Danfoss Controller for controlling or refrigeration Installation guide

Brand: Danfoss

Model: Controller for controlling or refrigeration

Category: Thermostats

Type: Installation guide

REFRIGERATION AND

AIR CONDITIONING

Controllers for controlling

of refrigeration appliances

and cold rooms

AKC 121A and AKC 121B

Function description

2 Function description RC.1M.D5.02 © Danfoss 05/2004 AKC 121A / AKC 121B

Contents

Validity This function description was worked out in March 2004, and applies to AKA 121A with software

version 2.3x and AKC 121B software version 1.5x.

Introduction ..........................................................................................................................................3

Thermostat function ............................................................................................................................4

1. ON/OFF - thermostat ..................................................................................................................................................4

2. Modulating thermostat .............................................................................................................................................4

Night operation .................................................................................................................................................................5

Settings .........................................................................................................................................................................5

Signal from gateway override function ............................................................................................................5

Deﬁ nition of thermostat sensor locations .......................................................................................................5

Start and stop of control ......................................................................................................................7

Function switch .................................................................................................................................................................7

Forced closing ....................................................................................................................................................................7

Day/night operation .............................................................................................................................8

Defrosting function ..............................................................................................................................9

Start of defrost ...................................................................................................................................................................9

Defrost stop ..................................................................................................................................................................... 10

Start after defrost ........................................................................................................................................................... 11

Gas defrost ....................................................................................................................................................................... 11

Defrost with warm brine ............................................................................................................................................. 11

Sensors ................................................................................................................................................12

Relay output DO1 ...............................................................................................................................12

Door function ......................................................................................................................................12

Temperature alarms ...........................................................................................................................13

Alarm limits ..................................................................................................................................................................... 13

Time delay ........................................................................................................................................................................ 13

Language ............................................................................................................................................14

Clock function .....................................................................................................................................14

Supporting text ..................................................................................................................................14

Access codes ........................................................................................................................................15

Display signal ......................................................................................................................................15

Emergency refrigeration ....................................................................................................................15

Sensor correction ...............................................................................................................................15

Alarms and messages .........................................................................................................................16

Service .................................................................................................................................................19

Measurements ................................................................................................................................................................ 19

Forced control of outputs ........................................................................................................................................... 19

Plant measurement/data ...................................................................................................................20

Operation of AKA 21 ..................................................................................................................................................... 20

PC operation .................................................................................................................................................................... 20

Installation considerations ................................................................................................................20

List of literature ..................................................................................................................................20

AKC 121A / AKC 121B Function description RC.1M.D5.02 © Danfoss 05/2004 3

Introduction Together with valve and sensors, AKC 121A and AKC 121B constitutes a complete refrigerated surface

control for refrigeration appliances and small coldrooms.

The controller can be used in installations where injection of refrigerant is carried out by a thermo-

static expansion valve, or in installations where brine is the refrigerant.

The controllers functions replace all other automatic controls, containing, day and night thermostats,

defrost, fan control, rail heat control, alarm functions, etc. The controller is equipped with DANBUSS

data com muni cation and is operated by means of control panel type AKA 21 and/or a PC.

Menu structure

Shown in the following section is the menu selection to be made to set the functions. The settings are

indicated the way they appear in the control panel type AKA 21, e.g.

Level 1 Level 2 Level 3 (Level 4)

Defrost Control Scheduel Def.1 Start Times No. Per Day

___

(Number of defrosts is set)

Def1 Sc1 Def1 Sc1 Hour ___

(Hour value is set)

The toal menu is contained in the document "Menu operation via AKA 21".

Setting of the various functions takes place via a menu system. The menu system is based on several

levels according to the following principle.

The controller's main function is to control the

temperature via a signal from a temperature

sensor -SAir.

A solenoid valve is used as actuator.

Two refrigeration sections can be controlled. The

sections are marked A and B.

The temperatures are controlled individually in

the two sections, whereas the other functions,

like defrost start, night operation, rail heat etc.

are common functions.

• AKC 121A is used for controlling refrigeration

appliances

• AKC 121B is used for controlling cold rooms

4 Function description RC.1M.D5.02 © Danfoss 05/2004 AKC 121A / AKC 121B

The controller is able to control the temperature in two sections.

In AKC 121A one or two sensors are placed in each section.

In AKC 121B only one sensor is placed in each section.

In each of the two sections the thermostat function must be deﬁ ned. You may choose between:

1. ON/OFF - thermostat

The controller compares the measured air temperature in the section with the set temperature, and

when the air temperature drops to the cutout value, refrigeration is stopped (the relevant solenoid

valve closes).

Fan operation (AKC 121B only)

With a setting you select whether the fan is to operate or be stopped during the thermostat’s

cutout period.

