Danfoss AK-PC 551 User guide

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User Guide

Capacity Controller AK-PC 551

ADAP-KOOL® Refrigeration Control System

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Introduction

Application

The controller is used for capacity regulation of compressors and condensers in small refrigeration applications. A maximum of 8 compressors and one condenser can be regulated. For example:

• One suction group + one condenser group

• Two suction groups + one shared condenser (max. 4 + 4 steps)

• One compressor group, max. 8 steps

• One condenser group, max. 8 steps

Advantages

• Energy savings via:

- Optimisation of suction pressure

- Night time increase

- Floating condensing pressure

- Load limitation

Input and output

There are a limited number of available inputs and outputs. For each signal type, though, the following can be connected:

• Analogue inputs, max. 8 pcs. Signal from pressure transmitters, temperature sensors, voltage signal, etc.

• Digital inputs, max. 8 pcs. Signal from automatic safety control, day/night signal, etc.

• Relay outputs, max. 6 pcs. Connection of compressors, condenser fans

• Solid state outputs, max. 2 pcs.

- Control of capacity valve on a Copeland digital scroll

- Control of unloader on a Copeland stream compressor.

- Control of both unloaders on a Bitzer CRII If the outputs are not used for these functions, they can be used as ordinary relay outputs

• Analogue outputs, max. 2 pcs. Speed control of compressors or condenser fans.

Operation

The daily operation can be set up directly on the controller or via an external display device. During set-up, the display images will be adjusted so that only the relevant images are opened for additional setting and end-user operation. The operation is password protected, and three levels of access can be granted. The controller contains several languages. Select the preferred language at start-up.

Data communication

The controller has built-in modbus data communication, and it can be connected to an AK-SM 800 type system device.

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Suction Group

Compressor types

The following types of compressors can be used for regulation:

• Single-step compressors (one can be speed-regulated)

• Compressor with unloaders

• Scroll compressors (one can be a digital scroll)

• Copeland Stream compressor with one unloader (4 cylinders)

• Bitzer CRII compressor with two unloaders (4-cylinders)

Capacity regulation

The cut-in capacity is controlled by signals from the connected pressure transmitter/temperature sensor and the set reference. Set a neutral zone around the reference . In the neutral zone, the regulating compressor controls the capacity so that pressure can be maintained. When it can no longer maintain the pressure within the neutral zone, the controller will cut out or cut in the next compressor in the sequence. When further capacity is either cut out or cut in, the capacity from the regulating compressor will be modiﬁed accordingly to maintain the pressure within the neutral zone (only where the compressor has variable capacity). – When the pressure is higher than the “reference + a half neutral

zone”, cut-in of the next compressor (arrow up) is permitted.

– When the pressure is lower than the “reference - a half neutral

zone”, cut-out of a compressor (arrow down) is permitted.

– When the pressure is within the neutral zone, the process

will continue with the currently activated compressors.

Control sensor

Normally, a suction group is controlled based on a signal from the Po pressure transmitter. If control on a brine, the S4 sensor must be the control sensor. The Po pressure transmitter must also be installed, as it is used for frost protection.

The reference

At set or variable reference can be used for regulation. For example, the variable reference can be used for a night time increase or Po optimisation. Enter a set point here so that a contribution from the Po optimisation or night time increase is added. This contribution can raise or lower the reference, as determined by the momentary cooling need. To limit the reference from values that are too high or too low, set a max. and min. limit.

Load shedding

When the load shedding function is activated, the maximum permissible compressor capacity will be limited to the set limit. In this way, the total electrical load in the store is limited. The threshold value may not be set lower than the compressor’s lowest capacity step/”Start speed”.

Po ref.

Max.

Min.

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Condenser

Fan control

The fans can be controlled incrementally using the controller’s relays, or they can be speed-controlled via the controller’s analogue output. Speed control can be via a frequency VLT-type transformer. If the fans have EC motors, the 0-10 V signal can be used directly.

Step and speed simultaneously. (Parallel signals in step with each other.) This function is primarily used to control a frequency converter, but if the frequency converter fails, external wiring will switch over to step control.

During night operation, the noise level of the fans can be kept down. This is done by limiting the cutin capacity. For speed control, keep the number of revolutions low. Omit step cutin for step-by-step activation.

The limitation is bypassed if safety functions Sd max. and Pc max. start to function.

Control

Regulation is carried out based on a signal from the Pc pressure transmitter or an S7 media temperature sensor. The signal is compared with the regulation reference.

The regulation reference can originate from one or more of the following functions:

• Fixed reference

• Variable reference, which follows the outdoor temperature. When the outdoor temperature drops, the reference will drop by a corresponding amount. This variable reference requires the installation of an Sc3 outdoor temperature sensor. The sensor must be positioned so that it registers the correct outdoor temperature. In other words, it must be shielded from direct sunlight and located near the airway of the condenser. This regulation requires setting a min. and max. reference, so that the regulation process is kept within the given limits.

• Increase the reference for heat recovery. Here the reference is raised to a ﬁxed value when a signal is received on a DI input. The reference value can be higher than the set max. reference. When the temperature of the heat recovery has been reached and the DI signal disappears, the reference will drop once again, though it will do so over the course of a few minutes to prevent abrupt changes in the reference.

Media temperature If controlling a media temperature, the control sensor must be set to S7. This temperature sensor must be located in the desired medium. The Pc pressure transmitter must also be installed. It is used for high-pressure monitoring.

Max. ref.

Min. ref.

Ref. for heat recovery

Temperature sequence for heat recovery

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Safety functions

Min./max. suction pressure Po

The suction pressure is recorded continuously. If the measured value falls below the set minimum limit, the compressors will immediately cut out. If it exceeds the max. value, an alarm will be generated once the time delay has elapsed.

Max. condensing pressure Pc

If the condensing pressure reaches the upper permissible value, the controller will connect all condenser fans to keep the pressure down. At the same time, a portion of the compressor capacity will be disconnected. If the pressure remains near the threshold value, even more compressors will be disconnected. All compressors will be disconnected immediately if the threshold value is exceeded.

LP switch

On/oﬀ signal on a DI input If a signal is received, all compressors will immediately be stopped.

HP switch

On/oﬀ signal on a DI input If a signal is received, all compressors will immediately be stopped. Fan capacity will increase depending on how much the Pc measurement exceeds the reference.

Sensor failure

If lack of signal from one of the connected temperature sensors or pressure transmitters is registered an alarm will be given.

• In the event of a Po error, regulation will continue with a set capacity in daytime operation (e.g. 50%), and a set capacity in night operation (e.g. 25%), but with a minimum of one step.

• In the event of a Pc error, the condenser capacity that corresponds to how much compressor capacity is connected will cut in. Compressor regulation will remain normal.

• When there is an error on the Sd sensor the safety monitoring of the discharge gas temperature will be discontinued.

• When there is an error on the Ss sensor the monitoring of the superheat on the suction line will be discontinued.

• In the event of an error on the outdoor temperature sensor, Sc3, the permanent setting value will be used as a reference.

• In the event of an error on the S4 sensor, regulation will continue with the Po signal, but the reference will be lowered by 5 K.

• In the event of an error on the Saux sensor, the thermostat output will go to the rest position.

NB: A faulty sensor must be OK within 10 minutes before a sensor

alarm is cancelled.

A sensor alarm can be reset manually by pushing the "Xbutton" for 2 seconds when the alarm is shown in the display "Active alarms".

General DI alarms

On/oﬀ signal on a DI input The regulator contains three general alarm inputs, to which alarm text and delay times can be connected. Alarm and text will appear when the delay time has elapsed.

Min./max superheating via Ss measurement

Temperature sensor on an AI input. If superheating is higher or lower than the set limits, an alarm will be generated once the time delay has elapsed.

Max. discharge gas temperature Sd

Temperature sensor on an AI input. A signal can be received from a Pt 1000 Ohm sensor on the pressure pipe.

• Common Sd for the whole compressor group If the temperature nears the set max. temperature, the capacity of the compressor will be reduced

• Compressor Sd

if it is an Sd from a Copeland digital scroll, a Copeland stream or Bitzer CRII the capacity will be increased so that the compressor can cool down itself).

The compressors will be stopped if the temperature nears the set max. temperature value.

General thermostat

It is possible to install one general thermostat if there is a relay output and an analogue input available.

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Display overview

End-user overview

The images in this daily user interface will depend on how the set-up is made. They will illustrate what is regulated. For example: One or two suction groups, one condenser group, or a combination. See examples below:

1 suction groupe

1 condenser

group

2 suction groups

and

1 condenser

group

Each of the four rows above is continued with three additional displays. The arrow in the top corner of the display shows the way to the next display in the same area of operation. By clicking the right arrow you can see these three displays:

Active alarms Cleared Alarms Information on the controller

When an alarm is sent from the controller, you must advance to this display to see the alarm text.

