Danfoss AK-PC 782A User guide

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User Guide

Pack controller Type AK-PC 782A

Capacity controller for transcritical CO2 booster control

SW Ver. 3.5x

www.danfoss.com

User Guide | Pack controller, type AK-PC 782A

Contents

1. Introduction ............................................................................3

1.1 Application ...........................................................................................3

1.2 Principles ..............................................................................................4

2. Design of a controller .............................................................7

2.1 Module survey ....................................................................................7

2.2 Common data for modules ......................................................... 10

2.3 Controller ........................................................................................... 11

2.3.1 Extension module AK-XM 101A ...................................13

2.3.2 Extension module AK-XM 102A / AK-XM 102B ......15

2.3.3 Extension module AK-XM 103A ...................................17

2.3.4 Extension module AK-XM 204A / AK-XM 204B ......19

2.3.5 Extension module AK-XM 205A / AK-XM 205B ......21

2.3.6 Extension module AK-XM 208C ................................... 23

2.3.7 Extension module AK-OB 110 ...................................... 25

2.3.8 Extension module EKA 163B / EKA 164B .................. 26

2.3.9 Graphic display MMIGRS2 ............................................. 26

2.3.10 Power supply module AK-PS 075 / 150 / 250..........27

2.3.11 Communication module AK-CM 102 ......................... 28

2.4 Preface to design ............................................................................ 29

2.5 Design of a compressor and condenser control .................31

2.6 Ordering ............................................................................................. 39

3. Mounting and wiring ............................................................40

3.1 Mounting ........................................................................................... 40

3.2 Wiring ................................................................................................. 42

4. Conﬁguration and operation ...............................................45

4.1 Conﬁguration ................................................................................... 45

4.1.1 Connect PC.......................................................................... 45

4.1.2 Authorization ..................................................................... 47

4.1.3 Unlock the conﬁguration of the controllers ............48

4.1.4 System set-up .....................................................................49

4.1.5 Set plant type ..................................................................... 50

4.1.6 Set control of suction group MT ..................................51

4.1.7 Set oil management ........................................................ 55

4.1.8 Set up control of condenser fans ................................ 56

4.1.9 Set-up of high pressure control ................................... 58

4.1.10 Set up control of receiver pressure.............................59

4.1.11 Set-up Receiver Reference with

Low Pressure Multi Ejectors ......................................... 62

4.1.12 Set up control of heat recovery ................................... 63

4.1.13 Set up KPI and COP calculation ................................... 65

4.1.14 Set up Display .................................................................... 66

4.1.15 Set-up Functions for General purpose ...................... 67

4.1.16 Separate thermostats ...................................................... 68

4.1.17 Separate pressostats ........................................................68

4.1.18 Separate voltage signals ................................................ 69

4.1.19 Separate alarm inputs ..................................................... 69

4.1.20 Separate PI functions ...................................................... 70

4.1.21 Conﬁguration of inputs and outputs .........................71

4.1.22 Set alarm priorities ........................................................... 73

4.1.23 Lock conﬁguration ........................................................... 74

4.1.24 Check conﬁguration ........................................................ 75

4.2 Check of connections .................................................................... 77

4.3 Check of settings............................................................................. 79

4.4 Schedule function .......................................................................... 81

4.5 Installation in network .................................................................. 82

4.6 First start of control ........................................................................ 83

4.6.1 Start the control ................................................................ 84

4.6.2 Manual capacity control ................................................. 85

5. Regulating functions ............................................................86

5.1 Suction group .................................................................................. 86

5.2 Capacity control of compressors...............................................87

5.2.1 Capacity distribution methods .................................... 89

5.2.2 Power pack types – compressor combinations ..... 90

5.2.3 Compressor timers ........................................................... 94

5.2.4 Compressor with variable capacity ............................ 94

5.2.5 Load shedding ................................................................... 96

5.2.6 Injection ON ........................................................................ 96

5.2.7 Liquid injection in common suction line ................. 97

5.2.8 Safety functions ................................................................. 98

5.3 Oil management ...........................................................................100

5.4 Condenser / Gas cooler ..............................................................102

5.4.1 Capacity control of condenser ...................................102

5.4.2 Reference for gas cooler temperature ....................102

5.4.3 Capacity distribution .....................................................104

5.5 Condenser couplings ..................................................................105

5.6 Safety functions for condenser ................................................105

5.7 CO transcritical system and heat recovery .........................106

5.7.1 Circuit for heat recovery or hot tap water..............107

5.7.2 Circuit for recovery for heating ..................................108

5.7.3 Circuits for control of CO gas pressure ..................112

5.7.4 Ejector control ..................................................................114

5.7.5 Receiver control ...............................................................118

5.7.6 Safety procedures ..........................................................119

5.7.7 Actions on low receiver pressure .............................120

5.7.8 Parallel Compression ....................................................121

5.8 Setpoint Management ................................................................125

5.9 General monitoring functions .................................................129

5.10 Miscellaneous ................................................................................131

5.11 KPI and COP calculations ...........................................................136

5.12 Appendix A –

Compressor combinations and coupling patterns...........138

5.13 Appendix B – Alarm texts .......................................................... 144

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User Guide | Pack controller, type AK-PC 782A

1. Introduction

1.1 Application

AK-PC 782A are complete regulating units for capacity control of compressors and condensers in a transcritical CO booster system with parallel compressor. The controller is with oil management, heat recovery function and CO 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 must be carried out by suction pressure P0. (The P0 signal for the parallel compressor is supplied by the pressure transmitter on the receiver). Among the diﬀerent functions are:

• Capacity control of up to 10 compressors on MT and 8 on IT

• Capacity control of up to 4 compressors on LT

• Up to 3 unloaders for each compressor

• Control of oil separator and oil receiver

• Speed control of one or two compressors in each group

• Up to 6 safety inputs for each compressor

• Option for capacity limitation to minimize consumption peaks

• If 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

• 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

• CO gas cooler control and receiver control

• Ejector regulation: HP, LE (liquid)

• Safety monitoring of fans

• The status of the outputs and inputs is shown by means of lightemitting diodes on the front panel

• Alarm signals can be generated via data communication

• Alarms are shown with texts so that the cause of the alarm is easy to see.

• Plus some completely separate functions that are totally independent of the regulation – such as alarm, thermostat, pressure and PI-regulating functions.

SW = 3.5x

Examples

Traditional capacity control

Prec

Heat recovery functions, controlling the condensing pressure and receiver pressure

User Guide | Pack controller, type AK-PC 782A

1.2 Principles

The great advantage of this series of controllers is that it can be extended as the size of the plant is increased. It has been developed for refrigeration control systems, but not for any speciﬁc application – variation is created through the read-in software and the way you choose to deﬁne the connections. The same modules that are used for each regulation and the composition can be changed, as required. With these modules (building blocks) it is possible to create a multitude of various kinds of regulations. But it is you who must help adjusting the regulation to the actual needs – these instructions will assist you to ﬁnd your way through all the questions so that the regulation can be deﬁned and the connections made.

Controller

Top part

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.

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

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.

Examples

A regulation with few connections can be performed with the controller module alone.

If there are many connections, one or more extension modules have to be mounted.

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User Guide | Pack controller, type AK-PC 782A

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, set up and operation of the various functions is carried out via the controller’s menu displays.

Displays

The menu displays are dynamic, so that diﬀerent settings in one menu will result in diﬀerent setting possibilities in other menus. A simple application with few connections will give a set-up with few settings. A corresponding application with many connections will give a set-up with many settings. From the overview display there is access to further displays for the compressor regulation and the condenser regulation. At the bottom of the display there is access to a number of general functions, such as “time table”, “manual operation”, “log function”, “alarms”, and “service” (conﬁguration).

Network linking

The controller can be linked up to a network together with other controllers in an ADAP-KOOL® refrigeration control system. After the set-up, operation can be performed at a distance with e.g. our software program type AKM.

Users

The controller comes supplied with several languages, one of which can be selected and employed by the user. If there are several users, they may each have their choice of language. All users must be assigned a user proﬁle which either gives access to full operation or gradually limits the operation to the lowest level that only allows you “to see”. Language selection is part of the Service Tool settings. If the language selection is not available in the Service Tool for the current regulator, English texts will be displayed.

External display

An external display can be ﬁtted in order for P0 (Suction) and Pc (Condensing) readings to be displayed. A total of 4 displays can be ﬁtted and with one setting it is possible to choose between the following readings: suction pressure, suction pressure in temperature, Ss, Sd, condenser pressure, condenser pressure in temperature, 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 ﬁtted.

User Guide | Pack controller, type AK-PC 782A

Light-emitting diodes

A number of light-emitting diodes makes it possible to follow the signals that are received and transmitted by the controller.

Log

From the log function you can deﬁne the measurements you wish to be shown. The collected values can be printed, or you may export them to a ﬁle. You can open the ﬁle in Excel. If you are in a service situation, you can show measurements in a trend function. The measurements are then made real-time and displayed instantly.

n Power n Comm n DO1 n Status n DO2 n Service Tool n DO3 n LON n DO4 n I/O Extension n DO5 n Alarm n DO6 n DO7 n Display n DO8 n Service Pin

Slow ﬂash = OK

Quick ﬂash = answer from gateway

Constantly ON = error

Constantly OFF = error

Flash = active alarm/not cancelled

Constant ON = Active alarm/cancelled

Alarm

The display gives you an overview of all active alarms. If you wish to conﬁrm that you have seen the alarm you can cross it oﬀ in the acknowledge ﬁeld. If you want to know more about a current alarm you can click on it and obtain an information display on the screen. A corresponding display exists for all earlier alarms. Here you can upload information if you need further details about the alarm history.

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User Guide | Pack controller, type AK-PC 782A

2. Design of a controller

This section describes how the controller is designed. The controller in the system is based on a uniform connection platform where any deviations from regulation to regulation is determined by the used top part with a speciﬁc software and which input and output signals the relevant application will require. If it is an application with few connections, the controller

2.1 Module survey

Controller module – capable of handling minor plant requirements.

Extension modules

When the complexity becomes greater and additional inputs or outputs are required, modules can be attached to the controller. A plug on the side of the module will transmit the supply voltage and data communication between the modules.

Top part

The upper part of the controller module contains the intelligence. This is the unit where the regulation is deﬁned and where data communication is connected to other controllers in a bigger network.

Connection types

There are various types of inputs and outputs. One type may, for example, receive signals from sensors and switches. Another may receive a voltage signal, and a third type may be outputs with relays etc. The individual types are shown in the table below.

module (top part with belonging bottom part) may be suﬃcient. If it is an application with many connections, it will be necessary to use the controller module plus one or more extension modules. This section will give you a survey of possible connections plus assistance in selecting the modules required by your actual application.

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 analogue input signal must for instance not be connected to a digital input).

Programming of connections

The controller must know where you connect the individual input and output signals. This takes place in a later conﬁguration where each individual connection is deﬁned based on the following principle:

• to which module?

• at which point (”terminals”)?

•

what is connected (e.g. pressure transmitter/type/pressure range)?

User Guide | Pack controller, type AK-PC 782A

Extension module with additional analogue inputs

External display for suction pressure etc.

Bottom part

Controller with analogue inputs and relay outputs.

Extension module with additional relay outputs and additional analogue inputs.

Top part

Extension module with 2x analogue 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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User Guide | Pack controller, type AK-PC 782A

1. Controller

Type Function Application

AK-PC 782A

Controller for capacity control of MT (10 compressors), IT (8 compressors) and LT (4 compressors). Up to 3 unloaders per compressor, 8 fans and max. 220 inputs/outputs.

Transcritical CO booster control, parallel compression / Oil management / Heat recovery / CO gas pressure

2. Extension modules and survey of inputs and outputs

Type Analogue

inputs

For sensors, pressure transmitters etc.

Controller 11 4 4 - - - -

Extension modules

AK-XM 101A 8

AK-XM 102A 8

AK-XM 102B 8

AK-XM 103A 4 4

AK-XM 204A 8

AK-XM 204B 8 x

AK-XM 205A 8 8

AK-XM 205B 8 8 x

AK-XM 208C 8 4

On/Oﬀ outputs On/oﬀ supply voltage

Relay (SPDT)

Solid state Low voltage

(DI signal)

(max. 80 V)

High voltage (max. 260 V)

Analogue outputs

0 – 10 V DC For valves

Stepper output

with step control

Module with switches

For override of relay outputs

The following extension module can be placed on the PC board in the controller module. There is only room for one module.

AK-OB 110 2

3. AK operation and accessories

Type Function Application

Operation

AK-ST 500 Software for operation of AK controllers AK-operation

- Cable between PC and AK controller USB A-B (Standard IT cable)

Accessories Power supply module 230 V / 115 V to 24 V DC

AK-PS 075 18 VA

Supply for controllerAK-PS 150 36 VA

AK-PS 250 60 VA

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

EKA 163B Display

EKA 164B Display with operation buttons

MMIGRS2 Graphic display with operation

Accessories Communication modules for controllers where modules cannot be connected continuously

AK-CM 102 Communication module

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

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

Data communication for external extension modules

On the following pages there is data speciﬁc to each module.

User Guide | Pack controller, type AK-PC 782A

2.2 Common data for modules

Supply voltage 24 V DC/AC ±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

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

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

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

Voltage signal 0 – 10 V

Contact function (On/Oﬀ) On at R < 20 ohm

Analogue outputs 0 – 10 V Accuracy +/- 100 mV On/oﬀ supply voltage inputs Low voltage

Relay outputs SPDT

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

Stepper outputs Used for valves with stepper input 20 – 500 step/s

Ambient temperature During transport -40 – 70 °C

Enclosure Material PC / ABS

Weight with screw terminals Modules in 100- / 200- / controller-series Ca. 200 g / 500 g / 600 g

Approvals EU low voltage directive and EMC requirements

The mentioned data applies to all modules. If data is speciﬁc, this is mentioned together with the module in question.

0 / 80 V AC/DC

High voltage 0 / 260 V AC

AC-1 (ohmic) 4 A AC-15 (inductive) 3 A U Min. 24 V

frequently, e.g. Ejector valves, Oil valves, fans and AKV valves

During operation -20 – 55 °C ,

Class IP10, VBG 4 Mounting For mounting on panel wall or DIN rail

are complied with

Dimensions

Accuracy: ±0.5 °C ±0.5 °C between -50 °C and 50 °C ±1 °C between -100 °C and -50 °C ±1 °C between 50 °C and 130 °C

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

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

Oﬀ: U < 2 V On: U > 10 V

Oﬀ: U < 24 V On: U > 80 V

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

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

Separate supply to stepper outputs : 24 AC/DC

0 – 95% RH (non condensing) No shock inﬂuences / vibrations

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

E31024 for PC-module

E357029 for XM and CM-modules

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

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User Guide | Pack controller, type AK-PC 782A

2.3 Controller

Function

There are several controllers in the series. The function is determined by the programmed software, but on the outside the controllers are identical – they all have the same connection possibilities: 11 analogue 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 AC or DC 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 module 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

If it is a system manager AK-SM .., then 1-999

Service PIN

When the controller is connected to the data communication cable, the gateway must have knowledge of the new controller. This is obtained by pushing the key PIN. The LED “Status” will ﬂash when the gateway sends an acceptance message.

Operation

The conﬁguration operation of the controller must take place from the software program “Service Tool”. The program must be installed on a PC, and the PC must be connected to the controller via the USB-B plug on the front of the unit.

Light-emitting diodes

There are two rows with LEDs indicating: Left row:

• Voltage supply to the controller

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

• Status of outputs DO1 to DO8

Right row:

• Software status (slow ﬂash = OK)

• Communication with Service Tool

• Communication on LON

• Communication with AK-CM 102

• Alarm when LED ﬂashes – 1 LED that is not used

• Communication with display on RJ11 plug

• “Service Pin” switch has been activated

Address

n Power n Comm n DO1 n Status n DO2 n Service Tool n DO3 n LON n DO4 n I/O Extension n DO5 n Alarm n DO6 n DO7 n Display n DO8 n Service Pin

Keep the safety distance!

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

Slow ﬂash = OK Quick ﬂash = answer from gateway Constantly ON = error Constantly OFF = error

Flash = active alarm/not cancelled Constant ON = Active alarm/cancelled

A small module (option board) can be placed on the bottom part of the controller. The module is described later in the document.

User Guide | Pack controller, type AK-PC 782A

Point

Analogue inputs on 1 - 11

Solid state outputs on 12 - 15

Relay or AKV coil fx 230 V AC

Pt 1000 ohm/0°C

AKS 32R

AKS 32

On/Oﬀ Ext.

Option Board

3: Brown

2: Blue

1: Black

3: Brown

2: Black

1: Red

AKV

Signal

Signal type

S1 S2 Saux_ SsA

Pt 1000 SdA Shr Stw Sgc

P0A P0B PcA PcB Paux Pgc Prec

AKS 32R /

AKS 2050

MBS 8250

-1 - xx bar

AKS 32

-1 - zz bar

0 - 5 V ...