2. Modulating thermostat

The control is in principle the same as the above mentioned one, but the control is now handled by

a PI function. This results in smaller ﬂ uctuations of the regulating air temperature when loads are

stable, whereby a higher and more constant air humidity is obtained.

The function ensures constant temperature control with a tempera ture value placed halfway

between the thermostat’s cutin and cutout values.

The PI controller’s operating parameters are optimized automatic-ally via the set cutin and cutout

values and the valve’s opening degree.The diﬀ erential will inﬂ uence the controller’s ampliﬁ cation,

and consequently it cannot be set lower than at 2K on account of the regulating stability.

Thermostat function

AKC 121A / AKC 121B Function description RC.1M.D5.02 © Danfoss 05/2004 5

Melting function

(only for control of refrigeration where the temperature range is from -5 to +10°C). The function will

see to it that the refrigera ted surface is not frosted over.

This function becomes operative whenever the valve’s accumulated ON time passes one hour. The

frost on the refrigerated surface will now be melted to water (or to ice, if there is a lot of frost). In

this way a better air ﬂ ow is created at the refrigerated surface at the same time as the insulating

eﬀ ect of the frost disappears.

Night operation

If night setback is required, you deﬁ ne it by setting any value, except 0 (zero). A positive value will give

night setback, and a negative value will lower the temperatures.

The deﬁ nition of night operation is described in the section named Day/night operation.

Settings

Select the thermostat function for the two sections by selecting number 1 or 2:

(1, if ON/OFF, 2, if modulating).

If a modulating thermostat is selected, the reference temperature will be the “set cutout temperature

plus half the diﬀ erential”.

Conﬁ guration Settings Thermostat TherMode A___

TherMode B___

Controller A Thermostat Ctrl. Settings CutOut °C A ___

Diﬀ . K A ___

Dt Night A ___

Controller B...... ..

Signal from gateway override function

Signals can be received from an override function via DANBUSS. When the oﬀ set signal is received, the

thermostat reference will change.

Deﬁ nition of thermostat sensor locations

AKC 121B: The sensor can be placed in the air before or after the evaporator.

AKC 121A: There are three possible locations (1, 2 and 3), where the sensors are placed in the air right

in the evaporator inlet, in the evaporator outlet, or both before and after the evaporator:

1) Sensor is placed in the return air to the evaporator.

6 Function description RC.1M.D5.02 © Danfoss 05/2004 AKC 121A / AKC 121B

2) The sensor is placed in the outlet air from the evaporator.

3) Two sensors are mounted. One on either side of the evaporator ( weighted control).

The measured values are weighted with a percentage of S3 (air inlet) and a percentage of S4 (air

outlet).

Example:

S4 measures -25°C and S3 measures -20°C.

Required as regulation parameter is a weighted average consisting of 60% S4 and the rest from S3

(only the S4 share is programmed).

This gives a regulating value of på 0.6 x -25°C + 0.4 x -20°C = -23°C

When placed like this, the S4 sensor's inﬂ uence must be set, i.e. S4 Day % (S3 is weighted automati-

cally). During night operation the inﬂ uence may be diﬀ erent.

S4 Day % ___

S4 Night % ___

Deﬁ ne the selected sensor placing with settings 1, 2 or 3:

Ther. Sx ___

AKC 121A / AKC 121B Function description RC.1M.D5.02 © Danfoss 05/2004 7

Function switch

The function switch is used for stopping and starting the regulat ing function. The switch has three

positions:

- Regulation (Setting = +1)

- Controller stop (Setting = 0)

- Service (Setting = -1)

Main Function Main Function Settings Main Switch +1/0/-1

If the switch is set in pos. 0 or -1, all the controller’s functions are inactive. In the menu the “Standby

mode” message is shown, when setting is selected to "0" or "-1". If the switch is in pos. +1, regulation is

started for the functions selected as “ON”.

Forced closing

The control can also be stopped by means of an external signal (when the ON input is cut out). The

individual outputs will depend on whether it is “ON-A”, “ON-B” or both that are cut out.

The forced closing signal can also be received from the gateway’s override function. When the signal is

received, both sections will be closed by force.

The sections may also be stopped individually with a setting in the controller.

