pin.

6. The controller is now ready to be congured.

Internal communication between the modules: Quick ash = error Constantly On = error

■ Power

■ Comm

■ DO1 ■ Status

■ DO2 ■ Service Tool

■ DO3 ■ LON

■ DO4 ■ I/O extension

■ DO5 ■ Alarm

■ DO6

■ DO7

■ DO8 ■ Service Pin

Status on output 1-8

Slow ash = OK Quick ash = 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

50 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

4. Conguration and operation

This section describes how the controller:

• Is congured

• Is operated

We have decided to work on the basis of the example we went through previously, i.e. compressor control with 4 compressors and high pressure control using heat recovery and gas cooler.

The example is shown two pages in.

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 51

Conguration

Connect PC

PC with the program “Service Tool” is connected to the controller.

The controller must be switched on rst and the LED “Status” must ash 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

Select the name SUPV and key in the access code.

The rst 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.

52 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Refrigerating plant example

We have decided to describe the setup by means of an example comprising a MT 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 781 + extension modules.

Compressor Group

• MT circuit

• Refrigerant CO2 (R744)

• Variable compressor and 3 single step compressors

• 4 only compressors with "Best t"

• Safety monitoring of each compressor

• Common high-pressure monitoring

• Po setting -15°C, night displacement 5 K

• Oil management of each compressor

High pressure control:

• Gas cooler with speed controlled fans (Pgc Max. = 100 bar)

• High pressure control with signal from Sgc and Shp

• Pc regulates oating based on outdoor temperature sensor Sc3

• Control of high pressure valve ICMTS

• Heat recovery for hot tap water. Relay and 0-10 V

• Heat recovery for heating. Relay and 0-10 V

Receivers:

• Monitoring of liquid level of refrigerant

• Control of pressure in refrigerant receiver (reference 34 bar)

• Control of pressure in oil receiver

Fan in plant room

• Thermostat control of fan in engine room

Safety functions:

• Monitoring of Po, Pc, Sd and superheat in suction line

• Po max = -5°C, Po min = -35°C

• Pc max = 103.5 bar

• Sd max = 120°C

• SH min = 5 °C, SH max = 35 °C

• Monitoring of low and high level in oil receiver

There is also an internal main switch as a setting. Both, this and the external compressor stop must be “ON” before any adjustment is made.

Warning The main switch will stop all regulations, including high-pressure regulation.

Other

• Start/stop of heat recovery tw and hr

• External compressor stop used

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 53

Conguration - continued

Authorization

1. Go to Conguration 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 dierent 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 specic 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 padlock at the top left corner of the display.

54 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Conguration - continued

Unlock the conguration of the controllers

1. Go to Conguration menu

2. Select Lock/Unlock conguration

3. Select Conguration lock

Press the blue eld with the text Locked

The controller can only be congured when it is unlocked.

The values can be changed when it is locked, but only for those settings that do not aect the conguration.

4. Select Unlocked

Select Unlocked.

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 55

Conguration - continued

System setup

1. Go to Conguration menu

2. Select System setup

3. Set system settings

All settings can be changed by pressing in the blue eld with the setting and then indicating the value of the required setting.

In the rst eld you enter a name for what the controller will be controlling. The text written in this eld 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.

56 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Conguration - continued

Set plant type

1. Go to Conguration menu

2. Select plant type

Press the line Select plant type.

3. Set plant type

4. Set Common functions

Press the +-button to go on to the

6. Quick basis setup

Our example The comments for the example are shown on the following pages, in the middle column.

In our example we want the controller to control both a compressor group and a condenser group. We therefore select the plant type One pack.

Subsequent options are then available, but only those options allowed by the current selection.

Select the refrigerant type, here CO2, further options are made available, etc.

In our example, the cooling (MT) is regulated.. (If it was a cascade control/two step system, the other controller would need to be set to "LP".)

The settings for our example can be viewed in the display.

This setting is special.

Here the user can select a pre-dened system. We do not use this function in our example, but perform the adjustments individually.

Adjust only the two lines with "Smart"

(Only when the refrigerant selected is CO2) Here you can 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.

General If you want to know more about the dierent conguration 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 between "One Suction", "One condenser" or both "One Pack"

4- Plant type continued Refrigerant

Select refrigerant type Refrigerant factors K1, K2, K3 Only used if “Po refrigerant type” is set to custom (contact Danfoss for information)

Pack type

MT = Medium temperature. LT = Low temperature

HP control

High pressure control enabled. To be adjusted later on.

Receiver control

Receiver control enabled. To be adjusted later on.

IT Compressor

Parallel compressor (there are special settings; see the section on page 122).

Heat recovery

Heat recovery enabled. To be adjusted later on.

Oil management

Oil control enabled. To be adjusted later on.

Quick setup

A choice will give a number of predened combinations, which at the same time determine the connection points. The display options depend on previous settings. At the end of the manual there is an overview of the options and connection points. After conguration of this function, the controller will shut down and restart. After the restart, a large number of settings will have been made. These include the connection points. Continue with the settings and check the values. If you change some of the settings, the new values will come into force.

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.

Show Tc

If selecting "yes" the Pc pressure will also be shown as temperature.

Comp. cap. out to AO

If selecting "yes" indicate the current capacity of an output.

Comp. run signal DO

If “yes” is selected, an output is reserved that shows if the compressors are operating.

5 – Quick relative setup

Smart = Setting the controller’s overall pressure values. The remaining pressure values will be set automatically.

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Conguration - continued

Set control of compressors

1. Go to Conguration menu

2. Select Suction group

3. Set values for the reference

The conguration 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:

- Suction set point = -15°C

- Night oset value = 5 K. 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 oset + oset from external 0-10 V signal 1: Reference = set reference + oset from P0 optimization Setpoint ( -80 to +30°C) Setting of required suction pressure in °C

Oset via Ext. Ref

Select whether a 0-10V external reference override signal is required Oset at max input (-100 to +100 °C) Displacement value at max. signal (10) Oset at min input (-100 to +100 °C) Displacement value at min. signal (0 V) Oset lter (10 - 1800 Sec) Here you can set how quickly the reference must become effective.

Night Oset 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 Oset (-25 to +25 K) Displacement value for suction pressure in connection with an active night setback signal (set in Kelvin) Max reference (-50 to +80 °C) Max. permissible suction pressure reference Min reference (-80 to +25 °C) Min. permissible suction pressure reference

4 - Compressor application

Select one of the available compressor conguration here

Press the +-button to go on to the

4. Set values for capacity control

Press the +-button to go on to the next page

There are several pages, one after the other. The black bar in this eld tells you which of the pages is currently displayed. Move between the pages using the + and - buttons.

If a screw compressor is chosen in the rst line, its type must be determined in the next line.

In our example we select:

- External compressor stop

-VSD + single step

- 4 compressors

- P0 as signal to the regulation

- Best t

Screw compressorer

The following options are available for screw compressors

No. of compressors Set number of compressors (total)

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.

Variable compressor type

Choose between speed control or PWM (digital scroll).