Main switch Day/ Night Door

0 - 10 V

Active at:

Closed

Open

Level switch

Active at:

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

Please see the signal on the page with the module.

Oﬀ

Point 1 2 3 4 5 6 7 8 9 10 11

Type AI1 AI2 AI3 AI4 AI5 AI6 AI7 AI8 AI9 AI10 AI11

24 and 25 used only when "Option board ﬁtted"

Point 12 13 14 15 16 17 18 19

Type DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8

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 (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 15 & 27: 12 V max. 100 mA in total.

Terminal 16 & 28: 5 V max. 100 mA in total.

Terminal 17, 18, 29, 30: (Cable screen)

The screen on the pressure transmitter cables must only be connected at the end of the controller.

Relay outputs on 16 - 19

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User Guide | Pack controller, type AK-PC 782A

2.3.1 Extension module AK-XM 101A

Function

The module contains 8 analogue 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 LEDs are used. They indicate the following:

• Voltage supply to the module

• Communication with the controller is active (red = error)

User Guide | Pack controller, type AK-PC 782A

Point

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

AKS 32R / AKS 2050 MBS 8250

-1 - xx bar Paux Pgc Prec

AKS 32

-1 - zz bar

Point 1 2 3 4

Type AI1 AI2 AI3 AI4

Point 5 6 7 8

Type AI5 AI6 AI7 AI8

Terminal 9 & 15: 12 V max. 100 mA in total.

Terminal 10 & 16: 5 V max. 100 mA in total.

Terminal 11, 12, 13, 14: (Cable screen) The screen on the pressure transmitter cables must only be connected at the end of the controller.

...

0 - 5 V 0 - 10 V

Signal Module Point

1 (AI 1) 1 - 2

Terminal

Signal type /

Active at

2 (AI 2) 3 - 4

3 (AI 3) 5 - 6

On/Oﬀ

Ext. Main switch Day/ Night Door Level switch

Active at:

Closed

Open

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

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User Guide | Pack controller, type AK-PC 782A

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

Function

The module contains 8 inputs for on/oﬀ voltage signals.

Signal

AK-XM 102A is for low voltage signals. AK-XM 102B is for high voltage signals.

Supply voltage

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

Light-emitting diodes

They indicate:

• Voltage supply to the module

• Communication with the controller is active (red = error)

• Status of the individual inputs 1 to 8 (when lit = voltage

AK-XM 102A

Max. 24 V

On/Oﬀ: On: DI > 10 V AC/DC Oﬀ: DI < 2 V AC/DC

AK-XM 102B

Max. 230 V

On/Oﬀ: On: DI > 80 V AC Oﬀ: DI < 24 V AC

User Guide | Pack controller, type AK-PC 782A

Point

Signal Active at

DI Ext.

AK-XM 102A: Max. 24 V AK-XM 102B: Max. 230 V

(The module can not register a pulse signal from e.g. a reset function.)

Main switch

Day/ Night

Comp. safety 1

Comp. safety 2

Level switch

Closed

(voltage on)

Open

(voltage

oﬀ)

Point 1 2 3 4

Type DI1 DI2 DI3 DI4

Point 5 6 7 8

Type DI5 DI6 DI7 DI8

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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User Guide | Pack controller, type AK-PC 782A

2.3.3 Extension module AK-XM 103A

Function

The module contains : 4 analogue inputs for sensors, pressure transmitters, voltage signals and contact signals. 4 analogue 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 LEDs are used. They indicate the following:

• Voltage supply to the module

• Communication with the controller is active (red = error)

Max. load

I < 2.5 mA R > 4 kΩ

Accuracy

Analog inputs: +/- 10 mV Analog outputs: +/- 100 mV

User Guide | Pack controller, type AK-PC 782A

Point

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 MBS 8250

-1 - xx bar

AKS 32

-1 - zz bar

Point 1 2 3 4

Type AI1 AI2 AI3 AI4

Point 5 6 7 8

Type AO1 AO 2 AO3 AO4

Terminal 9: 12 V max. 100 mA in total.

Terminal 10: 5 V max. 100 mA in total.

Terminal 11, 12: (Cable screen) The screen on the pressure transmitter cables must only be connected at the end of the controller.

Galvanic isolation: AI 1-4 ≠ AO 1-2 ≠ AO 3-4

...

0 - 5 V 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

On/Oﬀ Ext.

Main switch Day/ Night

Door

Active at:

Closed

Open

5 (AO 1) 17 - 18

6 (AO 2) 19 - 20

7 (AO 3) 21 - 22

8 (AO 4) 23 - 24

Level switch

0 – 10 V

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User Guide | Pack controller, type AK-PC 782A

2.3.4 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 LEDs. They indicate the following: 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

AK-XM 204A AK-XM 204B

Fuses

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

Max. 230 V AC-1: max. 4 A (ohmic) AC-15: max. 3 A (Inductive)

AK-XM 204B Override of relay

Keep the safety distance!

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

User Guide | Pack controller, type AK-PC 782A

Point

Signal Active at

Comp. 1

Comp. 2

Fan 1

Alarm

Solenoid valve

Oﬀ

Point 1 2 3 4 5 6 7 8

Type DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8

Signal Module Point Terminal Active at

1 (DO 1) 25 - 27

2 (DO 2) 28 - 30

3 (DO 3) 31 - 33

4 (DO 4) 34 -36

5 (DO 5) 37 - 39

6 (DO 6) 40 - 41 - 42

7 (DO 7) 43 - 44 - 45

8 (DO 8) 46 - 47 - 48

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User Guide | Pack controller, type AK-PC 782A

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

Function

The module contains: 8 analogue 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 LEDs. They indicate the following: 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

Fuses

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

AK-XM 205A AK-XM 205B

max. 10 V

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 205B Override of relay

User Guide | Pack controller, type AK-PC 782A

Point

Pt 1000 ohm/0°C

AKS 32R

AKS 32

On/Oﬀ

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 MBS 8250

-1 - xx bar

AKS 32

-1 - zz bar

0 - 5 V 0 - 10 V

Ext. Main switch

Active at:

Day/ Night

Closed Door Level

Open

switch

Comp 1 Comp 2 Fan 1

Active at:

Alarm Light

on Rail heat Defrost

Oﬀ Solenoid valve

Point 1 2 3 4 5 6 7 8

Type AI1 AI2 AI3 AI4 AI5 AI6 AI7 AI8

Point 9 10 11 12 13 14 15 16

Type DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8

Signal Module Point Terminal Signal type /Active at

Terminal 9 & 21: 12 V max. 100 mA in total.

Terminal 10 & 22: 5 V max. 100 mA in total.

Terminal 11, 12, 23, 24 :

(Cable screen) The screen on the pressure transmitter cables must only be connected at the end of the controller.

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 - 38 - 39

14 (DO6) 40 - 41 - 42

15 (DO7) 43 - 44 - 45

16 (DO8) 46 - 47 - 48

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User Guide | Pack controller, type AK-PC 782A

2.3.6 Extension module AK-XM 208C

Function

The module contains: 8 analogue inputs for sensors, pressure transmitters, voltage signals and contact signals. 4 outputs for stepper motors.

Supply voltage

The supply voltage to the module comes from the previous module in the row. Here supplied with 5 VA.

An additional and separated power supply must be installed, which must be galvanically separated from the supply for the control range. Class II is required. (Power requirements: 7.8 VA for controller + xx VA per valve).

2 separated UPS´s are recommended, one for the pack controller and another AK-XM 208C module if the valves need to open/ close during a power failure. If the AK-CM 102 module is installed it is also recommended a separated UPS.

Light-emitting diodes

There is one row with LEDs, indicating the following:

• Voltage supply to the module

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

• Step1 to step4 OPEN: Green = Open

• Step1 to step4 CLOSE: Green = Close

• Red ﬂash = Error on motor or connection

Separate voltage supply is required 24 V AC/DC / fx. 13 VA

Output:

24 V DC

20-500 step/s

Max. Phase current = 325 mA RMS

∑ P

= 21 VA

max.

The connection to the valve must not be broken using a relay

max. 10 V

L = max. 30 m

Valve data

Type P

ETS 12.5 - ETS 400 KVS 15 - KVS 42 CCMT 2 - CCMT 8 CCM 10 - CCM 40 CTR 20

CCMT 16 - CCMT 42 5.1 VA

CCMT - 3L/5L/8L 4.0 VA

1.3 VA

Power supply to AK-XM 208C:

Fx: 7.8 + (4 x 1.3) = 13 VA  AK-PS 075 Fx: 7.8 + (4 x 5.1) = 28,2 VA  AK-PS 150

User Guide | Pack controller, type AK-PC 782A

Point

CCMT

Step / Terminal

ETS CCM / CCMT CTR KVS

Point 1 2 3 4 5 6 7 8

Type AI1 AI2 AI3 AI4 AI5 AI6 AI7 AI8

Terminal 17: 12 V max. 100 mA in total.

Terminal 18: 5 V max. 100 mA in total.

Terminal 19, 20: (Cable screen)

Point 9 10 11 12

Step 1 2 3 4

Type AO

1 25 26 27 28

2 29 30 31 32

3 33 34 35 36

4 37 38 39 40

White Black Red Green

Valve Module Step Terminal

1 (point 9) 25 - 28

2 (point 10) 29 - 32

3 (point 11) 33 - 36

4 (point 12) 37 - 40

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User Guide | Pack controller, type AK-PC 782A

2.3.7 Extension module AK-OB 110

Function

The module contains two analogue 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

Accuracy

Analog outputs: +/- 100 mV

AO 0 - 10 V

Module

Point 24 25

Type AO1 AO 2

AO2

AO1

User Guide | Pack controller, type AK-PC 782A

2.3.8 Extension module EKA 163B / EKA 164B

Function

Display of important measurements from the controller, e.g. appliance temperature, suction pressure or condensing pressure. Setting of the individual functions can be performed by using the display with control buttons. It is the controller used that determines the measurements and settings that can occur.

Connection

The extension module is connected to the controller module via a cable with plug connections. You have to use one cable per module. The cable is supplied in various lengths.

Both types of display (with or without control buttons) can be connected to either display output A, B, C and D. Ex. A: P0. Suction pressure in °C. B: Pc. Condensing pressure in °C.

When the controller starts up, the display will show the output that is connected.

- - 1 = output A

- - 2 = output B etc.

EKA 163B EKA 164B

Placing

The extension module can be placed at a distance of up to 15 m from the controller module.

Point

No point has to be deﬁned for a display module – you simply connect it.

2.3.9 Graphic display MMIGRS2

Function

Setting and display of values in the controller.

Connection

The display connects to the controller via a cable with RJ11 plug connections.

Supply voltage

Received from the controller via cable and RJ11 connector. Do not connect a seperate power supply for this display.

Termination

The display must be terminated. Mount a connection between the terminals H and R. (AK-PC 782A is terminated internally.)

Placing

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

Point / Address

No point has to be deﬁned for a display – you simply connect it. However, the address must be veriﬁed. See the instructions accompanying the controller.

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To create access, the display must be connected and the address of MMIGRS2 must be activated.

Setting:

1. Press both the "x-button" and "enter button" and hold for 5 seconds. Subsequently the Bios menu is shown.

2. Select the line "MCX selection", press "enter"

3. Select the line "Man selection", press "enter"

4. The address is shown now. Please check that it is 001, press "enter". Then data is downloaded from the controller.

User Guide | Pack controller, type AK-PC 782A

2.3.10 Power supply module AK-PS 075 / 150 / 250

Function

24 V supply for controller.

Supply voltage

230 V AC or 115 V AC (from 100 V AC to 240 V AC)

Placing

On DIN-rail

Eﬀect

Type Output tension Output current Power

AK-PS 075 24 V DC 0.75 A 18 VA

AK-PS 150 24 V DC (adjustable) 1.5 A 36 VA

AK-PS 250 24 V DC (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

Class II

Supply to a controller

Connections

AK-PS 075

AK-PS 150

AK-PS 250

User Guide | Pack controller, type AK-PC 782A

2.3.11 Communication module AK-CM 102

Function

The module is a new communication module, meaning the row of extension modules can be interrupted. The module communicates with the regulator via data communication and forwards information between the controller and the connected extension modules.

Connection

Communication module and controller ﬁtted with RJ 45 plug connectors. Nothing else should be connected to this data communication; a maximum of 5 communication modules can be connected to one controller.

Communication cable

One metre of the following is enclosed: ANSI/TIA 568 B/C CAT5 UTP cable w/ RJ45 connectors.

Positioning

Max. 30 m from the controller (The total length of the communication cables is 30 m)

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.

Max. 32 VA

Max. 20 VA

Point

Connection points on the I/O modules should be deﬁned as if the modules were an extension of each other.

Address

The address for the ﬁrst communication module should be set to 1. Any second module should be set to 2. A maximum of 5 modules can be addressed.

Termination

The termination switch on the ﬁnal communication module should be set to ON. The controller should permanently be set to = ON.

Warning!

Additional modules may only be installed following the installation of the ﬁnal module. (Here following module no. 11; see the sketch.) After conﬁguration, the address must not be changed.

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User Guide | Pack controller, type AK-PC 782A

2.4 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 analogue input or as voltage on a low or high-voltage module.

• An ON/OFF output signal can be given in two ways. Either with a relay switch or with solid state. The primary diﬀerence is the permitted load and that the relay switch contains a cut-out switch.

Functions

Clock function

Clock function and change-over between summer time and winter time are contained in the controller. The clock setting is maintained for at least 12 hours at a power failure. The clock setting is kept updated if the controller is linked up in a network with a system manager.

Start/stop of regulation

Regulation can be started and stopped via the software. External start/stop can also be connected.

Warning! The function stops all regulation, including any high-pressure regulation. Excess pressure can lead to a loss of charge.

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 for the need for connections to be established.

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 analogue 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.

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.

Data communication

The controller module has terminals for LON data communication. The requirements to the installation are described in a separate document.

User Guide | Pack controller, type AK-PC 782A

Connections

In principle there are the following types of connections:

Analogue 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

• Pulse signal or reset signal

• Contact signal where the input is shortcircuited or ”opened”, respectively

• Voltage signal from 0 to 10 V

• Signal from pressure transmitter AKS 32, AKS 32R, AKS 2050 or MBS 8250.

• The supply voltage is supplied from the module’s terminal board where there is both a 5 V supply and a 12 V supply. When programming, the pressure transmitter’s pressure range must be set.

ON/OFF voltage inputs ”DI”

This signal must be connected to two terminals.

• The signal must have two levels, either 0 V or ”voltage” on the input. There are two diﬀerent extension modules for this signal type:

– low-voltage signals, e.g. 24 V – high-voltage signals, e.g. 230 V

When programming, the function must be set:

• Active when the input is without voltage

• Active when voltage is applied to the input.

ON/OFF output signals ”DO” There are two types, as follows:

• Relay outputs All relay outputs are with change-over

relay so that the required function can be obtained when the controller is without voltage.

• Solid state outputs Reserved for ejector valves, oil valves

and 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.

Analogue output signal ”AO”

This signal is to be used if a control signal is to be transmitted to an external unit, e.g. a frequency converter. When programming, the signal range must be deﬁned: 0-5 V, 1-5 V, 0-10 V or 2-10 V.

Pulse signal for the stepper motors. This signal is used by valve motors of the type ETS, KVS, CCM and CCMT. The valve type should be set during programming.

Limitations

As the system is very ﬂexible regarding the number of connected units, you must check whether your selection complies with the few limitations there are. The complexity of the controller is determined by the software, the size of the processor, and the size of the memory. It provides the controller with a certain number of connections from which data can be downloaded, and others where coupling with relays can be performed.

 The sum of connections cannot exceed 220 (AK-PC 782A).

 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 18 modules (controller + 17 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.

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Common pressure transmitter

If several controllers receive a signal from the same pressure transmitter, the supply to the aﬀected controllers must be wired so that it is not possible to switch oﬀ one of the controllers without also switching oﬀ the others. (If one controller is switched oﬀ, the signal will be pulled down, and all the other controllers will receive a signal which is too low).

Ejector valves

If ejector valves are used, the smallest ones must be connected to the solid state outputs.

User Guide | Pack controller, type AK-PC 782A

2.5 Design of a compressor and condenser control

Procedure:

1. Make a sketch of the system in question

2. Check that the controller’s functions cover the required application

3. Consider the connections to be made

4. Use the planning table  Note down the number of connections  add up

5. Are there enough connections on the controller module? – If not, can they be obtained by changing an ON/OFF input signal from voltage signal to contact signal, or will an extension module be required?

6. Decide which extension modules are to be used

7. Check that the limitations are observed

8. Calculate the total length of modules

9. The modules are linked together

10. The connection sites are established

11. Draw a connection diagram or a key diagram

12. Size of supply voltage/transformer

1. Sketch

Make a sketch of the system in question.