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Set-up overview

There are three ways in which the controller can be set up. Select the one that is easiest for you: either “Wizard”, “Quick settings” or a review of “all parameters”.

Start screen upon delivery

Operating principles

1. Select position using arrow keys

2. Select using “Enter” 

3. Use the “X” to return

Hold “Enter”  down for 2 seconds to come to password entry

Select a set-up method. End by pressing “Enter” 

The default password upon delivery is 300. Use the arrow keys to set the password. End by pressing “Enter” 

Main Menu

The ﬁrst setting is the Plant type

Wizard

Here you will be led through a series of settings, after which the controller will be ready for start. Image 1 of 28 is displayed here.

Quick

Select from the diﬀerent combinations of compressors and fans here. Also see the overview on pages 18 and 19.

3CDA + 2CB + FS 2CDA + 2CB + 3F 3CSA + 2CB + FS 2CSA + 2CB + 3F 4CA + 3CB + FS 3CA + 2CB + FS 2CA + 2CB + 3F 4CDA + FS 3CDA + FS 3CDA + 3F 2CDA + 2F 4CSA + FS

Example:

3CDA + 2CB + FS =

3 Compressors, one Digital, suction group A + 2 Compressors, suction group B + one fan, Speed controlled

4CA + FS 4CA + 4F 3CSA + FS 3CA + FS 3CA + 3F None

The following options are available here:

2 Comp + 1 Cond = suction group A + B and condenser Comp. + Cond. = suction group A and condenser Condenser = condenser only

When the Plant type has been selected, it will al-

Compressor = suction group A only None

low several settings to be made. For example:

Continue to the next menus. All settings are explained on the pages that follow.

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Start/stop

Plant type

Suction A

Main switch Main switch

Start and stop regulating here. The conﬁguration settings will require that regulating is stopped. If you try to enter a conﬁguration setting when regulating has started, the controller will ask if regulating should be stopped. When all settings have been made and the main switch is set to “ON”, the controller will enable the display of the various measurements. Regulation will start. (If an external main switch has been deﬁned, it must also be “ON” before regulating starts.)

Extern Main swich External main switch

It is possible to connect an external switch which can be used to start and stop regulating. Both the internal and external main switch must be ON before regulating starts. An external main switch can be deﬁned in the menu “Plant type” - “Main switch via DI”.

Select Plant type Plant settings:

The following must be regulated:

• Compressor group

• Condenser group

• One compressor group (A) + One condenser group

• Two compressor groups (A) and (B) + One condenser group

Refrigerant type Refrigerant setting

Before refrigeration is started, the refrigerant must be deﬁned. You may choose between the following refrigerants: R12, R22, R134a, R502, R717, R13, R13b1, R23, R500, R503, R114, R142b, user deﬁned, R32, R227, R401A, R507, R402A, R404A, R407C, R407A, R407B, R410A, R170, R290, R600, R600a, R744, R1270, R417A, R422A, R413A, R422D, R427A, R438A, R513A (XP10), R407F,

R1234ze, R1234yf, R448A, R449A, R452A.

Warning: Wrong selection of refrigerant may cause damage to the compressor. Other refrigerants: Here Setting "user deﬁned" is selected and then three factors - fac1, fac2 and fac3 and temperature glide (if necessary).

Unit of setpoints Device for controlling compressor and condenser

Select pressure or saturation temperature. (Can be set during initial set-up and must not be subsequently changed.)

Night signal via DI Night time operation via DI signal

Deﬁne an external switch here, so that the regulation reference can be raised and lowered externally.

1. Set the function to “Yes”

2. Go to I/O conﬁguration and select an available digital input. Set this input to “Night condition”

3. Next, deﬁne whether the function is to be active when the signal is ON, or when it is OFF.

Main Switch via DI Main switch via DI

Deﬁne an external main switch here, so that regulation can be started and stopped externally.

1. Set the function to “Yes”

2. Go to I/O conﬁguration and select an available digital input. Set this input to “Main switch”

3. Next, deﬁne whether the function is to be active when the signal is ON, or when it is OFF.

Mains frequency Frequency

Set the net frequency

Alarm output Alarm relay

Deﬁne an alarm relay here that will be activated in the event of an alarm.

1. Select the alarm priority that will activate the relay

• No relay

• Critical alarm

• Severe alarm

• All alarms

2. Go to I/O conﬁguration and select an available digital output. Set this output to “Alarm”

3. Next, deﬁne whether the relay will be active (pulled) when the alarm is ON, or when it is

OFF.

Alarm buzzer Alarm sound

Here the sound generator can be deﬁned to emit a sound in the event of an alarm. Select which alarm priority will activate the sound generator:

• No buzzer

• Critical alarm

• Severe alarm

• All alarms (In the event of an alarm, the sound generator can be stopped by moving across the active alarm screen; see page 6)

Control status Regulation status

SW: 1.6x

On / Oﬀ

Fac: None

Temp. / press Fac: Saturated

DI-demand

No / Yes Fac: No

DI-demand

No / Yes Fac: No

50 Hz / 60 Hz Fac: 50 Hz

DO-demand

Fac: No relay

Fac: No buzzer

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Control status Read the status of the control circuit here e.g.:

• No comp. - No compressor capacity available

• Normal ctrl - Normal control

• Alarm Comp. - Cannot start compressor due to alarm condition

• ON timer - Cannot stop compressor due to ON timer restriction

• Start timer - Cannot start compressor due to Start timer restriction

• Normal ctrl - Normal control - no compressor staging

• Inj. On Delay - Waiting for injection on delay to expire

• Cascade

• 1st comp del - First compressor run timer

• Pump down - Last compressor running to pump down limit

• Sensor error - Emergency control due to sensor error

• Load shed - Load shedding function active

• Sd High - Capacity control in High Sd safety prevention mode

• Pc High - Capacity control in High Pc safety prevention mode

• Manual ctrl - Capacity control in manual mode

• Main switch OFF - OFF

Actuel zone You will be able to see how the regulation is in relation to the reference here:

P0 error: No regulation

- Zone: The desired pressure is below the reference value NZ: The pressure is in place in relation to the reference value + Zone: The desired pressure is above the reference value

Control temp. The current value of the regulation sensor can be read here

Reference The total regulation reference can be read here

Running capacity Here the connected capacity can be read as a % of total capacity

Requested capacity Here the preferred connected capacity can be read as a % of total capacity

No. of running comp. The number of compressors in operation can be read here

PoA Pressure The measured pressure for the PoA pressure transmitter can be read here

ToA Saturated temp. The measured PoA pressure converted to temperature can be read here

MC PoA oﬀset The size of a reference displacement on Po required from the system unit

(suction pressure optimisation function) can be read here

Pc Pressure The measured pressure for pressure transmitter Pc can be read here

Tc Saturated temp. The measured Pc pressure converted to temperature can be read here

Day / Night status The status of the day/night function can be read here

Load shed The status of the load shed function can be read here

Injection ON A The status of the injection ON signal sent to the evaporator controllers can be read here

MC Load Shedding The status of the load shed signal received from the system device can be read here

MC Night Setback The status of the night increase signal received from the system device can be read here

Control settings Regulation settings

Control mode Regulation type

The regulation is normally set to “Auto”, but it can be changed to “Oﬀ” or “Manual”. When setting to “Manual”, a forced capacity setting can subsequently be entered in %.

Setpoint Enter the set point for the regulation (regulation reference = set point + diﬀerent oﬀsets) here

An oﬀset can originate from a night increase signal or from an override function on the system device.

Neutral zone Set the neutral zone around the reference here. Also see the illustration on page 3.

Night oﬀset If necessary, set the value by which the reference will be raised at night.

Keep the setting at 0 if regulating with Po optimisation from a system device.

Max Reference Set the highest permissible regulation reference here

Min Reference Set the lowest permissible regulation reference here

PI control selection Set how quickly the PI regulation must react here: 1 = slowly, 10 = very quickly.

(For “Custom” setting 0, the special settings options will open, i.e. Kp, Tn and time settings around the neutral zone. These options are only for trained staﬀ.)

Gain factor Kp The ampliﬁcation factor, Kp (can only be seen and set when the previous menu is set to “0”)

Integration time Tn Integration time Tn (see above) + Zone rate of change Change coeﬃcient for + zone (see above)

- Zone rate of change Change coeﬃcient for - zone (see above)

First step runtime At start-up, the cooling system must have time to cool down before PI regulation takes over

the regulation role and can cut in the next compressor. Set the time before the next compressor may be started here.