Control sensor

Po: Suction pressure Po is used for control S4: Media temperature S4 is used for control Pctrl: Control pressure from the low-pressure circuit for cascade

Po refrigerant type

Select refrigerant type

P0 Refrigerant factors K1, K2, K3

Only used if “Po refrigerant type” is set to custom (contact Danfoss for information)

Pctrl refrigerant type

Select refrigerant type

Pctrl refrigerant factors K1, K2, K3

Only used if “Pctrl refrigerant type” is set to custom (contact Danfoss for information)

Step control mode

Select coupling pattern for compressors Cyclic: Runtime equalisation between compressors (FIFO) Best t: Compressors are cut in/out in order to make the best possible t to actual load

MT/LT coordination

Control methods between cold and frost for cascade. MT Release: MT-control. The controller must connect to a relay so that a signal can be sent to the controller in the LT circuit. LT Release:LT-control. The controller must receive a signal from the controller in the MT-circuit. MT Coord: MT-control. A signal must both be received and sent. LT Coord: LT-control. A signal must both be received and sent. MT Coord release before start: LT starts and MT following. A signal must be both received and sent. LT-Comp.request delay LT-control. Delay on output signal to MT

58 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Conguration - continued

5. Set values for capacity of the compressors

Press the +-button to go on to the

6. Set values for main step and any unloaders

Press the +-button to go on to the

7. Set values for safe operation

Press the +-button to go on to the

In our example there are no unloaders and hence no changes.

In our example we select:

- Safety limit for discharge temperature = 120°C

- Safety limit for high condensing pressure = 103.5 bar

- Safety limit for low suction pressure = -40°C

- Alarm limit for high suction pressure = -5°C

- Alarm limit for min. and max. superheat, respectively = 5 and 35 K.

LT Comp. release delay

LT-control. Delay on input signal from MT

MT-Comp.request delay

MT-control. Delay on input signal from LT

MT Comp. release delay

MT-control. Delay on output signal to LT

Injection heat exchanger

Selects whether an output signal is to be sent for start/stop of liquid injection in a cascade heat exchanger

Pump down

Select whether a pump down function is required on the last running compressor Pump down limit Po (-80 to +30 °C) Set the actual pump down limit VSD min speed (0.5 – 60.0 Hz) Min. speed where the compressor must cutout VSD start speed (20.0 – 60.0 Hz) Minimum speed for start of Variable speed drive (Must be set higher than “VSD Min. Speed Hz”) VSD max speed (40.0 – 120.0 Hz) Highest permissible speed for the compressor motor

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 + o time)

PWM Min. capacity

Minimum capacity in the period time (without a minimum capacity the compressor will not be cooled)

PWM Max. capacity

Limitation of capacity during period time (100 = no limit)

Load shed limits

Select which signal is to be used for load limitation (only via network, a DI + network or two DI + network)

Load limitation period

Set the maximum time permitted for load limitation

Load shed limit 1

Set max capacity limit for load shed input 1

Load shed limit 2

Set max capacity limit for load shed input 2

Override limit Po

Any load below the limit value is freely permitted. If the P0 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 Kp Po (0.1 – 10.0) Amplications factor for PI regulation

Advanced control settings

Select whether the advanced capacity control settings should be visible

Po lter

Reduce changes in the Po reference

Pc lter

Reduce changes in the Pc reference

Minimize cycling

The control zone may vary for connections and disconnections when regulating with step coupling. See Section 5. Initial start time (15 – 900 s) The time after start-up where the cut-in capacity is limited to the rst compressor step.

Unloading mode

Select whether one or two capacity controlled compressors are allowed to be unloaded at the same time at decreasing capacity

5 - Compressors

In this screen the capacity distribution between the compressors is dened. Capacities that need to be set depend upon the “compressor application” and “Step control mode” that has been selected. Nominal capacity (0.0 – 100000.0 kW) Set the nominal capacity for the compressor in question. For compressors with variable speed drive the nominal capacity must be set for the mains frequency (50/60 Hz)

Unloader

Number of unload valves for each compressor (0-3)

6 - Capacity distribution

The installation is dependent on the combination of compressors and coupling pattern. Main step Set the nominal capacity of the main step (Set the percentage of the relevant compressor’s nominal capacity) 0 100%.

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 59

Conguration - continued

8. Set monitoring of compressor

Press the +-button to go on to the next page

9. Set operation time for compressor

Press the +-button to go on to the next page .

10. Set times for safety cutouts

Press the +-button to go on to the next page .

11. Set Misc. functions

In our example we use:

- Common high-pressure pressure control for all compressors

- One general safety monitoring unit for each compressor

(The remaining options could have been selected if specic 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.

In our example we do not use

these functions.

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 °C 3 K below the limit, the entire condenser capacity will be cutin and the compressor capacity reduced. If the limit is exceeded, the entire compressor capacity will be cutout.

Pc Max delay

Time delay for the alarm Pc max

P0 Min limit

Minimum value for the suction pressure in °C If the limit is reduced, the entire compressor capacity will be cutout.

P0 Max alarm

Alarm limit for high suction pressure P0

P0 Max delay

Time delay before alarm for high suction pressure P0.

Safety restart time

Common time delay before restarting the compressor. (Applicable to the functions: "Sd max. limit", Pc max. limit" and "P0 min. limit).

SH Min alarm

Alarm limit for min. superheat in suction line.

SH Max alarm

Alarm limit for max. superheat in suction line. SH alarm delay Time delay before alarm for min./max. superheat in suction line.

Individuel Sd pr. compressor

Select whether an Sd measurement should be made for each compressor.

Sd cut out temperature

Set the desired cut-out temperature.

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

Dene here whether this type of protection should be connected. For "General", there is a signal from each compressor.

9 - Minimum operation times

Congure the operation times here so "unnecessary operation" can be avoided. Restart time is the time interval between two consecutive starts.

10 - 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.

11 - 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.

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.

60 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Conguration - continued

Set oil management

1. Go to Conguration menu

2. Select Oil management

3. Set refrigeration circuit

Press the +-button to go on to the

We do not use safety relays in our example.

In this example, we want to control the oil receiver. This is done with a pressostat. Here, we have chosen a pressostat. The pressostat should be set as follows:

- Select pressure transmitter When the pressure drops in the receiver, the valve should open.

- Set the pressure level at which the valve should open. Set at 30 bar, here.

- Set the pressure level, at which the valve should close completely again. Set at 35 bar, here.

In the example, we have two level switches in the receiver. Both one high and one low.

3 LP sync to HP

Select this if the controller is on low pressure control and should be synchronised with high pressure regulation.

Use oil equalization

(Only possible with cyclic operation)

Interval time

Set how often a compressor must pause during full operation.

Equalization time

Set the duration of the oil equalisation (the pause).

Oil control safety relay

If this setting is set to YES, the controller will reserve a safety relay for each compressor. The relay terminal is connected in series to the compressor relay. The relay can hereby stop the compressor, if a lack of oil is registered when the compressor is force controlled. (Forced controlled to ON with the setting "Manual" or with the "changeover" on an extension module.) Danfoss recommends this function to avoid any compressor damages due to lack of care. (In order to keep things simple, this function is not used as an example.)

