Danfoss Controller type AKC 24W for control of water chillers vers. 4.4x Installation guide

Brand: Danfoss

Model: Controller type AKC 24W for control of water chillers vers. 4.4x

Type: Installation guide

Danfoss Controller type AKC 24W for control of water chillers vers. 4.4x is a complete control unit for water chillers or heat pumps. It features electronic step regulation based on the water temperature, adaptive refrigerant control with one or two expansion valves, frost protection function, monitoring and alarm functions, DANBUSS® data communication, and operation via control panel AKA 21 and/or PC.

RC.1J.F2.02 ➝ RC.1J.F3.02 11-1994

Controller for control of water chillers

AKC 24W

ADAP-KOOL

Functional description

2 Functional description RC.1J.F3.02 © Danfoss 11/94 AKC 24W

Contents Validity....................................................................................................................... 2

Installation considerations ..................................................................................... 2

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

System information.................................................................................................. 4

Operation .................................................................................................................. 4

Application ............................................................................................................... 5

Function swtich........................................................................................................ 5

Refrigerant ................................................................................................................ 5

Capacity regulation.................................................................................................. 6

Regulation ........................................................................................................ 6

Neutral zone and zone bands .......................................................................... 7

Media tempeature sensor................................................................................. 7

Frost protection ................................................................................................ 7

Compressor groups.......................................................................................... 8

Cutin and cutout of capacity steps and compressors....................................... 8

More capacity................................................................................................... 9

Signal from safety controls............................................................................. 10

Timer .............................................................................................................. 10

External displacement of reference temperature.............................................11

Expansion valve function...................................................................................... 12

Selection of function....................................................................................... 12

Pressure transmitter/temperature sensor....................................................... 12

Superheat....................................................................................................... 13

Forced closing................................................................................................ 14

MOP control ................................................................................................... 14

Kp / Tper ........................................................................................................ 14

Separate pressure transmitter........................................................................ 15

Expansion valve opening ............................................................................... 15

Service .................................................................................................................... 17

Measurements ............................................................................................... 17

Forced operation ............................................................................................ 17

Alarms and messages ........................................................................................... 18

Clock function ........................................................................................................ 21

Plant measurements/data...................................................................................... 22

Capacity regulation......................................................................................... 22

Expansion valve ............................................................................................. 22

Controller data................................................................................................ 22

Continuous updating ...................................................................................... 22

List of literature ...................................................................................................... 24

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 installation, for example, could still present problems. Electronic control is 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 fit the necessary safety devices.

Particular attention is drawn to the need for a “force closing” signal to controllers in the

event of compressor stoppage, and to the requirement for suction line accumulators.

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

Installation

considerations

This functional description was revised in October 1994 and applies to AKC 24W with

software version 4.4x.

Validity

AKC 24W Functional description RC.1J.F3.02 © Danfoss 11/94 3

AKC 24W is a complete control unit for water chillers or heat pumps. The unit

contains:

• Capacity regulator controlling the compressor capacity or water temperature.

• Adaptive refrigerant control with one or two expansion valves. With this the

refrigerant charge is optimally adapted to the load.

• Frost protection thermostat.

• Monitoring and alarm functions.

• DANBUSS

data communication.

• Operation via control panel AKA 21 and/or PC.

Capacity regulation

The controller’s main function is electronic step regulation based on the water

temperature which adapts the compressor’s capacity so that it always matches the

actual load.

The step regulator calculates the required capacity on the basis of actual water

temperature and on whether this is falling, or rising, in order to minimise the number

of step changes.

In addition to the step regulation function there is a built-in frost protection function

and monitoring of sensor errors.

Evaporator control

The controller has two built-in adaptive units for controlling the supply of refrigerant to

the evaporator.

The controller can operate one or two electronic expansion valves so that there is

constantly optimum charging of the evaporator.

The superheat is regulated by means of one temperature sensor (S2) and one

pressure transmitter for each evaporator.

Introduction

4 Functional description RC.1J.F3.02 © Danfoss 11/94 AKC 24W

Controller type AKC 24W is a unit in the ADAP-KOOL

refrigeration control system.

The controller can be linked up with other controllers in the system via a two-core

connection - the DANBUSS

Data Communication. Through this connection

information can be transmitted between the units, like settings, measurements, alarms

etc.