MAN / OFF / AUTO Fac: AUTO Min: 0 % Max: 100%

Min: -80°C (-1.0 bar) Max: 30°C (50 bar) Fac: -15°C (3.5 bar)

Min: 0,1 K (0.1 bar) Max: 20 K (5.0 bar) Fac: 6 K (0.4 bar)

Min: -25 K (-5.0 bar) Max: 25 K (5.0 bar) Fac: 0 K (0.0 bar)

Min: -50°C (-1.0 bar) Max: 80°C (50.0 bar) Fac: 80°C (40.0 bar)

Min: -80°C (-1.0 bar) Max: 25°C (40.0 bar) Fac: -80°C (-1.0 bar)

Min: 0 (custom) Max: 10 Fac: 5

Min: 0 s Max: 300 s Fac: 120 s

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Pump down Pump-down function

To avoid too many compressor starts/stops at a low load, it is possible to deﬁne a pumpdown function for the last compressor. In this case, the compressor will be cut out when the current suction pressure is down at the set “Pump-down limit Po”. (The setting must be greater than the safety limit for low suction pressure “PoA Min Limit”.)

Load shed limit Capacity limitation at “low shed signal”

Set how much compressor capacity can be cut in when a signal is received from either a DI input or a system device via data communication.

Emergency cap. day Emergency capacity in the event of a malfunction of the regulation sensor (suction pressure

sensor) Set the desired capacity that will apply during daytime operation. (If the S4 media temperature sensor becomes damaged/defective, use Po for regulation.)

Emergency cap. night Emergency capacity in the event of a malfunction of the regulation sensor (suction pressure

sensor) Set the desired capacity that will apply during night operation. (If the S4 media temperature sensor becomes damaged/defective, use Po for regulation.)

Comp. start delay Delay of compressor start after forced closing of expansion valves (at the end of a forced

close signal) The delay will result in the system device receiving a start signal for all the evaporator controls involved before the ﬁrst compressor is started.

Injection OFF delay Delay of the forced closing of expansion valves, if the controller calls for cut in of compres-

sors, but the compressors are in a locked situation and therefore cannot start.

Conﬁguration Conﬁguration

Control sensor Select the regulating sensor for the suction circuit:

• Pressure transmitter Po

• Media temperature sensor S4 (brine regulation). (Po is used for safety)

Compressor mode Set the type of compressor to be used for regulation:

• Multi all:****) All compressors have unloaders

• Multi + Single:****) First compressor has unloaders. The remaining ones are one-step units

• Speed+Multi: ***) First compressor is speed-controlled. The remaining ones are with unload-

ers.

• Speed+Single: ***) First compressor is speed-controlled. The remaining ones are one-step units

• CRII4+Multi **) First compressor is CRII4 compressor. The remaining ones are with unloaders

• CRII4+Single **) First compressor is CRII4 compressor. The remaining ones are one-step units

• Stream 4+Multi: **) First compressor is a stream compressor. The remaining ones are with

unloaders

• Stream 4+Single: **) First compressor is a stream compressor. The remaining ones are

one-step units

• Digital scroll: *) First compressor is a digital scroll. The remaining ones are one-step units

• Single-step only: All are one-step compressors

• None:

No. of compressors Set the number of compressors on the suction circuit

This is a total amount. (If both suction groups are selected, the max. number will be 4 for A and 4 for B.)

Lead comp. size Set the nominal compressor capacity for the ﬁrst compressor (it is deﬁned under

“Compressor mode”) That is, the capacity of either a “Digital scroll”, “Stream”, “Variable speed CRII” or “First compressor with unloaders”

Comp. size Set the nominal compressor capacity of the other compressors

For single-step only: All are of the same size, including the ﬁrst. For unloader all: All are of the same size, including the ﬁrst.

VSD Min. speed ***: For speed

Min. speed at which the compressor will cut out

VSD Start speed ***: For speed

Minimum speed at which the compressor will start (must be set to a higher value than “VSD Min. speed”)

VSD Max speed ***: For speed

Highest permitted speed for compressor

PWM period time *, **: For “Scroll” and “Stream”

Set the period time for the unloader valve (on time + oﬀ time)

CRII Period time **: For CRII

Set the period time for the unloader valve (on time + oﬀ time)

Yes /No Fac: No

Min: -80°C (-1.0 bar) Max: 30°C (50.0 bar) Facb: -40°C (0.3 bar)

Min: 0 % Max: 100% Fac: 100%

Min: 0 % Max: 100% Fac: 50%

Min: 0 % Max: 100% Fac: 25%

Min: 0 s Max: 180 s Fac: 30 s

Min: 0 s Max: 300 s Fac: 120 s

AI-demand

Po / S4 Fac: Po

DO-demand / AO-demand

Fac: Single step only

DO-demand

Min: 1 Max: 8 Fac: 0

Min: 1 kW Max: 100 kW Fac: 1 kW

Min: 10 Hz Max: 60 Hz Fac: 30 Hz

Min: 20 Hz Max: 60 Hz Fac: 45 Hz

Min: 40 Hz Max: 120 Hz Fac: 60 Hz

Min: 10 s Max: 20 s Fac: 20 s

Min: 10 s Max: 20 s Fac: 60 s

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Comp. 1 min cap.

*: For scroll and CRII Minimum capacity in the time period (without a minimum capacity the compressor will not be cooled)

Comp. 1 start cap

*: For scroll and CRII Start capacity: the compressor will only start when the capacity requirement reaches the value

Comp. 1 Sd temp. *, **: For “Scroll”, “Stream” and CRII

Deﬁne whether the controller should monitor the discharge gas temperature Sd from the compressor (NTC 86K or Pt 1000 Ohm).

Comp. 1 Sd max. *, **: For Scroll, Stream, CRII and yes to “Comp.1 Sd temp”

Set the maximum Sd temperature

No.of unloaders ****: For compressor with unloaders

Set how many unloaders there are on the compressor

Comp. safety input Compressor safety circuit

Deﬁne whether a DI input should be reserved for registration of each compressor safety circuit

LP switch via DI Low pressure safety circuit

Deﬁne whether a DI input should be reserved for registration of the signal from an LP switch

Load shedding via DI Load limitation

Deﬁne whether a DI input should be reserved for registration of the signal from a power meter

• None:

• DI: Load limitation must follow a DI input

• Night Mode: Load limitation must follow the status of the day/night signal. (The day/night signal can be received via a DI input, via time schedule or network.)

Sd disch. gas temp. Shared discharge temperature

Deﬁne whether signals from a common Sd sensor on the suction line (Pt 1000) should be received

Ss suction superheat Monitoring of superheat

Deﬁne whether a signal from a common Ss sensor on the suction line should be received

Injection ON fct. Stop injection into evaporators

If the compressors are prevented from starting, stop injection into the evaporators. Here deﬁne whether the function should be active and how the signal should be communicated. No: The function is not used Network: The controller sends a signal to the system unit, which then forwards it to the evaporator controls Relay: The function reserves a relay that pulls in if all compressors are stopped. All evaporator controls must be wired to this signal from the relay.

Compressor timers Compressor timers

Lead comp. Min ON Min. On-time for ﬁrst compressor

Set a forced On-time here during which the compressor will remain in operation before it can be switched oﬀ again. The setting is to prevent incorrect operation. To prevent a compressor breakdown, the setting must be made in accordance with the requirements of the compressor supplier.

Lead comp. Min OFF Min. Oﬀ-time for ﬁrst compressor

Set the forced Oﬀ-time during which the compressor must be oﬀ before it can be switched on again. The setting is to prevent incorrect operation.

Lead comp. Restart Min. period of time for re-starting the ﬁrst compressor.

Set the forced Oﬀ-time during which the compressor must be oﬀ before it can be switched on again. The setting is to prevent incorrect operation. To prevent a compressor breakdown, the setting must be made in accordance with the requirements of the compressor supplier.

Lead comp. Safety delay

Delay time before compressor no. 1 cut out for reasons of safety The time begins when a signal is received on the DI input (conﬁgure the DI input via “Conﬁguration” and “Comp. safety inlet”).

Comp. Min ON Min. On-time for remaining compressors

Set a forced On-time here during which the compressor will remain in operation before it can be switched oﬀ again. The setting is to prevent incorrect operation.

Comp. Min OFF Min. Oﬀ-time for remaining compressors

Set the forced Oﬀ-time during which the compressor must be oﬀ before it can be switched on again. The setting is to prevent incorrect operation.

Comp. Restart Min. period of time for restarting remaining compressors

Set the forced Oﬀ-time during which the compressor must be oﬀ before it can be switched on again. The setting is to prevent incorrect operation.

Min: 10% Max: 50% Fac: 10%

Min: 10% Max: 60% Fac: 30%

AI-demand

No / Yes Fac: No

Min: 0°C Max: 195°C Fac: 125°C

DO-demand

Min: 1 Max: 3 Fac: 1

DI-demand

Yes /No Fac: Yes

DI-demand

Yes /No Fac: No

DI-demand

Yes /No Fac: No

AI-demand

Yes /No Fac: No

AI-demand

Yes /No Fac: No

DO-demand

No /Network /Relay

Fac: No

Min: 0 min Max: 60 min Fac: 0 min

Min: 0 min. Max: 30 min Fac: 0 min

Min: 1 min. Max: 60 min Fac: 4 min

Min: 1 min. Max: 10 min Fac: 1 min

Min: 0 min. Max: 60 min Fac: 0 min

Min: 0 min. Max: 30 min Fac: 0 min

Min: 1 min. Max: 60 min Fac: 4 min

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Suction B

Condenser

Comp. Safety delay Delay time before compressors cut out for reasons of safety

The time begins when a signal is received on the DI input (conﬁgure the DI input via “Conﬁguration” and “Comp. safety inlet”).