2. Compressor and condenser functions

AK-PC 782A

Application

Both compressor group and condenser group x

Booster group x

Parallel compressor x

Regulation of compressor capacity

Regulation sensor. P0 x

PI-regulation x

Max. number of compressor steps: MT+IT / LT 10+8/4

Max. number of unloaders each compressor 3

Identical compressor capacities x

Diﬀerent compressor capacities x

Speed regulation of 1 or 2 compressors x

Run time equalisation x

Min. restart time x

Min. On-time x

Ejector regulation x

Liquid injection in suction line x

Liquid injection in cascade heat exchanger x

External start/stop of compressors x

Oil management

Receiver pressure control x

Monitoring of oil level in receiver x

Management of oil level in oil separator 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. Sgc or S7 x

Step regulation x

Max. number of steps 8

Speed regulation x

Step and speed regulation x

Speed regulation ﬁrst 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

User Guide | Pack controller, type AK-PC 782A

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

Common high pressure monitoring of compressors x

A bit more about the functions

Compressor

Regulation of up to 10 MT and 8 IT compressors and up to 4 LT compressors. All with up to 3 unloaders per compressor. Compressor No. 1 or 2 can be speed-regulated. The following can be used as control sensor: P0 - Suction pressure

Condenser

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

1) Sgc -Temperature at the gas cooler outlet (one or two Sgc

sensors can be conﬁgured).

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

safety.)

Speed regulation of condenser fans

The function requires an analogue output module. A relay output may be used for start/stop of the speed regulation. The fans may also be cut in and out by relay outputs.

Pulse wide modulating unloading

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

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 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 4 + 1

Separate thermostat functions 5

Separate pressostat functions 5

Separate voltage measurements 5

PI regulation 3

Max. input and output 220

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 cut-in and cut-out 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 cut-in and cut-out values. An associated alarm function may also be used.

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

3. Connections

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

• 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)

Analogue inputs

Temperature sensors

• Ss (suction gas temperature) Must always be used in connection with compressor regulation.

• Sd (discharge gas temperature)

Must be used when adjusting the heat receiver for heating.

• 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)

Must always be used in connection with compressor regulation.

• Sc3 (outdoor temperature) Must be used when regulation is performed with ﬂoating

condenser reference.

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

selected as S7.

• Saux (1-4), any extra temperature sensors Up to four additional sensors for monitoring and data collection

may be connected. These sensors can be used for general thermostat functions.

Pressure transmitters

• P0 Suction Pressure

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

• Pc Condensing Pressure

Must always be used in connection with compressor or

condenser regulation

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

• Pgc Gas cooler pressure.

• Prec. Pressure reading in the CO2 receiver.

• Paux (1-5)

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User Guide | Pack controller, type AK-PC 782A

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, AKS 32R or MBS 8250 can supply signals to a maximum of ﬁve controllers.

Voltage signal

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

control.

• Voltage inputs (1-5) Up to 5 extra voltage signals can be connected for monitoring

and data collection. These signals are used for general voltage input functions.

On/Oﬀ-inputs

Contact function (on an analogue input) or voltage signal (on an extension module)

• Common safety input for all compressors (e.g. common highpressure/low-pressure pressure switch)

• Up to 6 signals from the safety circuit of each compressor

• Signal from the condenser fan's 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/oﬀ signals for general alarm for monitoring

and data collection can be connected.

• Flow switch for heat recovery

• Level contacts

• Level contact on suction accumulator

On/oﬀ-outputs

Relay outputs

• Compressors

• Unloaders

• Fan motor

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

• Start/stop of liquid injection in suction line

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

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

• Alarm relay. I'm alive relay.

• Status relay: Floating allowed / not allowed

• On/oﬀ signals from general thermostats (1-5), pressure switches (1-5) or voltage input functions (1-5).

• Oil valves

Solid state outputs

These are primarily for ejector valves, oil valves and AKV valves. 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). Analogue outputs

• Speed regulation of the condenser’s fans.

• Speed regulation of the compressor

• Speed control of pumps for heat recovery

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

• Stepper signal for hot gas by-pass valve

Example Compressor group:

MT circuits:

• 3 compressors with "cyclic". One speed controlled

• Safety monitoring of each compressor

• Common high-pressure monitoring

• Po setting -10 °C, Po optimization from the system unit

LT circuits:

• 2 x compressors with "cyclic". One speed controlled

• Safety monitoring of each compressor

• Common high pressure monitoring

• Po setting –30 °C, Po optimization from the system unit

IT circuit:

• 1 compressor, speed controlled

• Receiver set point 36 bar

High pressure controls:

• Heat recovery for tap water

• Gas cooler

• Fans, speed controlled

Receivers:

• Optimal CO reveiver pressure

• Monitoring CO-level in the receiver

• Monitoring of high and low pressure

• Controlling the tap water receiver temperature, 55°C

Fan in plant room

• Thermostat control of fan in engine room

Safety functions:

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

• MT: Po max = -5 °C, Po min = -35 °C

• MT: Pc max = 110 bar

• MT: Sd max = 120 °C

• LT: Po max = -5 °C, Po min = -45 °C

• LT: Pc max = 40 bar

• LT: Sd max = 100 °C

• SH min = 5 °C, SH max = 35 °C

Other:

• Start/stop of heat recovery to Tw

• External main switch used

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

• AK-PC 782A controller

• AK-XM 205A input and output module

• AK-XM 208C stepper output module

• AK-XM 103B analogue input and output module

• AK-OB 110 analogue output module

User Guide | Pack controller, type AK-PC 782A

4. Planning table

The table helps you establish whether there are enough inputs and outputs on the basic controller.

If there are not enough of them, the controller must be extended by one or more of the mentioned extension modules.

Note down the connections you will require and add them up

Analogue input signal

Example

On/oﬀ voltage signal

Example

On/oﬀ voltage signal

Example

On/Oﬀ output signal

Example

Analogue output signal 0-10 V

Stepper output

Example

Analogue inputs

Temperature sensors, Ss, Sd, Sc3, S7, Stw.., Shr.., Sgc 13

Extra temperature sensor / separate thermostats /PI-regulation 1

Pressure transmitters, P0, Pc, Pctrl. Prec / separate pressostats

Voltage signal from other regulation, separate signals

Heat recovery via thermostat

On/oﬀ inputs Contact 24 V 230 V

Safety circuits, common for all compressors

Safety circuits, Oil pressure Max. 1/Comp.

Safety circuits, comp. Motor protection

Safety circuits, comp. Motor temp.

Safety circuits, comp. High pres. thermostat

Safety circuits, comp. High pres. pressostat

Safety circuits, general for each compressor 6

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

Safety circuits, ﬂow switch

External start/stop 1

Night setback of suction pressure

Separate alarm functions via DI

Load shedding

Start of Heat recovery 1

Liquid level receiver / suction accumulator, Oil level 1

Pulsation pressure

On/oﬀ outputs

Compressors, motors 6

Unloaders

Fan motors, circulation pumps 3

Alarm relay, I'm alive relay, ﬂoating allowed

Inject ON Max. 2

Separate thermostat and pressostat functions and voltage measurements

Heat recovery function via thermostat Max.1

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

Solenoid valve for Oil, ejector valve.

3-way valve 1

Analogue control signal, 0-10 V

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

Valves with stepper motor. Parallel valves, if applicable 3

Sum of connections for the regulation 30 0 0 12 5+3 Sum = max. 220

Number of connections on a controller module 11 11 0 0 0 0 8 8 0 0 0

5. Missing connections, if applicable

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

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

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

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

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

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

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

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

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

5 P = Max. 5 / module

19 - 0 4 5+3

Max.1/suction group

Max. 5+5+5

Sum of power

1 pcs. á 8 VA = 8

Sum =

Sum = max. 32 VA

Limitations

The example:

None of the limitations are exceeded => OK

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User Guide | Pack controller, type AK-PC 782A

8. Length

If you use many extension modules, the controller’s length will grow accordingly. The row of modules is a complete unit which cannot be broken. If the row becomes longer than desired, the row can be broken by using AK-CM 102.

The module dimension is 72 mm. Modules in the 100-series consist of one module. Modules in the 200-series consist of two modules. The controller consist of three modules. The length of an aggregate unit = n x 72 + 8

or in an other way:

Module Type No. at Length

Controller module 1 x 224 = 224 mm Extension module 200-series _ x 144 = ___ mm Extension module 100-series _ x 72 = ___ mm

Total length = ___ mm

9. Linking of modules

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

However, you must not change the sequence, i.e. rearrange the modules, after you have made the set-up 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.

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.

Example continued: Controller module + 2 extension modules in 200-series + 1 extension module in 100 series = 224 + 144 + 144 + 72 = 584 mm.

Example continued

When the regulation has started, the controller will check all the time 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.

User Guide | Pack controller, type AK-PC 782A

10. Determine the connection points

All connections must be programmed with module and point, so in principle it does not matter where the connections are made, as long as it takes place on a correct type of input or output.

• The controller is the ﬁrst module, the next one is 2, etc.

• A point is the two or three terminals belonging to an input or output (e.g. two terminals for a sensor and three terminals for a relay).

The preparation of the connection diagram and the subsequent programming (conﬁguration) should take place at the present time. It is most easily accomplished by ﬁlling in the connection survey for the relevant modules. Principle:

Name On module On Point Function

fx Compressor 1 x x Close fx Compressor 2 x x Close fx Alarm relay x x NC fx Main switch x x Close fx P0 x x AKS 2050-1 to 159 bar

Module Point

Mind the numbering. The right-hand part of the controller module may look like a separate module. But it is not.

The connection survey from the controller and any extension modules are uploaded from the paragraph "Module survey. E.g. controller module:

Signal Module Point Terminal

1 (AI 1) 1 - 2

2 (AI 2) 3 - 4

3 (AI 3) 5 - 6

Example continued

Signal Module Point

Discharge temperature - Sd-MT

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

Discharge temperature - Sd-IT 3 (AI 3) 5 - 6 Pt 1000

Suction gas temperature- Ss-MT 4 (AI 4) 7 - 8 Pt 1000

Thermostat sensor in plant room

- Saux1

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

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

Tap water temperature - Stw8 8 (AI 8) 19 - 20 Pt 1000

Temp. gas cooler output Sgc 9 (AI 9) 21 - 22 Pt 1000

Gas cooler pressure Pgc 10 (AI 10) 23 - 24 AKS 2050-159

Refrigerant receiver, Prec CO

Hot gas dump 12 (DO 1) 31 - 32 ON

Circulation pump tw 13 (DO 2) 33 - 34 ON

MT Compressor 1 (VLT start) 16 (DO 5) 39 - 40 - 41 ON

MT Compressor 2 17 (DO6) 42 - 43 - 44 ON

MT Compressor 3 18 (DO7) 45 - 46 - 47 ON

IT Compressor (VLT start) 19 (DO8) 48 - 49 - 50 ON

Speed control MT compressor 24 - 0-10 V

Speed control IT compressor 25 - 0-10 V

Signal

Temp. by-pased gas Shp

Level switch, CO2 receiver 2 (AI 2) 3 - 4 Open

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

Outdoor temperature, Sc3 4 (AI 4) 7 - 8 Pt 1000

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

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

Module Point

1 (AI 1) 1 - 2 Pt 1000

5 (AI 5) 9 - 10 Pt 1000

11 (AI 11) 25 - 26 AKS 2050-159

14 (DO 3) 35 - 36

15 (DO 4) 37 - 38

1 (AI 1) 1 - 2 Pt 1000

8 (AO 4) 15 - 16

Terminal

Signal type /

Active at

Signal type /

Active at

Signal type /

Active at

Note: The safety relays should not be ﬁtted onto a module

with override changeovers, as they can be put out of operation by an incorrect setting.

- Columns 1, 2, 3 and 5 are used for the programming.

- Columns 2 and 4 are used for the connection diagram.

Signal

MT compressor 1 safety circuits

MT compressor 2 safety circuits 2 (AI 2) 3 - 4 Open

MT compressor 3 safety circuits 3 (AI 3) 5 - 6 Open

LT compressor 1 safety circuits 5 (AI 5) 9 - 10 Open

LT compressor 2 safety circuits 6 (AI 6) 11 - 12 Open

Heat recovery tw2 7 (AI 7) 13 - 14 Pt 1000

Heat recovery tw3 8 (AI 8) 15 - 16 Pt 1000

Signal to by-pass valve, Vrec 9 (step 1) 25 - 26 - 27 - 28 CCMT

Signal to high pressure valve, Vhp 10 (step 2)

Signal to 3-way valve V3gc 11 (step 3) 33 - 34 - 35 - 36 CTR

Signal Module Point

Discharge temperature - Sd-LT

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

External main switch 3 (AI 3) 5 - 6 Closed

MT Compressors common safety circuits

IT Compressors common safety circuits

LT Compressors common safety circuits

Heat recovery tw4 7 (AI 7) 17 - 18

Suction pressure - P0-LT 8 (AI 8) 19 - 20 AKS 2050-59

LT Compressor 1 (VLT start) 9 (DO 1) 25 - 26 - 27 ON

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

Fan motors (VLT start) 11 (DO 3) 31 - 32 - 33 ON

3-way valve, tap water, Vtw 13 (DO 5) 37 - 38 - 39 ON

Room fan 15 (DO7) 43 - 44 - 45 ON

Module Point

1 (AI 1) 1 - 2 Open

4 (AI 4) 7 - 8

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

1 (AI 1) 1 - 2 Pt 1000

4 (AI 4) 7 - 8 Open

5 (AI 5) 13 - 14

6 (AI 6) 15 - 16

12 (DO 4) 34 - 35 - 36

14 (DO6) 40 - 41 - 42

16 (DO8) 46 - 47 - 48

Terminal

29 - 30 - 31 - 32

Terminal

Signal type /

Active at

CCMT

Signal type /

Active at

Open

Pt 1000

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User Guide | Pack controller, type AK-PC 782A

11. Connection diagram

Drawings of the individual modules may be ordered from Danfoss. Format = dwg and dxf.

You may then yourself write the module number in the circle and draw the individual connections.

Example continued:

The supply voltage for the pressure transmitter should be taken from the same module that receives the pressure signal. The screen on the pressure transmitter cables must only be connected at the end of the controller.

User Guide | Pack controller, type AK-PC 782A

12. Supply voltage

Supply voltage is only connected to the controller module. The supply to the other modules is transmitted via the plug between the modules. The supply must be 24 V +/-20%. One power supply must be used for each controller. The power supply must be a class II. The 24 V must not be shared by other controllers or units. The analogue 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 CO 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 + 1 extension module in 100 series 2 VA

------

Power supply size (least) 20 VA

+ Separate power supply for the module with the stepper motors: 7,8 + 1,3 + 1,3 + 5,1 = 15,5 VA.

Power supply size

The power consumption grows with the number of modules used:

Module Type No. á Eﬀect

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

Common pressure transmitter

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User Guide | Pack controller, type AK-PC 782A

2.6 Ordering

1. Controller

Type Function Application Language Code no.

AK-PC 782A

Controller for capacity control of MT-, LT-, IT- compressors and condensers. With oil management, multi ejector and high pressure regulation

Transcritical CO2 booster control

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

080Z0192

2. Extension modules and survey for inputs and outputs

Type Analogue

inputs

For sensors, pressure transmitters etc.

Controller 11 4 4 - - - - -

Extension modules

AK-XM 101A 8 080Z0007 AK-XM 102A 8 080Z0008 AK-XM 102B 8 080Z0013 AK-XM 103A 4 4 080Z0032 x AK-XM 204A 8 080Z0011 AK-XM 204B 8 x 080Z0018 AK-XM 205A 8 8 080Z0010 x AK-XM 205B 8 8 x 080Z0017 AK-XM 208C 8 4 080Z0023 x The following extension module can be placed on the PC board in the controller module.

There is only room for one module. AK-OB 110 2 080Z0251 x

On/Oﬀ outputs On/oﬀ supply voltage

(DI signal)

Relay (SPDT)

Solid state Low volt-

age (max. 80 V)

High voltage (max. 260 V)

Analogue outputs

Stepper outputs

0-10 V DC For valves

with step control

Module with switches

For override of relay outputs

Code no.

