LG RCAW070PBAA Owner's manual

P/NO : MFL63291701

www.lg.com

Operation & Maintenance Manual

CHILLER

AIR-COOLED SCREW

Please read this manual carefully before operating

your set and retain it for future reference.

TYPE : Chiller Air-cooled Screw R134a

MODELS : RCAW - COMPACT

2 Chiller Air-cooled Screw

SAFETY CONSIDERATIONS

Warning...................................................................................................................................3

Caution....................................................................................................................................7

GENERAL

Manipulation of HMI Unit.......................................................................................................11

CONTROLS

PLC and HMI Unit .................................................................................................................21

Machine on/off control...........................................................................................................30

START-UP

Pre Start-up ..........................................................................................................................31

Start-up Procedure................................................................................................................32

Operation Limits....................................................................................................................34

OPERATION

Sequence of Operation .........................................................................................................40

Sensors.................................................................................................................................45

SERVICE

Cycle Components................................................................................................................46

Control System .....................................................................................................................59

Maintenance .........................................................................................................................70

TROUBLE SHOOTING............................................................................................................71

APPENDIX

Wiring Diagram .....................................................................................................................79

Cycle Diagram ......................................................................................................................89

Check List .............................................................................................................................90

Air cooled Screw Operation & Maintenance Manual

TABLE OF CONTENTS

Safety Considerations

Operation & Maintenance Manual 3

Installing, starting up, and servicing this equipment can be hazardous due to system pressures, electrical com-

ponents, and equipment location (roof, elevated structures, etc). Only trained, qualified installers and service

technicians should install, start up, and service this equipment. When working on this equipment, observe pre-

cautions in the literature, and on tags, stickers, and labels attached to the equipment, and any other safety pre-

cautions that apply. Follow all safety codes. Wear safety glasses and work gloves. Use care in handling, rig-

ging, and setting this equipment, and in handling all electrical components.

To prevent injury to the user or other people and property damage, the following instructions must be followed.

■ Incorrect operation due to ignoring Instructions in the manual will cause harm or damage. The seriousness is

classified by the following indications.

■ We do not have any responsibility for any failure caused by careless management and natural disaster, and

power cord failure regardless of warranty period.

■ The content in the manual could be changed for the improvement of product without notice.

■ Meanings of symbols used in this manual are as shown below.

This symbol indicates the possibility of death or serious injury.

This symbol indicates the possibility of injury or damage to properties only.

Be sure not to do.

Be sure to follow the instruction.

All wiring must comply with local require-

ments and the instructions given in this

manual.

• If the power source capacity is inadequate or

electric work is performed improperly, electric

shock or fire may result.

Ask the dealer or an authorized technician to

install the chiller.

• Improper installation by the user may result in

water leakage, electric shock, or fire.

SAFETY CONSIDERATIONS

Safety Considerations

4 Chiller Air-cooled Screw

For re-installation of the installed product,

always contact a dealer or an Authorized

Service Center.

•

There is risk of fire, electric shock, explosion, or injury.

Do not install, remove, or re-install the unit by

yourself (customer).

•

There is risk of fire, electric shock, explosion, or injury.

Do not store or use flammable gas or

combustibles near the chiller.

• There is risk of fire or failure of product.

Use the correctly rated breaker or fuse.

• There is risk of fire or electric shock.

Do not install the product on a defective

installation stand.

• It may cause injury, accident, or damage to the

product.

When installing and moving the chiller to

another site, do not charge it with a

different refrigerant from the refrigerant spec-

ified on the unit.

• If a different refrigerant or air is mixed with the

original refrigerant, the refrigerant cycle may mal-

function and the unit may be damaged.

Do not reconstruct to change the settings of

the protection devices.

• If the pressure switch, thermal switch, or other

protection device is shorted and operated forcibly,

or parts other than those specified by LGE are

used, fire or explosion may result.

Ventilate before operating chiller when gas

leaked out.

• It may cause explosion, fire, and burn.

Securely install the cover of control box and

the panel.

• If the cover and panel are not installed securely,

dust or water may enter the air-cooled unit and

fire or electric shock may result.