Compressor status Compressor status

Comp. 1 Sd gas Read the Sd temperature of the compressor here.

Comp. 1 status Read the operating status for compressor 1 here. The following information may appear:

Alarm - Alarm situation Main Sw. oﬀ - Compressor is stopped Manual ctrl. - Compressor is cut out on safety input (DI safety input) High Sd temp. - Stopped due to high Sd temperature Ready - Compressor is ready to start OFF timer - Compressor is waiting for Min OFF timer to expire Min. ON timer - Compressor is waiting for Min ON timer to expire Running - Compressor is running Disabled - Compressor has been taken out of operation (compressor service)

Comp. 2.... The same function for the remaining compressors

Compressor capacity Compressor capacity

Comp. 1 cap Read the connected capacity of the compressor (0-100%) here

Comp. 2...... The same function for the remaining compressors

Compressor runhours Compressor run hours

Reset runtime/cycles Reset all of the hour counters and start counters for the subsequent compressors here.

Comp.1 Runtime L Read the total operating time of the compressor (in hours) here

Comp.2..... The same function for the remaining compressors

Compressor cycles Compressor cycles

Comp.1 Cycle total Read the number of times the compressor has been started here

Comp.2..... The same function for the remaining compressors

Compressor service Compressor service

Comp.1 out of service The compressor can be taken out of operation, so that the controller regulates without this

compressor. No = Normal regulation Yes = Regulating is carried out without this compressor, and no alarms are generated by it.

Comp.2..... The same function for the remaining compressors

Suction group B. Please see descriptions under suction group A (Bitzer CRII can not be used in suction group B.)

Control status Regulation status

Control status Here you can read the status of the condenser circuit, e.g.:

• Main Sw. oﬀ - Main switch = OFF

• Ready - Capacity control is ready

• Running - Capacity control is in normal run mode

• Capacity control is stopped because all compressors are stopped

• Manual ctrl - Capacity control is set in manual control mode

• High Pc/Sd - Capacity forced to 100% due to High Pc/High Sd prevention functions

• Safety limit - Capacity forced to 100% due to external HP switch/HP safety/Sd safety limit violation

• Night limit - Capacity control limited due to night silencer limitation

Control temp. The current value of the regulation sensor can be read here

Reference The total regulation reference can be read here

Running capacity Here the connected capacity can be read as a % of total capacity

Requested capacity Here the preferred connected capacity can be read as a % of total capacity

No. of running fans The number of fans in operation can be read here

Tc Saturated temp. The measured Pc pressure converted to temperature can be read here

Pc Pressure The measured pressure for pressure transmitter Pc can be read here

S7 Media Here the measured media temperature with sensor S7 can be read (only if S7 has been

selected as the regulation sensor during “Fan conﬁguration”)

Sc3 air on cond. The measured outdoor temperature with sensor Sc3 can be read here

Heat recovery status Here the status of the heat recovery function can be read

HP safety switch The status of the HP safety switch can be read here

Control settings Control settings

Control mode Regulation type

The regulation is normally set to “Auto”, but it can be changed to “Oﬀ” or “Manual”. When setting to “Manual”, capacity can then be forced set in %.

Setpoint Enter the set point for the condenser regulation here.

Also set a value if regulating with a ﬂuid reference (set point value used in the event of an outside temperature sensor error).

Min: 1 min. Max: 10 min Fac: 0 min

Yes /No Fac: No

MAN / OFF / AUTO Fac: AUTO Min: 0 % Max: 100%

Min: -25°C (-1.0 bar) Max: 90°C (159 bar) Fac: 35°C (15.0 bar)

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Page 13

Sc3 oﬀset Temperature oﬀset for regulation with ﬂuid reference.

Regulation reference = Sc3 measurement + Sc3 oﬀset

Min. reference Set the lowest permissible regulation reference here

Max. reference Set the highest permissible regulation reference here

Heat recocery SP Temperature set point for heat recovery function (only when the function is selected during

conﬁguration)

Heat rec. ramp down Ramp-down of regulation reference after heat recovery

Set how quickly the reference for condenser pressure should be made after heat recovery ends. Enter the change in degrees Kelvin per minute.

Capacity limit night Capacity limitation at night

The speed of the fans can be limited here when regulating using speed control. During step-by-step activation, the start of the step-by-step process is limited.

Gain factor Kp Ampliﬁcation factor for PI regulation

If the Kp value is lowered, regulation runs more smoothly

Integration time Tn Integration time for PI regulation

If the Tn value is increased, regulation will run more smoothly

Fan conﬁguration Conﬁguration of fans

Control sensor Selection of regulation sensor:

• Pc pressure transmitter

• S7 media temperature sensor (Pc must be installed for safety monitoring)

Reference mode Set the reference for regulation here

• Fixed reference; the reference here will be the deﬁned set point

• Variable reference; the reference here will follow the outside temperature, which is meas-

ured with Sc3.

Capacity ctrl. mode Set the way in which the fans should be controlled here

• Variable; the fans are controlled by a 0-10 V signal from an analogue output. If it is deﬁned in “VSD Start via DO”, a relay will be able to start and stop the frequency converter.

• Step; on/oﬀ control of fans will be via relays

• Variable + step. The signals are parallel, so external wiring can switch over to step, e.g. if the frequency converter fails.

No. of fans Enter the number of fans here.

For step-by-step activation, select the number of relays. The relays will cut in/out sequentially, e.g. 123-321. For speed control, select 1 or higher. No relay is reserved, but the setting makes it possible to deﬁne the monitoring of fans.

Control type Normally, PI-regulation is used, but this can be changed to a P-regulation if the design of the

system necessitates this.

• PI Ctrl: Regulation is carried out here with as little deviation between the reference and measurement as possible.

• P-band ctrl: Capacity is cut in here after proportional regulation.

VSD Start speed Set the start value of the frequency converter here.

The value must be higher than the VSD min. speed value.

VSD Min speed Set the minimum speed of the frequency converter here.

If lower capacity is required, this minimum speed should be maintained all the way down to 0% capacity. At 0% capacity, the system stops completely.

VSD Start via DO Deﬁne whether a relay should be connected to the frequency converter start/stop function

here:

• No: no relay

• Yes: the relay pulls in when the frequency converter needs to be in operation.

Monitor fan safety Deﬁne whether safety monitoring of the condenser fans should be performed.

• None: no monitoring

• Individual: a DI input is reserved for each fan

• Common: a DI input that is common for all condenser fans is reserved .

Fan at comp. OFF Select the way in which the fans should be controlled when all the compressors have

stopped.

• Normal regulation: Fans to be controlled in compliance with normal regulation.

• Energy-optimised: Fan capacity will be maintained at between 0 and 49% in a p-band of 5-15 K above reference.

Heat recovery via DI Deﬁne whether a heat recovery cycle should be started with a signal on a DI input here.

• No: No function

• Yes: A DI input is reserved. When a signal is registered, the heat recovery function reference will become active.

Min: 0 K Max: 20 K Fac: 6 K

Min: -25°C (-1.0 bar) Max: 100°C (159 bar) Fac: 10°C (5.0 bar)

Min: -25°C (-1.0 bar) Max: 100°C (159 bar) Fac: 50°C (35.0 bar)

Min: 20°C (-1.0 bar) Max: 90°C (159 bar) Fac: 50°C (30.0 bar)

Min: 0,1 K Max: 100 K Fac: 1 K

Min: 0 % Max: 100% Fac: 100%

Min: 0.5 Max: 50 Fac: 10

Min: 10 s Max: 900 s Fac: 180 s

AI-demand

Pc / S7 Fac: Pc

AI-demand

Setpoint / Floating Fac: Setpoint

AO-demand

Step / Speed Fac: Step

DO-demand

Min: 0 Max: 8 Fac: 0

P / PI Fac: PI

Min: 0% Max: 60% Fac: 35%

Min: 0% Max: 40% Fac: 20%

DO-demand

Yes / No Fac: No

DI-demand

Common /Individual Fac: None

Normal/Optimized Fac.: Normal

DI-demand

Yes / No Fac: No

AK-PC 551 User Guide RS8GY402 © Danfoss 2016-11 13

Page 14

Fan status Fan status

Fan speed Here a reading of the desired condenser fan capacity is provided in %

VSD start/stop Fan operation (frequency converter) status can be read here

Fan 1 The status of relay 1 (step 1 or relay for frequency transformer) is indicated here