With screw terminals

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 USB A-B (standard IT cable) - x

Accessories Power supply module 230 V / 115 V to 24 V DC

AK-PS 075 18 VA AK-PS 150 36 VA 080Z0054 x

Supply for controller

080Z0053 x

AK-PS 250 60 VA 080Z0055 Accessories External display that can be connected to the controller module. For showing, say, the suction pressure

EKA 163B Display 084B8574 EKA 164B Display with operation buttons 084B8575 MMIGRS2 Graphic display with operation 080G0294

- Cable between EKA display and controller

Cable between graphic display type MMIGRS2 and controller (controller with RJ11 plug)

Length = 2 m 084B7298 Length = 6 m 084B7299 Length = 1.5 m 080G0075 Length = 3 m 080G0076

Accessories Communication modules for controllers where modules cannot be connected continuously AK-CM 102 Communication module Data communication for external extension modules 080Z0064

continued

Example

User Guide | Pack controller, type AK-PC 782A

3. Mounting and wiring

This section describes how the controller:

• is ﬁtted

• is connected

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

• AK-PC 782A controller module

• AK-XM 205A input and output module

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

• AK-XM 103B analogue input and output module

• AK-OB 110 analogue output module

3.1 Mounting

Mounting of analogue output module

The basic module must not be connected to voltage.

1. Lift the top part oﬀ the basic module

The analogue extension module will supply a signal to frequency converter on MT and IT.

Press in the plate on the left-hand side of the light-emitting diodes and the plate on the right-hand side for the red address changers. Lift the top part oﬀ the basic module.

2. Mount the extension module in the basic module

3. Put the top part back onto the basic module

There are two outputs.

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User Guide | Pack controller, type AK-PC 782A

Mounting of extension module on the basic module

1. Move the protective cap

1. 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.

2. Assemble the extension module and the basic module.

The basic module must not be connected to voltage.

In our example, three extension modules are to be ﬁtted to the basic module. We have chosen to ﬁt the module with analogue outlets directly on the basic module and then the following module. The sequence is thus:

All the subsequent settings that aﬀect the three extension modules are determined by this sequence.

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.

Mounting and wiring - continued

User Guide | Pack controller, type AK-PC 782A

3.2 Wiring

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

1. Connect inputs and outputs

Here are the tables for the example:

Signal Module Point

Discharge temperature - Sd-MT

Suction gas temperature- Ss-MT

Discharge temperature - Sd-IT

Suction gas temperature- Ss-MT 4 (AI 4) 7 - 8 Pt 1000

Thermostat sensor in plant room

- Saux1

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

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

Tap water temperature - Stw8 8 (AI 8) 19 - 20 Pt 1000

Temp. gas cooler output Sgc 9 (AI 9) 21 - 22 Pt 1000

Gas cooler pressure Pgc 10 (AI 10) 23 - 24 AKS 2050-159

Refrigerant receiver, Prec CO

Hot gas dump 12 (DO 1) 31 - 32 ON

Circulation pump tw 13 (DO 2) 33 - 34 ON

MT Compressor 1 (VLT start) 16 (DO 5) 39 - 40 - 41 ON

MT Compressor 2 17 (DO6) 42 - 43 - 44 ON

MT Compressor 3 18 (DO7) 45 - 46 - 47 ON

IT Compressor (VLT start) 19 (DO8) 48 - 49 - 50 ON

Speed control MT compressor 24 - 0-10 V

Speed control IT compressor 25 - 0-10 V

1 (AI 1) 1 - 2 Pt 1000

2 (AI 2) 3 - 4 Pt 1000

3 (AI 3) 5 - 6 Pt 1000

5 (AI 5) 9 - 10 Pt 1000

11 (AI 11) 25 - 26 AKS 2050-159

14 (DO 3) 35 - 36

15 (DO 4) 37 - 38

Terminal

Signal type /

Active at

Remember the isolation ampliﬁer. If signals are received from diﬀerent controls, e.g. heat recovery for one of the inputs, a galvanically insulated module should be inserted.

The function of the switch functions can be seen in the last column.

There are pressure transmitters AKS 32R and AKS 2050 available for several pressure ranges. Here there are two diﬀerent ones. One up to 59 bar and two up to 159 bar.

Signal

Temp. by-pased gas Shp

Level switch, CO2 receiver 2 (AI 2) 3 - 4 Open

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

Outdoor temperature, Sc3 4 (AI 4) 7 - 8 Pt 1000

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

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

Signal

MT compressor 1 safety circuits

MT compressor 2 safety circuits 2 (AI 2) 3 - 4

MT compressor 3 safety circuits 3 (AI 3) 5 - 6 Open

LT compressor 1 safety circuits 5 (AI 5) 9 - 10 Open

LT compressor 2 safety circuits 6 (AI 6) 11 - 12 Open

Heat recovery tw2 7 (AI 7) 13 - 14 Pt 1000

Heat recovery tw3 8 (AI 8) 15 - 16 Pt 1000

Signal to by-pass valve, Vrec 9 (step 1) 25 - 26 - 27 - 28 CCM T

Signal to high pressure valve, Vhp 10 (step 2) 29 - 30 - 31 - 32 CCMT

Signal to 3-way valves V3gc 11 (step 3) 33 - 34 - 35 - 36 C TR

Module Point

1 (AI 1) 1 - 2 Pt 1000

8 (AO 4) 15 - 16

Module Point

1 (AI 1) 1 - 2

4 (AI 4) 7 - 8 Open

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

Terminal

Signal type /

Active at

Signal type /

Active at

Open

Signal Module Point

Discharge temperature - Sd-LT

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

External main switch 3 (AI 3) 5 - 6 Closed

MT Compressors common safety circuits

IT Compressors common safety circuits

LT Compressors common safety circuits

Heat recovery tw4 7 (AI 7) 17 - 18 Pt 1000

Suction pressure - P0-LT 8 (AI 8) 19 - 20 AKS 2050-59

LT Compressor 1 (VLT start) 9 (DO 1) 25 - 26 - 27 ON

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

Fan motors (VLT start) 11 (DO 3) 31 - 32 - 33 ON

3-way valve, tap water, Vtw 13 (DO 5) 37 - 38 - 39 ON

Room fan 15 (DO7) 43 - 44 - 45 ON

1 (AI 1) 1 - 2 Pt 1000

4 (AI 4) 7 - 8 Open

5 (AI 5) 13 - 14 Open

6 (AI 6) 15 - 16 Open

12 (DO 4) 34 - 35 - 36

14 (DO6) 40 - 41 - 42

16 (DO8) 46 - 47 - 48

Terminal

Signal type /

Active at

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User Guide | Pack controller, type AK-PC 782A

The connections for the example can be seen here.

Warning! Keep signal cables separate from cables with high voltage.

The screen on the pressure transmitter cables must only be connected at the end of the controller.

The supply voltage for the pressure transmitter should be taken from the same module that receives the pressure signal.

Remember separate power supply for AK-XM 208C.

User Guide | Pack controller, type AK-PC 782A

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

The supply voltage is 24 V, and the supply must not be used by other controllers or devices. The terminals must not be earthed.

4. Follow light-emitting diodes

When the supply voltage is connected, the controller will go through an internal check. The controller will be ready in just under one minute when the light-emitting diode ”Status” starts ﬂashing slowly.

5. When there is a network

Set the address and activate the Service Pin.

6. The controller is now ready to be conﬁgured.

Internal communication between the modules: Quick ﬂash = error Constantly On = error

n Power n Comm n DO1 n Status n DO2 n Service Tool n DO3 n LON n DO4 n I/O extension n DO5 n Alarm n DO6 n DO7 n Display n DO8 n Service Pin

Status on output 1-8

Slow ﬂash = OK Quick ﬂash = answer from gateway in 10 min. after network installation Constantly ON = error Constantly OFF = error

External communication Communication to AK-CM 102

Flash = active alarm/not cancelled Constant ON = Active alarm/cancelled

Network installation

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User Guide | Pack controller, type AK-PC 782A

4. Conﬁguration and operation

This section describes how the controller:

• is conﬁgured

• is operated

We have decided to work on the basis of the example we went through previously, i.e. MT-, LT-, IT-control, high pressure control, heat recovery and gas cooler.

4.1 Conﬁguration

4.1.1 Connect PC

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

For connecting and operating the "AK service tool" software, please see the manual for the software.

The ﬁrst time the Service Tool is connected to a new version of a controller, the start-up of the Service Tool will take longer than usual while information is retrieved from the controller. Time can be followed on the bar at the bottom of the display.

The controller must be switched on ﬁrst and the LED “Status” must ﬂash before the Service Tool program is started.

Start Service Tool programme

Select the name SUPV and key in the access code.

When the controller is supplied the SUPV access code is 123. When you are logged into the controller, an overview of it will always appear.

In 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.

User Guide | Pack controller, type AK-PC 782A

Refrigerating plant example: We have decided to describe the setup by means of an example comprising an MT-, LT- and IT group. The example is the same as the one given in the "Design" section, i.e. the controller is an AK-PC 782A + extension modules.

Compressor Group

MT circuits

• 3 compressors with "cyclic". One speed controlled

• Safety monitoring of each compressor

• Common high-pressure monitoring

• Po setting -10°C, Po optimization from the system unit

LT circuits

• 2 x compressors with "cyclic". One speed controlled

• Safety monitoring of each compressor

• Common high pressure monitoring

• Po setting –30°C, Po optimization from the system unit

IT circuit

• 1 compressor, speed controlled

• Receiver set point 36 bar

High pressure controls:

• Heat recovery for tap water

• Gas cooler

• Fans, speed controlled

Receivers:

• Optimal CO reveiver pressure

• Monitoring CO-level in the receiver

• Monitoring of high and low pressure

• Controlling the tap water receiver temperature, 55°C

Fan in plant room

• Thermostat control of fan in engine room

Safety functions:

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

• MT: Po max = -5°C, Po min = -35°C

• MT: Pc max = 110 bar

• MT: Sd max = 120°C

• LT: Po max = -5°C, Po min = -45°C

• LT: Pc max = 40 bar

• LT: Sd max = 100°C

• SH min = 5 °C, SH max = 35 °C

Other:

• Start/stop of heat recovery to Tw

• External main switch used

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

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

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User Guide | Pack controller, type AK-PC 782A

4.1.2 Authorization

1. Go to Conﬁguration menu

Press the orange set-up button with the spanner at the bottom of the display.

When the controller is supplied, it has been set with standard authorization for diﬀerent user interfaces. This setting should be changed and adapted to the plant. The changes can be made now or later.

2. Select Authorization

3. Change setting for the user ‘SUPV‘

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 set-up we go.

Press the line Authorization to get to the user set-up display.

Mark the line with the user name SUPV. Press the button Change.

4. Select user name and access code

This is where you can select the supervisor for the speciﬁc system and a corresponding access code for this person.

The controller will utilize the same language that is selected in the service tool but only if the controller contains this language. If the language is not contained in the controller, the settings and readings will be shown in English.

5. Carry out a new login with the user name and the new access code

To activate the new settings you must carry out a new login to the controller with the new user name and the relevant access code. You will access the login display by pressing the icon at the top left corner of the display.

User Guide | Pack controller, type AK-PC 782A

4.1.3 Unlock the conﬁguration of the controllers

1. Go to Conﬁguration menu

2. Select Lock/Unlock conﬁguration

3. Select Conﬁguration lock

Press the blue ﬁeld with the text Locked

The controller can only be conﬁgured when it is unlocked.

The values can be changed when it is locked, but only for those settings that do not aﬀect the conﬁguration.

4. Select Unlocked

Select Unlocked.

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User Guide | Pack controller, type AK-PC 782A

4.1.4 System set-up

1. Go to Conﬁguration menu

2. Select System setup

3. Set system settings

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

In the ﬁrst ﬁeld you enter a name for what the controller will be controlling. The text written in this ﬁeld can be viewed at the top of all screens, together with the controller's address.

When the time is set, the PC’s time can be transferred to the controller. When the controller is connected to a network, date and time will automatically be set by the system unit in the network. This also applies to change-over Daylight saving. In case of power failure, the clock will be kept running for at least 12 hours.

User Guide | Pack controller, type AK-PC 782A

4.1.5 Set plant type

1. Go to Conﬁguration menu

2. Select plant type

Press the line Select plant type.

3. Set plant type

Press the + button to go to the

4. Further plant settings

5. Disable alarm router

General: If you want to know more about the diﬀerent conﬁguration options, they are listed in the right column. The number refers to the number and picture in the column on the left. As the screen only shows the settings and readings that are required for a given set-up, all possible settings have also been included in the right column.

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

In our example, the controller must regulate a Booster System, High Pressure Control and IT Compressor.

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

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

There are several underlying pages. The black bar in this ﬁeld tells you which of the pages is currently displayed.

Browse the pages using the + and - buttons.

Alarm transmission to the front-end can be disabled. This can be used to avoid “Alarm Router full” message when the controller is disconnected from the front-end. The menu can only be accessed if “show advanced settings” is enabled (present under “Select plant type”).

To reenable the alarm transmission a re-scan must be executed from the front-end.

Note: The alarm transmission should only be disabled with great care as critical alarms will not be transmitted to the front-end. This could result in food loss or other damage.

3 - Plant type Application selection

Select between one of the 4 applications where: HP = High pressure control. MT=middle temperature. LT=low temperature. IT=parallel compression

3- after application selection Refrigerant

Only for CO systems. The refrigerant cannot be changed

Condenser fan control

Fan control is deﬁned here: Step, step+speed, just speed or speed for the ﬁrst fan+step for the rest

No of fans

Set the number of relay outputs that will be used

Heat recovery

Heat recovery enabled Domestic water, room heating or both To be set later

Oil management

Oil control enabled Choose between:

Select quick set-up

Here, you can reset all the controller settings back to the factory settings

4 - Additional system deﬁnitions Compressor combinations

No of compressors

Set the number of compressor units that will be used

External main switch

A switch may be connected for starting and stopping the regulation. (Also opens UPS selection) 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 fails

Night selected via DI

The switch to night mode takes place when the signal is received

Show advanced settings

This function opens the advanced settings in the various menus

Comp. cap. out to AO

If selecting "yes", an analogue output indicates the running capacity

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User Guide | Pack controller, type AK-PC 782A

4.1.6 Set control of suction group MT

1. Go to Conﬁguration menu

2. Select Suction group

3. Set values for the reference

Press the + button to go to the

4. Set values for capacity control

The conﬁguration menu in the Service Tool has changed now. It shows the possible settings for the selected plant type.

In our example we select the settings:

- P0 optimization

- Suction set point =

-10 °C The settings are shown here in the display.

3 - Reference mode

Displacement of suction pressure as a function of external signals 0: Reference = set reference + night oﬀset + oﬀset from external 0-10 V signal 1: Reference = set reference + oﬀset from P0 optimization Setpoint ( -80 – 30°C) Setting of required suction pressure in °C

Oﬀset via Ext. Ref

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

Night Oﬀset via DI

Select whether a digital input is required for activation of night operation. Night operation can alternatively be controlled via internal weekly schedule or via a network signal Night Oﬀset (-25 – 25 K) Displacement value for suction pressure in connection with an active night setback signal (set in Kelvin) Max reference (-50 – 80 °C) Max. permissible suction pressure reference Min reference (-80 – 25 °C) Min. permissible suction pressure reference

4 - Compressor application

Select one of the available compressor conﬁgurations here:

Press the + button to go to the

If a "Variable" or "screw compressor" is chosen in the ﬁrst line, its type must be determined in the next line.

In our example we select:

-VSD + single step

- 3 compressors

- Cyclic

Note: The two parameters ‘Control sensor’ and ‘Psuc max oﬀset’ are used to conﬁgure an application with Low Pressure Multi Ejectors. They are only visible when no IT suction group has been deﬁned“.

Lead compressor type

• Variable

The following options are available for variable:

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

Control sensor

Select the sensor for the compressor controller:

- “Po-MT” to control on the Po-MT sensor

- “Po-MT + Psuc-MT” to control both “Po-MT” and “Psuc-MT”. The compressors will be controlled on the sensor that is most above to its reference

Psuc max oﬀset

Set the diﬀerence between Psuc-MT and Po-MT references

Step control mode

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

User Guide | Pack controller, type AK-PC 782A

External coordination MT/LT

Select "yes" if you want to coordinate with an external LT controller

Ext. Coordination MT/LT

Visible if the controller is conﬁgured as "One pack + HP" ("plant type"  "application selection"). MT/LT coordination is automatically enabled for booster packs. For “One pack” applications, it can be enabled to operate using DI/DO.

MT/LT coord. threshold

Select when to start the MT compressor:

• “Neutral zone” to start when Po is in or above the neutral zone.

• “Reference” to start when above the Po reference.

• “Plus zone” to start when Po is in the plus zone.

LT coord. stop

Select when to stop the LT compressors:

• “MT compr.” to stop when MT is not ready.

• “MT Po” to stop when MT should start but is not ready.

Pump down

Select whether a pump down function is required on the last running compressor

Synchronous speed

No: There will be two analogue outputs available. Yes: There will be one analogue output.