Oil receiver

Select whether you wish to activate pressure regulation in one of the oil receivers.

Level switch receiver

Dene the desired level sensors. High / Both Low and High

Level alarm delay

Delay time tor level alarm

Input for pressure build

Select whether the pressure is controlled by a pressostat or signal from the pulse counter.

Comp. per. to start seq.

(For pulse counter): Percentage value of total pulses of the dierent compressors

Pressure buildup seq.

(For pulse counter) Select between: Only pulses from the HP circuit. Pulses from both HP and LP are included

Actual pressure

Measured value

Actual state

Status of oil separation

Cut out pressure

Receiver pressure for shutting o oil

Cut in pressure

Receiver pressure for turning on oil

High alarm limit

An alarm is given if a higher pressure is registered

High alarm delay

Time delay for alarm

High alarm text

AK-PC 781 Capacity controller RS8GG602 © Danfoss 2015-03 61

Conguration - continued

4. Set oil management for the compressors

Press the +-button to go on to the next page.

5. Set oil separator

In our example, the oil supply is controlled separately for each individual compressor. The settings are shown here in the diagram. The process is as follows: 20 seconds after the signal from the level switch is given, the oil injection starts. This pulsates three times with one minute intervals. Each pulse lasts one second. Then there is a pause for 20 seconds. If the level switch has not registered any oil at this point, the compressor is stopped.

In our example, there is only one single separator that has just one level switch. The settings are shown here in the diagram. The process is as follows: When a signal is given from the level switch, the discharging process to the receiver commences. This pulsates three times with one minute intervals. Each pulse lasts one second. If the level switch does not register an oil drop at this point, an alarm is given when the delay time has expired.

Write an alarm text

Low alarm limit

An alarm is given if a lower pressure is registered

Low alarm delay

Time delay for alarm

Low alarm text

Write an alarm text

4 Compressor oil setup

Select whether the oil supply to all the compressors is to be shared at the same time or whether each compressor is to be controlled separately.

Advanced stop

'Yes' means pulses will be allowed following compressor stop

Oil cycle pre delay

Delay time before oil pulses commence

Oil cycle post delay

Delay time for signal that will stop oil pulses

High oil alarm delay

If an activation of the level switch is not registered before the time has expired, an alarm will be given. (the compressor not use the oil).

No of periods

No. of pulses that are to be enabled in a oil lling sequence

No of periods before stop (Advanced stop = yes)

If oil is still missing after this number of pulses, the compressor is stopped. The remaining number of pulses will then be permitted.

Period time

Time between pulses

Oil valve open time

The valve's opening time for each pulse.

5 Separator

Select whether there should be one shared separator for all the compressors or one separator for each compressor.

Level detection

Select whether the separator is to be controlled by "Full sequence", "To Level" or "low and high" level switches.

Level alarm delay

Alarm given when using a level switch for low level.

Repeat oil return cycle

Time period between repeat emptying processes from the separator if the level switch stays at high level.

No oil sep. alarm delay

Alarm delay when a signal is given that oil is not being separated ("high" level contact not activated)

No of periods

No. of times the valve should open in emptying sequence

Period time

Time between valve openings.

Open time

The open time of the valve

62 Capacity controller RS8GG602 © Danfoss 2015-03 AK-PC 781

Conguration - continued

Setup control of condenser fans

1. Go to Conguration menu

2. Select Condenser fan control

3. Set control mode and reference

Press the +-button to go on to the

4. Set values for capacity regulation

In our example the condenser pressure is controlled on the basis of the Sgc and from Sc3 (oating reference). The settings shown here in the display.

In our example we use a number of fans that are all speed-controlled in parallel. The settings shown here in the display.

For your information the function ”Monitor fan safety” will require an input signal from each fan.

3 - PC reference Control sensor

Pc: The condensing pressure PC is used for regulation Sgc: The temperature at the outlet of the gas cooler (CO2 transcritical only) S7: Media temperature is used for regulation

Reference Mode

Choice of condenser pressure reference Fixed setting: Used if a permanent reference is required = “Setting” Floating: Used if the reference is changed as a function of Sc3 the external temperature signal, the congured "Dimensioning tm K"/"Minimum tm K" and the actual cut in compressor capacity. (Liquid is recommended for CO2 and heat recovery.)

Setpoint

Setting of desired condensing pressure in bar

Min. tm

Minimum average temperature dierence between Sc3 air and Pc condensing temperature with no load.

Dimensioning tm

Dimensioning average temperature dierential between Sc3 air and Pc condensing temperature at maximum load (tm dierence at max load, typically 8-15 K).

Min reference

Min. permitted condenser pressure reference

Max reference

Max. permitted condenser pressure reference

4 - Capacity control No of fans

Set number of fans.

Monitoring fan safety

Safety monitoring of fans. A digital input is used to monitor each fan.

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

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 congured 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 at 0% capacity

EC voltage max

Voltage value at 100% capacity

EC Voltage abs. max

Permissible live voltage for EC motor (overcapacity)

Absolut max Tc

Max value for Tc. If this Tc value is exceeded, the EC voltage will be raised to the value in “EC Voltage abs. max.”

Control type

Choice of control strategy P-band: The fan capacity is regulated via P-band control. The P band is congured as "Proportional band Xp" PI-Control: The fan capacity is regulated by the PI controller. Continues

Conguration - continued

Continued

Amplication factor for P/PI controller

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.

The following settings are not available when the refrigerant selected is CO2.

Monitor Air ow

Choose whether monitoring is required of the condenser's air ow via an intelligent error-detection method. Monitoring requires the use of a Sc3 outer temperature sensor, which must be tted by the condenser's air inlet. FDD setting Set error-detection function Tuning: The controller makes an adjustment to the condenser concerned. Note that tuning should only be done when the condenser is operating under normal operating conditions. ON: Tuning is completed and monitoring has commenced. OFF: Monitoring is cut out.

FDD sensitivity

Set the sensitivity of error-detection on the condenser’s air ow. Must only be changed by trained sta.

Air ow tuning value

Actual tuning values for air ow.

Conguration - continued

Setup control of high pressure

1. Go to Conguration menu

2. Select HP control

3. Set regulation values

The settings are shown here in the display

3 - HP control Output type

Select the signal type for controlling the ICMTS 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 oset

Adjust how much the pressure shall be increased by when the function "Extra capacity oset" is activated.

Pgc min.

Min. acceptable pressure in the gas cooler

Pgc max.

Max. acceptable pressure in the gas cooler

Advanced settings

Opens up the following selection possibilities

Pgc max. limit P-band

P-band under "Pgc max" where the valve's degree of opening is increased

dT Subcool

Desired subcooling temperature

Amplication factor

Integration time

Valve min. OD

Restriction of the ICMTS valve's degree of closing

Valve max. OD

Restriction of the ICMTS valve's degree of opening

Pgc HR min.