Remote service

The different messages and alarms can, via the telephone network, be transmitted by

modems to, say, a service company.

Address coding

An address code must be set by means of a number of switches on the controller’s

front plate. There are seven switches for the coding. How coding is performed is

explained in the installation instructions for the data communication cable (literature

No. RC.0X.A).

Connection of control panel type AKA 21

A plug for the connection of control panel AKA 21 is mounted right on the front plate of

AKC 24W. (If the control panel is to be used in any other place, a terminal box will

have to be installed (cf. the installation instructions for the data communication cable,

literature No. RC.0X.A).)

Data communication

To obtain correct data communication it is important that the installation instructions

for the data communication cable be adhered to (literature No. RC.0X.A).

The controller can be operated in two different ways. Either by using control panel

type AKA 21 or by means of a PC with system software type AKM.

AKA 21 operation

Setting of the different functions is performed via a menu system. The menu system is

built up on several levels where you change around between the different menus by

means of arrow keys.

The complete list of menus is contained in the document “Menu operation via AKA

21”. (Cf. list of literature).

PC operation

Operation takes place from a PC where Microsoft-Windows and System Software

type AKM have been installed. (The PC is connected to the system via Gateway type

AKA 24).

Setting of the different functions is performed by means of rolling menus and dialogue

boxes. Settings can either be made via the keyboard or by using a mouse.

For users of AKM system software the complete list of menus is found in the

document “Menu operation via AKM”. (Cf. list of literature).

System information

Operation

AKC 24W Functional description RC.1J.F3.02 © Danfoss 11/94 5

Application The controller may be used for the control of either heat pumps or water chillers.

The control function is in principle the same for the two types of regulation. The only

differences are the step regulator's function and the location of temperature sensor

S3 that registers the media temperature.

Water chiller control: S3 registers the water chiller's outlet temperature.

Capacity steps are cut in at rising S3 temperature.

Heat pump control: S3 registers the condenser's outlet temperature.

Capacity steps are cut in at falling S3 temperature.

Main Function Cooling (1) / Heating (2) Cool / Heat

1 / 2

The function switch is used for stopping and starting the control function.

- Normal control state (Setting = +1)

- Control stopped (Setting = 0)

- Service function (Setting = -1)

Main Function Main Switch Main Switch

-1 / 0 / 1

If the function switch is set at "stopped control" or "service" (0 or 1), all the

controller's functions will be inactive.

External function switch

The control can be started and stopped via an external contact function connected to

input DI3 (terminals H3 and H4). If the connection is interrupted, all control functions

will be stopped. (See also page 14).

The registered control parameters are preserved if the controller's supply voltage is

maintained.

The external function switch is only active, if the internal function switch is in position

+1 (normal control function).

Function switch

Before regulation can be commenced, the refrigerant must be defined. You can

choose between the following refrigerants:

1 R12 8 R23 15 R227

2 R22 9 R500 16 R401A

3 R134a 10 R503 17 R507

4 R502 11 R114 18 R402A

5 R717 12 R142b 19 R404A

6 R13 13 User-defined 20 AC 9000

7 R13b1 14 R32 21 R407A

22 R407B

The refrigerant is selected by keying a figure between 1 and 22. If you push 0, no

refrigerant has been selected.

Warning: Incorrect selction of refrigerant can cause damage to the compressor.

Main function Rfg. type 1..22 Rfg. type

___

Rfg. Fac. A1 ____

Rfg. Fac. A2 ____

Rfg. Fac. A3 ____

A subsequent change of refrigerant can only be performed in this way:

- Select new type

- The controller reports an error

Refrigerant

6 Functional description RC.1J.F3.02 © Danfoss 11/94 AKC 24W

- Interrupt supply voltage to the controller

- Wait five seconds

- Reconnect supply voltage

- Regulation can be started again

Other refrigerants?

The function has been prepared for the definition of a refrigerant that differs from the

above mentioned types. This definition can be made by keying the figure “13” plus a

number of subsequent parameters. This setting can only be made with assistance

from Danfoss.

The step regulator in the controller can control up to eight capacity steps that may be

distributed on one or two compressors. (The capacity distribution for compressors is

related to the input signals for the safety controls (DI 1 and DI 2).

ON/OFF capacity regulation is selected.

Capacity Ctrl. Cap. Settings Cap. Ctrl.