Fan 2..... The status of relay 2, 3, etc. (step 2, 3, etc.) is indicated here

Fan Runhours Fan Run hours

VSD Runtime total The number of hours the fans have been in operation (frequency converter operation) can

Fan 1 Runtime total The number of hours fan relay 1 has been in the On-position (frequency transformer

Fan 2..... The same function for the remaining fans

Fan cycles Number of fans starting

VSD cycles The number of fan starts (frequency converter) can be read here

Fan 1 Cycles total The number of times fan relay 1 has been in the On-position (frequency converter

Fan 2... The same function for the remaining fans

Safety monitoring

PoA Min limit Safety limits for min. PoA

PoA Max alarm Alarm limit for high PoA

PoA Max delay Delay time for issuing a PoA max. alarm

Superheat Min lim A Alarm limit for insuﬃcient superheating

Superheat Max lim A Alarm limit for excess superheating

Superheat delay A Delay time before alarm is generated for insuﬃcient or excess superheating

SdA Max limit Safety limit for max. SdA

PoB Min limit Same settings for a suction group B

PoB Max alarm

PoB Max delay

Superheat Min lim B

Superheat Max lim B

Superheat delay B

SdB Max limit

Pc max limit Safety limit for max. Pc

Tc Max limit Safety limit for max. Tc

Pc Max delay Time delay for Pc max. alarm

HP switch via DI Signal from an HP switch

Safety restart time Delayed start-up following safety cut-out

Sensor alarm reset Reset alarm after sensor error

be read here

has been On) is indicated here

has been on) is indicated here The controller checks that the fan has been active within the last 24 hours. If not, it will be forced to start in 5 minutes, in rotation with the other fans.

If a low value is registered, all compressors will cut out

If a high value is registered, an alarm will be generated

If a higher value is registered during a load limitation, the load limitation will be cancelled until Po has returned to the reference.

(Superheating is measured in the suction line by PoA and SsA.)

At 10 K under the set value, the compressor capacity will be reduced, and the entire condenser capacity will cut in. If the threshold is exceeded, the entire compressor capacity will cut out.

If Pc exceeds the value set here minus 3 K, the entire condenser capacity will cut in, and compressor capacity will be reduced by 1/3 for every 30 seconds. If Pc exceeds the threshold value, the entire compressor capacity will immediately cut out, and an alarm will be generated when the delay time expires.

The above setting for Pc max. limit can be read as a temperature here.

The alarm will only be generated when the time delay has elapsed.

Deﬁne whether a signal is to be received on a DI input here. The status of the signal can be read, and an alarm can be linked to it. Once a signal is received, compressor capacity will cut out.

If a safety cut-out has occurred due to “Sd max. limit”, “Pc max. limit” or “Po min. limit”, the compressors must be kept stopped for a deﬁned period of time. The amount of time can be set here.

When a sensor error has occurred, an O.K. signal must be registered within a speciﬁed number of minutes before the controller resets the alarm. The regulation will be resumed as soon as the sensor signal is O.K.

Min: -120°C (-1.0 bar) Max: 30°C (159 bar) Fac: -40°C (0.5 bar)

Min: -30°C (-1.0 bar) Max: 100°C (159 bar) Fac: 100°C (5.0 bar)

Min: 0 min. Max: 240 min. Fac: 5 min.

Min: 0 K Max: 20 K Fac: 0 K

Min: 20 K Max: 80 K Fac: 80 K

Min: 0 min. Max: 60 min. Fac: 5 min.

Min: 0°C Max: 195°C Fac: 80°C

Min: -1 bar Max: 159 bar Fac: 40 bar

Min: 0 min. Max: 240 min. Fac: 0 min.

DI-demand

Yes /No Fac: No

Min: 0 min. Max: 60 min. Fac: 1 min.

Min: 0 min. Max: 30 min. Fac: 10 min.

14 User Guide RS8GY402 © Danfoss 2016-11 AK-PC 551

Page 15

General functions

Digital input alarms General on/oﬀ alarm

No. of DI alarm fct. 1. Deﬁne how many general alarms there should be

DI1 Alarm text The following alarm texts can be selected:

Di1 Alarm delay Delay time for the DI1 alarm

DI2....3 The same setting option for a DI2 alarm and a DI3 alarm.

Thermostat General thermostat

Thermostat cut in Here set the temperature value at which the thermostat will cut in

Thermostat cut out Here set the temperature value at which the thermostat will cut out

Thermostat temp. The current sensor temperature of the thermostat can be read here

System

Display Select views on the display

Language Choose from the following languages:

Engineering units Device

Pressure units Pressure unit

Temperature units Temperature unit

Time format Time format

Screen saver time Screen saver time

User logout time Log-oﬀ time

Display contrast Adjust contrast

Here you can deﬁne up to 3 alarms that are not related to the regulation function. When a signal is received on the input, the controller will generate an alarm, but only after the related delay time has elapsed. The alarm can be deﬁned to be active for an on/oﬀ signal. An alarm text can be entered for the alarm. This text can be seen in the display and can be sent to a system device.

1. Deﬁne the appurtenant alarm text

2. Set the delay time for the alarm

3. Go to I/O conﬁguration and select an available digital input. Set this input to “General

alarm (no.)”

4. In the subsequent menu, deﬁne whether the alarm is to be active for an on/oﬀ signal.

• General alarm

• High pressure alarm

• Low pressure alarm

• High temperature alarm

• Low temperature alarm

• Oil level alarm

• Oil temperature alarm

• Liquid level alarm

• Leak detection alarm

• Inverter fault

One general thermostat can be deﬁned.

1. Deﬁne the function

2. Go to I/O conﬁguration and select an available analogue input. Set this input to

“Saux thermostat”

3. Go to I/O conﬁguration and select an available relay output. Set the output to “thermostat”.

(But only once the sensor input has been deﬁned and the main switch has been set to “On”.)

English, German, French, Danish, Spanish, Italian, Portuguese, Dutch, Russian, Polish, Czech, Turkish, Hungarian, Croatian, Serbian, Romanian

Select SI or Imperial (when setting the compressor capacity with U.S. values).

Select bar or PSIG

Select °C or °F.

Choose 12-hour or 24-hour format.

If no buttons have been pushed for a speciﬁc period of time, the light in the display will be minimised. The light level will be restored upon renewed activity.

If buttons have not been pressed within a speciﬁed period of time, the screen will return to the overview display. Afterwards, the user will have to log on again. If the time is changed, the new time will apply the next time the user logs in. If you log out here without waiting for the time-out period to elapse, go to the overview display and hold down the “X” button for 3 seconds.

DI-demand

Min: 0 Max: 3 Fac: 0

Min: 0 min. Max: 360 min. Fac: 5 min.

AI-demand

Yes / No Fac: No

Min: -50°C Max: 150°C Fac: 5°C

Min: -50°C Max: 150°C Fac: 10°C

Fac: UK English

SI / Imperial Fac: SI

Bar / PSIG Fac: bar

°C / °F Fac: °C

12 / 24 Fac: 24 h

Min: 1 min. Max: 60 min. Fac: 1 min.

Min: 1 min. Max: 60 min. Fac: 2 min.

Min: 0 Max: 100 Fac: 30

AK-PC 551 User Guide RS8GY402 © Danfoss 2016-11 15

Page 16

Password Access code

Password level 1

Password level 2

Password level 3

Real time clock Date and time

Weekly schedule Weekly plan

Monday open Time of opening, Monday

Monday close Time of closing, Monday

Tuesday op..... Times for remaining weekdays

Network Network

Modbus Address Set the address of the controller here if it is connected to a system device via data communi-

Baudrate The system unit usually communicates with 38.4.

Serial mode The value must not be changed

Reset to factory Return to factory settings

I/O conﬁguration

Here you can select functions for the individual inputs and outputs. To prevent faulty settings, only select functions that have been set up via the conﬁguration menus for the suction groups and the condenser.

For digital outputs, deﬁne whether the function will be active for an activated or deactivated relay. For digital inputs, deﬁne whether the function/alarm will be active for an interrupted or shut-oﬀ switch. For analogue outputs, deﬁne whether the output signal should be 0-5 V or 0-10 V For analogue inputs, deﬁne:

Temperature sensors: Normally, the sensor type is a Pt1000 model, but for digital scroll/stream discharge gas temperature monitoring, an NTC 86K@25°C can also be selected. Calibration value (+/- 10°C) Pressure sensors: Signal type: 0-20mA, 4-20mA, AKS32 (1-5V) or AKS32R (10-90% ratiometric of 5 V supply voltage) Minimum and maximum pressure range Calibration value (+/- 5.0 bar) If you have used “Quick conﬁgurations” or “Wizard” to set up the controller, the inputs and outputs will be automatically set up (for additional information, see the “Quick conﬁguration” or “Wizard” sections) Limitations: PWM outputs for digital scroll or stream compressors can only be selected on DO5 or DO6 Pressure transmitters with a current signal of 0-20 mA or 4-20 mA must be placed on analogue inputs AI1-AI4 Please note: If a function has been connected to an input or output and is subsequently deselected in the conﬁguration, the function in question will be marked with an exclamation mark (!). In this case, you must either activate the function in the conﬁguration, or deselect the function on the input or output in question.