If the chiller is installed in a small room, mea-

sures must be taken to prevent the

refrigerant concentration from exceeding the

safety limit when the refrigerant leaks.

• Consult the dealer regarding the appropriate

measures to prevent the safety limit from being

exceeded. Should the refrigerant leak and cause

the safety limit to be exceeded, harzards due to

lack of oxygen in the room could result.

Always ground the product.

• There is risk of fire or electric shock.

Always intstall dedicated circuit and breaker.

• Improper wiring or installation may cause fire or

electric shock.

Safety Considerations

Operation & Maintenance Manual 5

Do not damage or use an unspecified power

cord.

• There is risk of fire, electric shock, explosion, or

injury.

Use a dedicated outlet for this appliance.

• There is risk of fire or electrical shock.

Be cautious that water could not enter the

product.

•

There is risk of fire, electric shock, or product damage.

Do not touch the power switch with wet

hands.

•

There is risk of fire, electric shock, explosion, or injury.

When the product is soaked (flooded or

submerged), contact an Authorized Service

Center.

• There is risk of fire or electric shock.

Take care to ensure that nobody could step on

or fall onto the air-cooled unit.

• This could result in personal injury and product

damage.

Be careful of the rotating part.

• Be careful not to put your finger or a stick in the

rotating part of the fan or pump.

• Do not operate the fan with the protective net

removed. It can cause body injury.

Use of undesignated refrigerant and oil is pro-

hibited.

• Do not use undesignated refrigerant, freezer oil

and brine.

• It can have a critical effect on the compressor and

component defects.

• If you would like to use a substitute for the refrig-

erant, please contact the manufacturer.

Redesigning the control box is prohibited.

• Lock the control box with possible locking device

and if you need to open the control box inevitably,

turn off the main power first.

•

Do not touch the wiring or parts within the control box.

• It can cause electric shock, fire or defects.

Be careful of leakage.

•

If you find a leakage in the connected part such as

pump, piping etc., immediately stop the operation.

• It can cause electric shock, leakage or defects.

Follow the permitted pressure level.

• Follow the regulated pressure for cold water, cool-

ing water, refrigerant etc.

• It can cause electricity leakage or burn/frostbite

eruption or leakage.

Be cautious of fire, earthquake and lightning.

• If there is natural disaster such as fire or earth-

quake, or risk of lightning, immediately stop oper-

ating the unit.

• If you continue to operate the unit, it can cause a

fire or electric shock.

Safety Considerations

6 Chiller Air-cooled Screw

Changing the set value is prohibited.

• Do not change the set value of the safety device.

• If you operate the product with incorrectly set val-

ues, it can cause defect, fire or explosion.

• When you change the control setting value,

please consult with the specialized expert.

Electric shock prevention.

• When installing the freezer, always ground the

wire.

• It can cause electric shock.

Follow all safety codes.

• When working on this equipment, observe pre-

cautions in the literature, and on tags, stickers,

and labels attached to the equipment, and any

other safety precautions that apply.

Wear safety equipment.

• Wear safety glasses and work gloves.

•

Use care in handling, rigging, and setting this equip-

ment, and in handling all electrical components.

Shut off all power to this equipment during

installation and service.

•

Electrical shock can cause personal injury and death.

• There may be more than one disconnect switch.

Tag all disconnect locations to alert others not to

restore power until work is completed.

Always run fluid through heat exchangers

when adding or removing refrigerant charge.

•

It prevent potential damage to heat exchanger tubes.

• Use appropriate brine solutions in cooler fluid

loops to prevent the freezing of heat exchangers

when the equipment is exposed to temperatures

below 32°F(0°C).

Do not attempt to unbraze factory joints when

servicing this equipment. Cut lines with a tub-

ing cutter as required when performing ser-

vice.

• Compressor oil is flammable and there is no way

to detect how much oil may be in any of the refrig-

erant lines.

• Use a pan to catch any oil that may come out of

the lines and as a gage for how much oil to add to

system.

Do not re-use compressor oil.

• It may cause damage to the product.

Do not vent refrigerant relief valves within a building.