OFF / ON

In position OFF, all outputs to the capacity regulation are OFF.

Regulation

The cut-in compressor capacity is controlled by the actual value of the media

temperature, and whether the temperature is rising or falling.

- In the neutral zone there is no cut-in or cut-out of capacity steps.

- In the +zone and -zone band cut-in and cut-out depend on whether the media

temperature is rising or falling. Cut-in/cut-out takes place with the selected time

delays.

- In the ++zone and --zone band cut-in/cut-out takes place with the selected time

delays.

- Refrigeration will be stopped when temperatures are reached that are lower than the

set limit values.

The control function is based on the set value and the temperature measured with the

media sensor.

Capacity Ctrl. Cap. Settings Media

___

Capacity regulation

AKC 24W Functional description RC.1J.F3.02 © Danfoss 11/94 7

When the media temperature is too high, an alarm message is sent. It is transmitted if

the set temperature value is exceeded.

Capacity Ctrl. Cap. Settings Media Al

___

Neutral zone and zone bands

The neutral zone is set.

The +zone and -zone band is set.

The time delay of the +zone and -zone band is set.

The time delay of the ++zone and --zone band is set.

Capacity Ctrl. Cap. Settings NZ K

___

+zone K

___

-zone K

___

Capacity Ctrl. Adv. Capacity Settings +zone s

___

-zone s

___

+ +zone s

___

- -zone s

___

Media temperature sensor

Measurement of the media temperature can freely take place with one of the following

sensors:

1: S3 S3 Media temperature (temperature sensor, from 100 to 150 °C)

2: S4 S4 Media temperature (temperature sensor, from 100 to 150 °C)

3: P0 A Suction pressure (pressure transmitter type AKS 32, from -1 to 12 bar,

1-5 V)

4: P0 B Suction pressure (pressure transmitter type AKS 32, from -1 to 12 bar,

1-5 V)

5: P AUX Condensing pressure (pressure transmitter type AKS 32,

from -1 to 34 bar, 1-5 V)

Sensor input and type are selected by keying a figure between 1 and 5.

Capacity Ctrl. Adv. Capacity Settings Media Sens

1...5

Frost protection

The controller has a built-in thermostat function that provides protection against too

low-temperature. A temperature sensor or a pressure sensor is placed where the

temperature has to be monitored. Measuring can be done with one of the following

sensors:

0: Function is not used

1: S3 Media temperature (temperature sensor, from 100 to 150 °C)

2: S4 Media temperature (temperature sensor, from 100 to 150 °C)

3: P0 A Suction pressure (pressure transmitter type AKS 32, from 1 to 12 bar,

1-5 V)

4: P0 B Suction pressure (pressure transmitter type AKS 32, from 1 to 12 bar,

1-5 V)

5: P AUX Condensing pressure (pressure transmitter type AKS 32,

from 1 to 34 bar, 1-5 V)

6: P0 A and P0 B Lower of the two pressure transmitter values is followed

Sensor input and type are selected by keying a figure between 0 and 6.

Capacity Ctrl. Adv. Capacity Settings Limit Sens

0...6

The temperature value is set (select a value outside of the neutral zone).

Capacity Ctrl. Cap. Settings Limit.

___

The controller will automatically convert a pressure signal to a temperature value. If a

temperature lower than the set one is registered, one compressor step will be cut out

after one second. If the temperature is still too low, the next capacity step will be cut-

out after one second, etc. Renewed cut-in will automatically be commenced when the

8 Functional description RC.1J.F3.02 © Danfoss 11/94 AKC 24W

temperature again exceeds the set value plus a temperature differential plus the time

delay "Del. ( )" (see later).

The cut-out time of one second and the temperature differential for renewed cut-in can

be changed by using Danfoss' system software type AKM. The cut-out time can be set

between 1 and 300 seconds, and the temperature differential between 1 and 5 K.

Compressor groups

The controller can operate up to eight compressor steps distributed on one or two

compressors. The compressor steps must be defined in two groups, so that the

controller will know which steps belong to compressor A and which to compressor B.

Define first the number of steps for compressor A. After that, the total number of steps

to be regulated by the controller.

The value in "Max. step A" will determine the outputs that belong to compressor A (DO

1 - DO x).