Read the min. acceptable pressure in the high pressure circuit during heat recovery

Pgc HR oset

Read 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 dene the regulation curve during transcritical operation. Set the required temperature value.

V3gc

Indicates whether a gas bypass valve is used on the gas cooler.

Bypass low limit

If the sensor Sgc records a temperature that is lower than the selected value, the gas will be routed outside of the gas cooler (e.g. startup during very low ambient temperatures).

Bypass permitted after

Minimum time during which the gas must be fed through the gas cooler before bypass is permitted.

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.

Conguration - continued

Setup control of receiver pressure

1. Go to Conguration menu

2. Select Receiver control

3. Set regulation values

The settings are shown here in the display

3 - Receiver control Output type

Select the signal type for controlling the gas bypass valve:

- Voltage signal

- Stepper motor signal via AK-XM208C

- 2 stepper motor signal for parallel valves

Prec reference

Select the reference for the pressure in the receiver

Amplication factor

Integration time

Valve min. OD

Limitation of the CCM valve's degree of closing

Valve max. OD

Limitation of the CCM valve's degree of opening.

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

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 di.

Dierence at which hot gas is turned o again

IT comp. state

The signal received from the IT controller can be read here

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 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.

Conguration - continued

Setup control of heat recovery

1. Go to Conguration menu

2. Select heat recovery

3. Dene heat recovery circuits

4. Dene heat circuit requirement for pressure variation

In our example, we have selected CO2 as the refrigerant. This opens for the displayed settings. In our example we have both a circuit for hot tap water and a circuit for heating.

3 -Heat recovery Heat recovery mode (applies only when the refrigerant

selected is not CO2). See also page 111. Choice of method for heat recovery No: Heat recovery not used Thermostat: Heat recovery operated from thermostat Digital input: Heat recovery operated from signal on a digital input.

Heat recovery relay

Choose whether an output is required that should be activated during heat recovery.

Heat recovery ref

Reference for the condensing pressure, when heat

HFC

recovery is activated.

Heat recovery ramp down

Congure how quickly the reference for the condenser pressure should be ramped down to normal level after heat recovery. Congure in Kelvin per minute.

Heat recovery cutout

Temperature value where the thermostat cuts-out the heat recovery.

Heat recovery cutin

Temperature value where the thermostat cuts-out the heat recovery.

Heat recovery circuit (applies only when the refrigerant

selected is CO2). See also page 116. Here you select which recovery circuits shall be regulated:

- None

- Circuit for hot tap water

- Circuit for heating

- Both hot tap water and heating

4 - Heat reclaim type

Here you dene how the condensing pressure (HP) shall be

regulated when the recovery circuit for heating requires heat:

- No HP oset (simple control)

- HP oset. Here the controller must receive a voltage signal. The oset values that apply to the max. value must be dened in the heat circuit settings. See next page.

- Max heat reclaim. Here the controller must receive a voltage signal, but the regulation is increased to also control the pump, fans and gas cooler bypass.

Press the +-button to go on to the

Conguration - continued

5. Setup values for tap water circuits

Press the +-button to go on to the

In our example we use the settings shown

5 - Tap water circuits (settings are available only when the

refrigerant selected is CO2, and shall be regulated on a

circuit for tap water). Control mode: Here the regulation of the circuit can be started (auto) and stopped (o). Reference: The required temperature for the sensor Stw8 can be set here. Thermostat band: The acceptable temperature variation around the reference: Control signal. . Choose between:

Stw8: if regulation shall be done using only this sensor. S4-S3: (and a Delta T value) if the controller shall regulate

using this temperature dierence, until the Stw8 reference is met. (During S4-S3 regulation, the pump must always be speed-regulated). Stw8 + Stw8A: if two temperature sensors are installed in

the hot water receiver. Variable speed: Here the pump type is selected. Either variable speed or on/o. Advanced settings: The following options are made available:

Flow switch: Must normally be selected for safety purposes

Kp: Amplication factor

Tn: Integration time

Min. pump speed: Pump speed for start/stop

Max. pump speed: The pump's max. permissible speed

Flowswitch delay: Duration of stable signal before the new status is used in the regulation.

6. Setup values for heating circuit

In our example we use the settings shown

6 - Heat reclaim circuits (settings are available only when

the refrigerant chosen is CO2, and regulation shall be

done using a circuit for heating). Control mode: Here the regulation of the circuit can be started (auto) and stopped (o). Reference: Here the required temperature of sensor Shr8 (or Shr4) is set. Thermostat band: The permissible temperature variation around the reference: Control signal: Choose between:

Shr8: if regulation shall be done using only this sensor. S4-S3: (and a Delta T value) if the controller shall regulate

using this temperature dierence, until the Shr8 reference has been met. Shr4: regulation is done using this sensor, but Shr8 shall also be installed. (During S4-S3 regulation or Shr4 regula-

tion the pump shall always be speed-regulated). Variable speed: Here the pump type is selected. Either variable speed or on/o. Heat consumers: (Only when the condensation pressure shall be increased during heat recovery). The number of signals that can be received is set here. The signal can be either 0-10 V or 0-5 V. (Settings under "Advanced" will be used 0-100% for the signal).

Heat consumer lter

The highest of the received signals are made known over this period

Additional heat output

The function will reserve a relay. The relay will pull in when the signal for the heat removers reaches 95%. Advanced settings: The following options are made available:

Flow switch: Must normally be selected for safety pur-

poses

Kp: Amplication factor

Tn: Integration time

Tc max HR: Value at which the bypass of the gas cooler

will terminate.

HR PUMP CONTROL

Min. pump speed: Pump speed for start/stop

Max. pump speed: The pump's max. permissible speed

Pump stop limit: Signal in % at which the pump is

stopped again

Pump start limit: Signal in % at which the pump is started

HP CONTROL

Pgc HR min: Basic reference for the pressure when exter-

nal voltage signal is received.

Conguration - continued

Pgc HR oset: Pressure displacement at max. voltage signal HP low limit: Signal in % at which "Pgc HR min." comes into force. HP high limit: Signal in % at which "Pgc HR oset" value is used. FAN CONTROL Fan - Max Cond. Ref oset: Set the displacement at which the fans shall fully stop. Fan low limit: Signal in % at which throttling of the fans commences Fan high limit: Signal in % at which the fans are stopped BYPASS CONTROL V3gc bypass stop limit: Signal in % at which the gas cooler connects again after completed disconnect. V3gc bypass start limit: Signal in % at which the gas

cooler is disconnected. Flowswitch delay: Duration of stable signal before the new status is used in the regulation.

Conguration - continued

Setup Display

1. Go to Conguration menu

2. Select Display setup

3. Dene which readings are to be shown for the individual outputs

In our example, separate displays are not used. The setting is included here for information.