• Outlet from relief valves must be vented outdoors in accordance with the latest edition of ANSI/ASHRAE

(American National Standards Institute/American Society of Heating, Refrigeration and Air Conditioning

Engineers) 15 (Safety Code for Mechanical Refrigeration).

• The accumulation of refrigerant in an enclosed space can displace oxygen and cause asphyxiation.

• Provide adequate ventilation in enclosed or low overhead areas. Inhalation of high concentrations of

vapor is harmful and may cause heart irregularities, unconsciousness or death. Misuse can be fatal.

Vapor is heavier than air and reduces the amount of oxygen available for breathing. Refrigerant causes

eye and skin irritation.

Safety Considerations

Operation & Maintenance Manual 7

Do not leave refrigerant system open to air any longer than necessary.

• Seal circuits being serviced and charge with dry nitrogen to prevent oil contamination when timely

repairs cannot be completed.

Always check for gas (refrigerant) leakage

after installation or repair of product.

• Low refrigerant levels may cause failure of

product.

Do not install the product where the noise or

hot air from the air-cooled unit could damage

the neighborhoods.

• It may cause a problem for your neighbors.

Keep level even when installing the product.

• To avoid vibration or water leakage.

Do not install the unit where combustible gas

may leak.

• If the gas leaks and accumulates around the

unit, an explosion may result.

Use power cables of sufficient current

carrying capacity and rating.

• Cables that are too small may leak, generate

heat, and cause a fire.

Do not use the product for special purposes,

such as preserving foods, works of art, etc. It

is a consumer chiller, not a precision refriger-

ation system.

• There is risk of damage or loss of property.

Keep the unit away from children.

• It can cause the injury, such as cutting the finger.

Also the damaged fin may result in degradation of

capacity.

When installing the unit in a hospital, commu-

nication station, or similar place, provide suffi-

cient protection against noise.

•

The inverter equipment, private power generator, high-

frequency medical equipment, or radio communication

equipment may cause the chiller to operate erroneous-

ly, or fail to operate. On the other hand, the chiller may

affect such equipment by creating noise that disturbs

medical treatment or image broadcasting.

Do not install the product where it is exposed to sea wind (salt spray) directly.

• It may cause corrosion on the product. Corrosion, could cause product malfunction or inefficient opera-

tion.

Safety Considerations

8 Chiller Air-cooled Screw

Do not use the chiller in special

environments.

• Oil, steam, sulfuric smoke, etc. can significantly

reduce the performance of the chiller or damage

its parts.

Make the connections securely so that the

outside force of the cable may not be applied

to the terminals.

• Inadequate connection and fastening may gener-

ate heat and cause a fire.

Be sure the installation area does not deterio-

rate with age.

• If the base collapses, the chiller could fall with it,

causing property damage, product failure, or per-

sonal injury.

Be very careful about product transportation.

•

When transporting the chiller, always consult with

the specialized expert.

When transporting the chiller, make sure to comply

with the method regulated in the manual. If not, it

can cause overturn, fall etc.

Safely dispose of the packing materials.

•

Packing materials, such as nails and other metal or

wooden parts, may cause stabs or other injuries.

•

Tear apart and throw away plastic packaging bags

so that children may not play with them. If children

play with a plastic bag which was not torn apart, they

face the risk of suffocation.

Turn on the power at least 12 hours before

starting operation.

• Starting operation immediately after turning on

the main power switch can result in severe

damage to internal parts. Keep the power switch

turned on during the operational season.

Do not touch any of the refrigerant piping dur-

ing and after operation.

• It can cause a burn or frostbite.

Do not operate the chiller with the panels or

guards removed.

• Rotating, hot, or high-voltage parts can cause

injuries.

Do not directly turn off the main power switch

after stopping operation.

• Otherwise it may result in oil supply shortage or

other problems.

Use a firm stool or ladder when cleaning or

maintaining the chiller.

• Be careful and avoid personal injury.

Safety Considerations

Operation & Maintenance Manual 9

Be careful of disposal.

• When disposing the device, request to the spe-

cialized expert.

Be careful of high voltage.