AKC 121A

Start and stop of control

Outputs/functions Only ON-A cut out

or section A stopped

Only ON-B cut out

or section B stopped

ON-A and ON-B cut out or

stopped

Section A Solenoid valve Oﬀ Active Oﬀ

Defrost Oﬀ Active Oﬀ

Section B Solenoid valve Active Oﬀ Oﬀ

Defrost Active Oﬀ Oﬀ

DO1 for rail heat Active Active Oﬀ

for day/night function Independent of forced closing function

for fan control Active Active Oﬀ

Alarm output (function alarms) Section A alarms

stopped

Section B alarms stopped Alarms are stopped

Monitoring of sensors On if the ON-function is interrupted

Oﬀ if the section is stopped

Alarm thermostats Oﬀ for section A Oﬀ for section B Oﬀ

AKC 121B

Outputs/functions Only ON-A

cut out or section A

stopped

Only ON-B

cut out or section B

stopped

ON-A and ON-B

cut out or stopped

Section A Solenoid valve Oﬀ Active Oﬀ

Fan relay Oﬀ Active Oﬀ

Section B Solenoid valve Active Oﬀ Oﬀ

Fan relay Active Oﬀ Oﬀ

DO1 for day/night function Independent of forced closing function

for defrost Active Active Oﬀ

Alarm output (function alarms) Section A alarms

stopped

Section B alarms stopped Alarms are stopped

Monitoring of sensors On On On

Alarm thermostats Oﬀ for section A Oﬀ for section B Oﬀ

8 Function description RC.1M.D5.02 © Danfoss 05/2004 AKC 121A / AKC 121B

Change between day and night operation can be accomplished by means of an external signal, by

means of a time schedule in the controller or by means of a signal from the gateway’s override func-

tion.

External signal

A signal connected to input DI1 and the DI1 function is deﬁ ned for “Night operation”.

(The DI input may be used for two functions. Either for activating the night setback or for starting a

defrost cycle).

Internal time schedule

Start and stop times must be set for each day of the week.

Principle

Deﬁ nitions:

Night: Time when the night setback starts.

Day: Time when the night setback stops.

Night = 0 or Day = 0:

When one of the two times is set at 0, or when both are set at 0, there will be no night setback the

day and night in question.

Night = 1 and Day = 1:

When the two settings are set at the same time, there will be night setback throughout that day

and night.

Day/night operation

AKC 121A / AKC 121B Function description RC.1M.D5.02 © Danfoss 05/2004 9

There is a common defrost start for both sections (A and B).

If the controller is in position “Forced closing”, defrost cannot be performed. If a defrost is in progress

and you change over to “Forced closing”, the defrost will stop.

AKC 121A

During defrost the fans can be set to be stopped or to be in operation, if they are controlled by output

DO1. The defrost stop is individual for the two sections, and can be based on either time or tempera-

ture. The defrost stop may however be made dependent on the other section, so that refrigeration will

not start until defrost has been completed in both sections.

AKC 121B

With a setting you can select whether the fan for the section is to operate during a defrost cycle or

whether it should be stopped.

The defrost stop must take place at the same time for both sections, as there is only one defrost relay.

The stop can either be based on time or temperature.

Start of defrost

Defrost can be started in four ways (which may all be selected simultaneously).

Once the defrost has been started, it will continue until it is stopped on time or temperature.

1. Manual defrost

Manual defrost is started from control panel type AKA 21 or a PC. The setting will automatically

change back to when the defrost has been completed.

Defrost Control Defrost Start Method Man. Def. OFF / ON

2. External signal

Defrost is started with a contact function connected to terminals 106/107. The signal must be an

impulse signal of at least two seconds’ duration.

If the external signal is still active 30 minutes after cooling is resumed, there will be an alarm. The

alarm ceases when the signal is removed.

Conﬁ guration Settings DI 1 Conﬁ g Def(1) Night(2) DI 1 Conﬁ g. __

When the setting is 1, a signal on the input will start a defrost cycle.

(When the setting is 2, the input signal will be used for day/night operation. Read that section).

3. Internal clock

Defrost is started by means of a weekly programme that is set in the controller. The times have rela-

tion to the controller’s clock function.

Three individual schedules with up to 8 defrosts per schedule can be programmed. Subsequently,

the individual week days can be deﬁ ned to follow one of the three schedules.

Defrosting function

Signal from gateway override function

Signals can be received from an override function via DANBUSS. When the signal is received, there is

change-over to night operation.

Settings:

Deﬁ nition of function:

Day / Night =

0: No night setback

1: Night operation according to signal at DI input

2: Night operation according to internal time clock

3. Night operation according to signal from the gateway’s override function

Common Settings Day / Night Ctrl. Settings Day/Night ___

Mo Day h ___

Mo Night h ___

Tu.....

etc.

10 Function description RC.1M.D5.02 © Danfoss 05/2004 AKC 121A / AKC 121B

Defrost Control Defrost Start method Def Sched OFF / ON

Schedule 1 Def.Start Times No. Per Day ___

Def1 Sc1 Def1 Sc1 Hour ___

Def1 Sc1 Min ___

Def2 Sc1 Def2 Sc1 Hour ___

Def2 Sc1 Min ___

etc.

Schedule 2Def.Start Times No. Per Day ___

Def1 Sc2 Def1 Sc2 Hour ___

etc.