Early stop enable

Select this to limit the time that the last compressor is allowed to run inside the minus zone

Early stop delay

Set the maximum time that the last compressor is allowed to run inside the minus zone. Pump down limit Po (-80 – +30 °C) Set the actual pump down limit VSD min speed (0.5 – 60 Hz) Min. speed where the compressor must cut out VSD start speed (20 – 60 Hz) Minimum speed for start of Variable speed drive (must be set higher than “VSD Min. Speed Hz”) VSD max speed (40 – 120 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 by-pass valve (on time + oﬀ time)

PWM Min. capacity

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

PWM Start capacity

Minimum capacity at which the compressor will start (must be set to a higher value than "PWM Min. capacity")

Load shed limits

Select which signal 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 T0

Any load below the limit value is freely permitted. If the T0 exceeds the value, a time delay is started. If the time delay runs out, the load limit is cancelled

Override delay 1

Max. time for load shed limit, if T0 is too high

Override delay 2

Max. time for load shed limit, if T0 is too high

Easy PI Selection

Group setting for the 4 control parameters: Kp, Tn, + acceleration and - acceleration. If the setting is set to “user deﬁned” the 4 control parameters can be ﬁne-tuned:

Kp To (0.1 – 10.0) Ampliﬁcations factor for PI regulation

Tn To

Integration time for PI-regulation

+ Zone acceleration (A+)

Higher values result in a faster regulation

- Zone acceleration (A-)

Higher values result in a faster adjustment

Advanced settings

To ﬁlter

Reduce fast changes in the To reference

Pc ﬁlter

Reduce fast changes in the Pc reference Initial start time (15 – 300 s) The time after start-up where the cut-in capacity is limited to the ﬁrst compressor step

Unloading mode

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

AO ﬁlter

Reduce fast changes at the analogue output

AO max. limit

Limit the voltage on the analogue output.

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User Guide | Pack controller, type AK-PC 782A

5. Set values for capacity of the compressors

Press the + button to go to the

6. Set values for main step and any unloaders

Press the + button to go to the

7. Set values for safe operation

Press the + button to go to the

The compressor capacity is set in displaced volume per hour. m3/h. See compressor data.

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

In our example we select:

- Safety limit for discharge temperature = 120°C

- Safety limit for high condensing pressure = 100 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.

5 - Compressors

In this screen, the capacity distribution between the compressors is deﬁned. Capacities that need to be set depend upon the “compressor application” and “Step control mode” that has been selected. Nominal capacity (1 – 1000 m3/h) Set the nominal capacity for the compressor in question. For compressors with variable speed drive the nominal capacity must be set for the mains frequency (50/60 Hz)

Unloader

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

6 - Capacity distribution

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

Unload

Readout of the capacity on every unloading 0 – 100%

7 - Safety Emergency cap. day

The desired cut-in capacity for day operation 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 cut in. If the limit is exceeded, the entire compressor capacity will be cut out

Pc Max limit

Maximum value for the condenser pressure in bar. 3 K below the limit, the entire condenser capacity will be cut in and the compressor capacity reduced. If the limit is exceeded, the entire compressor capacity will be cut out.

Tc max. limit

Limit value read in °C (If selected for display in the condenser conﬁguration)

Pc Max alarm delay

Time delay for the alarm Pc max.

T0 Min limit

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

T0 Max alarm

Alarm limit for high suction pressure P0

T0 Max delay

Time delay before alarm for high suction pressure P0

Safety restart time

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

SH Min alarm

Alarm limit for min. superheat in suction line

SH Max alarm

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

User Guide | Pack controller, type AK-PC 782A

8. Set monitoring of compressor

Press the + button to go to the

9. Set operation time for compressor

Press the + button to go to the

10. Set Misc. functions

In our example we use:

- Common high-pressure pressure control for all compressors

- One general safety monitoring unit for each compressor

(The remaining options could have been selected if speciﬁc safety controls for each compressor had been required).

Set min. OFF-time for the compressor relay. Set min. ON-time for the compressor relay. Set how often the compressor is allowed to start.

The settings only apply to the relay that cuts the compressor motor in and out. They do not apply to unloaders.

If the restrictions overlap, the controller will use the longest restriction time.

In our example we do not use these functions.

8 - Compressor safety Common safety

Choose whether an overall, common safety input for all compressors is desired. If the alarm is activated, all compressors will be cut out.

Oil pressure etc

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

Sd sensor pr. compressor

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

Max discharge temp.

Cut-out temperature.

Sd compressor alarm delay

Delay time for the alarm

Sd compressor safety cutout

Set whether safety cut-out should be enabled

9 - Minimum operation times

Conﬁgure the operation times here so "unnecessary operation" can be avoided. Recycle time is the time interval between two consecutive starts.

Safety timer Cutout delay

The time delay resulting from drop-out of automated safety measures and until the compressor-error is reported. This setting is common for all safety inputs for the relevant compressor.

Recycle delay

Minimum time before a compressor should be OK after a safety cut-out. After this interval it can start again.

10 - Misc. functions Ctrl. of Injection On

DO: Select this function if a relay must be reserved for the function. (The function must be wired to controllers with expansion valves in order to close liquid injection for the safety cut-out of the last compressor.) Network: The signal is sent to the controllers via data communication.

Compressor start delay

Delay time for compessor start

Injection Oﬀ delay

Delay time for "Injection oﬀ"

Liq. inj suction line

Select this function if a liquid injection is required in the suction line in order to keep the discharge gas temperature down. Regulation can be done either using a solenoid valve and a TEV, or using an AKV valve.

AKV OD suction line

Readout of opening degree of the valve in %

Inject start SH

Superheat value where the liquid injection starts

Inject diﬀ SH

Diﬀerential of superheat for the injection control

Inject start Sd temp.

Start temperature for liquid injection in suction line

Inject diﬀ Sd temp.

Diﬀerential when adjusted on Sd

SH Min suction line

Minimum superheat in suction line

SH Max suction line

Maximum superheat in suction line

AKV period time

Periode time for AKV valve

Inject delay at start up

Delay time for liquid injection at start-up

Afterwards, the settings for the LT group and IT group continue. In principle, the same settings are carried out.

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User Guide | Pack controller, type AK-PC 782A

4.1.7 Set oil management

1. Go to Conﬁguration menu

2. Set Oil management

In our example, oil management has not been included.

The settings are only displayed for information purposes and apply to the “Fixed pressure” control which is conﬁgured in the "Plant Type display".

3. Set Oil receiver

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

3 Level switch receiver

Deﬁne the desired level sensors: High Both Low and High

Level alarm delay

Delay time for level alarm

Actual pressure

Measured value

Actual state

Status of oil separation

Cut out pressure

Receiver pressure for shutting oﬀ oil

Cut in pressure

Receiver pressure for turning on oil

High alarm limit

An alarm is given if a higher pressure is registered

High alarm delay

Time delay for alarm

Low alarm limit

An alarm is given if a lower pressure is registered

Low alarm delay

Time delay for alarm

Press the + button to go to the

4. Set oil separator

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.

4 Separator

Select whether there should be one shared separator for all the compressors or two separators (MT and IT)

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

User Guide | Pack controller, type AK-PC 782A

4.1.8 Set up control of condenser fans

1. Go to Conﬁguration menu

2. Select Condenser fan control

3. Set control mode and reference

Press the + button to go 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 (ﬂoating reference). The settings shown here in the display.

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

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

3 - Sensor and Reference Control sensor

Sgc: The temperature at the outlet of the gas cooler S7: Medium temperature is used for regulation

Reference Mode

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

Setpoint

Setting of desired condensing pressure in temperature

Min. tm

Minimum average temperature diﬀerence between Sc3 air and Pc condensing temperature with no load

Dimensioning tm

Dimensioning average temperature diﬀerential between Sc3 air and Pc condensing temperature at maximum load (tm diﬀerence at max load, typically 2-4 K)

Sgc max reference

Maximum permissible gas cooler outlet temperature. This function limits the reference for Sgc.

Show Tc

Set whether Tc should be displayed

4 - Capacity control Capacity control mode

Select control mode for condenser: Step: Fans are step-connected via relay outputs Step/speed: The fan capacity is controlled via a combination of speed control and step coupling Speed: The fan capacity is controlled via speed control Speed 1.step: First fan speed controlled, rest step coupling 2 groups with speed: The capacity is divided into groups

No of fans

Set number of fans (If two groups are selected, this setting is the number in group 1)

Number of fans in group 2

The number in group 2 must be greater than or equal to the number in group 1

Speed limit for group 1

The speed can be limited to minimize the noise

Monitoring fan safety

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

Fan speed type

VSD (and normal AC motors) EC motor = DC controlled fan motors

VSD start speed

Minimum speed for start of speed control (must be conﬁgured higher than "VSD Min. Speed")

VSD min Speed

Minimum speed whereby speed control is cut out (low load)

VSD safety monit.

Choice of safety monitoring of frequency converter. A digital inlet is used for monitoring the frequency converter

EC Start capacity

The regulation awaits this need to arise before supplying voltage to the EC motor

EC voltage min

Voltage value at minimum capacity (20% = 2 V @ 0 – 10 V)

EC voltage max

Voltage value at 100% capacity (80% = 8 V @ 0 – 10 V)

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User Guide | Pack controller, type AK-PC 782A

EC Voltage abs. max

Permissible live voltage for EC motor (overcapacity)

Absolut max Sgc

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

Control type

Choice of control strategy P-band: The fan capacity is regulated via P-band control. The P band is "100/Kp" PI-Control: The fan capacity is regulated by the PI controller

Ampliﬁcation 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

V3gc

Indicates whether a gas by-pass valve is used on the gas cooler. On/oﬀ: Three-way valve controlled by a relay Step valve: Modulating CTR type three-way valve Voltage: Three-way valve, e.g. controlled using 0 – 10 V at on/oﬀ:

Bypass low limit - Shp

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. start-up during very low ambient temperatures)

Bypass min. oﬀ time

Minimum time during which the gas must be fed through the gas cooler before bypass is permitted. At Stepper and Voltage:

Amplifcation factor for the PI controller.

Integration time for PI controller.

Min. opening degree Max. opening degree

User Guide | Pack controller, type AK-PC 782A

4.1.9 Set-up of high pressure control

1. Go to Conﬁguration menu

2. Select HP control

3. Set regulation values

Press the + button to go to

the next page

4. Set ejector function

The settings are shown here in the display

3 - HP control Vhp output type

Select the signal type for controlling the high pressure valve:

- Voltage signal

- Stepper motor signal via AK-XM 208C

- 2 Stepper motor signals for parallel valves

Extra capacity oﬀset

Adjust how much the pressure shall be increased, when the function "Extra capacity oﬀset" is activated

Pgc min.

Min. acceptable pressure in the gas cooler

Pgc max.

Max. acceptable pressure in the gas cooler

Advanced settings Vhp min. OD

Restriction of the valve's closing degree

Pgc max. limit P-band

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

dT Subcool

Desired subcooling temperature

Ampliﬁcation factor

Integration time

Pgc HR min.

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

Pgc HR max

Read permissible pressure during heat recovery

Ramp down bar/min.

Here you may select how quickly the reference must be changed after a completed heat recovery

Temp. at 100 bar

Temperature at 100 bar. Here you may deﬁne the regulation curve during transcritical operation. Set the required temperature value.

4 - Ejector control

Select the Multi Ejector's capacity. The size will then be shown for each valve’s capacity. The function is described on page 114-117.

In the next display, the capacity is adjusted for liquid ejectors. The next display is not visible if liquid ejectors are conﬁgured in the

We do not use ejector control in our example.

previous display.

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.

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User Guide | Pack controller, type AK-PC 782A

4.1.10 Set up control of receiver pressure

1. Go to Conﬁguration menu

2. Select Receiver control

3. Set parameters for receive reference

3. Receiver reference Prec ref Mode

Select one of the available reference options for the IT compressor control:

• "Fixed SP” for a constant reference,

• “Ext. Oﬀset” for a constant reference plus an oﬀset from an analogue input,

• “IT Optimize” for automatic calculation of the optimum reference,

• “Delta P” for a constant oﬀset above MT suction pressure reference (using Delta P reference parameter).

Prec set point / Prec reference

Select the setpoint or display actual reference for the receiver pressure

Trec set point / Prec reference

Display saturated temperature for Prec setpoint / Prec reference

Prec max.

Max. permissible pressure in the receiver. Exceeding this limit results in an alarm.

Prec min.

Min. permissible pressure in the receiver. Overpassing this limit results in an alarm

Enable Delta P min

When enabled, receiver reference is calculated to guarantee minimum pressure diﬀerence with MT suction pressure reference.

Delta P reference

Minimum pressure diﬀerence between actual receiver reference and MT suction pressure reference.

Show Trec on overview

Set whether Trec should be shown in overview display

Ext. Oﬀset max

When the reference mode is “Ext. Oﬀset”, then set the maximum oﬀset.

Prec min reference / Prec max reference

When the reference mode is “IT optimize” or “Delta P” then set the minimum and maximum values for receiver reference. Select this to minimize the ﬂoating range of receiver pressure indicating the amount of gas entering the receiver.

AC support

Enable request signal (DI) and release signal (DO) for air conditioning AC. When AC is released, the controller is expecting AC load to contribute to receiver load.

AC Prec min ref / AC Prec max ref

Additional limitation to the pressure range of receiver reference that only applies when AC is requested via DI. Select the option to guarantee a maximum and minimum AC temperature.

Receiver inlet min vapour

Maintains a minimum gas pressure in the receiver. The % value indicates the minimum allowed quality of vapour at receiver inlet.

User Guide | Pack controller, type AK-PC 782A

4. Set control parameters

4. Receiver control

Monitor liquid level

Choose whether liquid level should be monitored:

• “Low Level Switch”

• “High Level Switch”

• “High and Low Level Switch”

Liquid alarm delay

Time delay for the alarm

Receiver Valve

The following settings are speciﬁc to Vrec receiver valve(s):

Vrec output type

Select the Vrec output type for gas by-pass valve:

• “1 Stepper” for a single stepper motor signal via AK-XM 208C

• “2 Stepper (synchronic)” for two stepper motor signals operated simultaneously

• “2 Stepper (sequential)” for two stepper motor signals operated in sequence

• “Voltage (AO)” for a voltage signal

Vrec min. OD

Limitation of the Vrec valve's closing degree

Vrec max. OD

Limitation of the Vrec valve's opening degree

Easy PI selection

Group setting for the control parameters: Kp, Tn. If the setting is set to “user deﬁned”, the control parameters can be ﬁne-tuned:

Vrec Kp

Ampliﬁcation factor for PI regulation

Vrec Tn

Integration time for PI regulation

Hot gas dump enable

Select whether hot gas should be supplied if the receiver pressure falls too low

Hot gas dump cut-in

Receiver pressure at which hot gas is turned on

Hot gas dump delta

Diﬀerence at which hot gas is turned oﬀ again

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User Guide | Pack controller, type AK-PC 782A

IT Coordination

The following settings are speciﬁc for coordinating with suction group IT:

IT Smart start enable

Enable automatic calculation of “IT Start Vrec OD”, depending on Vrec valve types, IT size and operating conditions.

IT Start Vrec OD

Opening degree for the Vrec valve when the IT compressor is

to start.

IT Start tuning

Allow the user to modify “IT Start Vrec OD” when “IT Smart start” is enabled. A value of zero makes the controller aim for minimum speed of the ﬁrst IT compressor, a negative value makes the IT start earlier (lower ﬂow rate) and a higher value makes the IT start later (higher ﬂow rate).

IT Start delay ﬁlter

Time constant for ﬁltering Vrec OD when it is compared against "IT Start Vrec OD" for starting the IT compressors

IT End delay

The duration that the IT compressor must have been stopped before regulation is transferred to Vrec.

IT Comp. Sgc min.

The temperature limit for operation with an IT compressor. This will not start when a lower value is detected, regardless of the opening degree of the Vrec valve.

Emergency Action

Enable speciﬁc control emergency action from other controllers as a result of too low/high receiver pressure.

Vhp close on high Prec

Enable override of maximum OD for high pressure valve Vhp as action against high receiver pressure.

Vhp open on low Prec

Enable override of minimum OD for high pressure valve Vhp as action against low receiver pressure.

MT Cut-on high Prec

Enable to cut oﬀ MT compressor capacity as action against high receiver pressure.

User Guide | Pack controller, type AK-PC 782A

4.1.11 Set-up Receiver Reference with Low Pressure Multi Ejectors

Designed to work with Low Pressure Multi Ejectors, this mode is available when the MT suction control is conﬁgured to alternate between two pressure transducers (Po-MT and PsucMT).

Receiver reference is always calculated as oﬀset from MT suction reference. It uses a higher or a lower oﬀset, determined by a digital input.

The related parameters are explained to the right.

For information on how to set these parameters, please see the application guide: “Low pressure lift ejector system”

Delta P reference

Display the current pressure diﬀerence between the Prec reference and Po-MT reference.

LP Ej Delta P low

Specify the pressure diﬀerence between the Prec reference and Po-MT reference for the lower Prec reference (DI deactived).

LP Ej Delta P high

Specify the pressure diﬀerence between the Prec reference and Po-MT reference for the higher Prec reference (DI active).