•

Install separate wiring for the power and always install

and use dedicated power supply and circuit breaker.

• It can cause electric shock or fire.

Be careful of high temperature.

• Because the machine part can be hot, do not

touch it with any part of your body.

• It can cause burns.

Be careful of restarting.

• When the safety device of the product operates,

resolve the cause before re-operating.

•

If you repeat this arbitrarily, it can cause fire and defect.

Be careful of device installation.

• Be careful of the clearance of the device during

the installation and make sure there are no sur-

rounding obstacles for the air cooling type and

that it is well ventilated.

Be careful of sound or odor.

• If you hear a weird sound or smell weird odor,

immediately stop operating the unit and contact

the service center.

• It can cause fire, explosion and injury.

Check.

• Execute the periodic check. If an issue is found,

stop operating the unit and contact the service

center.

•

Insufficient check can cause fire, explosion and defect.

Use appropriate tools.

• Use appropriate tools used for the repair and

make sure to calibrate the measuring devices

precisely before use.

•

If you use inappropriate tools etc, it can cause an accident.

Be careful of air cooling type heat exchanger.

• Because the condenser of the air cooling type

device is sharp, do not touch the condenser.

• Protective net must always be kept installed.

• It can cause an injury.

It can cause an injury.

• Check the safety label of the safety device.

• Follow upper precautions and labels. If not, it can

cause injury or damage such as a fire etc.

• To prevent the generation of condensed water,

the connecting pipe to the evaporator, as well as

the evaporator itself, must be insulated.

Do not use jumpers or other tools to short out

components, or to bypass or otherwise depart

from recommended procedures.

• Any short-to-ground of the control board or

accompanying wiring may destroy the electronic

modules or electrical components.

Do not attempt to bypass or alter any of the

factory wiring.

• Any compressor operation in the reverse direction

will result in a compressor failure that will require

compressor replacement.

Safety Considerations

10 Chiller Air-cooled Screw

Consult a water treatment specialist for proper

treatment procedures.

• Hard scale may require chemical treatment for its

prevention or removal

Water must be within design flow limits, clean

and treated.

•

This make it possible to ensure proper machine per-

formance and reduce the potential of tubing damage

due to corrosion, scaling, erosion, and algae.

• LG assumes no responsibility for chiller or con-

denser damage resulting from untreated or

improperly treated water.

Rig unit from the top heat exchanger only.

• Rigging from the bottom heat exchanger will

cause the unit to be lifted unsafely.

• Personal injury or damage to the unit may occur

Welding is not recommended in the cooler

heads or nozzles.

• In the event that welding must be performed,

remove the chilled water flow switch and entering

and leaving fluid thermistors before welding.

• Reinstall flow switch and thermistors after welding

is complete. Failure to remove these devices may

cause component damage.

Harsh chemical, household bleach or acid

cleaners should not be used to clean outdoor

or indoors coils of any kind.

• These cleaners can be very difficult to rinse out of

the coil and can accelerate corrosion at the

fin/tube interface where dissimilar materials are in

contact. If there is dirt below the surface of the

coil, use the Environmentally Sound Coil Cleaner.

Do not use high-pressure water or air to clean

coils.

• It may cause fin damage

•

High Velocity Water or Compressed Air should

never be used to clean a coil. The force of the

water or air jet will bend the fin edges and increase

airside pressure drop. Reduced unit performance

or nuisance unit shutdown may occur.

Do not overcharge system.

• Overcharging results in higher discharge pressure

with higher cooling fluid consumption, possible

compressor damage and higher power consump-

tion.

Do not add oil at any other location.

• It may cause improper unit operation

Compressor oil is pressurized.

• Use proper safety precautions when relieving

pressure.

Turn controller power off before servicing con-

trols.

• This ensures safety and prevents damage to con-

troller.

General

Operation & Maintenance Manual 11

GENERAL

This manual is composed of information on control, operation, start-up, service and troubleshooting of RCAW Air Cooled

Chiller.

■ Manipulation of HMI(Human Machine Interface) Unit

If it is strongly recommended that the user NOT change any programing without consulting

LGE service personnel. Unit damage may occur from improper programming.