Schedule 3Def.Start Times etc.

Extended Program Schedules Mon. Sched. 1/2/3 ___

Tue. Sched. 1/2/3 ___

etc.

Defrost stop

You may choose between two kinds of defrost stop and they can be selected individually for sections

A and B.

1. Stop based on temperature and with time as security

Here the evaporator’s temperature is measured with sensor "S5" or S

def

. When this temperature is

equal to or higher than the tempera ture set for defrost stop, the defrost will stop in the section in

question. Cooling will not be resumed until the defrost has been completed in all sections. In AKC

121B the defrost must be stopped simultaneously in the two sections, as there is only one defrost

relay.

If the defrost time exceeds the set max. defrost time, the defrost stops. This will happen even if

the defrost stop temperature has not been reached (max. defrost time will function as safegu ard).

When the defrost is stopped on time, the alarm message “Max. def. period exceeded” will appear for

the section in question.

Defrost Control Defrost Stop Temp(1)/Time(2) Temp/Time A 1 / 2

MaxDefTim A ___

Def Stop °C A ___

....B.....

Select "Stop on temperature and time as security" by putting "Temp/Time" = 1.

"MaxDefTime" is the setting of max. defrost time in minutes.

"Def. Stop °C" is the setting of the temperature at the defrost sensor, when defrost has to be

stopped.

In AKC 121B it is possible to deﬁ ne the air sensor (Sair) as the sensor providing the signal for defrost

stop.

The setting is called DefStop Sx.

When there is an error in a defrost sensor, an alarm appears and the defrost stop will then be based

on time in the relevant section. Defrost stop for the other section will still be based on temperature.

2. Stop based on time

A ﬁ xed defrost time is set here. When this time has elapsed, the defrost will be stopped and cooling

will be resumed.

Defrost Control Defrost StopTemp(1)/Time(2) Temp/Time 1 / 2

MaxDefTimA ___

... B...

Select "Stop based on time" by setting "Temp/Time( )" in position 2

"MaxDefTim( )" is the setting of defrost time in minutes.

A defrost in progress can be stopped manually by setting “Main Swtich” in pos. 0 for a moment.

AKC 121A / AKC 121B Function description RC.1M.D5.02 © Danfoss 05/2004 11

Start after defrost

After a defrost it is possible to start the refrigeration and fan operation in the following ways:

a. Start of refrigeration

When the defrost has been stopped by temperature in a section, refrigeration of the section can

wait until the defrost has been completed in the other section. The two sections will then start their

refrigeration at the same time.

The “ON” setting will provide common start of the refrigeration.

Defrost Control Defrost StopTemp(1)/Time(2) ComDefStop OFF / ON

b. Delayed fan start

AKC 121A

Relay output DO1 must be deﬁ ned to control the fans, if this function is to be used. Read the “Relay

output DO1” section.

AKC 121B

There are two relays designed for fan control. One for section A and another for section B.

Only when the fans are controlled via the relay output can the “delayed fan start” function be used.

Drops of water left on the refrigerated surface after a defrost can be bound to the surface (used

primarily in coldrooms).

When the defrost has been completed, refrigeration will start, the refrigerated surface will be

cooled down, and once the delay time has elapsed, the fans will start.

The time delay is set in minutes (0 min., if applicable).

Defrost Control Defrost StopTemp(1)/Time(2) Fan Del. m ___

Gas defrost

AKC 121A

For systems with TEV valves and gas defrost there is a pumpdown timer on both section A and B. There

are individual settings for the two sections. The defrost output of a section is not activated until the

relevant pumpdown time has elapsed.

After defrost, a draindown delay may likewise be deﬁ ned for draining and dripping of the evaporator

before cooling is resumed. Draindown delay can be set individually for sections A and B.

AKC 121B

As there is only one defrost relay, gas defrost -if applicable -must take place at both sections at the

same time.

Defrost with warm brine

In brine systems with central defrost it is necessary to keep the solenoid valves for all cooling surfaces

open during the defrost cycle. In such systems it is possible to stop the defrost in-dividually based on

temperature.

With settings "Stop on temperature" and "Central defrost = ON" the solenoid valve will remain open

until the defrost stop temperature has been reached. The solenoid valve will then close. When "Max

defrost time" has subsequently been reached, regulation will be resumed. ("Max defrost time" must be

set to the time at which the central solenoid valve is open to warm brine).

If "Stop on time" is selected, the system cannot be stopped on temperature because the solenoid

valve is kept open during the entire defrost cycle (Max defrost time).

Fan operation during defrost (AKC 121B only)

With a setting you determine whether the fan in the section is to operate or be stopped during de-

frost.