Examples:

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Capacity Ctrl. Adv. Capacity Settings Max. step A

___

Max. step

___

Cut-in and cut-out of capacity steps and compressors

Time delays

1. Capacity steps

Please refer to the section "Regulation".

2. Compressors

To protect the compressor against frequent start-ups, a time delay can be

included. The compressor cannot start again until this time has elapsed.

Capacity Ctrl. Adv. Capacity Settings Del A min. ___

Del B min. ___

Sequence for cut-out of capacity steps

When capacity steps are cut out, the sequence can be selected in one of the

following ways:

1. A linear cut-out is performed. I.e., the cut-in and cutout sequence is not

changed (last cut-in step will be cut-out first when the required capacity again

drops).

2. A re-allocation is made of the steps on the border between compressor A and

compressor B. This function will ensure that compressor B will not stop before

the control unit cuts-out the last step of compressor A.

AKC 24W Functional description RC.1J.F3.02 © Danfoss 11/94 9

Example:

Setting = 1 Setting = 2

Capacity Ctrl. Adv. Capacity Settings Step mode

1 / 2

Operating time of the compressors

The sequence of the compresssors' operating time can be defined.

1. Compressor A to start first, then B will be allowed.

2. Compressor B to start first, then A will be allowed.

3. Automatic equalisation of operating time between compressors A and B.

At the different start-ups the compressor with the lowest number of operating

hours will start first. The factory has put in a time differential of 25 hours.

(With Danfoss' system software type AKM this time differential can be

changed to anywhere between 0 and 100 hours).

The function is selected by keying a number between 1 and 3.

Capacity Ctrl. Adv. Capacity Settings Time share

1 / 2 / 3

More capacity

When the last capacity step had been cut in ("Max. step" setting) and there is still a

need for more capacity, the DO 9 output will be activated. The output may for instance

be used for start-up of a spare water chiller, or, in connection with cascade coupling, of

several controllers. The output must not be used for controlling a ninth compressor

step, as it is not interrupted when safety inputs DI 1 and DI 2 are cut-out.

You may choose between two criteria causing the DO9 output to be activated.

Setting = 1: (Capacity requirements)

- When all valid steps have been cut-in, and more capacity is required

- If there has been a safety cut-out in one or both circuits, and additional

capacity is required

Setting = 2: (Thermostat function)

- When the signal from the media sensor exceeds the value set in the menu

10 Functional description RC.1J.F3.02 © Danfoss 11/94 AKC 24W

"DO9 set °C". (The relay outputs will fall again when the signal has come

down to the set value minus a set differential).

NB! This thermostat function depends on whether the "Cap. Ctrl." setting

is in position ON or OFF, or whether the "Main Switch" setting is +1 or 0.

Capacity Ctrl. Adv. Capacity Settings DO9 mode

1 / 2

DO9 set

___

DO9 diff K

___

Signal from safety controls

The controller has two inputs receiving signals about the status of the safety circuit.

The inputs are connected to an extra set of NC relays in the safety circuit. (The safety

circuit must stop the compressor without involving AKC 24W). If the safety circuit is

cut-out, the controller will cut-out the capacity steps for the compressor concerned (A

or B) and possibly stop its injection function. (See also page 14).

Regulation will continue with the other compressor.

Input DI 1 is connected to the safety circuit for compressor A.

Input DI 2 is connected to the safety circuit for compressor B.

(Interrupted connection (DI 1, DI 2) will stop the regulation.

K1 and K2 must have gold-plated contacts.

Timer

The compressors' operating time is registered by a timer. This registration can be used

in two ways:

1. Display of operating time.

The number of operating hours divided by 10 is shown. In other words, a total

operating time of, say, 700 hours will be indicated with the figure 70.

Capacity Ctrl. Cap. Measurements Run A h/10

Run B h/10

2. Service message

The controller can transmit a message stating when the next service is due.

The function is used, as follows:

Read the timer as described earlier. Add a value to the value read, and enter

the new figure in the controller. When the timer reaches this figure, the "Time

for compr A(B) inspection" message will be sent.

Note that the displayed value must be the number of hours divided by 10.

AKC 24W Functional description RC.1J.F3.02 © Danfoss 11/94 11

Example: Display = 70 and service is required in 1000 hours. The display

70 corresponds to 700 hours. Add the 1000 hours, and you obtain 1700

hours. This value is entered in the menu with the figure 170.