The menu structure of the HMI unit is shown in the below. As you can see, there are 7 menu items for user interface.

Moving among menu items are accomplished by the manipulation of the arrow keys ◁▷. To see the detail information

of the each menu item, press the arrow key ▽. To start up the chiller start button must be pressed for more than 3 sec-

onds. Similarly, to shut down the chiller, stop button must be pressed for more than 3 seconds.

Main Menu

System Setting

User Setting

Content

System Setting

Main Display

Par. Setting

Content

Par. Setting

System Setting

Delay Setting

Content

Alarm Display

Delay Setting

User Setting

Content

Delay Setting

Par. Setting

Alarm Display

Content

LG

Flooded Air-Cool Screw Chiller

SYS 2.71 PG 14.01

I/O Display

User Setting

Alarm Display

Content

User Setting

I/O Display

Main Display

Content

Fig. 1

General

12 Chiller Air-cooled Screw

Main Menu

The main menu is composed of 4 screen cuts. Moving among them is accomplished by the manipulation of the arrow

keys ▽△. The main menu shows configured control parameter of the PLC, temperature inputs, and accumulated com-

pressor running hour and current running capacity

In the below main menu, hand/auto mode is configured to be auto control, control mode is configured to be local control.

These two items are configurable through user setting menu. The auto control represents the operation mode using

scheduling program without key manipulation or remote signal. Contrarily, hand control represents the operation mode

using key manipulation or remote signal.

All temperature readings are displayed on the main menu. The temperature readings include chilled water entering tem-

perature (CHW In Temp), outdoor air temperature (Ambient Temp), compressor exhaust temperature (Exhaust Temp),

chilled water leaving temperature (CHW Out Temp), and condenser refrigerant leaving temperature (Condensate

Temp).

Compressor running hours(Comp Running Hrs) means accumulated running hours of the compressor. This value can

be initialized by operator if needed. For example, if we replace the compressor with new one, the value must be initial-

ized.

The running capacity can be 0%, 25%, 50%, 75%, or 100% according to the actual compressor capacity control.

Main Menu

System Setting

User Setting

Content

Date2009/03/03

CHW In Temp

Ambient Temp

Exhaust Temp

CHW Out Temp

Condensate Temp

Status Message Closed-down

Comp Running Hrs

Running Capacity

Hand/Auto Mode

Control Mode

Start Interval

Modbus

Auto Control

Local Control

Complete

Use

13:05:00

+17.9 C

+16.9 C

+17.3 C

+17.9 C

+17.2 C

2Hr

0%

Fig. 2

General

Operation & Maintenance Manual 13

User Setting

The user setting is composed of 8 screen cuts. Moving among them is accomplished by the manipulation of the arrow

keys ▽ △. Through user setting, operator can configure control parameters of the chiller. The Control parameters of

compressor controls, start mode, control mode and scheduling program. To initiate configuration, press the SET key.

With confirming highlighted item after pressing the SET key, the operator can change the value of a digit of the selected

item by the arrow keys ▽ △‚ or can change the selected digit by the arrow keys ◁▷. After changing the value of all

digits of the selected item, pressing ENT makes the highlighted item to be changed to the next one. Pressing ESC dur-

ing changing makes the changed to be canceled.

The compressor control parameters (Temp Setting) include chilled water leaving temperature reference setpoint (Target

Temp), compressor shutdown temperature (Outage Temp), compressor restart temperature(Restart Temp). The chilled

water leaving temperature reference setpoint is desirable temperature configured by the operator. The allowable range

of the temperature is 5°C ~ 12°C(41°F ~ 53.6°F). The default value of it is 7°C (44.6°F).