12 Function description RC.1M.D5.02 © Danfoss 05/2004 AKC 121A / AKC 121B

AKC 121A

The controller is provided with a relay output which can be used for one of the following three func-

tions; (the function is deﬁ ned with setting 1, 2 or 3).

Conﬁ guration Settings DO1 Conﬁ g Rail Night Fan DO1 Conﬁ g ___

1. Rail heat control

To save energy costs it is possible to control the power supplied to the rail heat by means of im-

pulses. The function is common to both evaporator sections. The function can be used for both day

operation and night operation.

The rail heat is always on during defrost.

If impulse control is required, set the “RailCycl m” period and the percentage of the period of time

where the rail heat is ON during day operation and night operation, respectively.

Common Controller Railheat Pulsing (Day/Night) RailOnDay % ____

RailOnNgt % ____

RailCycl m ____

The time period is set in minutes (a short “RailCycl m” period and a heavy load will reduce the life-

time of the relay).

2. Day/night function. Where the relay is operated during night operation.

3. Fan control

After a defrost the start of the fans can be delayed, so that the water drops are bound to the refrig-

erated surface. Read the “Start after defrost” section.

AKC 121B

The controller is provided with a relay output which may be used for one of the following two func-

tions:

1. Defrost. Where the relay is then operated during the defrost.

2. Day/night function. Where the relay is also operated during night operation.

Relay output DO1

Sensors AKC 121A

If there are sensor inputs (fx. S4 or S5) they may be used for optional registration or for an alarm func-

tion for temperatures.

Read the “Temperature alarms” section.

All six sensor inputs S3, S4 and S5 (A and B) are connected to an alarm function. If the sensors are not

mounted, there will be alarms due to missing sensors. The alarms can however be suppressed with a

setting. Read the “Alarms and messages”/setting 0 section.

AKC 121B

If sensors S

Def

are not used for defrost stop, the signals from these sensor inputs may be used for op-

tional monitoring or an alarm function. Cf. the section named “Temperature alarms”.

All four sensor inputs S

AIR

and S

Def

(A and B) are connected to an alarm function. If the sensors are not

ﬁ tted, alarms will be caused by the missing sensors. The alarms may however be suppressed by means

of a setting. Cf. the section “Alarm and messages”/setting 0.

AKC 121B only

Each section has a digital input for connection to a door switch.

When the input is open, the section will register this as if the door is open and sound the alarm when

the time delay has expired.

The fan can be deﬁ ned to stop or operate when the door is open. A stopped fan will also stop the re-

frigeration. If the fan however is deﬁ ned to operate during defrost, the fan will also operate if the door

is opened and a defrost is in progress.

If the function is not used for a door function, the input must be shortcircuited to avoid the alarm.

Conﬁ guration Settings Door function Door DelayA ___

FanOpDoor A ___

Door DelayB ___

FanOpDoor B___

Door function

AKC 121A / AKC 121B Function description RC.1M.D5.02 © Danfoss 05/2004 13

Temperature alarms The function is used for sounding the alarm before the product temperature at the site becomes criti-

cal.

You can set alarm limits and time delays for high and low tempera tures. Alarm will be given if the set

limit is exceeded, but not until the time delay has expired.

All sensor inputs are connected to two alarm limits, no matter what the sensors are used for. In cases

where a sensor input is not used, the alarm can only be cancelled by suppressing it. Read the “Alarms

and messages”/setting 0 section.

It is possible to set the temperature alarms that are to be received.

- No alarms / - Alarms permitted / - Alarms permitted, but not when regulation is stopped.

Alarm limits

Alarm limits can be set individually for each sensor.

The required temperature is indicated in °C.

Controller A Air Temp.Alarm Settings HighSxx A ___

Low Sxx A ___

Controller B ....

The high-temperature limit will however be raised in the following situations:

- During night operation with the value “Dt Night K” (only if the night setback value is positive, how-

ever).

- If a signal is received from an override function via DANBUSS:

- the thermostat function will be overridden (peak load function)

- the alarm limit will be raised (extremely hot summerday)

Time delay

Three time delays for alarms are set for each section:

For too high temperature:

High1Del m: Time delay after activation of the ON input,

time delay following defrost,

time delay after a power failure

The time delay will apply until the actual air temperature has dropped below

the "upper alarm limit".

High2Del m: Time delay during normal regulation

For too low temperature:

Low Del m: After the time delay the alarm will sound

The time delay is indicated in minutes:

Controller A Air Temp.Alarm Settings HighDel1A ___

HighDel2A ___

Low Del.A ___

Controller B .....

Example

IN: Thermostaten cut-in value

OUT: Thermostaten cut-out value

Lim: Alarm limit for high temperature and

low temperature

S: Alarme ceases

Curve 1: Cooling stage

(1): Time delay "High1Del m" has been exceeded. Alarm becomes active.