Capacity Ctrl. Adv. Capacity Settings Max A h/10 ___

Max B h/10 ___

NB! When operation is based on system software type AKM, the

actual number of hours is shown

The timer's range is from 0 to 320,000 hours.

External displacement of reference temperature

The reference temperature can be displaced by sending an external voltage signal to

terminal "REF". The voltage must be either 0 - 10 V or 2 - 10 V.

With this signal the reference can be displaced by up to 50 K in positive or negative

direction. 10 V gives max. displacement.

The change of reference is damped with a time constant of approx. 30 seconds.

The function is set to one of the following values:

0: No displacement.

1: Displacement with 0 - 10 V signal

New reference = set ref. + voltage signal x "Ext.Max K" / 10

2: Displacement with 2 - 10 V signal

New reference = set ref. + (voltage signal minus 2) x 1,25 x "Ext.Max K" / 10

Capacity Ctrl. Adv. Capacity Settings Ext. Ref.

0 / 1 / 2

Ext. Max K ___

If displacement of the reference temperature is performed with a potentiometer, the

voltage to the potentiometer may be taken from the controller. Below is an example

where the setting must be 2.

12 Functional description RC.1J.F3.02 © Danfoss 11/94 AKC 24W

Expansion valve

function

The controller has two separate injection regulations that can control the injection into a

shell and tube evaporator.

The adjustment possibilities are the same for the two regulations. Below, () will indicate

that the setting applies to both the A and B regulations. Used as expansion valves are

TQ or PHTQ valves. The capacity requirement will determine which.

Selection of function

The injection function may be selected ON or OFF.

Injection Ctrl. ( ) Inj. Settings Inj.Ctrl. ( )

OFF / ON

Pressure transmitter/temperature sensor

Each of the two expansion valve functions is controlled by signals from a temperature

measurement (S2) and a pressure measurement (P0).

The pressure transmitter must be of type AKS 32 with a pressure range from -1 to 12

bar, (1-5 V).

Injection Ctrl. ( ) Adv. Inject Settings Use AKS 32

If the two evaporators operate with the same evaporating pressure, you need only use

one pressure transmitter.

At the same evaporating pressure with one pressure transmitter the signal is connected

to regulator B, as follows.

AKC 24W Functional description RC.1J.F3.02 © Danfoss 11/94 13

Superheat

The controller can operate the expansion valve in various ways depending on the

required function. Choose between the following functions:

1. Fixed superheat

The superheat is set with fixed values, so that each

cut-in capacity step has a given superheat

reference.

Capacity Ctrl. Adv. Capacity Settings SH step 1

___

SH step 2

___

SH step 8

___

2. Adaptive regulation based on the evaporator load by

means of MSS search (MSS = Minimum Stable

Signal).

The reference set for the first step of compressor A

or B is used during start-up (see point 1). The

superheat is limited by the min. and max. superheat

settings.

3. Regulation based on the TQ valve’s “OD%” opening

degree (Loadap).

The reference follows a defined curve. This curve is

defined with three values: “SH close”, “SH min.” and

“SH max.”. These three values must be selected, so

that the curve will lie between the MSS curve and

the curve for mean temperature differential ∆Tm

(temperature difference between the media

temperature and the evaporating temperature).

Setting example = 4, 6 and 10 K).

4. As “function 3”, but now there is no connection between the compressor regulation’s

safety circuit and the valve regulation.

(Application example: Two compressors and one valve, and where equalisation of

the operating time between compressors is required).

5. As “function 4”, but the TQ valve is kept in stand-by posi-tion here when the last

compressor is stopped.

Cf. also the survey in the next section. Depicted there is the TQ valve’s status at

different input signals and selected functions.

Define function to be used:

Injection Ctrl. ( ) Inj. Settings Adap. Mode: ( )

1...5

Warning! Due to the risk of liquid flow, “SH min.” should not be set lower than approx.

2-4 K.

At functions 3, 4 and 5, the “SH close” value must also be set.

Injection Ctrl. ( ) Adv. Inject Settings SH min K

___

SH max K

___

SH close K

___

14 Functional description RC.1J.F3.02 © Danfoss 11/94 AKC 24W

Forced closing

The injection function can be stopped by means of an external signal.