Setting Values

Value Setting Keys

SET

ENTER

Moving to Next Item

ESC

Canceling Setting

Moving to Next Digit

User Setting

I/O Display

Main Menu

Content

Temp Setting

Target Temp

Outage Temp

Restart Temp

Mode Selection

Control Mode

Hand/Auto Mode

Modbus

Time Modify

Date Setting

Time Setting

Week Modify

Week Setting

Week

Revision Code

Oil Preheat

0

Mon Start

Mon Stop

Tues Start

Tues Stop

Sun Start

Sun Stop

5 C ~12 C

SET

Non-use

SET

Changing Value

7.0

C

5.0

C

12.0

C

Remote

Hand

Use

Local Control

Auto Control

2009/03/03

13:20:10

OFF

Mon

Min

OFF

Delay

08:00:00

18:00:00

06:00:00

17:00:00

10:00:00

14:30:00

Fig. 3

General

14 Chiller Air-cooled Screw

Compressor shutdown temperature means the temperature where the compressor must be shut downed by low temper-

ature. Here, the default value is 5.0°C(41°F). Compressor restart temperature means the temperature where the com-

pressor must restart after shutdown. Here the default value is 12°C(53.6°F). By difference between the shutdown tem-

perature and the restart temperature, the compressor is protected from frequent starting.

Operation mode and control mode of main menu are able to be changed in user setting. The operation mode can be

either hand or auto. When the operation mode is auto, the chiller runs according to programmed schedule. Contrary,

when the start mode is hand, the chiller runs according to key manipulation by operator or remote signal.

The control mode can be either local or remote. When the mode is local, the chiller runs according to key manipulation

by operator, Contrary, when the mode is changed to remote, a remote contact is substitute the key operation, and con-

sequently, the chiller can be operated remotely.

Through the time amending, the operator can change system clock. Because the clock is maintained even with power

loss, there is no need to set the clock again after power on.

Through the revision code, the operator can change password. Some functions of the HMI unit are protected by the

password.

Oil preheating time is also configurable in user setting in the unit of minute.

General

Operation & Maintenance Manual 15

The I/O display is composed of 9 screen cuts. Through the I/O Display, switch status of signal inputs to the PLC can be

identified. In the I/O display, ON means close status of a contact and OFF means open status of contact.

The remote control means remote start input to the PLC. When the contact is closed and the control mode is remote,

the chiller starts from stop. When the control mode is local, the switch input is disregarded.

The oil system means the serially connected input of oil flow switch and oil level switch. When both of the oil flow and

the oil level are normal during running compressor, both are closed, and consequently the oil system is also closed.

When anyone of them is abnormally opened, the switch input to the PLC is also changed into open. The PLC considers

the open status of the switch to be oil system alarm.

The compressor contactor switches indicate the status of compressor run. When only the main contactor is closed, the

compressor is in the Star-start phase, and when the both of them are closed, the compressor is in the Delta-start phase.

Because the contactor switches are contactor status input to the PLC, the contactor inputs must be differentiated from

output to the contactors. When there is any problem with a contactor, the input from the contactor and the output the

contactor can be different. Consequently, the PLC evaluates the normality of the contactors by checking inputs after

making outputs to the contactors be on.

The antifreeze S/W indicated the contact status from the anti-freezing switch. The switch is normally closed, and opens

when temperature is under setting value. The PLC considers the openness of the switch to be anti-freezing switch

alarm.

The pressure means the serially connected input of high pressure cutout switch and low pressure cutout switch. Both

switches are packaged in a dual pressure switch. Both switches are normally open. But if compressor discharge pres-

sure is over the setting value of the high pressure cutout switch or if compressor suction pressure is under the setting

value of the low pressure cutout switch, the cutout switch opens. The PLC considers the openness of the switch to be

pressure alarm.

I/O Display

User Setting

Alarm Display

Content

Remote Control

System Oil

Main Contactor

Contactor

Low Temp Switch

Pressure Switch

Phase Protect

Chilled Flow

Dif-pressure

Comp Overload

Fan 1A1B

Fan 2A3A

Fan4A5A OFF

OFF

Fan2B3B

Fan4B5B

Emergency Stop

Alarm Output OFF

M1 Contactor OFF

M2 Contactor OFF

M3 Contactor OFF

25% Magnet Valve

50% Magnet Valve

OFF

75% Magnet Valve

Pump

Fan1A1B

Fan2A3A

Fan4A5A

Fan2B3B

Fan4B5B OFF

SV2 Magnet Valve OFF

DISCRETE INPUTS2

DISCRETE INPUTS1

DISCRETE INPUTS3

DISCRETE INPUTS4

DISCRETE INPUTS6

DISCRETE INPUTS5

DISCRETE OUTPUT1

DISCRETE OUTPUT2

DISCRETE OUTPUT3

OFF

Fig. 4

General

16 Chiller Air-cooled Screw

The liquid flow switch detects chilled water flow, and the water flow must build during running the chiller. The openness

of the switch during starting up or running compressor is considered to be water flow alarm by the PLC.