Curve 2: Normal regulation where the temperature becomes too high.

(2): Time delay "High2Del m" has been exceeded. Alarm becomes active.

Curve 3: Temperature becomes too low

(3): Time delay "Low Del m" has been exceeded. Alarm becomes active.

14 Function description RC.1M.D5.02 © Danfoss 05/2004 AKC 121A / AKC 121B

Language There are six languages in the controller, English, German French, Danish, Spanish and Swedish.

When the required language has been selected, the individual functions will be shown in this lan-

guage, both when there is operation via AKA 21 and system software type AKM.

NB! When you operate system software type AKM it is important that the language code is set before

an upload of the controller’s data is carried out to the AKM programme (it is the set language that will

be picked up by the AKM programme).

Select one of the controller’s languages by means of the following settings:

0: English

1: German

2: French

3: Danish

4: Spanish

6: Swedish

Activate the selected language by pushing "Enter" and then push "Clear".

Main Function Main Function Settings Language___

The controller contains a clock function, which is used for the functions “Internal time schedule” and

“defrost start with internal clock”.

Settings have to be made of days, hours and minutes.

AKC --- Adr. Clock Clock: Day 1-7 (1=Monday, 7=Sunday)

Clock : Hour 0-23

Clock: Min. 0-59

Note:

The clock has to be reset after a power failure.

If the controller is connected to an installation with gateway type AKA 243/244, the gateway will auto-

matically re-set the clock function.

Clock function

When the controller is set from control panel type AKA 21, it is possible to show auxiliary text in the

display for a few func tions.

This is done by pushing the key “Help” when the required function is shown in the display. A brief text

will now appear which describes the setting. For example:

Function is shown Push "Help" Auxiliary line 1 and 2 appears

Push "↓" Auxiliary line 3 and 4 appears

etc.

Finish by pushing "←", and you will return to the function.

In the menu is shown which functions are provided with auxiliary text.

Supporting text

AKC 121A / AKC 121B Function description RC.1M.D5.02 © Danfoss 05/2004 15

The controller can be operated with system software type AKM and control panel type AKA 21.

Both operating modes may give access to several levels, depending on the user’s knowledge of the

various functions.

System software type AKM:

The diﬀ erent users are deﬁ ned here with initials and passwords. Access is now granted to exactly the

functions the user is allowed to operate.

The operation is described in the AKM manual.

Control panel type AKA 21:

Access can be given to three user levels here:

1) Access without use of password.

See alarms. Display selected temperatures. Change temperature in the refrigeration appliance. Start

defrost.

2) Access via code 1

Setting of selected functions, acknowledgement of alarms.

3) Access via code 2

All settings in the menu system can be performed.

The operation is described in “Menu operation via AKA 21”.

If access code is set in pos. “0” (factory setting), there is free access to the system without the use of a

password.

AKC --- Adr. Chg. Code1 ___

Chg. Code 2 ___

Access codes

Emergency refrigeration If a thermostat sensor turns faulty (S3/S4 A or B), alarm will be given, and there will be a change-over

to emergency control.

The controller constantly registers the valve’s opening degree. When the sensor fails, the controller will

maintain the average opening degree registered during the past three hours. (Two values are saved at

all times: one for day operation and one for night operation).

Sensor correction The input signal from all connected sensors can be corrected.

A correction will only be required, if the sensor cable is long and has a small cross section.

All displays and functions will use the corrected value.

Conﬁ guration Settings Sensor Calibration Corr ( )___

The air temperature measured at the refrigeration surface can be read on a display. It must be an LCD

display type AKA 14 or AKA 15. The display is normally ﬁ tted to the appliance, so that the customer can

see the air temperature. A display can be mounted in each section.

You may choose between the following sensor displays deﬁ ned with settings 1 - 5.

AKC 121A: AKC 121B:

1: S3 S Air

2: S4 S Def/Aux

3: S5

4: "Ther Air"

5: "Weighted ( )"

Shown at ”Ther Air ” is the value according to which the thermostat is operating.

Shown at ”Weighted ( )” is an intermediate value between the S3 and the S4 temperatures. The ratio is

deﬁ ned in the S4 Day % and S4 Night % settings

Change of view

The read-out can be displaced either in positive or negative direction. The setting has to be made via

the function Oﬀ set K A or Oﬀ set K B.

Codes

The display can show you the following codes:

"dEF" : Appears during defrost, and 15 minutes after the end of the defrost.

"AL1" : Appears when there are errors in sensors attached to the display function.

"- - -" : Appears if the display function is not active.

Display signal

In connection with the controller’s functions there are a number of alarms and messages that become

visible in case of an error or wrong operation.