Digital outputs

1: 2: 3: 4: . . 8:

Digital inputs

1: 2: 3: .. 8:

The settings in the controller can be protected with three levels of access codes. Level 1: End user settings, such as changing the weekly plan Level 2: Adjusting installer level Level 3: Conﬁguration of system settings (conﬁguration menu) The access code is a number between 001 and 999.

Used by weekly plan and alarm function.

Set the opening and closing hours of the store here The times can be used to change the regulation reference for suction pressure and for lower fan speeds at night.

cation.

If it is changed in the system unit to for example, "SLV" mode (19.2), setting must also be changed to 19.2 here in the controller.

If this function is set to “YES”, all settings will be returned to factory default settings, and the alarm list will be cleared.

On/oﬀ outputs

When a function that needs to use an output is deﬁned, it will be possible to select this function on one of the available relay outputs. Select a relay and continue with the setting. In the last setting you will have the option of selecting the function you wish to connect to the relay and whether the function is to be active when the relay is activated or deactivated. Attention! Relay outputs must not be inverted at unloader valves. The controller inverts the function itself. There will be no voltage at the bypass valves when the compressor is not in operation. Power is connected immediately before the compressor is started. If it is a function that requires frequent switching between on/oﬀ (e.g. unloader on a scroll compressor, a Stream or a Bitzer CRII), use the solid state relay for this connection. There are solid state relays on output numbers 5 and 6.

On/oﬀ inputs

When a function is deﬁned that uses an input, it will be possible to select this function on one of the available on/oﬀ inputs. Select an input and continue on into the setting. In the ﬁnal setting you will have be able to select which function you wish to connect to the input.

Fac: 100

Fac: 200

Fac: 300

Year, month, date Hours, minutes

Hours, minutes

Min: 0 1 Max: 120 Fac: 1

Fac: 384

Fac: 8E1

On Oﬀ

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Page 17

Analog outputs

3: 4:

Analog inputs

1: 2: 3: 4: . . 8:

I/O Status

Digital outputs

1: . 8:

Digital inputs

1: . 8:

Analogue outputs

3: 4:

Analog inputs

1: . 8:

I/O Summary

DO: Max 8, Used:__ DI: Max 8, Used:__ AO: Max 2, Used:__ AI: Max 8, Used:__

I/O Manual control

Digital outputs Manual control of a relay output

Analog outputs Manual control of analogue output

Alarm priorities

General

Standby mode: Sensor error: Refrigerant: Output in MANUAL:

Suction group A

Low pressure: High pressure: Compressor safety:

Suction group B

Low pressure: High pressure: Compressor safety:

Condenser

High pressure: Fan safety:

0-10 V outputs

When a function has been deﬁned that needs to use a variable voltage outlet, it will be possible to select this function on one of the available AO outputs (only AO3 and AO4 are available). Select one of the two outputs and continue on in the setting process. In the last setting you will have the option of selecting which function you wish to link to the output.

Analogue inputs

When a function is deﬁned that needs to use a temperature sensor or a pressure transmitter, it will be possible to select this function on one of the available AI inputs. Select an input and continue on into the setting. In the ﬁnal setting you will be able to select which function you wish to connect to the input. Saux is a sensor for a general thermostat. (A type AKS 2050 pressure transmitter, for high pressure, emits a signal as an AKS 32R.)

Status of on/oﬀ outputs

Here you can see if the function is on or oﬀ.

Status of on/oﬀ inputs

Here you can see the status of the function/alarm.

Status of analogue outputs

Here you can see the size of the output signals as a % of max. signal.

Status of analogue inputs

Here you can see pressure and temperature values received by the controller. The values include calibration

Inputs and outputs used

Here you can see how many of the diﬀerent inputs and outputs are available. You can also compare this amount with how many have been conﬁgured. If too many have been deﬁned, an exclamation mark (!) will appear.

Under normal regulation, the function of the relay will be in “Auto”. In the event of an override, the function will be switched to either “On” or “Oﬀ”. Remember to switch to “Auto” when the override is to be completed.

During normal regulation, the function of the output will be “Auto”. In the event of an override, the function must ﬁrst be changed to “Manual”, after which the output signal can be changed from 0-100%. Remember to switch to “Auto” when the override is to be completed.

Alarm priorities

The controller will issue an alarm notiﬁcation if a speciﬁc incident occurs. Each incident is set to indicate the importance of each alarm, but it is possible to modify the importance of each. Choose from between the following priority levels:

Critical: Important alarms that require a high level of attention. Severe: Alarms of intermediate importance Normal: No important alarms Disable: Alarms set to this priority level will be cancelled.

Factory setting for the alarm can be seen on page 21.

0-10 V 0-5 V

Pressure signal:

AKS 33 AKS 32R AKS 32 2-10 V 0-20 mA 0-10 V 0-5 V

Temperature signal:

NTC-86K Pt 1000 ohm

None

Auto / On / Oﬀ

Auto / Man

0-100%

Critical Servere Normal Disable

AK-PC 551 User Guide RS8GY402 © Danfoss 2016-11 17

Page 18

Quick setup

Quick conﬁgurations This setting will reserve inputs and outputs for the following compressors and fans:

The various connections are shown on the next page.

App. no. Display Suction group A Suction group BCondenser

Speed Digital

(Scroll / steam)

17 3CDA + 2CB + FS 1 2 2 x

16 2CDA + 2CB + 3F 1 1 2 3

15 3CSA + 2CB + FS 1 2 2 x

14 2CSA + 2CB + 3F 1 1 2 3

13 4CA + 3CB + FS 4 3 x

12 3CA + 2CB + FS 3 2 x

11 2CA + 2CB + 3F 2 2 3

10 4CDA + FS 1 3 x

9 3CDA + FS 1 2 x

8 3CDA + 3F 1 2 3

7 2CDA + 2F 1 1 2

6 4CSA + FS 1 3 x

5 4CA + FS 4 x

4 4CA + 4F 4 4

3 3CSA + FS 1 2 x

2 3CA + FS 3 x

1 3CA + 3 F 3 3

0 None After making a selection, the setting will return to “None”

After making a selection you must:

1. Set the type of refrigerant

2. Check the types of pressure transmitters

3. Check the min. and max. settings on the pressure transmitters

Factory setting: Po A/B = AKS 32R, min=-1.0 bar, max.=12 bar Pc = AKS 32R, min. = -1.0 bar, max. = 34 bar SdA = NTC 86K

Setup Wizard This wizard will lead you through the necessary settings, i.e. a total of approximately

20 to 35 display screens, depending on what is selected along the way. The selection will also result in a connection to a given input and output. You yourself will see this connection in the IO conﬁguration menu. If applicable, see page 20.

1-step 1-step Step Speed

18 User Guide RS8GY402 © Danfoss 2016-11 AK-PC 551

Page 19

Fan

C1A C2A C3A C1B C2B Main

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Fan

safe.

Sw.

C1A C2A C1B C2B Main

Digi

Sw.

C1 C2 C3 C4 Main

C1 C2 C3 Main

C1 C2 Main

Digi

On/Oﬀ Analog Analog Digital

DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8 AO3 AO4 AI1 AI2 AI3 AI4 AI5 AI6 AI7 AI8 DI1 DI2 DI3 DI4 DI5 DI6 DI7 DI8

PoA PoB Pc Sc3 SdA

Alarm Fan

C2B Fan

Speed

VSD

Fan1 Fan2 Fan3 PoA PoB Pc Sc3 SdA

PWM

PoA PoB Pc Sc3 C1A C2A C3A C1B C2B Main

Fan

Alarm C1A

PoA PoB Pc Sc3 C1A C2A C1B C2B Main

Speed

VSD

PoA PoB Pc Sc3 C1A C2A C3A C4A C1B C2B C3B Fan

Speed

PoA PoB Pc Sc3 C1A C2A C3A C1B C2B Main

Speed

Alarm Fan

Speed

VSD

PoA Pc Sc3 SdA

Alarm Fan

Fan

PoA Pc Sc3 SdA

Speed

Alarm Fan

VSD

Fan

PWM

Speed

VSD

Fan2 Fan3 Alarm PoA Pc Sc3 SdA

PWM

Alarm PoA Pc Sc3 SdA

PWM

PoA Pc Sc3 C1 C2 C3 C4 Main

Fan

Alarm C1

PoA Pc Sc3 C1 C2 C3 C4 Main

Speed

Alarm Fan

VSD

Speed

VSD

PoA Pc Sc3 C1 C2 C3 Main

Fan

Alarm C1

PoA Pc Sc3 C1 C2 C3 Main

Speed

Alarm Fan

VSD

Speed

VSD

App. no. Display Output Input

Connections used in “Quick conﬁgurations”