The DP switch means differential pressure switch input to the PLC. Normally, the switch must be closed when the com-

pressor runs. The switch opens when the differential pressure between condenser and evaporator is lower than the set-

ting value even with running compressor. The PLC considers the openness of the switch with running compressor to be

differential pressure alarm.

The overload switch is compressor internal protector that measures the temperature of motor winding and compressor

discharge. When any of the temperatures exceeds predetermined value, the switch opens. The PLC considers the

openness of the switch to be compressor overload alarm.

The fan contactor inputs are interconnected with their own overload relay contact, so they must be closed with running

fans.

The emergency stop switch must be closed, when the emergency switch is in normal position. When the switch is

pushed by operator, the emergency stop switch opens and all output from the PLC are disconnected. The PLC consid-

ers the openness of the switch to be emergency alarm.

The discrete outputs generated from the PLC are also displayed on the screen cut.

Alarm means the alarm notification to external devices by the PLC. If any system alarm is detected by the PLC, the

alarm will be closed by the PLC.

Main contactor, M2 contactor, and M3 contactor are outputs to the magnetic contactors for the compressor. When the

compressor starts, main contactor(M1) and M3 contactor are energized to start the compressor with star winding topolo-

gy. After a few seconds, the winding topology is changed into delta topology by de-energizing the M3 and energizing M2

instead. During running the compressor, the main contactor and the M2 contactor hold to be energized.

The 25% mgv, 50% mgv, and 75% mgv represent outputs to magnet valves for compressor loading. The magnet valves

are installed on the compressor. The capacity control by the control of the magnet valves is shown in the below table.

The fan outputs are outputs to the magnetic contactors of the fans by the PLC.

Step

100% Off Off Off

75% On Off Off

50% Off On Off

MINIMUM Off Off On

Magnet Valve

75% 50% 25%

Table 1

General

Operation & Maintenance Manual 17

Alarm Display

Through the alarm display, recent 10 alarms are displayed with their invocation time.

The alarm also can be cleared in this screen cut. After pressing SET key, the value at affirm entry is changed to clear by

pressing the arrow keys ▽△. Pressing ENT key after the value is changed into clear makes the clearance of the alarm

history be effective.

Fig. 5

Alarm Display

Delay Setting

User Setting

Content

Alarm History 1/10

5E Alarm

2009/03/03 Date 12:53:50Time

Clear ----

Alarm History 2/10

5E Alarm

2009/03/03 Date 12:53:50Time

Clear

Alarm History 10/10

5E Alarm

2009/03/03 Date 12:53:50Time

Clear

General

18 Chiller Air-cooled Screw

System Setting

The system setting is composed of 2 screen cuts. Through the system setting, the temperature readings can be adjust-

ed when there are some problems with the sensor themselves. Additionally running hours can be cleared in this screen.

After pressing SET key, the value at running hrs clear entry is changed to clear by pressing the arrow keys ▽△.

Pressing ENT key after the value is changed into clear makes the clearance of the alarm history be effective.