LP Ej Delta P high delay

After deactivating the digital input for the reference "Delta P high", the parameter “LP Ej Delta P high delay” delays switching back to the reference "Delta P low" for the speciﬁed time. After activating the digital input, a 30 sec delay is always applied to switching back to the reference "Delta P high".

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User Guide | Pack controller, type AK-PC 782A

4.1.12 Set up control of heat recovery

1. Go to Conﬁguration menu

2. Select heat circuits

3. Setup values for tap water circuits

4. Setup values for heating circuit

(The heat circuits are deﬁned in the menu “Select plant type”)

The menu for domestic water is empty when regulation is only carried out on room heating.

3 - Tap water circuits (settings are available only when there shall be regulated on a circuit for tap water)

V3tw output type

DO: The valve is controlled by a relay output Stepper: The valve is controlled by a stepper valve Control mode: Here the regulation of the circuit can be started (auto) and stopped (oﬀ) Setpoint: The required temperature for the sensor Stw8 can be set here

Use ext. ref. oﬀset

A 0 – 10 V signal must displace the temperature reference

Max. Ext. ref. oﬀset

Reference displacement at max. signal (10 V) 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 diﬀerence, until the Stw8 reference is met. (During S4-S3 regulation, the pump must always be speedregulated).

Stw8 + Stw8A: if two temperature sensors are installed in the

hot water receiver Stw4: regulation is done using this sensor Variable speed: Here the pump type is selected. Either variable speed or on/oﬀ

Advanced settings:

The following options are made available:

Flow switch: Must normally be selected for safety purposes

Kp: Ampliﬁcation 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

The room heating circuit is not used in our example. The image is shown for information purposes. The menu for room heating is empty when regulation is only carried out on domestic water.

4 - Heat recovery V3hr output type

DO: The valve is controlled by a relay output Stepper: The valve is controlled by a stepper valve

Heat reclaim type for heating

Here you deﬁne how the condensing pressure (HP) shall be regulated when the recovery circuit for heating requires heat:

• No HP oﬀset (simple control)

• HP oﬀset. Here the controller must receive a voltage signal. The

oﬀset values that apply to the max. value must be deﬁned 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 pump activation and deactivation and the by-pass valve.

Control mode: Here the regulation of the circuit can be started (auto) and stopped (oﬀ) Setpoint: Here the required temperature of sensor Shr8 (or Shr4) is set

Use ext. ref. oﬀset

A 0-10 V signal must displace the temperature reference

User Guide | Pack controller, type AK-PC 782A

Max. Ext. ref. oﬀset

Reference displacement at max. signal (10 V) 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 diﬀerence, until the Shr8 reference has been met Shr4: regulation is done using this sensor (During S4-S3 regulation or Shr4 regulation the pump shall

always be speed regulated) Variable speed: Here the pump type is selected. Either variable speed or on/oﬀ Heat consumers: (Only when the condensation pressure shall be increased during heat recovery). The number of signals that can be received are 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 ﬁlter

Reduce fast changes in heat consumer signal

Additional heat output

The function will reserve a relay. The relay will energize when the signal for the heat removers reaches 95%. Flowswitch delay: Duration of stable signal before the new status is used in the regulation

Advanced settings: The following options are made available:

Flow switch: Must normally be selected for safety purposes

Kp: Ampliﬁcation 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

HR stop limit: Signal in % at which the pump is stopped again

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

HP CONTROL

Pgc HR min: Basic reference for the pressure when external

voltage signal is received.

Pgc HR max: Max pressure reference when external voltage

signal is received.

Ref. oﬀset low limit: Signal in % at which "Pgc HR min." comes

into force

Ref.oﬀset high limit: Signal in % at which "Sgc max" value is used

BYPASS CONTROL (at on/oﬀ regulation)

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 cuts out

64 | BC245386497365en-000801 © Danfoss | Climate Solutions | 2022.02

User Guide | Pack controller, type AK-PC 782A

4.1.13 Set up KPI and COP calculation

1. Go to Conﬁguration menu

2. Select KPI setup

In our example, KPI control is not used. The settings are included here for information.

2 - KPI Setup KPI calculation (KPI = Key Performance Indicator)

If "Yes" is selected, the function will optionally request a signal from the sensor liquid line (Sliquid temp)

Selected RFG

The system’s refrigerant type is read here

Total swept volume MT

The total swept volume for all of the MT compressors is read here

Total swept volume IT

The total swept volume for all of the IT compressors is read here

Total swept volume LT

The total swept volume for all of the LT compressors is read here

HR active

The system's Heat Recovery state (active or not) is read here

Coldest cabinet MT

Set the desired temperature of the MT circuit’s coldest refrigeration case

Coldest cabinet LT

Set the desired temperature of the LT circuit’s coldest refrigeration case

User Guide | Pack controller, type AK-PC 782A

4.1.14 Set up Display

1. Go to Conﬁguration menu

2. Select Display setup

3. Deﬁne which readings are to be shown for the individual outputs

3 - Display set-up

Display

The following can be read for the four outputs: Comp. control sensor P0 in temperature P0 in barSs Sd Cond. control sensor Tc Pc bar S7 Sgc Pgc bar Prec bar Trec Speed Compressor

Unit readout

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

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

User Guide | Pack controller, type AK-PC 782A

4.1.15 Set-up Functions for General purpose

1. Go to Conﬁguration menu

2. Select General purpose

3. Deﬁne number of required functions

In our example we select one thermostat function for temperature control in the compressor room.

The following number of diﬀerent functions can be deﬁned: 5 thermostats 5 pressostats 5 voltage signals 10 alarm signals 6 PI-regulations

User Guide | Pack controller, type AK-PC 782A

4.1.16 Separate thermostats

1. Select thermostats

2. Select actual thermostat

3. Deﬁne 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:

• Whether the thermostat should also be shown in overview display 1. (The function is always shown in overview display 2)

• Name

• Which of the sensors /(Signal) 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

4.1.17 Separate pressostats

1. Select pressostats

2. Select actual pressostat

3. Deﬁne the required pressostat functions

3 - Pressostats

Settings as the thermostats

In our example, separate pressostat functions are not used.

User Guide | Pack controller, type AK-PC 782A

4.1.18 Separate voltage signals

1. Select Voltage inputs

2. Select actual voltage signal

3. Deﬁne the required names and values attached to the signal

In our example we do not use this function, so the display has been included for your information only. The name of the function may be xx and further down in the display the alarm texts may be entered. The values ”Min. and Max. Readout” are your settings representing the lower and upper values of the voltage range. 2V and 10V, for example. (The voltage range is selected during the I/O setup). For each voltage input deﬁned the controller will reserve a relay output in the I/O setup. It is not necessary to deﬁne this relay if all you require is an alarm message via the data communication.

3 - Voltage inputs

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

Show on overview Name Select sensor (signal, voltage)

Select the signal which the function should use Actual value = readout of the measurement

Actual state

= readout of outlet status Min. readout State readout values at minimum voltage signal

Max. readout

State readout 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

4.1.19 Separate alarm inputs

1. Select General alarm inputs

2. Select actual alarm signal

3. Deﬁne 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:

• Show on overview

• Name

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

• Alarm text

User Guide | Pack controller, type AK-PC 782A

4.1.20 Separate PI functions

1. Select PI functions

2. Select actual PI-function

3. Deﬁne the required names and values attached to the function

3 - General PI Control

The function can be used for optional regulation

Adjust for each regulation:

• Show on overview

• Name

• Quick settings Here is a list of suggestions for PI regulations:

In our example we do not use this function, so the display has been included for your information only.

• Control mode: Oﬀ, Manual or Auto

• Control type: P or PI

• External DI ctrl: Adjusted to "On" if there is an external switch that can start/stop the regulation.

• Input type: Choose which signal the regulation shall receive: Temperature, pressure, pressure converted to temperature, voltage signal, Tc, Pc, Ss, Sd etc.

• Reference: Either ﬁxed or signal for the variable reference: Choose between: : Non, temperature, pressure, pressure converted to temperature, voltage signal, Tc, Pc, Ss, DI etc.

• Setpoint: If ﬁxed reference is chosen

• Reading the total reference

• Output: Here you select the outlet function (PWM = pulse width modulated (e.g. AKV valve)), Stepper signal for a stepper motor or voltage signal

• Alarm mode: Choose whether an alarm shall be attached to the function. If it is set to "On", alarm texts and alarm limits can be entered

• Advanced ctrl. settings:

– Ref. X1, Y1 and X2,Y2: Points that deﬁne and limit the variable

reference

– PWM period time: Period during which the signal has been on

and oﬀ. – Kp: Ampliﬁcation factor – Tn: Integration time – Filter for reference: Duration for smooth changes to the

reference – Max. error: Maximum permissible fault signal at which the

integrator remains in the regulation – Min. control output: Lowest permitted output signal – Max. control output: Maximum permitted output signal – Start-up time: Time at start-up at which the output signal is

force-controlled – Start-up output: The output signal size at the start-up time. – Stop output signal. Size of the output signal when regulation

is oﬀ

User Guide | Pack controller, type AK-PC 782A

4.1.21 Conﬁguration of inputs and outputs

1. Go to Conﬁguration menu

2. Select I/O conﬁguration

3. Conﬁguration of Digital outputs

Press the + button to go to

the next page

4. Set up On/oﬀ inputs

Press the + button to go to

the next page.

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

• Digital outputs

• Digital inputs

• Analogue outputs

• Analogue inputs

Load Output Module Point Active at

Hot gas dump DO1 1 12 ON

Circulation pump tw DO2 1 13 ON

MT Compressor 1 (VLT start) DO5 1 16 ON

MT Compressor 2 D06 1 17 ON

MT Compressor 3 DO7 1 18 ON

IT Compressor (VLT start) DO8 1 19 ON

LT Compressor 1 (VLT start) DO1 4 9 ON

LT Compressor 2 DO2 4 10 ON

Fan motors (VLT start) DO3 4 11 ON

3-way valve, tap water, Vtw DO5 4 13 ON

Room fan DO7 4 15 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.

Attention! Relay outputs must not be inverted at unloader valves. The controller inverts the function itself. There will be no voltage at the by-pass valves when the compressor is not in operation. Power is connected immediately before the compressor is started.

Function Input Module Point Active at

Level switch, CO2 receiver AI2 2 2 Open

Start/stop of heat recovery tw AI3 2 3 Closed

MT Compressor 1 Gen. Safety AI1 3 1 Open

MT Compressor 2 Gen. Safety AI2 3 2 Open

MT Compressor 3 Gen. Safety AI3 3 3 Open

IT Compressor Gen. Safety AI4 3 4 Open

LT Compressor 1 Gen. Safety AI5 3 5 Open

LT Compressor 2 Gen. Safety AI6 3 6 Open

External main switch AI3 4 3 Closed

MT compressors common safety

LT compressors common safety AI6 4 6 Open

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

AI4 4 4 Open

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. 1-2 Injection suction line Injection ON Fan 1 / VSD Fan 2 - 8 HP Control Ejector Valve gas cooler V3gc Hot gas Dump 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 PWM

4 - Digital inputs

The possible functions are the following: Ext. Main switch Ext. compr. stop Ext. power loss Night setback Load shed 1 Load shed 2 All compressors: Common safety Comp. 1 Oil pressure safety Over current safety Motor protect. safety Disch. temp. safety Disch. press. safety General safety VSD comp. Fault

Do for Comp. 2-8

Fan 1 safety

Do for fan 2-8

VSD cond safety Oil receiver low Oil receiver high Oil separator low 1-2 Oil separator high 1-2 AC limit Rec. low liquid level Rec. high liquid level 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

User Guide | Pack controller, type AK-PC 782A

5. Conﬁguration of Analogue outputs

Press the + button to go

to the next page

6. Conﬁguration of Analogue Input signals

Function Output Module Point Type

Speed control, MT compressor AO1 1 24 0 – 10 V

Speed control, IT compressor AO2 1 25 0 – 10 V

Speed control, LT compressor AO1 2 5 0 – 10 V

Speed control, fan gas cooler AO2 2 6 0 – 10 V

Speed control, pump tw AO3 2 7 0 – 10 V

Signal to by-pass ventil, Vrec Step 1 3 9 CCMT

Signal to high pressure valve, Vhp Step 2 3 10 CCMT

3-way valve, gas cooler, V3gc Step 3 3 11 CTR

Sensor Input Module Point Type

Discharge gas temperature - Sd-MT AI1 1 1 Pt 1000

Suction gas temperature - Ss-MT AI2 1 2 Pt 1000

Discharge gas temperature - Sd-IT AI3 1 3 Pt 1000

Suction gas temperature - Ss-IT AI4 1 4 Pt 1000

Thermostat sensor in plant room

- Saux1

Suction pressure - P0-MT AI6 1 6 AKS 2050-59

Condenser pressure - Pc-MT AI7 1 7 AKS 2050-159

Tap water temperature - Stw8 AI8 1 8 Pt 1000

Temp. gas cooler outlet Sgc AI9 1 9 Pt 1000

Gas cooler pressure Pgc AI10 1 10 AKS 2050-159

Refrigerant receiver, Prec CO

Temp. by-passed gas Shp AI1 2 1 Pt 1000

Outdoor temp, Sc3 AI4 2 4 Pt 1000

Heat recovery tw2 AI7 3 7 Pt 1000

Heat recovery tw3 AI8 3 8 Pt 1000

Discharge gas temperature - Sd-LT AI1 4 1 Pt 1000

Suction gas temperature - Ss-LT AI2 4 2 Pt 1000

Heat recovery tw4 AI7 4 7 Pt 1000

Suction pressure - P0-LT AI8 4 8 AKS 2050-59

AI5 1 5 Pt 1000

AI11 1 11 AKS 2050-159

5 - Analogue outputs

The possible signals are the following: 0 – 10 V 2 – 10 V 0 – 5 V 1 – 5 V 10 – 0 V 5 – 0 V Stepper output Stepper output 2 Stepper user deﬁned and Valve setup: see section "Miscellaneous"

6 - Analogue inputs

The possible signals are the following: Temperature sensors:

• Pt1000

• PTC 1000

Pressure transmitters:

• AKS 32, -1 – 6 bar

• AKS 32R, -1 – 6 bar

• AKS 32, - 1 – 9 bar

• AKS 32R, -1 – 9 bar

• AKS 32, - 1 – 12 bar

• AKS 32R, -1 – 12 bar

• AKS 32, - 1 – 20 bar

• AKS 32R, -1 – 20 bar

• AKS 32, - 1 – 34 bar

• AKS 32R, -1 – 34 bar

• AKS 32, - 1 – 50 bar

• AKS 32R, -1 – 50 bar

• AKS 2050, -1 – 59 bar

• AKS 2050, -1 – 99 bar

• AKS 2050, -1 – 159 bar

• MBS 8250, -1 – 159 bar

• User deﬁned (ratiometric 10 – 90% of 5 V supply). Min. and max. value of the sensor range must be set in relative pressure.

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

Oil 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.

User Guide | Pack controller, type AK-PC 782A

4.1.22 Set alarm priorities

1. Go to Conﬁguration menu

2. Select Alarm priorities

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

Disconnected

Log Alarm relay selection Net-

Non High Low - High

X 4

work

See also alarm text page 131.

AKM dest.

Press the + button to go to the next page

4. Set alarm priorities for condenser

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

Press the + button to go to the next page

User Guide | Pack controller, type AK-PC 782A

5. Set alarm priorities for thermostat and extra digital signals

4.1.23 Lock conﬁguration

1. Go to Conﬁguration menu

2. Select Lock/Unlock conﬁguration

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

3. Lock Conﬁguration

The controller will now make a comparison of selected functions and deﬁne inputs and outputs. The result can be seen in the next section where the set-up is controlled.

Press the ﬁeld Conﬁguration lock. Select Locked. The set-up of the controller has now been locked. If you subsequently want to make any changes in the controller’s set-up, remember to unlock the conﬁguration ﬁrst.

User Guide | Pack controller, type AK-PC 782A

4.1.24 Check conﬁguration

1. Go to Conﬁguration menu

2. Select I/O conﬁguration

3. Check conﬁguration of Digital Outputs

This control requires that the set-up is locked. (Only when the set-up is locked, are all settings for in- and outputs activated).

An error has occurred, if you see the following:

The set-up of the digital outputs appears as it is supposed to according to the wiring made.

A 0 – 0 next to a deﬁned function. If a setting has reverted to 0-0, you must control the set-up 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 has been set up for something diﬀerent

The error is corrected by setting up the output correctly. Remember that the set-up must be unlocked before you can change module and point numbers.

Press the + button to go to the next page

4. Check conﬁguration of Digital Inputs

Press the + button to go to the next page

The set-up 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 set-up again.

This may be due to the following:

• The input or the output has been set up; but the set-up 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 set-up must be unlocked before you can change module and point numbers.