3 - Display setup

Display

The following can be read for the four outputs.. Comp. control sensor P0 in temperature P0 i bar-absolute Pctrl bar-absolute S4 Ss Sd Cond. control sensor Tc Pc bar-absolute S7 Sgc Shp Pgc bar-absolute Prec bar-absolute Stw8 Shr8 Speed Compressor

Unit readout

Choose whether readings are to be in SI units (°C and bar) or (US-units °F and psi)

Conguration - continued

Setup Functions for General purpose

1. Go to Conguration menu

2. Select General purpose

3. Dene number of required functions

In our example we select one thermostat function for temperature control in the compressor room and one alarm function for monitoring the liquid level in the receiver.

The following number of dierent functions can be dened: 5 thermostats 5 pressostats 5 voltage signal 10 alarm signals 3 PI-regulations

Conguration - continued

Separate thermostats

1. Select thermostats

2. Select actual thermostat

3. Dene the required thermostat functions

In our example we select

one thermostat function for

monitoring the plant room

temperature.

We have subsequently entered a

name for the function.

3 - Thermostats

The general thermostats can be used to monitor the temperature sensors that are used, as well as 4 extra temperature sensors. Each thermostat has a separate outlet to control external automation. For each thermostat adjust

• 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

Alarm delay high

Time delay for high alarm

Alarm text high

Indicate alarm text for the high alarm

Low alarm limit

Alarm delay low

Time delay for low alarm

Alarm text low

Indicate alarm text for low alarm

Separate pressostats

1. Select pressostats

In our example, separate pressostat functions are not used.

2. Select actual pressostat

3. Dene the required pressostat functions

3 - Pressostats

Settings as the thermostats

Conguration - continued

Separate voltage signals

1. Select Voltage inputs

2. Select actual voltage signal

3. Dene the required names

and values attached to the signal

In our example we do not use this function, so the display has been included for your information only. The name of the function may be xx and further down in the display the alarm texts may be entered.

The values ”Min. and Max. Readout” are your settings representing the lower and upper values of the voltage range. 2V and 10V, for example. (The voltage range is selected during the I/O setup).

For each voltage input dened the controller will reserve a relay output in the I/O setup. It is not necessary to dene this relay if all you require is an alarm message via the data communication.

3 - Voltage inputs

The general volt inlet can be used to monitor external voltage signals. Each volt inlet has a separate outlet to control external automatic controls. Set the number of general voltage inputs, specify 1-5:

Name 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 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. Dene the required names

and values attached to the signal

In our example we select one alarm function for monitoring the liquid level in the receiver. We have subsequently selected a name for the alarm function and

for the alarm text.

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

• Name

• Delay time for DI alarm (common value for all)

• Alarm text

Conguration - continued

Separate PI functions

1. Select PI functions

2. Select actual PI-function

3. Dene 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

• Name

• Control mode: O, 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 or Sd.

• Signal at variable reference: Choose between: : Non, temperature, pressure, pressure converted to temperature, voltage signal, Tc, Pc, Ss or DI.

• Reading the signal for the variable reference (not shown in the display)

• 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.

• Ref. calc A: Constant for variable value included in the reference. (Reference = Ax + B)

• Ref. calc B: Fixed value included in reference

• 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: Regulation parameters can now be selected.

• PWM period time: Period during which the signal has been on and o.

• Kp: Amplication factor

• Tn: Integration time

• Minimum reference: Lowest permitted reference

• Maximum reference: Maximum permitted reference

• 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.

Conguration - continued

Conguration of inputs and outputs

1. Go to Conguration menu

2. Select I/O conguration

3. Conguration of Digital outputs

Press the +-button to go on to the next page

4. Setup On/o inputs

The following displays will depend on the earlier denitions. The displays will show which connections the earlier settings will require. The tables are the same as shown earlier.

• Digital outputs

• Digital inputs

• Analog outputs

• Analog inputs

Load Output Module Point Active at

Solenoid valve, oil, Comp. 1 DO1 1 12 ON

Solenoid valve, oil, Comp. 2 DO2 1 13 ON

Solenoid valve, oil, Comp. 3 DO3 1 14 ON

Solenoid valve, oil, Comp. 4 DO4 1 15 ON

Solenoid valve, oil separator DO5 1 16 ON

Circulation pump tw D06 1 17 ON

Circulation pump hr DO7 1 18 ON

Room fan DO8 1 19 ON

Compressor 1 DO1 2 9 ON

Compressor 2 DO2 2 10 ON

Compressor 3 DO3 2 11 ON

Compressor 4 DO4 2 12 ON

Start /stop of VLT for fans DO5 2 13 ON

3-way valve, tap water, V3tw DO6 2 14 ON

3-way valve, Heat circuit, V3hr DO7 2 15 ON

3-way valve, gas cooler, V3gc DO8 2 16 ON

We set up the controller’s digital outputs by keying in which module and point on this module each one of these has been connected to. We furthermore select for each output whether the load is to be active

when the output is in pos. ON or OFF.

Function Input Module Point Active at

External compressor stop AI4 1 4 Closed

Level switch, oil, comp.1 AI8 1 8 Closed

Level switch, oil, comp.2 AI9 1 9 Closed

Level switch, oil, comp.3 AI10 1 10 Closed

Level switch, oil, comp.4 AI11 1 11 Closed

Level switch, oil, receiver High AI1 2 1 Closed

Level switch, oil, receiver Low AI2 2 2 Closed

Level switch, oil, Separator AI3 2 3 Closed

Level switch, CO2 receiver AI4 2 4 Open

Reset of compressor stop AI5 2 5

Compressor 1 Gen. Safety DI1 4 1 Open

Compressor 2 Gen. Safety DI2 4 2 Open

Compressor 3 Gen. Safety DI3 4 3 Open

Compressor 4 Gen. Safety DI4 4 4 Open

Start/stop of heat recovery hr DI5 4 5 Closed

All compressors common safety DI6 4 6 Open

Flow switch FStw

Flow switch FShr

Start/stop of heat recovery tw AI2 5 3 Closed

DI7 4 7 Open

DI8 4 8 Open

Pulse pressure

We set up the controller’s digital input functions by keying in which module and point on this module each one of these has been connected to. We furthermore select for each output whether the function is to be active when the output is in pos. Closed or Open. Open has been selected here for all the safety circuits. This means that the controller will receive signal under normal operation and register it as a fault if the signal is interrupted.

3 - Outputs

The possible functions are the following: Comp. 1 Unloader 1-1 Unloader 1-2 Unloader 1-3

Do for Compressor. 2-8

Oil valve comp. 1-8 Lp comp. oil pulse Oil valve 1-4 (8) Oil valve separat. 1-8 MT Comp. release LT Comp. request Injection heat exchanger Injection suction line Injection ON Fan 1 / VSD Fan 2 - 8 HP Control Valve gas cooler V3gc Heat recovery Valve tap water V3tw Pump tap water tw Valve heat recov. V3hr Pump heat recov. hr Additional heat Alarm I'm alive relay Thermostat 1 - 5 Pressostat 1 - 5 Volt input 1 - 5 PI 1-3

4 - Digital inputs

The possible functions are the following: Ext. Main switch Ext. compr. stop Ext. power loss Night setback Load shed 1 Load shed 2 LT Comp. Release MT Comp. Request 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. Fault

Do for Comp. 2-8

Fan 1 safety

Do for fan 2-8

VSD cond safety Reset comp. lockout LP comp.oil counter Oil receiver low Oil receiver high Oil level comp.1-8 Oil separator low 1-8 Oil separator high 1-8 Heat recovery tw enable hr enable Flow switch tw Flow switch hr DI 1 Alarm input DI 2-10 ... PI-1 Di ref External DI PI-1

Conguration - continued

Press the +-button to go on to the next page.