Fig. 6

System Setting

Main Display

Par. Setting

Content

Temp and Hours Correction

Chilled In

Chilled Out

Condensate Temp

Ambient Temp

Exhaust Temp

Limit Comp Hrs

Clear Comp Hrs

+0.0 °C

100000

----

General

Operation & Maintenance Manual 19

Parameter Setting

Fig. 7

Par. Setting

System Setting

Delay Setting

Content

Fan Start Temp3

Fan Start Temp2

Fan Start Temp1

Load Interval

Limit Temp

Low Temp

Outage DT

Restart DT

H Exhaust Temp

90.0 C

SET

10.0~20.0

1.0~5.0

1.0~3.0

SET

1.0~3.0

34.0~37.9

29.0~33.9

25.0~28.9

29.0~200.0

35.0 C

30.0 C

26.0 C

60S

15.0 C

2.0 C

80.0~150.0

The system setting is composed of 3 screen cuts. Through the parameter setting, the control parameters of control oper-

ations can be identified and changed. To initiate the change, press the SET key. With confirming highlighted item after

pressing the SET key, the operator can change the value of a digit of the selected item by the arrow keys ▽△or can

change the selected digit by the arrow keys ◁▷. After changing the value of all digits of the selected item, pressing

ENT makes the highlighted item to be changed to the next one. Pressing ESC during changing makes the changed to

be canceled.

Firstly, Fan control transition points (fan full opening, fan off1, and Fan off2) can be configured. From the transition

points, fan full opening means the condenser refrigerant leaving temperature setpoint for running all condenser fans.

When actual temperature is over the setpoint, all condenser fans must run. Similarly, the fan off1 means the condenser

refrigerant leaving temperature setpoint for running 8 condenser fans. And the fan off2 means the condenser refrigerant

leaving temperature setpoint for running 6 condenser fans. Consequently, minimum 6 condenser fans run when the

chiller operates, and the number of condenser fans is proportional to the condenser refrigerant leaving temperature. The

configurable range is shown in the below picture.

Secondly, system clock can be also changed here.

The compressor discharge alarm point temperature cannot be changed only, only informative to operator.

The load limit temp is the temperature setpoint where the capacity override is activated. When the chilled water leaving

temperature is over the value, the compressor is prevented from running with 100% capacity and the capacity of the

compressor is limited to 75%.

The anti-freezing temp is another method to protect the chiller from too low chilled water temperature additional to anti-

freezing switch shown in I/O display.

General

20 Chiller Air-cooled Screw

Delay Setting

Fig. 8

Delay Setting

Par. Setting

Alarm Display

Content

Temp Alarm

System Oil

Water Flow

System Pressure

Start Interval

Comp Start Delay

Comp Stop Delay

Fan Feedback

Contactor-feed

DP Delay

Comp Protect

Fan Stop Delay 30S

SET

15.0~60.0

0.3~1.5

0.3~5.0

90.0~350.0

0.5~1.5

1.0~30.0

10.0~900.0

1.0~20.0

0.0~900.0

8~15

20~200

60~200

3.0S

30.0S

9.0S

3.0S

10Min

30S

60S

2.0S

3.0S

300.0S

1.0S

The delay setting is composed of 3 screen cuts. In this display, control sequence delay and alarm determination delay

are configurable.

Start interval is delayed interval between consecutive starts. The delay is counted after the compressor is shut downed

and the next start is delayed for the elapse of the time. The startup delay is the delay between water pump run and com-

pressor run at startup phase. When the PLC receives start signal from operator, the PLC initiate the water pump firstly.

And after the defined delay, the PLC starts the compressor sequentially.

The outage delay is delay between minimization of the compressor capacity and compressor stop. When the PLC

receive stop signal from operator the PLC reset the capacity valves into minimum capacity position. And after the

defined delay, the PLC stop the compressor sequentially.

Oil preheat is startup delay of the chiller after receiving start signal. When the chiller is stopped preheating is performed

automatically. So through this delay, the preheating time is reserved.

The fan feedback delay is delay to check switch inputs from the magnetic contactors of the fans after energizing the

magnetic contactors. Similarly, the contactor feedback is delay to check switch inputs from the magnetic contactors of

the compressors after energizing the magnetic contactors.

DP means the delay for the determination of differential pressure alarm after the switch is opened. Comp protect is the

delay for the determination of compressor overload alarm by the internal protector of the compressor. Similarly, dis-

charge temp means the delay for the determination of high compressor discharge temperature alarm.

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LG RCAW070PBAA Owner's manual

LG RCAW070PBAA Owner's manual

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