User Guide | Pack controller, type AK-PC 782A

5. Check conﬁguration of Analogue Outputs

Press the + button to go to the next page

6. Check conﬁguration of Analogue Inputs

The set-up of the analogue outputs appears as it is supposed to according to the wiring made.

The set-up of the analogue inputs appears as it is supposed to according to the wiring made.

User Guide | Pack controller, type AK-PC 782A

4.2 Check of connections

1. Go to Conﬁguration menu

2. Select I/O status and manual

3. Check Digital Outputs

Press the + button to go to the next page

Before the control is started, we check that all inputs and outputs have been connected as expected.

This control requires that the set-up 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

4. Check Digital Inputs

Press the + button to go 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.

User Guide | Pack controller, type AK-PC 782A

5. Check Analogue outputs

6. Put the control of the output voltage back to automatic

Set Control of output voltage to manual Press in the Mode ﬁeld. Select MAN.

Press in the Value ﬁeld Select for example 50%. Press OK. On the output you can now measure the expected value: In this example 5 volts

Example of the connection between a deﬁned output signal and a manual set value.

Deﬁnition Setting

0 % 50 % 100 %

0 - 10 V 0 V 5 V 10 V

1 - 10 V 1 V 5.5 V 10 V

0 - 5 V 0 V 2.5 V 5 V

2 - 5 V 2 V 3.5 V 5 V

10 - 0 V 10 V 5 V 0 V

5 - 0 V 5 V 2,5 V 0 V

Press the + button to go to the next page

7. Check Analogue inputs

Check that all sensors show sensible values. In our case we have no values. This may be due to the following:

• The sensor has not been connected.

• The sensor is short-circuited.

• The point or module number has not been set up correctly.

• The conﬁguration is not locked.

User Guide | Pack controller, type AK-PC 782A

4.3 Check of settings

1. Go to the overview

Before the control starts, we check that all the settings are as they should be.

The overview display will now show one line for each of the general functions. Behind each icon there is a number of displays with the diﬀerent settings. All these settings have to be checked.

2. Select suction group

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

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

4. Check the individual pages

The last page contains control data.

5. Go back to the overview. Repeat for IT and LT

6. Select condenser group

User Guide | Pack controller, type AK-PC 782A

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

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

8. Check the individual pages

The last page contains reference settings.

9. Go back to the overview and move on to the rest of the functions

10. General functions

When all the functions in overview display 1 have been reviewed, it is time to look at the "General functions" in overview display 2. Press the + button to access.

The ﬁrst is the thermostat group

Check the settings.

11. Then the pressure switch group

Check the settings.

12. Proceed with the remaining functions

13. The controller set-up has been completed

All the deﬁned general functions are shown in overview display

2. In addition to always being shown in display 2, functions can be selected to be shown in display 1. Individual functions can be selected for display in display 1 via the "Show in overview display" setting.

User Guide | Pack controller, type AK-PC 782A

4.4 Schedule function

1. Go to Conﬁguration menu

2. Select schedule

3. Set up 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 day of the week and set the time for the day period. Continue with the other days. A complete weekly sequence is shown in the display.

User Guide | Pack controller, type AK-PC 782A

4.5 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.

3. Wait for answer from the system unit

Depending on the size of the network it may take up to one

minute before the controller receives an answer as to whether it has been installed in the network.

When it has been installed, the Status LED will start to ﬂash

faster than normal (once every half second). It will continue with this for about 10 minutes.

4. Carry out new login via Service Tool

If the Service Tool was connected to the controller while you

installed it in the network, you must carry out a new login to the controller via the Service Tool.

The controller has to be remote-monitored via a network. In this network we assign address number 3 to the controller. The same address must not be used by more than one controller in the same network.

Requirement to the system unit

The system unit must be:

- AK-SM 720.

- AK-SM 800 serie.

If there is no answer from the system unit:

If the Status LED does not start ﬂashing faster than normal, the controller has not been installed in the network. The reason for this may be one of the following:

The controller has been assigned an address out of range

Address 0 cannot be used.

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 ADAPKOOL® Refrigeration Controls” RC8AC.

User Guide | Pack controller, type AK-PC 782A

4.6 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

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, we have a series of alarms. We will tidy them up so that we only have those that are relevant.

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 start-up 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.

User Guide | Pack controller, type AK-PC 782A

4.6.1 Start the control

1. Go to Start/Stop display

Press the blue manual control button at the bottom of the display.

2. Start control

Press in the ﬁeld against Main switch. Select ON.

The controller will now start controlling the compressors and the fans.

Note: Control does not start until both the internal and external switches are “ON”.

Any external compressor stop breaker must be "ON" for the compressors to start.

User Guide | Pack controller, type AK-PC 782A

4.6.2 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 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:

4. Set capacity in percentage

Press in the blue ﬁeld Manual capacity.

Press the blue ﬁeld Control mode. Select MAN.

Set the capacity to the required percentage. Press OK.

User Guide | Pack controller, type AK-PC 782A

5. Regulating functions

This section describes how the diﬀerent functions work.

5.1 Suction group

Controlling sensor

The capacity distributor can regulate according to the suction pressure P0. The IT compressors are also regulated according to the suction pressure, but the signal is received from the receiver - Prec. See page 118 for IT description

An error in the controlling sensor will mean that regulation continues with fx. 50% cut-in in daily operation and e.g. 25% cut-in at night, but for a minimum of one step.

Reference The reference for the regulation can be deﬁned in 2 ways: Either P0Ref = P0 setting + P0 optimization + night displacement or P0Ref = P0 setting + Ext. Ref + night displacement

P0 setting

A basic value for the suction pressure is set.

P0 optimization

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

Night displacement

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

• Signal on an input

• From a system unit override function

• Internal time schedule

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 set-up it is deﬁned how big a displacement is to take place at max. signal (10 V) and at min. signal.

Limitation of reference

To safeguard yourself against a too high or too low regulation reference, a limitation of the reference must be set.

P0 ref

Max.

Min.

Forced operation of the compressor capacity in the suction group

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

Forced operation via overload of requested capacity

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

Forced operation via overload of digital outlets

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

Forced operation via change-over switches

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

Coordination between the LT and MT compressors

The LT (low pressure) compressors are only permitted to start when MT (medium pressure) is ready, but has not necessarily started the compressors.

LT will then start when required. When this happens, MT will register the pressure increase and immediately start the MT compressors in line with the desired pressure.

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

User Guide | Pack controller, type AK-PC 782A

Time

Requested

5.2 Capacity control of compressors

Capacity control

AK-PC 782A can control 3 compressor groups - MT, IT and LT. Each compressor can have up to 3 unloaders. One or two of the compressors can be equipped with speed regulation.

The cut-in capacity is controlled by signals from the connected pressure transmitter and the set reference. Set a neutral zone around the reference . In the neutral zone, the regulating compressor controls the capacity so that pressure can be maintained. When it can no longer maintain the pressure within the neutral zone, the controller will cut out or cut in the next compressor in the sequence. When further capacity is either cut out or cut in, the capacity from the regulating compressor will be modiﬁed accordingly to maintain the pressure within the neutral zone (only where the compressor has variable capacity).

• When the pressure is higher than the “reference + a half neutral zone”, cut-in of the next compressor (arrow up) is permitted.

• When the pressure is lower than the “reference - a half neutral zone”, cut-out of a compressor (arrow down) is permitted.

• When the pressure is within the neutral zone, the process will continue with the currently activated compressors. Unload valves (if present) will activate, depending on whether suction pressure is above or below the reference value.

Suction pressure P0

Example:

4 compressors of equal size - The capacity curve will look like this

capacity %

C3 C3 C3

C2 C2 C2 C2

C1 C1 C1 C1 C1 C1 C1

Cut-out of the last compressor stage: Normally, the last compressor step will only be cut out when the required capacity is 0% and the suction pressure is below the neutral zone.

Operation time ﬁrst step

At start-up the refrigeration system must have time to be stable before the PI controller takes over the control. For this purpose, at start-up of a plant, a limitation is made of the capacity so that only the ﬁrst capacity step will cut in after a set period (to be set via "runtime ﬁrst step").

Pump down function:

To avoid too many compressor starts/stops with low load, it is possible to deﬁne a pump down function for the last compressor.

Change capacity

The controller will cut in or cut out capacity based on these basic rules:

Increase capacity:

The capacity distributor will start extra compressor capacity as soon as the requested capacity has increased to a value which allows the next compressor step to start. Referring to below example - a compressor step is added as soon as there is “Room” for this compressor step below the requested capacity curve.

Decrease capacity:

The capacity distributor will stop compressor capacity as soon as the requested capacity has decreased to a value which allows the next compressor to stop. Referring to below example - a compressor step is stopped as soon as there is no more “Room” for this compressor step above the requested capacity curve.

If the pump down function is used, the compressors will be cut out when the actual suction pressure is down to the conﬁgured pump down limit. When the pump down limit is approaching the neutral zone, it will be limited to NZ minus 1 K. This can occur if receiver pressure has been optimized.

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

For the IT compressor, pump down will be controlled by the receiver and MT temperature.

User Guide | Pack controller, type AK-PC 782A

Variable integration time

There are two parameters to make Tn variable. This allows control to be more rapid the further pressure deviates from the reference. The A+ setting will lower Tn when the pressure is above the reference, and the A- setting will lower Tn when the pressure is below the reference.

Tn has been set to 120 s in the graph below, and falls to 60 s if the pressure is above the reference and to 40 s if the pressure is below the reference. Above the reference: Set Tn divided by the A+ value. Below the reference: Set Tn divided by the A- value. The controller calculates the curve in such a manner that regulation is smooth.

Regulation parameters

To make it easier to start up the system, we have grouped regulation parameters into sets of commonly used values, called "Easy-settings". Use these to choose between sets of settings appropriate for a system which responds slowly or quickly. The factory setting is 5. If you need to ﬁne-tune the control, select the "User deﬁned" setting. All parameters can then be freely adjusted.

Easy-

Settings

1 = Slowest 1.0 200 3.5 5.0

2 1.3 185 3.5 4.8

3 = Slower 1.7 170 3.5 4.7

4 2.1 155 3.5 4.6

5 = Default 2.8 140 3.5 4.4

6 3.6 125 3.5 4.2

7 = Faster 4.6 110 3.5 4.1

8 5.9 95 3.5 4.0

9 7.7 80 3.5 3.8

10= Fastest 9.9 65 3.5 3.5

User deﬁned 1.0 - 10.0 10 - 900 1.0 - 10.0 1.0-10.0

Kp Tn A+ A-

Regulation parameters

User Guide | Pack controller, type AK-PC 782A

5.2.1 Capacity distribution methods

The capacity distributor can work based on 2 distribution principles.

Coupling pattern – Cyclical operation:

This principle is used if all compressors are of the same type and size. The compressor cuts in and cuts out in accordance with the "First In First Out" principle (FIFO) to equalise operating hours between the compressors. Speed-regulated compressors will always be cut in ﬁrst, and the variable capacity is used to ﬁll capacity gaps between the subsequent steps.

Timer restrictions and safety cut outs

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

If a compressor with unloaders is not allowed to start due to a timer striction, no single step compressor is allowed to start. When the timer restriction has expired the compressor with unloaders will start.

Operating time equalisation

The operating hour equalizing is carried out between compressors of the same type with the same total capacity.

• At the diﬀerent start-ups, the compressor with the lowest number of operating hours will be started ﬁrst.

• At the diﬀerent stops, the compressor with the highest number of operating hours will be stopped ﬁrst.

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

Coupling pattern – Best ﬁt operation

This principle is used if the compressors are of diﬀerent sizes. The capacity distributor will cut-in or cut-out the compressor capacity in order to ensure the least possible capacity jump. Speed-regulated compressors will always be cut in ﬁrst, and the variable capacity will be used to ﬁll capacity gaps between the subsequent steps.

Timer restrictions and safety cut outs

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

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

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

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

User Guide | Pack controller, type AK-PC 782A

20 kW 20 kW

5.2.2 Power pack types – compressor combinations

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

• One or two speed controlled compressors

• Capacity controlled piston compressors with up to 3 unloader valves

• Single step compressors – piston

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

Combination Description Coupling

One-step compressors. *1 x x

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

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

All compressors with unload valves. *2

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

A speed-regulated compressor combined with a compressor with unload valve(s) and 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 onestep compressors *4

pattern

Cyclical

x x

*1) For a cyclical coupling pattern, the one-step compressors

must be the same size

*2) For compressors with unload valves, it is generally true that

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

*3) Speed-regulated compressors can have diﬀerent sizes in rela-

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

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

Capacity-regulated compressors with unload valves

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

Unloader control mode = 1

Here the capacity distributor allows only one of the compressors to be unloaded at a time. The advantage of this setting is that it avoids operating with several compressors unloaded, which is not energy eﬃcient.

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

Best ﬁt

Cap.%

C2.2

C2.1 C2.1 C2.2

C2.1

C2C2C2

C1.2 C1.2 C1.2 C1.2 C2.1

C1C1C1C1C1C1C1

C2.2

C2.1C1.1C1.1C1.1C1.1C1.1C1.1

• 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 that it reduces the number of compressor start/stops.

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

Cap.%

C2.2

C2.1 C2.1

C2.2

C2.1

C2.2

C2 C2

C2.1

C1.2C1.2C1.2C1.2

C1.1 C2.1C1.1C1.1C1.1C1.1C1.1

C2C2

C1C1C1C1C1C1C1C1C1

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

• When C1 is completely unloaded, compressor C2 with one-step is unloaded before C1 is cut out.

C2.1

C2C2C2

C2C2

User Guide | Pack controller, type AK-PC 782A

Speed control compressors:

The controller is able to use speed control on the leading compressor in diﬀerent compressor combinations. The variable part of the speed controlled compressor is used to ﬁll in capacity gaps of the following compressor steps.

General regarding handling:

One or two of the deﬁned capacity steps for the compressor regulation may be connected to a speed control unit that may be a frequency converter type VLT, for example.

An output is connected to the frequency converter’s ON/OFF input and at the same time an analogue output ”AO” is connected to the frequency converter’s analogue input. The ON/OFF signal will start and stop the frequency converter and the analogue signal will indicate the speed. It is only the compressor deﬁned as compressor 1 (1+2) that can be speed controlled.

When the step is in operation, it will consist of a ﬁxed capacity and a variable capacity. The ﬁxed capacity will be the one that corresponds 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 that 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).

Max.

Start

Min. Min.

Max.

Start

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.

Max.

Start

Min.

ON OFF

Cut-in

The speed-controlled compressor will always be the ﬁrst to start and the last to stop. The frequency converter will be started when a capacity requirement corresponding to the mentioned ”Start speed” arises (the relay output changes to ON and the analogue 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 cut-out on speed controlled compressor

If the speed controlled compressor is cut out on safety, other compressors are allowed to start. As soon as the speed controlled compressor is ready to start it will be the ﬁrst compressor to start.

As mentioned before the variable part of the speed capacity should be bigger than the capacity of the following compressor steps in order to achieve a capacity curve without “holes”. In order to illustrate how the speed control will react at diﬀerent pack combinations a couple of examples will be given here:

User Guide | Pack controller, type AK-PC 782A

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:

Requested

40 kW

20 kW

Start speed

Min. speed

capacity %

90 Hz

40 Hz

C3 C3 C1

C1 C2 C2 C2 C2 C1

80 Hz

30 Hz

Time

10 kW

30 – 90 Hz

10 kW 10 kW

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 cut in 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:

Requested

60 kW

capacity %

20 kW

25 – 50 Hz

20 kW 20 kW

Start speed

Min. speed

40 kW

20 kW

50 Hz

25 Hz

50 Hz

C1 C1C3

C1 C2 C2 C2 C2 C1

25 Hz

Time

As the variable part of the speed controlled compressor is smaller than the following compressor steps, the capacity curve will have some holes that cannot be ﬁlled out by the variable capacity.

1) The speed controlled compressor will be cut in 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.

User Guide | Pack controller, type AK-PC 782A

Analogue output

Max. speed

Two speed-regulated compressors

The controller is capable of regulating the speed of two compressors of the same or diﬀerent sizes. The compressors can be combined with one-step compressors of the same or diﬀerent sizes, depending on the choice of coupling pattern.

General regarding handling:

Generally, the two speed-regulated compressors are managed according to the same principle as for one speed-regulated compressor. The advantage of using two speed-regulated compressors is that it allows for a very low capacity, which is an advantage for low loads. At the same time, it produces a very large, variable regulating area.

Compressor 1 and 2 both have their own relay outlets to start/stop separate frequency converters, for example of type VLT. Both frequency converters use the same analogue output signal AO which is connected to the frequency converters’ analogue signal input (they can, however, be conﬁgured to run individual signals). The relay outputs will start and stop the frequency converter and the analogue signal will indicate the speed.

The precondition for using this regulating method is that both compressors have the same frequency range.