The signal causes the TQ valve to close, and in some cases it is kept in stand-by

position (TQ is kept warm). This will prevent drop-out of the LP pressure control and

liquid hammer during the subsequent start-up.

Closing can be carried out in three ways:

- The input signal to DI 3 can be interrupted.

The signal also cuts out the capacity regulation, but the TQ valve is kept in stand-by

position when the superheat is defined with function 5.

- The input signal to DI 1 (DI 2) is interrupted.

The signal also cuts out all capacity steps belonging to the regulation (A or B). (If the

superheat is defined for function 4, the TQ valves will keep on regulating. They will

also regulate, if function 5 is selected, but only if it is one of the inputs that is cut out.

See below).

- Short-circuit of sensor S2().

This signal will not influence the controller’s step regulator.

Survey of the TQ valve’s activity with different input signals

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NB! If the capacity regulation is not used (Cap.Ctrl. = OFF), the safety circuit for the

regulation will have no influence on the injection function (the TQ valve will regulate,

whatever the DI input position).

MOP control

(MOP = Maximum Operating Pressure)

The MOP function enters into operation when the set MOP temperature is reached.

The superheat reference is subsequently increased. In this way the valve's opening

degree is reduced.

Injection Ctrl. ( ) Inj. Settings MOP

OFF / ON

The MOP temperature is set in °C.

Injection Ctrl. ( ) Inj. Settings MOP

___

Kp / Tper

Amplification factor (Kp) and time period (Tper) are set.

Kp and Tper are used for optimising the superheat regulation, only if this regulation is

unstable.

The period is the time interval between two max. superheat values. Fast fluctuations

(up to 60 seconds) are not included.

AKC 24W Functional description RC.1J.F3.02 © Danfoss 11/94 15

Setting procedure:

If the system is unstable, the period is registered.

1. If the period is longer than the set period:

Set Tper at the same value as the registered one. If the system is still not stable,

lower Kp until it is stable.

2. If the period is shorter than the set period:

Set Kp at a lower value to make the system stable. The regulation can now be

optimised by setting Tper at the same value as the newly registered period.

Injection Ctrl. ( ) Adv. Inject Settings Kp

___

T per sec

___

The controller also uses the Td regulation parameter. The value of this parameter can

be changed, but only with the use of Danfoss' system software type AKM.

Separate pressure transmitter

It is possible to connect a pressure transmitter which can monitor a required pressure.

The signal is not used in the controller, but can be shown on the control panel's display

or on a connected PC.

The pressure transmitter is connected to input "P aux".

The pressure transmitter must be of type AKS 32 with a pressure range from -1 to 34

bar, (1-5 V).

Expansion valve opening

The expansion valve (TQ or PHTQ) is controlled by a voltage signal from the controller.

The valve's opening degree is determined by:

- The power supply from the controller

- The valve's spring tension (adjustment)

- The system pressure at the valve (pressure equalisation)

Adjustments should only be performed by specially trained persons.

P band (K max Curve)

A change of the K max Curve parameter corresponds to a change of the valve's

internal max. operating temperature (the pressure in the actuator).

Adjustment to a higher value may be necessary, if there is a major pressure

drop across the liquid distributor.

Lower value = colder valve = smaller opening

Higher value = warmer valve = bigger opening

Adjustment:

Start the refrigeration and cool with max. load on the system. Then read the "TQ

open ( )" menu.

Injection Ctrl. ( ) Inj. Measurements TQ open ( ) %:

___

The value should be approx. 80 to obtain the best regulation.

If the value is too low or too high, adjust the K max Curve menu (when the "K

Max Curve" value is lowered, the "TQ open" value is raised).

Injection Ctrl. ( ) Adv. inject Settings Kmax Curve:

___

Warning! If the value is too high, the valve is heated more than necessary.

When it has to close at a later stage, the valve will react very slowly (liquid flow/

compressor damage). If the liquid is not sufficiently subcooled, for example, the

valve will try to open more (the valve is warming up).

Standby temperature

The TQ valve's stand-by temperature is set at the valve's opening temperature.

On large systems it may be necessary to raise the standby temperature, so that

the valve will have time to open before the compressor cuts out due to low

pressure. But this may only happen if solenoid valve has been mounted in the

liquid line right in front of the TQ valve.