5. Conguration of Analog

outputs

Press the +-button to go on to the next page

6. Conguration of Analog Input signals

Function Output Module Point Type

Voltage signal for high pressure valve, ICMTS

Stepper signal for by-pass valve, CCM Step 1 3 9 CC M

Speed control, compressor AO1 5 5 0 - 10 V

Speed control, gas cooler fan AO2 5 6 0 - 10 V

Speed control, pump - tw AO3 5 7 0 - 10 V

Speed control, pump - hr AO4 5 8 0 - 10 V

Sensor Input Module Point Type

Disch. gas temperature - Sd AI1 1 1 Pt 1000

Suction gas temperature - Ss AI2 1 2 Pt 1000

Outdoor temp. - Sc3 AI3 1 3 Pt 1000

Thermostat sensor in plant room Saux1

Suction pressure - Po AI6 1 6 AKS 2050-59

Condenser pressure - Pc

Refrigerant receiver, Prec-CO2 AI7 2 7 AKS 2050-159

Oil receiver, Prec-Oil AI8 2 8 AKS 2050-159

Tap water temperature - Stw2 AI1 3 1 Pt 1000

Tap water temperature - Stw3 AI2 3 2 Pt 1000

Tap water temperature - Stw4 AI3 3 3 Pt 1000

Tap water temperature - Stw8 AI4 3 4 Pt 1000

Heat reclaim temperature Shr2 AI5 3 5 Pt 1000

Heat reclaim temperature Shr3 AI6 3 6 Pt 1000

Heat reclaim temperature Shr4 AI7 3 7 Pt 1000

Heat reclaim temperature Shr8 AI8 3 8 Pt 1000

Temp. gas cooler outlet Sgc AI1 5 1 Pt 1000

Temp. by-pased gas Shp AI2 5 2 Pt 1000

Gas cooler pressure Pgc AI4 5 4 AKS 2050-159

AO1 1 24 0-10 V

AI5 1 5 Pt 1000

AI7 1 7 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 dened: 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

• User dened (only ratiometric, min. and max value of the pressure range must be set)

S4 Cold brine Pctrl Po suction pres. Ss suction gas Sd disch. temp. Pc Cond. Pres. S7 Warm brine Sc3 air on Ext. Ref. Signal

• 0 – 5 V,

• 0 -10 V Olie receiver HP control Pgc Prec Sgc Shp Stw2,3,4,8 Shr2,3,4,8 HC 1-5 Heat recovery Saux 1 - 4 Paux 1 - 3 Voltage input 1 - 5

• 0 -5 V,

• 0 -10 V,

• 1 – 5 V,

• 2 – 10 V PI-in temp PI-ref temp PI- in voltage PI-in pres. PI-ref pres.

Conguration - continued

Set alarm priorities

1. Go to Conguration menu

2. Select Alarm priorities

Very many functions have an alarm connected. Your choice of functions and settings has connected all the relevant alarms that are current. They will be shown with text in the three pictures. All alarms that can occur can be set for a given order of priority:

• ”High” is the most important one

• ”Log only” has lowest priority

• ”Disconnected” gives no action The interdependence between setting and action can be seen in the table.

3. Set priorities for Suction group

Setting

High X X X X 1

Medium X X X 2

Low X X X 3

Log only X 4

Disconnected

Se also alarm text page 136.

Log Alarm relay selection Net-

Non High Low - High

work

AKM dest.

Press the +-button to go on to the next page

4. Set alarm priorities for condenser

In our example we select the settings shown here in the display

Conguration - 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

Conguration - continued

Lock conguration

1. Go to Conguration menu

2. Select Lock/Unlock conguration

3. Lock Conguration

Press in the eld against Conguration 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 rst to

unlock the conguration.

The controller will now make a comparison of selected functions and dene inputs and outputs. The result can be seen in the next section where the setup is controlled.

Conguration - continued

Check conguration

1. Go to Conguration menu

2. Select I/O conguration

3. Check conguration of Digital Outputs

Press the +-button to go on to the next page

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 dened 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 dierent.

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..

4. Check conguration 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.

Conguration - continued

Press the +-button to go on to the next page

5. Check conguration of Analog Outputs

Press the +-button to go on to the next page

6. Check conguration 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.

Check of connections

1. Go to Conguration 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.

Check of connections - continued

5. Check Analog outputs

Set Control of output voltage to manual Press in the Mode eld.

Select MAN.

Press in the Value eld

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 dened output signal and a manual set value.

Denition 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 conguration is not locked.

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 dierent settings. It is all these settings that have to be checked.

3. Move on through all the individual displays for the suction group

Change displays with the +- button. Remember the settings at the bottom of the pages – the ones that can only be seen via the ”Scroll bar”.

4. Safety limits

5. Go back to the overview

The last page contains safety limits and restart times.

6. Select condenser group

Check of settings - continued

7. Move on through all the individual displays for the condenser group.

Change displays with the +- button. Remember the settings at the bottom of the pages – the ones that can only be seen via the ”Scroll bar”.

8. Safety limits

The last page contains safety limits and restart times.

9. Go back to the overview and Move on to the thermostat group

Check the settings.

10. Go back to the overview and Move on to the press-

sostat group

Check the settings.

11. Go back to the overview and on to the general

alarm inputs

Check the settings.

12. The controller setup has been completed.

Schedule function

1. Go to Conguration 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.

Installation in network

1. Set the address (here, for example 3)

Turn the right-hand address switch so that the arrow will point at 3. The arrow of the two other address switches must point at 0.

2. Push the Service Pin

Press down the service pin and keep it down until the Service Pin LED lights up.

The controller has to be remote-monitored via a network. In this net-

work we assign address number 3 to the controller.

The same address must not be used by more than one controller in the

same network.

Requirement to the system unit

The system unit must be a gateway type AKA 245 with software version

6.0 or higher. It is capable of handling up to 119 AK controllers.

3. Wait for answer from the system unit

Depending on the size of the network it may be up to one minute before the controller receives an answer as to whether it has been installed in the network. When it has been installed the Status LED will start to ash 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. It is capable of handling up to 200 AK controllers.

If there is no answer from the system unit

If the Status LED does not start ashing 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.

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.

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 eld 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.

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.)

Press the blue eld against Control mode Select MAN.

4. Set capacity in percent

Press in the blue eld against Manual capacity.

Set the capacity to the required percentage. Press OK.