17 3CDA + 2CB + FS C1A C2A C3A C1B C1A

16 2CDA + 2CB + 3F C1A C2A C1B C2B C1A

15 3CSA + 2CB + FS C1A C2A C3A C1B C2B Fan

14 2CSA + 2CB + 3F C1A C2A C1B C2B Fan1 Fan2 Fan3 Alarm C1A

13 4CA + 3CB + FS C1A C2A C3A C4A C1B C2B C3B Alarm Fan

12 3CA + 2CB + FS C1A C2A C3A C1B C2B Fan

11 2CA + 2CB + 3F C1A C2A C1B C2B Fan1 Fan2 Fan3 Alarm PoA PoB Pc Sc3 C1A C2A C1B CB2 Main

10 4CDA + FS C1 C2 C3 C4 C1

9 3CDA + FS C1 C2 C3 C1

8 3CDA + 3F C1 C2 C3 Fan1 C1

7 2CDA + 2F C1 C2 Fan1 Fan2 C1

6 4CSA + FS C1 C2 C3 C4 Fan

5 4CA + FS C1 C2 C3 C4 Fan

4 4CA + 4F C1 C2 C3 C4 Fan1 Fan2 Fan3 Fan4 PoA Pc Sc3 C1 C2 C3 C4 Main

3 3CSA + FS C1 C2 C3 Fan

2 3CA + FS C1 C2 C3 Fan

1 3CA + 3 F C1 C2 C3 Fan1 Fan2 Fan3 Alarm PoA Pc Sc3 C1 C2 C3 Main

0 None

Example of display view:

3CDA + 2CB + FS = 3 compressors, one is digital, suction group A + 2 compressors, suction group B + one fan, are speed-controlled

Page 20

Connections when using Setup Wizard

If you have used the Setup Wizard for the conﬁguration, the controller will automatically assign the selected functions to inputs and outputs in accordance with the following prioritised order:

Digital outputs (DO1-DO8):

• Pulse output for control of the capacity valves for digital scroll, stream or Bitzer CRII will be located on solid state outputs DO5 and DO6

• Compressor start and unloaders for suction groups A and B, respectively

• Fans

• Injection ON

• Alarm

Digital inputs (DI1-DI8):

• Compressor safety inputs for suction groups A and B, respectively

• Fan safety input

• External main switch (start/stop)

• HP safety switch

• LP safety switch for suction groups A and B, respectively

• Night status

• Heat recovery

• Load sheeding

• General alarm inputs DI1-DI3

Analogue outputs (AO3-AO4)

• Compressor speed control for suction groups A and B, respectively

• Condenser speed control

The assignment of functions on the respective inputs and outputs can be regulated in “IO conﬁguration”. Here is an example of 3 compressors and 3 fans:

Analogue inputs (AI1-AI8)

• PoA and PoB suction pressure is located on AI1 and AI2, respectively

• Pc condensation pressure is located on AI3

• Sc3 outside temperature is located on AI4

S4A and S4B media temperature

• S7 media temperature, condenser

• Sd comp. 1 discharge gas temperature for digital scroll/stream compressor for suction groups A and B, respectively

• Ss suction gas temperature for section groups A and B, respectively

• Sd discharge gas temperature for suction groups A and B, respectively

• Saux for general thermostat

In this image you can see how many outputs and inputs your settings have provided.

Page 21

Alarm list

Alarm text Reason Priority

General alarms

Standby mode (Main sw. OFF) Alarm when control is stopped by internal or external Main Switch (DI input "Main Switch") Standby mode Normal

PoA sensor error Pressure transmitter signal from PoA defective

PoB sensor error Pressure transmitter signal from PoB defective

S4A sensor error Temperature signal from S4A media temp. sensor defective

S4B sensor error Temperature signal from S4B media temp. sensor defective

SsA sensor error Temperature signal from SsA suction gas temp. defective

SsB sensor error Temperature signal from SsB suction gas temp. defective

SdA sensor error Temperature signal from SdA discharge gas temp. Sd defective

SdB sensor error Temperature signal from SdB discharge gas temp. Sd defective

Pc sensor error Pressure transmitter signal from Pc defective

S7 sensor error Temperature signal from S7 media sensor on condenser defective

Sc3 sensor error Temperature signal from Sc3 air on condenser defective

Sd Comp. 1A sensor error Temperature signal from "Sd comp. 1A" discharge gas temp. on digital scroll/Stream compressor is

Sd Comp. 1B sensor error Temperature signal from "Sd comp. 1B" discharge gas temp. on digital scroll/Stream compressor is

Saux - sensor error Temperature signal from Saux thermostat sensor is defective

Refrigerant not selected Alarm if no refrigerant has been selected Refrigerant not set Normal

Output in manual mode An output is set in manual mode Output in MAN mode Normal

IO conﬁguration error Not all inputs and output functions have been assigned to hardware Inputs or outputs* (can not be set) Normal

GA1 - "Alarm text" Alarm on general alarm input DI 1 (DI input "Gen. Alarm 1 - alarm text depend upon conﬁgured text) General alarm 1 Normal

GA2 - "Alarm text" Alarm on general alarm input DI 2 (DI input "Gen. Alarm 2 - alarm text depend upon conﬁgured text) General alarm 2 Normal

GA3 - "Alarm text" Alarm on general alarm input DI 3 (DI input "Gen. Alarm 3 - alarm text depend upon conﬁgured text) General alarm 3 Normal

Suction A alarms

PoA Low suction pressure Minimum safety limit for suction pressure PoA has been violated

LP A safety switch cut out Low safety limit for external low pressure switch has been violated (DI input "LP switch A")

PoA High suction pressure High alarm limit for PoA has been exceeded High pressure PoA Critical

SsA High superheat Superheat in suction line A too high (measured by PoA and SsA)

SsA Low superheat Superheat in suction line A too low (measured by PoA and SsA)

SdA High discharge temp. Safety prevention limit for SdA discharge temperature has been exceeded (10K below safety limit) High disch. temp.SdA Critical

Comp. 1A High disch. temp Safety limit for discharge gas temperature of digital scroll/Stream/CRII compressor has been exceeded

Compressor 1-8A safety cut out

Suction B alarms

PoB Low suction pressure Minimum safety limit for suction pressure PoB has been violated Low pressure PoB

LP B safety switch cut out Low safety limit for external low pressure switch has been violated (DI input "LP switch B")

PoB High suction pressure High alarm limit for PoB has been exceeded High pressure PoB Critical

SsB High superheat Superheat in suction line B too high (measured by PoB and SsB)

SsB Low superheat Superheat in suction line B too low (measured by PoB and SsB)

SdB High discharge temp. Safety prevention limit for SdB discharge temperature has been exceeded (10K below safety limit) High disch. temp.SdB Critical

Comp. 1B High disch. temp Safety limit for discharge temperature of digital scroll/Stream compressor has been exceeded

Compressor 1-4B safety cut out

Condenser alarms

Pc High condensing pressure High prevention safety limit for condensing pressure Pc has been violated (3K below safety limit)

HP safety switch cutout High safety limit for external high pressure switch has been violated (DI input "HP switch")

Common fan safety cut out A Fan is reported defective via common safety input (DI input "Fan safety")

Fan 1 safety cut out Fan no. 1-8 is reported defective via individual safety input (DI input "Fan 1-8 safety")

defective

Compressor no. 1-8 A has been cut out on general safety input (DI input "Comp.1-8 A safety")

Compressor no. 1-4 B has been cut out on general safety (DI input "Comp.1-4 B safety")

setting

Sensor error Normal

Low pressure PoA Normal

Superheat A Normal

Compressor safety A Normal

Superheat B Normal

Compressor safety B Normal

High pressure Pc Critical

Fan safety Normal

Default

value

Normal

* The alarm "IO conﬁguration error" is activated if not all IO functions have been assigned to a hardware Input or output. Often the reason is that too many functions have been selected via the conﬁguration of the controller. Go to the menu point "Main menu => IO status => IO summary". In this screen you can see if you have conﬁgured too many functions of a certain type - indicated by an exclamation mark " ! " Please refer to the screen example, were too many DO functions have been conﬁgured. Solve the problem by adapting the DO functions to the max. No of DO outputs.

Sensor alarms Sensor alarms shut oﬀ automatically when the sensor has been O.K. for 10 minutes. If you have corrected the sensor error and want to perform a manual, forced removal of the alarm, go to the “Alarm detail display” Press and hold the “X” key for 2 seconds here.

Page 22

ERR31 Alarm on the external display - MMIGRS2

If the communication to the display is not carried out correctly, it will send an “ERR31” error notiﬁcation. This may be caused by the displayed terminations not being installed, or that there have been interruptions in data communication during the time when the display retrieves the basic information from the controller. Once the terminations have been inspected, you should then check the software version of the external display. This is done by holding down the Enter key and the X key for 5 seconds, until the Bios menu appears. Next, press the X key and read oﬀ the software version in the bottom right corner. The software version must be 1.13 or newer.