The speed-regulated compressors will always be the ﬁrst to start and the last to stop.

20 kW 20 kW 40 kW

Cut-in

The ﬁrst speed-regulated compressor will be started when there is a capacity requirement which matches the setting. The "Start speed" (relay outlet changes to on and the analogue outlet is supplied with a voltage that matches this speed). It is now up to the frequency converter to bring the speed up to the "Start speed". The capacity step will now be cut in and the desired capacity determined by the controller. The start speed should always be set so high that a good lubrication of the compressor is quickly reached during start-up. For a cyclical coupling pattern, the subsequent speed-regulated compressor will be cut in when the ﬁrst compressor runs at max. speed and the desired capacity has reached a value that allows the cut-in of the next speed-regulated compressor at start speed. Afterwards, both compressors will be cut in together and will run in parallel. The following one-step compressors will be cut in and out in accordance with the selected coupling pattern.

Start speed

Min. speed

Comp. 1

Comp. 2

Comp. 3

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-out

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 ﬁrst to start. The following speed-regulated compressor will be cut in when the ﬁrst compressor runs at max. speed and the desired capacity has reached a value that allows the cut-in of the next speed-regulated compressor at start speed. Afterwards, both compressors will be cut in together and they will run in parallel. The following one-step compressors will be cut in and out in accordance with First-In-First-Out principle in order to equalise operating hours.

User Guide | Pack controller, type AK-PC 782A

10 kW

30 – 90 Hz 30 – 90 Hz

20 kW 20 kW 40 kW

Cap. %

Start speed

90 Hz

C2 C2

C2C1 C3C4 C4 C4

C3C3

C1 C1

C4 C3

C2 C1

56.7 Hz

90 Hz

45 Hz

63.3 Hz

30 Hz

Min. speed

Example:

• Two speed-regulated compressors with a nominal capacity of 20 kW and frequency range 25 – 60 Hz

• Two one-step compressors, each of 20 kW

20 kW

25 – 60 Hz

20 kW 20 kW 20 kW

Start speed

Min. speed

Cap. %

35 Hz

C1C1 C3 C3 C3 C1C4

60 Hz

C1 C1C4 C4

50 Hz

25 Hz

Best ﬁt

During best-ﬁt operations, the speed-regulated compressors can have diﬀerent sizes and they will be handled in such a way that the best possible capacity adjustment is achieved. The smallest compressor will be started ﬁrst, then the ﬁrst will be cut out and the second compressor will cut in. Finally, both compressors will be cut in together and will run in parallel. The following one-step compressors will, in every case, be handled in accordance with the best-ﬁt coupling pattern.

Example:

• Two speed-regulated compressors with a nominal capacity of 10 kW and 20 kW respectively

• Frequency range of 25-60 Hz

• Two one-step compressors of 20 and 40 kW respectively

5.2.3 Compressor timers

Time delays for cut-ins and cut-outs

To protect the compressor against frequent restarts, three time delays can be put in:

• A minimum time to run from a compressor’s start-up and until it may be restarted

• A minimum time (ON-time) for the compressor to operate before it may be stopped again

• A minimum OFF time to run from a compressor stops and until it may be restarted

When unloaders are cut in and out, the time delays will not be used.

Timer

The operating time of a compressor motor is registered continuously. You can read out:

• operating time for the previous 24-hour period

• total operating time since the timer was last set to zero-set

Equalizing operating hours

Operating hours are also summed in the "Equalization time" ﬁeld. During cyclical operation, this ﬁeld is used for equalizing operating hours.

Coupling counter

The number of relay cut-ins and cut-outs is registered continuously. The number of starts can be read out here:

• Number during the previous 24-hour period

• Total number since the counter was last set to zero-set

Two independent speed-regulated compressors

If the two speed-regulated compressors need to be controlled asynchronously, they must each have their own analogue voltage signal. The controller ﬁrst starts one of the speed-regulated compressors. If more capacity is required, the other speed-regulated compressor is started, and then the single compressors.

Max. speed

Nominal

Start speed

Min. speed

The ﬁrst is run up to maximum speed. Number two is then activated and run up to nominal speed – and kept there. The speed of number one is reduced at the same time, so the capacity is balanced. All variations are now handled by number one. If number one reaches maximum speed, number two will also be raised. If number one reaches minimum speed, it will be kept there while number two takes over the variation below its nominal speed. When engaging and disengaging, the total hours of operation for the compressors is compared, so they are run an equal number of hours.

Analogue outputs

5.2.4 Compressor with variable capacity

Digital scroll compressor

The capacity is divided into period times as "PWM per". 100% capacity is delivered when cooling takes place for the whole period. An oﬀ time is required by the by-pass valve within the period and an on time is also permitted. There is "no cooling" when the valve is on. The controller itself calculates the capacity needed and will then vary it according to the cut-in time of the by-pass valve. A limit is introduced if low capacity is needed so that the cooling does not go below 10%. This is because the compressor can cool itself. This value can be increased if necessary.

Refrigeration No refrigeration

Period time

Min. capacity

User Guide | Pack controller, type AK-PC 782A

Copeland Stream compressor

The PWM signal can also be used to control one stream compressor with one unloader valve (Stream 4) or one with two unloaders (Stream 6). Stream 4: The compressor capacity is distributed by up to 50% for

one relay and the remaining 50-100% for the unloader.

Stream 6: The compressor capacity is distributed by up to 33% for

one relay and the remaining 33-100% for the unloader.

Bitzer CRII Ecoline

CRII 4: The pulse signal can also be used to control one CRII with

two unloaders (4-cylinder version).

The compressor capacity can be controlled from 10 to

100%, depending on the pulsation of the unloaders. The compressor start signal is connected to a relay output, and the unloaders are connected to solid state output e.g. DO1 and DO2.

Unloader 1

Unloader 2

Unloader 2 follows unloader 1, but it remains displaced by a half period.

CRII 6: The pulse signal can also be used to control one CRII with

three unloaders (6-cylinder version). The compressor signal is connected to one relay output. The two unloaders are connected to solid state output fx

DO1 and DO2. The third is connected to a relay output. The compressor capacity can be controlled from 10 to

67%, depending on the pulse of the unloaders. The relay is then connected to the third unloader. When

this relay is oﬀ, the capacity will be controlled between 33

and 100%.

Individual Sd monitoring

When regulating with Sd monitoring, one of the three compressor types will increase capacity if the temperature nears the Sd limit. This will result in better cooling of the unloaded compressor.

User Guide | Pack controller, type AK-PC 782A

Comp. cap. %

5.2.5 Load shedding

On some installations there is the desire to limit the cut-in compressor capacity so that one can limit the total electrical load in the store for periods. (The IT circuit is not directly aﬀected)

This limitation can be activated in the following way:

• Via signal from the network

• Via signal on one DI input + signal via the network

• Via signal on two DI inputs + signal via the network

The signal via the network will result in the same function as if the signal was received on DI 1.

For each digital inlet a limit value is attached for the maximum allowable cut-in compressor capacity so that one can carry out the capacity limitation in 2 steps.

When a digital inlet is activated, the maximum allowable compressor capacity is limited to the set limit. This means that if the actual compressor capacity upon activation of the digital inlet is higher than this limit, then so much compressor capacity is cut out that it will then be on or under the set maximum limit value for this digital inlet. The threshold value may not be set lower than the compressor's lowest capacity step/"Start speed".

100%

80%

60%

40%

20%

Load shed DI 1

Load shed DI 2

When both load-shedding signals are active, the lowest limit value for the capacity will be the one that is applicable.

Load limit 1 Load limit 2

5.2.6 Injection ON

The electronic expansion valves in the refrigeration appliances must be closed when all the compressors are prevented from starting. In this way the evaporators will not be ﬁlled with liquid which is subsequently passed on to a compressor when regulation is restarted. One of the compressor control relays may be used for this function, or the function can be obtained via data communication.

with relay

with data communication

The function is described based on the sequence of events below: T1) The last compressor is cut out T2) The suction pressure has increased to a value corresponding

to Po Ref + ½ NZ + 2 K” but no compressor can start due to restart timers or safety cut-out

T3) The time delay “Injection OFF delay” elapses and the injection

valves are forced to close via relay signal or via network signal

T4) The ﬁrst compressor is now ready to start. The forced closure

signal via the network is now cancelled.

T5) The time delay “Comp. Start delay” expires and the forced

closure signal via the relay switch is cancelled simultaneously with the ﬁrst compressor being allowed to start

Max. time

A max. period with low compressor capacity can be set. When the period expires, the system switches to normal regulation until the suction pressure is once again in place. Load shedding will then be permitted.

Overriding of load shedding:

To avoid load shedding leading to temperature problems for the chilled products, an overriding function is ﬁtted.

A overriding limit is set for the suction pressure as well as a delay time for each digital inlet.

If the suction pressure during load shedding exceeds the set P0 overriding limit and the attached delay times for the two digital inlets expire, then load shedding overrides the signals so that the compressor capacity can be increased until the suction pressure is again under the normal reference value. The load shedding can then be activated again.

Alarm:

When a load shedding digital inlet is activated, an alarm will be activated to inform that the normal control has been bypassed. This alarm can however be suppressed if so desired.

The reason why the forced closure signal via the network is cancelled before the ﬁrst compressor starts, is that it will take some time to distribute the signal to all appliance controllers via the network.

User Guide | Pack controller, type AK-PC 782A

5.2.7 Liquid injection in common suction line

The discharge pressure gas temperature can be kept down by means of liquid injection into the suction line (not IT circuit). With a thermostatic expansion valve in series with a solenoid valve. The solenoid valve is connected to the controller.

Ss Po Sd

Inject diff. Sd

Inject start Sd

Inject diff. SH

Inject start SH

Control can be carried out in two ways:

1. The liquid injection is exclusively controlled on the basis of the superheat in the suction line. Two values are set – a starting value and a diﬀerential where the injection is stopped again.

2. The liquid injection is both controlled by the superheat (as described above) and by discharge temperature Sd. Four values are set – two as mentioned above and two for the Sd function, a starting value and a diﬀerential. The liquid injection is started when both starting values have been passed, and is stopped again when just one of the two functions cuts out.

Direct using an electrically operated expansion valve of the type AKV

Four values are adjusted - a start value for the Sd temperature, min. and max. values for overheating and a period time for the AKV valve. Actual used OD for the liquid injection is the highest of the two above (see above ﬁg.) The width of the P-Band for the Sd control is hardcoded to be 20K and cannot be changed. The valve will be closed too, when all compressors are stopped.

As a safety function the AKV valve will be closed anyway, as soon as the SH gets below 8K, to protect the compressors from getting liquid into the suction port.

The pulse width modulating signal for the AKV valve shall be taken from one of the controller's four solid state outputs.

Time delay

A time delay can be set which ensures that the injection is delayed with the set value after start-up of the ﬁrst compressor.

Calculation of OD% for the injection into the suction line

AKV OD% as function of SH

AKV OD% as function of Sd

User Guide | Pack controller, type AK-PC 782A

5.2.8 Safety functions

Signal from the compressor’s safety controls

The controller can monitor the status of each compressor’s safety circuit. The signal is taken directly from the safety circuit and connected to an input. (The safety circuit must stop the compressor without involving the controller). If the safety circuit is cut out, the controller will cut out all output relays for the compressor in question and give an alarm. Regulation will continue with the other compressors.

General safety circuit

If a low-pressure switch is placed in the safety circuit it must be placed at the end of the circuit. It must not cut out the DI signals. (There is a risk that the regulation will become locked and that it will not start again). This also applies to the example below.

If an alarm is needed which also monitors the low-pressure thermostat, a “general alarm” can be deﬁned (an alarm that does not aﬀect the control). See the following section “General monitoring functions”.

Extended safety circuit

Instead of a general monitoring of the safety circuit this monitoring function can be extended. In this way, a detailed alarm message is issued which tells you which part of the safety circuit has dropped out. The sequence of the safety circuit must be established as shown, but not all of them need necessarily be used.

Oil pressure safety Over current safety

Motor protect. safety

Discharge temp. safety

Discharge pressure safety

Common safety circuit

A common safety signal can also be received from the whole suction group. All compressors will be cut out when the safety signal cuts out. The function may not be connected to an external main switch.

Time delays with safety cut-out:

In connection with safety monitoring of a compressor it is possible to deﬁne two delay times:

Cut-out delay time: Delay time from signal from the safety circuit until the compressor relays cut out and alarm is given (note that the delay time is common to all security inlets for the compressor concerned)

Safety re-start time: The minimum time a compressor must be OK after a safety cut-out until it may start again.

Monitoring of superheat

This function is an alarm function which continuously receives measured data from suction pressure P0 and suction gas Ss. If superheat is registered which is lower or higher than the set limit values, an alarm will be given when the time delay has passed.

Monitoring of max. discharge gas temperature (Sd)

Common Sd monitoring

The function gradually cuts out compressor steps if the discharge temperature becomes higher than permitted. The cut-out limit can be deﬁned in the range from 0 to +195°C.

The function is started at a value that is 10 K below the set value. At this point the entire condenser capacity is cut in at the same time as 25% of the compressor capacity is cut out (but minimum one step). This is repeated every 30 seconds. The alarm function is activated. If the temperature rises to the set limit value all compressor steps are immediately cut out.

The alarm is cancelled and renewed cut-in of compressor steps is permitted when the following conditions are met:

- the temperature has dropped to 10 K below the limit value

- the time delay prior to restart has been passed (see later) Normal condenser control is permitted again when the temperature has dropped to 10 K below the limit value.

Individual Sd monitoring

The aﬀected compressor will be disconnected here when the temperature exceeds the threshold value.

- The piston compressor will be reconnected when the temperature has dropped 10 K

- The screw compressor will be reconnected when the temperature has dropped 20 K

- The capacity of compressors with variable capacity is increased if the temperature is approaching the limit. Once it has been cut out, it will only be connected when the temperature has dropped 10 K. If signals are also obtained from the embedded NTC sensor, the disconnect value for this temperature will always remain at 130 °C and the reconnect value at 120 °C.

User Guide | Pack controller, type AK-PC 782A

Monitoring of min. suction pressure (P0)

The function promptly cuts out all compressor steps if the suction pressure becomes lower than the permitted value. The cut-out limit can be deﬁned in the range from -120 to +30°C. The suction is measured with pressure transmitter P0.

At cut-out the alarm function is activated:

The alarm is cancelled and renewed cut-in of compressor steps is permitted when the following conditions are met:

- the pressure (temperature) is above the cut-out limit

- the time delay has elapsed (see later).

Monitoring of max. condensing pressure (Pc)

The function cuts in all condenser steps and cuts out compressor steps one by one if the condensing pressure becomes higher than permitted. The cut-out limit is set in bar. The condensing pressure is measured with pressure transmitter Pc_.

The function takes eﬀect at a value which is 3 K below the set value. At this time the entire condenser capacity is cut in at the same time as 25% of the compressor capacity is cut out (but min. one step). This is repeated every 30 seconds. The alarm function is activated.

If the temperature (pressure) rises to the set limit value, the following will happen:

- all compressor steps will immediately be cut out

- the condenser capacity will remain cut in

Delay of Pc max alarms

It is possible to delay the “Pc max alarm" message. The controller will still disconnect the compressors, but the sending of the alarm itself is delayed. The delay is useful on cascade systems where the max. Pc limit is used to disconnect compressors in the low-pressure circuit if the high-pressure compressors have not started.

Time delay

There is a joint time delay for “Monitoring of max. discharge gas temperature” and “Min. suction pressure”. After a cut-out, regulation cannot be recommenced until the time delay has been passed. The time delay starts when the Sd temperature has again dropped to 10 K below the limit value or P0 has risen above the P0 min. value.

Alarm for too high suction pressure

An alarm limit can be set which will become eﬀective when the suction pressure becomes too high. An alarm will be transmitted when the set time delay has been passed. The regulation continues unchanged.

Monitoring max. receiver pressure

If the receiver pressure is approaching the max. value, the compressors will be cut out as described under ‘Monitoring max. condenser pressure’. An alarm will be transmitted when this limit is exceeded.

The alarm will be cancelled and renewed cut-in of compressor steps is permitted when the following conditions are met:

- the temperature (pressure) falls to 3 K below the limit value

- the time delay for restart has been passed

User Guide | Pack controller, type AK-PC 782A

5.3 Oil management

Principle

The controller can control the pressure in an oil receiver and ensure the evacuation of two oil separators. The evacuation is carried out with a number of pulses, e.g. of 1 second duration followed by a pause of 1 minute.

The system can be controlled by signal from:

• Level switch on oil separator

• Pressure transmitter on oil receiver

All oil valves are closed when "Main switch" is Oﬀ.

Examples of oil circuits:

Separator 1

Receiver

Separator 1

Separator 2

Receiver

Danfoss AK-PC 782A User guide

Specifications and Main Features

Frequently Asked Questions

User Manual