Distinction is made between important and not quite so important messages. The importance of

certain types of information has been established, while others may be changed, as required.

The importance is indicated with the following settings:

1. "Alarms"

This is important information from the controller.

- The controller’s alarm output is activated

- The information is transmitted on the DANBUSS network together with status value 1

- If a gateway type AKA 243/244 is connected which is deﬁ ned as master, its relay output DO2 will

be activated for two minutes

- Later, when the alarm is cancelled, the same information will be repeated, but this time with status

value 0.

2. "Messages"

This is less important information from the controller.

- The information is transmitted on the DANBUSS network together with status value 2

- Later, when the alarm is cancelled, the same information will be repeated, but this time with status

value 0

3. "Alarms"

As "1", but the DO2 output on a master gateway will not be activated.

0. "Suppressed information"

This information stops at the controller. It is transmitted nowhere.

List of alarm activitie

Alarm

importance

Alarm

status

AKC

alarm relay

AKC

alarm LED

AKA 21

LED

AKA 243/244

DO2 relay

Alarm OFF FLASHES FLASHES OFF 2 min.

No alarm ON ON OFF ON

Alarm ON FLASHES FLASHES ON

No alarm ON ON OFF ON

Alarm OFF ON FLASHES ON

No alarm ON ON OFF ON

Alarm ON ON OFF ON

No alarm ON ON OFF ON

Information from the controller

Below, the information is shown together with the importance of it. The information is shown in brack-

ets "[ ]". If there are several ﬁ gures in the bracket, the setting can be changed (the factory setting is

shown in bold type).

Standby mode [ 1, 2, 0 ]

The main switch is either set in position "Controller stop" or "Service".

Check clock settings [ 1, 2, 3, 0 ]

Check the time in the clock function. Error messages are given after power failures/start-up of

the controller.

Max. Def. period exceeded( ) [ 1, 2, 3, 0 ]

Defrost has stopped based on time, and not as required based on temperature. An alarm is

given on the alarm output, but it is cancelled again after ﬁ ve minutes.

Alarms and messages

Sx Error ( ) [ 1, 2, 3, 0]

The sensor is interrupted, shortcircuited or not mounted. Change-over to emergency proce-

dure. Depending on the sensor for which an error has been reported, the controller will select

a procedure.

High air temp( ) [ 1, 2, 3, 0 ]

Too high air temperature

The air temperature measured with an alarm sensor has exceded the deﬁ ned upper limit for

the alarm time delay. If the air tempera ture ﬂ uctuates back to the normal regulation range, the

alarm output is reset.

Low air temp( ) [ 1, 2, 3, 0 ]

The air temperature measured with an alarm sensor has exceded the deﬁ ned lower limit for

the alarm time delay. If the air tempera ture ﬂ uctuates back to the normal regulation range, the

alarm output is reset.

Wrong Signal on Def Start input [ 1, 2, 3, 0 ]

There is still an active signal for defrost start on terminals 106/107 although defrost was

terminated half an hour ago! There will be an alarm when the half hour time delay has been

exceeded.

Cf. also section on defrost start with external signal.

Ctrl. Oﬀ ( ) [1, 2, 3, 0] (AKC 121A only)

The section is stopped via the conﬁ guration.

Door ( ) Alarm [1, 2, 3, 0] (AKC 121B only)

There is an alarm from the door function. The door has been open for a longer period than

permitted. When the door is closed, the alarm will be cancelled.

This is how the various messages are transmitted:

Information is in principle sent twice.

1) An alarm message when the error is discovered.

2) A message about cancellation of the alarm situation, when the error disappears again.

(In connection with a sensor alarm, there may be 10 minutes between the two messages).

This procedure has a diﬀ erent inﬂ uence on the below-mentioned systems:

Single systems (systems with control panel type AKA 21)

Information can be shown on the screen, when an “E” (error) is observed.

The error message cannot be removed from AKA 21, as long as the cause of the error has not

been removed. When the cause of the error message has been removed, the error message will

remain visible in AKA 21 until it is acknowledged by pushing “Enter”.

Network (Systems with PC or AKA 243/244 with printer and control panel type AKA 21)

Here the information can be transmitted to the PC or the printer. Accompanying this message

is indication whether it is a new error or an earlier error that has been transmitted. On control

panel type AKA 21 only “new” alarms can be seen in this situation. Old errors that are transmit-

ted cannot be seen.

To use this function, you have to make a setting in the controller.

The individual messages will now be sent to the printer or the PC along with a status which is

either 1, 2, 3 or 0.

1 means that it is new and important information (information deﬁ ned with setting = 1)

2 means that it is new, but not quite so important information (information deﬁ ned with

setting = 2)

3 means that it is new and important information (information deﬁ ned with setting = 3)

0 means that the error has been deleted.