Injection Ctrl. ( ) Adv. inject settings Standby K:

___

Opening point (TQ adjust)

The opening point (TQ adjust) is only adjusted, if the refrigerating system is

undergoing a special optimisation. The function is an alternative to the control of

the "Y-measurement" of the orifice. It can only be used when the evaporating

temperature is registered with a pressure transmitter.

Adjustment:

1. The TQ valve's spring is tightened with 5-6 clockwise turns. In this way it is

ensured that adjustment is started with a closed valve.

2. The injection function is put in position OFF.

Injection Ctrl. ( ) Inj. settings Inj. ctrl ( ):

OFF

3. Check that use of pressure transmitter is in position ON.

Injection Ctrl. ( ) Adv. inject settings Use AKS 32:

4. Adjustment permitted.

Injection Ctrl. ( ) Adv. inject settings TQ adjust:

5. The compressor is started and the evaporating pressure (P0) lowered to the

normal operating pressure for the evaporator in question. Now cut out the

compressor.

6. Opening of TQ valve permitted.

Injection Ctrl. ( ) Inj. settings Inj. ctrl ( ):

7. Wait at least two minutes (valve is warming up).

8. Slowly slacken the TQ valve's spring (turn it counter-clockwise) until the liquid

flow starts. Listen to the TQ valve's outlet tube, or read it on a manometer for

P0 or Ps.

Hint! A screwdriver may be used as stethoscope. Place the point of the

screwdriver on the TQ valve's outlet tube and listen to the other end of the

screwdriver.

9. When the opening point has been found, tighten the spring again by half a

turn.

10. Stop the adjustment.

Injection Ctrl. ( ) Adv. inject settings TQ adjust:

OFF

Before regulation is started, the connected functions should be checked. E.g.,

expansion valve, sensors, compressor steps and alarm output.

Measurements

All sensor temperatures and values from pressure transmitters can be read and

controlled here.

It is furthermore possible to read the status of the digital input signals.

Service mode Measurement P0 A bar

P0 B bar

P aux bar

S1 A

S2 A

S1 B

S2 B

Ext. Ref. V

DI 3

TQ A

TQ B

Safety A

Safety B

Forced operation

The components connected to the AKC 24W outputs can be controlled.

Warning! There is no regulation when the outputs are forced to operate. The

compressor should be stopped!

Admission requirements

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

1. The function switch must be put in position Service

Main Function Main Switch Main Switch

-1

2. "Manual control" is put in position ON

Service mode Manual Control Man. Ctrl.

The individual outputs can now be forced.

Expansion valve

Forced control of the TQ (PHTQ) valve's degree of opening.

The setting value is in per cent of the power supply to the valve.

This function is for instance used when the system has to be evacuated

(setting = 100%).

Warning! Liquid flow in the evaporator may damage the compressor.

Service mode Manual Control TQ A %

___

TQ B %

___

Capacity steps

ON/OFF setting of the individual capacity steps.

Service mode Manual Control Step 1

OFF / ON

Step 2

OFF / ON

Step 3

OFF / ON

Step 4

OFF / ON

Step 5

OFF / ON

Step 6

OFF / ON

Step 7

OFF / ON

Step 8

OFF / ON

Service

More capacity

ON/OFF setting of the "more capacity" output.

Service mode Manual Control More Cap

OFF / ON

Alarm

ON/OFF setting of the alarm output.

Service mode Manual Control Alarm Out

OFF / ON

The "OFF" setting will activate the alarm.

(ON relay closed. OFF = relay inoperative, cut out)

When forced operation is concluded, the "Man.Ctrl." setting must be put in position

OFF before you abandon the service function. The status of the outputs will then

return to the factory-set values.

IIn connection with the controller’s functions there are a number of alarms and mes-

sages which become visible in case of a fault or incorrect operation.

Distinction is made between important information and not so important information.

The degree of importance is fixed for some, whilst others can be changed if required.

(This change can only be made when a PC is connected to the system and settings

have to be made in each of the relevant controllers).

The importance is indicated by means of the following:

1. "Alarms"

This is important information from the controller.

- The controller’s alarm output is activated.

- Information is transmitted on the DANBUSS

network together with status value 1.

- If a gateway type AKA 24 is connected and it is defined as master, its relay output

DO2 will be activated for two minutes (AKA 24 with software version 2.0 or later).