Once the display’s software version has been checked, check the display’s settings as follows:

1. Hold the Enter key and the X key down for 5 seconds, until the Bios menu appears.

2. Select the “MCX selection” menu

- Select the “Clear UI” line and press Enter

- Select the “Autodetect” line and press Enter

3. Press the X key to return to the Bios menu

4. Select the “COM selection” menu

- Select the “CAN” line and press Enter

5. Press the X key to return to the Bios menu

6. Select the “Start up mode” menu

- Select the “Remote application” line and press Enter

7. Press the X key to return to the Bios menu

8. Select the “CAN” menu

- Select the “Baudrate” line and then select the “Autobaud” setting and press Enter

- Select the “Node ID” line and set the value to 126 and press Enter

9. Press the X key to return to the Bios menu

10. Select the “Application” menu and press Enter.

The display will once again retrieve data from the controller. This process will take about 5 minutes.

Page 23

Connections

Connection, lower level Connection, upper level

Separate

supply!

Electric noise

Signal cables for sensors, DI inputs, data communication

DO DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8 Σ 1-8

I Max. 10 A

U All 24 V or all 230 V a.c.

Supply Voltage.

(3.5)

10 A (3.5)

6 A (4)

0.5 A min. 50 mA Ioﬀ < 1,5 mA

6 A (4)

6 A

32 A

(4)

AO - Analogue output, 2 pcs. AO3 - AO4

The supply voltage is either 24 V or 110-230 V. See the label on the reverse side of the controller.

÷ = Plugs normally not used

However, if connecting to an external display, a jumper must be inserted between the connections "H" and "R".

Must be used when using a frequency converter or EC motors. Connect 24 V on N and L (separate supply). Avoid earth fault current. Use double-insulated transformer. The secondary side must not be earthed. Obtain 0-10 volts from terminals N and AO3, respectively N and AO4. PAY ATTENTION TO THE POLARITY of N.

and display must be kept separate from high voltage (230 V) electric cables:

- Use separate cable trays

- Keep a distance between high voltage and signal cables of at least 10 cm

- Cables longer than 3 m at the DI input should be avoided

Warning

The supply voltage of AI may not share the signal with other controllers.

Modbus

It is important that the installation of the data communication cable be done correctly. Cf. separate literature No. RC8AC. Remember termination at the bus termination.

AI - Analogue inputs, 4 pcs. AI1 - AI4

Pressure transmitters

• Ratiometric: 10-90% of supply, AKS 32R

• Signal: 1-5 V, AKS 32

• Power: 0-20 mA / 4-20 mA, AKS 33 (supply = 12 V)

Temperature sensor

DO - Digital outputs, 8 pcs. DO1 - DO8

DO5 and DO6 are solid state relays. The relays are de-rated to the speciﬁed values. If an alarm relay is deﬁned, it will be driven under normal op-

• Pt 1000 ohm, AKS 11 or AKS 21.

• NTC 86K ohm @ 25°C, from digital scroll.

Factory settings

AI1=PoA, AI2=PoB, AI3=Pc, AI4=Outdoor temperature SC3. eration and it will drop in the event of alarms and insuﬃcient power to the controller.

DI - Digital switch inputs, 8 pcs. DI1 - DI8

The connection may be a shut-down or interruption function.

Select what is to be activated during conﬁguration.

÷ = Plugs normally not used

AKS 32R

10-90% ratiometric

AI - Analogue inputs, 4 pcs. AI5 - AI8

AKS 32

1-5 V

Pressure transmitters

• Ratiometric: 10-90% of supply, AKS 32R

• Signal: 1-5 V, AKS 32

Temperature sensor

• Pt 1000 ohm, AKS 11 or AKS 21.

• NTC 86K ohm @ 25°C, from digital scroll

AKS 33

0-20mA 4-20mA

Page 24

The capacity from the digital scroll compressor

Only DO5 or DO6

The capacity is divided into period times as "PWM period time". 100% capacity is delivered when cooling takes place for the whole period. An oﬀ time is required by the bypass 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 capacity control 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

Copeland Stream compressor

The pulse signal can also be used to control one stream compressor with one unloader valve *(4 cylinders version). The compressor capacity is distributed by up to 50% for one relay and the remaining 50-100% for the unloader. The unloader is connected to DO5 or DO6.

Bitzer CRII

The pulse signal can also be used to control one of the CRII with 2 unloaders (4 cylinders version). Compressor capacity can be controlled from 10 to 100% depending on the pulsation of the unloaders. The unloaders are connected to DO5 and DO6..

Unloader 1

Unloader 2

Unloader 2 follows unloader 1 but is oﬀset a ½ period.

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.

Injection oﬀ

The electronic expansion valves in the cooling appliances must be closed when all the compressors are prevented from starting. As a result, the evaporators will not be ﬁlled with ﬂuid that can be led to a compressor when the regulation process restarts. One of the compressor control relays can be used for this function, or the function can be prompted via data communication.

Page 25

Data External display

Supply voltage

8 analog Input

8 digital input

Relay output to capacity control

2 Voltage output

Display output For type MMIGRS2

Data communication

Environments

Enclosure IP 20

Weight 0,4 kg

Mounting DIN-rail

Connection terminals max. 2.5 mm2 multi core

Approvals

Pressure transmitter / temperature sensor

Kindly refer to catalogue RK0YG...

Capacitive load

The relays are not suitable for the direct coupling of the capacitive loads such as LED and on / oﬀ control of EC motors. All loads with a switch mode power supply has to be connected with a suitable contactor or the like.

24 V a.c. +/-15% 50/60 Hz, 17 VA 24 V d.c. (20-60 V ), 17 VA 230 a.c. (85-265 V) 50/60 Hz, 20 VA

Pressure meauring: Ratiometric pressure transmitter type AKS 32R 1-5 volt pressure transmitter type AKS 32 0-20 (4-20) mA pressure transmitter type AKS 33

Temperature measurement Pt 1000 ohm/0°C NTC - 86K from digital scroll / stream

From contact function E.g. to: Start/stop of regulation Monitoring of safety circuits General alarm function

4 pcs. SPDT (8A)

2 pcs. SPST (16A)

2 pcs. Solid State. PWM for scroll unload

0-10 V d.c. Ri = 1kohm Separate 24 V supply required

Modbus for AK-SM 800

-20 - 60°C, During operations

-40 - 70°C, During transport

20 - 80% Rh, not condensed

No shock inﬂuence / vibrations

EU Low Voltage Directive and EMC demands re CE-marking complied with LVD tested acc. EN 60730-1 and EN 60730-2-9 EMC-tested acc. EN61000-6-2 and 3 UL approval

AC-1: 6 A (ohmic) AC-15: 4 A (inductive)

AC-1: 10 A (ohmic) AC-15: 3.5 (inductive)

Imax. = 0.5A Imin. = 50 mA. Leak<1.5 mA Not short-circuit protected

An external display is only for front assembly (IP 20) Connection only via cable with plug. See ordering.

Termination

Connect H-R

Important!!

Termination Connect H-R

Ordering

Type Function Operation Supply voltage Code no.

230 V 080G0281

With buttons and display

AK-PC 551 Capacity controller

With external display and

1.5 m wire for display unit

MMIGRS2 Display unit With buttons and display - 080G0294

Wire for display unit, L = 1.5 m, 1 pcs. 080G0075

Wire for display unit, L = 3 m, 1 pcs. 080G0076

24 V 080G0283

230 V 080G0282

24 V 080G0288

Page 26

Mounting /Dimensions

For DIN rail mounting only (IP 20)

Installation considerations

List of literature

Accidental damage, poor installation, or site conditions, can give rise to malfunctions of the control system, and ultimately lead to a plant breakdown. Every possible safeguard is incorporated into our products to

Installation guide for extended operation RC8AC Here you can see how a data communication connection to ADAP-

KOOL® Refrigeration control systems can be established. prevent this. However, a wrong installation, for example, could still present problems. Electronic controls are no substitute for normal, good engineering practice. Danfoss will not be responsible for any goods, or plant components, damaged as a result of the above defects. It is the installer's responsibility to check the installation thoroughly, and to ﬁt the necessary safety devices. Special reference is made to the necessity of signals to the controller when the compressor is stopped and to the need of liquid receivers before the compressors. Your local Danfoss agent will be pleased to assist with further advice, etc.

Danfoss can accept no responsibility for possible errors in catalogues, brochures and other printed material. Danfoss reserves the right to alter its products without notice. This also applies to products already on order provided that such alternations can be made without subsequential changes being necessary in specifications already agreed. All trademarks in this material are property of the respecitve companies. Danfoss and Danfoss logotype are trademarks of Danfoss A/S. All rights reserved.

ADAP-KOOL®

Danfoss AK-PC 551 User guide

Specifications and Main Features

Frequently Asked Questions

User Manual