5. Regulating functions

This section describes how the dierent functions work

Suction group

Controlling sensor selection

Depending on use, the capacity distributor can regulate according to the suction pressure P0, a media temperature S4 or separate control pressure Pctrl in a dierent refrigeration circuit, e.g. cascade system. Cap. Ctrl sensor = P0 / S4 /Pctrl

Example 1 – P0

Example 2 – S4 media sensor

Parallel compression

(Only on CO2 system and control of receiver pressure) If the controller is to control an IT compressor for parallel compression, the following regulation settings will be required:

• The system type must be set to LT

• The regulation sensor must be set to Po (the signal received from the receiver - Prec).

Handling of sensor error

Cap. Ctrl. Sensor = P0 When P0 is used as the regulating sensor, an error in the signal will mean that regulation continues with 50% cutin in daily operation and 25% cut-in at night, but for a minimum of one step.

Cap. Ctrl. Sensor = S4 Provided that S4 is used as a regulating sensor, an error in this sensor will mean that regulation continues from the P0 signal, but in accordance with a reference that lies 5K under the real reference. If there is an error on both S4 and P0, regulation will continue with 50% cut-in in daily operations and 25% of cut-in in night operations, but for a minimum of one step.

When the controlling sensor is selected as S4, P0 is used as a safety function for low suction pressure and will ensure disconnection of compressor capacity (frost protection).

Example 3 – Pctrl sensor

Cap. Ctrl. Sensor = Pctrl When Pctrl is used as a controlling sensor, an error in this sensor will mean that regulation continues after the P0 signal, but in accordance with a reference that lies 5 K under the real reference. If there is an error on both Pctrl and P0, regulation will continue with e.g. 50% cut-in in daily operations and e.g. 25% cut-in in night operations, but for a minimum of one step.

When Pctrl is used as controlling sensor, a refrigerant type for this pressure transmitter must be set, e.g. CO2. P0 is used as a safety function against insucient suction pressure and will ensure disconnection of compressor capacity. On cascade systems the signal from Pctrl can be used by both the high-pressure and low-pressure controls either for the controlling sensor or high-pressure monitoring.

Reference

The reference for the regulation can be dened in 2 ways:

Either P0Ref = P0 setting + P0 optimization + night displacement or P0Ref = P0 setting + night displacement + Ext. Ref

P0 setting

A basic value for the suction pressure is set.

Forced operation of the compressor capacity in the suction group

A forced operation of the capacity can be carried out which disregards the normal regulation. Depending on the selected form of forced operation, the safety functions will be cancelled.

Forced operation via overload of requested capacity

The control is set to manual and the desired capacity is set in % of the possible compressor capacity.

P0 optimization

This function displaces the reference so that regulation will not take place with a lower suction pressure than required. The function cooperates with controllers on the individual refrigeration appliances and a system manager. The system manager obtains data from the individual regulations and adapts the suction pressure to the optimum energy level. The function is described in the manual for the System manager. With this function you can read which appliance is most heavily loaded at the moment as well as the displacement allowed for the suction pressure reference.

Night displacement

The function is used to change the suction pressure reference for night time operation as an energy saving function. With this function the reference can be displaced by up to 25 K in positive or negative direction. (When you displace to a higher suction pressure, a positive value is set). Displacement can be activated in three ways:

• Signal on an input

• From a master gateway’s override function

• Internal time schedule

The “night displacement” function should not be used when regulation with the override function “P0-optimisation” is performed. (Here the override function will itself adapt the suction pressure to the max. permissible).

Forced operation via overload of digital outlets

The individual outputs can be set to MAN ON or MAN OFF in the software. The control function disregards this but an alarm is sent out that the outlet is being overridden.

Forced operation via change-over switches

If the forced operation is done with the switch-over on the front of an expansion model, this is not registered by the control function and no alarm is sounded. The controller continues to run and couples with the other relays.

If a short change in the suction pressure is needed (for example, up to 15 minutes in connection with defrosting) the functions can be applied. Here the PO-optimisation will not have time to compensate for the change.

Override with a 0 - 10 V signal

When a voltage signal is connected to the controller the reference can be displaced. In the setup it is dened 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.

Min.

Capacity control of compressors

PI-control and control zones

AK-PC 781 can control up to 8 compressors. Each compressor can have up to 3 unloaders. One or two of the compressors can be equipped with speed regulation.

The calculation of the requested compressor capacity takes place on the basis of a PI control, but the set up is carried out in the same way as for a neutral zone which is divided into 5 dierent control zones as shown in below sketch.

Suction pressure P0

The width of some of the zones can be set via the settings “+ Zone K”, “NZ K” and “- Zone K”. Furthermore it is possible to adjust zone timers which is equal to the Tn integration time for the PI controller whenever the suction pressure is in the zone in question (please see sketch above).

In the “+ Zone” and “++ Zone” the controller will normally increase the requested capacity as the suction pressure is above the set point. But if the suction pressure is decreasing very fast the requested capacity might decrease also in these zones.

In the “- Zone” and “-- Zone” the controller will normally decrease the requested capacity as the suction pressure is below the set point. But if the suction pressure is increasing very fast the requested capacity might increase also in these zones.

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.

Example: 4 compressor of equal size - The capacity curve will look like this

By setting a zone timer to a higher value will make the PI controller slower in this zone and by setting the zone timer lower will make the PI controller faster in this zone.

The amplication factor Kp is adjusted as parameter ”Kp Po” In the neutral zone the controller is only allowed to increase or decrease the capacity by means of speed control and/or switching of unloader valves. In the other zones the controller is also allowed to increase/ decrease capacity by means of starting and stopping compressors.

Operation time rst 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 rst capacity step will cutin after a set period (to be set via "runtime rst step").

Requested capacity

The readout “Requested capacity” is the output from the PI controller and it shows the actual requested compressor capacity by the PI controller. The rate of change in the requested capacity depends upon in which zone the pressure is and whether the pressure is stable or whether it is constantly changing.

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 at "-Zone" or in "—Zone"

Pump down function:

To avoid too many compressor starts/stops with low load, it is possible to dene 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 congured pump down limit.

Note that the congured pump down limit should be set higher than the congured safety limit for low suction pressure "Min Po".

The Integrator is looking at the deviation between the set point and the current pressure only and increases/reduces the requested capacity correspondingly. The amplication factor Kp on the other hand only looks at the temporary pressure changes.

Dynamic extension of the neutral zone

All refrigeration systems have a dynamic response time when starting and stopping compressors. In order to avoid that the controller will start/stop compressors shortly after each other, the controller must be allowed some extra time after a compressor start/stop to see the eect of the previous change in running capacity.

In order to achieve this, a dynamic extension of the zones is added.

The zones will be extended for a short period of time when starting or stopping a compressor. By extending the zones the PI controller will be slowed down in a short period of time after a change in compressor capacity.