- Later, when the alarm is discontinued, 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 “message” is discontinued, the same information will be repeated

but this time with status value 0.

0. “Suppressed information”

This information stops at the controller. It is not transmitted anywhere.

List of alarm activities

mralA

ecnatropmi

mralA

sutats

W42CKA

yalermrala

W42CKA

DELmrala

12AKA

DEL

42AKA

yaler2OD

mralAFFOSEHSALFSEHSALF.nim2FFO

mralaoNNOFFOFFONO

mralANOSEHSALFSEHSALFNO

mralaoNNOFFOFFONO

mralANOFFOFFONO

mralaoNNOFFOFFONO

Alarms and messages

Information from the controller

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

shown in brackets “[ ]”. If there are several figures in the bracket, the setting can be

changed (the factory setting is shown in bold type).

Sx Error ( ) [ 1 ]

Sx may be the S1 and S2 (in regulation A or B), S3 or S4 sensor. The sensor

may be cut out, short-circuited or not mounted. When there are errors in S1 or

S2, the controller will stop the regulation in question and cut out the group of

capacity steps.

(This does not apply to short-circuits of S2 sensors. When there are errors in S3

or S4, both the A and the B regulation will be stopped, and all capacity steps will

be cut out.

P0 Error ( ) [ 1 ]

P0 can be P0A, P0B or Paux.

The transmitter may be cut-out, short-circuited or not mounted. When there are

errors in P0A or P0B, the controller will stop the regulation in question and cut-

out all capacity steps.

NTC Error TQ( ) [ 1 ]

An error of the temperature measurement in TQ (PHTQ) has been registered.

The connection is interrupted or short-circuited, or the max. heating time has

been exceeded. When there is an error, the controller will stop the regulation in

question and cut-out the group of capacity steps. Manual reset will be required.

Safety ( ) Cut out [ 1,2,0 ]

The respective safety circuit is cut-out. When there is an error the controller will

stop the regulation in question and cut-out the group of capacity steps.

Cut off below Limit temp [ 1, 2,0 ]

The temperature at the selected limit sensor is lower than the limit temperature.

When there is an error, both the A and the B regulation will be stopped, and all

capacity steps will be cut-out at intervals. Regulation will recommence when the

temperature again exceeds the limit temperature and when the time delay "--

zone" and "Del ( )" has elapsed.

Max step A > Max step [ 1, 2,0 ]

Wrong values have been set in the "Max step A" and/or "Max step" menus.

Rfg. type not selected [ 1, 2,0 ]

No refrigerant has been selected. Before regulation can be started, the controller

must have its type of refrigerant set.

Rfg. type change after power up [ 1, 2,0 ]

Refrigerant type changed after start-up of controller.

Warning! Change of refrigerant type may cause damage to the compressor.

See section on choice of refrigerant.

Standby Mode [ 1, 2,0 ]

Regulation is manually stopped/started via the "Main switch" menu. When the

regulation has been stopped, there will be a few messages that cannot be

transmitted.

Time for Compr.( ) inspection [ 1, 2,0 ]

The set operating time for the compressor has been reached. Send for service.

Set the "Max ( ) h/10" menu to the time for the next message.

Too high Media temperature [ 1, 2,0 ]

A media temperature is registered which is higher than the set alarm value

("Media AL °C).

Adj. Error TQ( ) AKS 32 not ON [ 1, 2,0 ]

A setting error has been committed. A pressure sensor is mounted, but a tem-

perature sensor has been chosen in the menu.

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 mes-

sages).

This procedure has a different influence 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 24 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 transmitted cannot be seen.

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

can only be made from a PC.

The "Auto reset" setting is put in position "ON".

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

status which is either 1, 2 or 0.

1 means that it is new and important information (information defined with

setting = 1)

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

defined with setting = 2)

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 defined in the system.

Setting of the address is performed directly in each controller via a number of

switches (cf. instructions).

Network systems

A defined PC or AKA 24 with printer will here be the receiver of alarms for the

connected units.

- Each controller is given an address, so that the unit is defined in the system.

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

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Danfoss Controller type AKC 24W for control of water chillers vers. 4.4x Installation guide

Danfoss Controller type AKC 24W for control of water chillers vers. 4.4x Installation guide

Danfoss Controller type AKC 24W for control of water chillers vers. 4.4x Installation guide

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