Who are the alarm receivers

Single systems

Control panel type AKA 21 will here be the receiver of alarms from the connected units.

- Each controller is given an address, so that the unit is deﬁ ned in the system. Setting of the ad-

dress is performed directly in each controller via a number of switches (cf. instructions).

Network systems

A deﬁ ned PC or AKA 243/244 with printer will here be the receiver of alarms for the connected

units.

- Each controller is given an address, so that the unit is deﬁ ned in the system. Setting of the

address is performed via a number of switches (cf. instructions).

- Each controller is given a system address. A system address consists of a network number and

an address (the address is the same as the one set in in the controller). The network number

is set automatically by the master gateway.

Alarm output on AKC 121A / 121B

The output will only be activated when the setting is [1] and [3] (see above). Activation will

take place for as long as the defect remains active.

The output is a “cut-out function” where the following applies:

No alarm: The relay contact between terminals 20 and 21 is connected.

Alarm: The relay contact between terminals 20 and 21 is interrupted.

Service

This function is used in connection with installation, service and fault-ﬁ nding on the plant. By means

of it, the connected functions can be checked, e.g. fan, rail heat, Tc signal, compres sor, defrost heating

element, valve, sensors and alarm functions.

Measurements

All the diﬀ erent input signals and output signals can be read here.

Service Mode Measurements of........

(Please refer to the menu operation)

Forced control of outputs

The components connected to the controller outputs can be controlled.

NB! There is no monitoring when there is forced control on the outputs.

Access requirements

To gain access to the service function, two settings have to be made:

1. The function switch must be put in position Service.

Main Function Main Function Settings Main Switch = -1

(The display shows the message “Standby mode” to indicate that regulation has been

stopped, and that all outputs are OFF).

2. "Manual Control" must be On

Service Mode Manual control of Outputs Man. Ctrl. = ON

(The service function is activated).

The individual outputs can now be controlled by force.

Please refer to the menu operation

Valve

Forced control of the solenoid valve

Defrost / Fan

Forced control of relay used for defrost / fan operation.

Relay output DO1

Forced control of DO1 relay:

Alarm

Forced control of alarm relay

Oﬀ will activate the alarm (cut-out output = active alarm).

When the forced control comes to an end, the service setting “Man. Ctrl.” must be put in position OFF

before the service function is abandoned. The status of the outputs will now return to the factory-set

values.

If you leave the service function without putting “Man. Ctrl.” in position OFF and changing the function

switch (Main Switch = 0 or 1), “Man.ctrl.” will automatically move into position OFF. At the same time

the output settings will return to the factory-set values.

Functions and measurements pertaining to the refrigerating plant can be shown on the control

panel’s display or on the PC. Displayed temperatures are indicated in °C or K, and functions with ON or

OFF.

Operation of AKA 21

All relevant measurements and functions can be shown on the control panel's display.Please refer to

the menu description.

A display reading ***** indicates that no sensor has been mounted. Or that it is defective.

Constant updating

If a constant updating of a menu section is required, e.g. a temperature display, the display on the

control panel can be locked on the menu.

Procedure: Show the required menu picture on the display, and push “Enter” key for three seconds.

Updating function is cancelled again by pushing one of the arrow keys.

Furthermore the following controller data will be displayed:

Code No. Prog. Ver. Controller's code No. and software version

System address Controller's system adress

Alarm report to Systemaderess (end receiver) to which alarms have to be transmitted

(can only be set from a Master Gateway)

Gateway Address Address of nearest gateway that is to give alarms

PC operation

All measurements and settings from control panel type AKA 21 that are described above can be

shown/set from a PC.

Operation can be accomplished with system software type AKM or AK Monitor, and depending on

how the installation and setup have been arranged, all or only a few selected measurements and

settings can be shown.

Plant measurement/data

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 prevent this. However, a wrong installa-

tion, for example, could still present problems. Electronic controls are no substitute for normal, good

engineering practice.

Danfoss wil 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 ﬁ t the necessary

safety devices.

Your local Danfoss agent will be pleased to assist with further advice, etc.

Installation considerations

Function description ............................................................................................................................................RC.1M.D

Installation guide for data communication cable ..................................................................................... RC.0X.A

AKC 121A Menu operation via AKA 21 (software based) .............................................................. RC.1M.A

Mounting instructions (supplied) ..................................................................................... RI.1M.V

Table of entry of menu settings (supplied) ...................................................................RI.1M.X

AKC 121B Menu operation via AKA 21 (software based) ..............................................................RC.1M.J

Mounting instructions (supplied) ..................................................................................... RI.1P.M

Table of entry of menu settings (supplied) ...................................................................RI.1P.N

List of literature

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 speciﬁ cations already agreed.

RC-ET