The amplitude of the zone extension depends upon the actual running compressor capacity and upon the size of the compressor step which is being stopped/started. The amplitude of the zone extension is bigger when running with low compressor capacity and when starting/stopping big compressor capacity steps. However the time period for the zone extension is constant – after a xed time period after a compressor start/stop the dynamic zone extension is reduced to 0. Via the “Minimize number of couplings” setting it is possible to inuence how big the amplitude of the dynamic zone extension should be in order to minimize the cycling of the compressors. By setting “Minimize number of couplings” to “No reduction” there will be no dynamic extension of the zones. By setting “Minimize number of couplings” to “Low”, “Medium” or “High” the dynamic extension of the zones will be activated. The amplitude of the zone extension will be highest when “Minimize number of couplings” is set to “High”. Please refer to the next sketch which shows an example with 6 compressor steps and with “Minimize number of couplings” set to “High”. Please also note that the dynamic extension of the zones is highest at low compressor capacity.

“Minimize number of couplings” = “High”

Actual band

As a consequence of the dynamic extension of the zones the suction pressure might very well change zone for a period of time when the controller is starting/stopping a compressor i.e. the suction pressure is in the +Zone, but as the controller starts a compressor, the zones are extended for a period of time and during this period of time the suction pressure will be in the NZ.

In the controller the readout “Actual band” will show in which zone the PI controller is operating – this includes the extension of the zones.

The dynamic expansion of the neutral zone is not used when one of the compressors in the group is speed-regulated.

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 rst, and the variable capacity is used to ll 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 dierent startups the compressor with the lowest number of operating hours will be started rst.

- At the dierent stops the compressor with the highest number of operating hours will be stopped rst.

- For compressors with several steps, the operating time equalizing is carried out between the compressors’ main steps.

Coupling pattern – Best t operation

This principle is used if the compressors are of dierent 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 rst, and the variable capacity will be used to ll capacity gaps between the subsequent steps.

Timer restrictions and safety cut outs If a compressor is prevented from starting because it is “hanging” on the restart timer or is safety-cut out, this step is replaced by another compressor or another combination.

- The left column shows the operating hours, according to which the controller equalises.

- The middle column shows (as a percentage) to what extent the individual compressor has been activated within the last 24hours.

- The right column shows the compressor's current operating time. The value should be reset when the compressor is replaced.

Power pack types – compressor combinations

The controller is able to control power packs with up to 8 compressors of various types:

- One or two speed controlled compressor

- Capacity controlled piston compressors with up to 3 unloader valves

- Single step compressors – piston

In appendix A there is a more detailed description of the coupling patterns for the individual compressor applications with associated examples.

The following is a description of some general rules for handling capacity-regulated compressors, speed-regulated compressors and also for two speed-regulated compressors.

Capacity-regulated compressors with unload valves

"Unloader control mode" determines how the capacity distributor should handle these compressors.

The chart below shows the compressor combination which the controller is capable of controlling. The chart also shows which coupling pattern can be set for the individual compressor combinations.

Combination Description Cou-

One-step compressors. *1 x x

A compressor with an unload valve, combined with one-step compressors. *2

Two compressors with unload valves, combined with one-step compressors. *2

All compressors with unload valves. *2

A speed-regulated compressor combined with one-step compressors. *1 and *3

A speed-regulated compressor combined with several compressors with unload valves. *2 and *3

Two speed-regulated compressors combined with one-step compressors *4

Screw compressor combined with one-step compressors

pling pattern

Cyclical

x x

Best t

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 ecient.

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.

For example: Two capacity-regulated compressors of 20 kW, each with 2 unload valves, cyclical coupling pattern.

Two screw compressors combined with one-step compressors

Three screw compressors combined with one-step compressors

• For decreasing capacity, the compressor with the most operating hours is unloaded (C1).

• When C1 is completely unloaded , compressor C2 with one-step

The following types of screw compressor may be used for regulation

Screw with unloader 0%, 50%, 100%

*1) For a cyclical coupling pattern, the one-step compressors must be the same size. *2) For compressors with unload valves, it is generally true that they must have the

same size, the same number of unload valves (max 3) and the same sized main steps. If compressors with unload valves are combined with one-step compressors, all compressors should be the same size.

*3) Speed-regulated compressors can have dierent sizes in relation to subsequent

compressors.

*4) When two speed-regulated compressors are used, they must have the same

frequency range. For cyclical coupling patterns, the two speed-regulated compressors should be the same size and the subsequent one-step compressors should also be the same size.

Screw with two unloaders 0, 33%, 66%, 100%

Screw with three unloaders + PWM 0 - 100%

is unloaded before C1 is cut out.

Speed control compressors:

The controller is able to use speed control on the leading compressor in dierent compressor combinations. The variable part of the speed controlled compressor is used to ll in capacity gaps of the following compressor steps.

General regarding handling:

One of the dened 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 dened as compressor 1 (1+2) that can be speed controlled.

When the step is in operation it will consist of a xed capacity and a variable capacity. The xed 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 rst 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 rst 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 dierent pack combinations a couple of examples will be given here:

a) Variable capacity bigger than following compressor steps:

When the variable part of the speed controlled compressor is bigger than the following compressors there will be no “holes” in the capacity curve. Example: 1 speed controlled compressor with a nominal capacity at 50Hz of 10kw - Variable speed range 30 – 90Hz 2 one step compressors of 10 kW

Fixed capacity = 30 HZ / 50 HZ x 10 kW = 6 kW Variable capacity = 60 HZ / 50Hz x 10 kW = 12 kW

The capacity curve will look like this:

As the variable part of the speed controlled compressor is bigger than the following compressor steps, the capacity curve will be without holes.

1) The speed controlled compressor will be cutin when the requested capacity has reached the start speed capacity.

2) The speed controlled compressor will increase speed until it reaches max speed at a capacity of 18 kW.

3) The one step compressor C2 of 10 kW is cut in and the speed on C1 is reduced too so that it corresponds to 8kW (40Hz)

4) The speed controlled compressor will increase speed until the total capacity reaches 28 kw at max speed

5) The one step compressor C3 of 10 kW is cut in and the speed on C1 is reduced too so that it corresponds to 8kW (40Hz)

6) The speed controlled compressor will increase speed until the total capacity reaches 38 kw at max speed

7) When reducing capacity the one step compressors will be cut out when the speed on C1 is at minimum

b) Variable part smaller than following compressor steps:

If the variable part of the speed controlled compressor is smaller than the following compressors there will be “holes” in the capacity curve.

Example: 1 speed controlled compressor with a nominal capacity at 50Hz of 20kw - Variable speed range 25 – 50Hz 2 one step compressors of 20 kW Fixed capacity = 25 HZ / 50 HZ x 20 kW = 10 kW Variable capacity = 25 HZ / 50Hz x 20 kW = 10 kW

The capacity curve will look like this:

As the variable part of the speed controlled compressor is smaller than the following compressor steps the capacity curve will have some holes that can not be lled 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.

Two speed-regulated compressors

The controller is capable of regulating the speed of two compressors of the same or dierent sizes. The compressors can be combined with one-step compressors of the same or dierent 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. 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 rst 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.

Cut-in The rst 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 rst 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.

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).

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 rst to start. The following speed-regulated compressor will be cut in when the rst 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.

Danfoss AK-PC 781 User guide

Specifications and Main Features

Frequently Asked Questions

User Manual