Technical Service Manual

Water Cooled
Screw Chiller

Model:

Commercial Air Conditioner Division

LSBLG***/MCF （Flooded Type）
Midea Group
Address: Midea Headquarters Building, 6 Midea Avenue, Beijiao, Shunde, Foshan,

Guangdong, China
Midea CAC After-service Application
Postal code: 528311

Tel: +86-757-26338346 Fax: +86-757-22390205

cac.midea.com global.midea.com

Note: The data in this book may be changed without notice for further improvement on

iOS Version Android Version quality and performance.

MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Contents

I. Safety precautions ................................................................................................. 3

1. Installation safety considerations................................................................................................. 3

2. Maintenance safety considerations ............................................................................................. 3

3. Repair safety considerations ....................................................................................................... 5

II. Product.................................................................................................................... 7
1. General Information ..................................................................................................................... 7

2. Features ....................................................................................................................................... 9

3. Specifications ............................................................................................................................. 14

4. Outline dimension ...................................................................................................................... 16

5. Refrigeration system .................................................................................................................. 17

6. Major system components ......................................................................................................... 18

7. Water flow .................................................................................................................................. 22

8. Operating range ......................................................................................................................... 25

9. Accessories................................................................................................................................ 26

III. Control .................................................................................................................. 27

1. Control flow chart ....................................................................................................................... 27

2. Energy adjustment ..................................................................................................................... 28

3. Start/stop process ...................................................................................................................... 29

4. Sensors ...................................................................................................................................... 30

5. Parts control ............................................................................................................................... 31

6. Operation part ............................................................................................................................ 39

7. Safety protection ........................................................................................................................ 52

IV. Electrical control .................................................................................................. 54

1. Electrical data ............................................................................................................................ 54

2. Electrical components................................................................................................................ 55

3. Electrical parts parameter setting .............................................................................................. 56

4. Field wiring ................................................................................................................................. 58

5. Wiring Diagrams ........................................................................................................................ 61

V. Installation ............................................................................................................ 70
1. Unit installation........................................................................................................................... 70

2. Water pipeline system installation ............................................................................................. 73

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
3. Wiring installation ....................................................................................................................... 80

VI.Commissioning .................................................................................................... 82
1. Pre start-up ................................................................................................................................ 82

2. Start-up ...................................................................................................................................... 86

VII.Maintenance ........................................................................................................ 88
1. Daily maintenance......................................................................................................................... 88

2. Maintenance.................................................................................................................................. 92

VIII.Troubleshooting ................................................................................................. 99
1. Protection items ............................................................................................................................ 99

2. Troubleshooting........................................................................................................................... 102

IX.Appendix ............................................................................................................. 105

1. Temperature-Resistance specifications sheet for the discharge temperature sensor ............... 105

2. Temperature-Resistance specifications sheet for the water temperature sensor, ambient

temperature sensor, oil temperature sensor. .................................................................................. 106

3. Temperature-Resistance specifications sheet for the EXV temp. sensor. ................................. 107

4. Sample selection sheet ............................................................................................................... 109

The manufacture reserves the right to discontinue-or change the specifications or design at any time
to improve the product.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

I. Safety precautions
Before use, carefully read these instructions .

1. Installation safety considerations

(1) Only authorized personnel, qualified and trained in HVAC system maintenance can access the unit. The
access limitation device must be installed by the customer (e.g. cut-off, enclosure). Units should be
inspected for damage upon receipt, before installation, and before powered on. Check the refrigerant
circuit(s) is (are) intact and in place, especially components and pipes. If in doubt, carry out a leak
tightness check and verify with the manufacturer that the circuit integrity has not been impaired. If
damage is detected upon receipt, immediately submit a claim with the shipping company. Midea
strongly recommends employing a specialist company to unload the machine.

(2) It is compulsory to wear personal protection equipment. Do not remove the skid or the packaging
until the unit is in its final position. Move these units with a fork lift truck, providing the forks are in the
right place.

(3) The units can also be lifted with slings, using only the designated lifting points marked on the unit.
Use slings that are the correct capacity, and always follow the lifting instructions on the certified
drawings supplied with the unit. Safety is only guaranteed, if these instructions are followed carefully.
If this is not the case, there is a risk of damage or injury. Never cover any safety devices. This
applies to the relief valve(s) in the refrigerant circuit(s). Ensure that the valves are correctly installed,
before operating the unit.

(4) The relief valves are designed and installed to ensure protection against overpressure caused by
fire. The relief valve must only be removed if the fire risk is fully controlled and after checking that
doing so is allowed by local regulations and authorities. This is the responsibility of the operator. If
the unit is installed in a room, the safety valves must be connected to discharge pipes.

Note:

These pipes must be installed in a way that ensures that people and property are not exposed to
refrigerant leaks. These fluids may be diffused in the air, but far away from any building air intake, or they
must be discharged in a quantity that is appropriate for a suitably absorbing environment. Install an
indicating device to show if part of the refrigerant has leaked from the valve. The presence of oil in the
outlet is a useful indicator that refrigerant has leaked. Keep the outlet clean to ensure that any leaks are
obvious. The calibration of a valve that has leaked is generally lower than its original calibration. The
new calibration may affect the operating range. To avoid tripping or leaks, replace or re-calibrate the
valve. Periodically check the relief valves. Ensure good ventilation, as an accumulation of refrigerant in
an enclosed space can displace oxygen and cause asphyxiation or explosions. Inhalation of high
concentrations of vapor is harmful and may cause heart irregularities, unconsciousness, or death. Vapor
is heavier than air and reduces the amount of oxygen available for breathing. These products cause eye
and skin irritation. Decomposition products are hazardous.

2. Maintenance safety considerations

2.1 Engineers safety considerations

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

(1) Engineers working on electric or refrigeration components must be authorized, trained and fully
qualified to do so. All refrigerant circuit repairs must be carried out by trained personnel fully
qualified to work on these units. He must have been trained and be familiar with the equipment and
the installation. All welding operations must be carried out by qualified specialists.

(2) The insulation must be removed and heat generation must be limited using a wet cloth. Any
manipulation (opening or closing) of a shut-off valve must be carried out by a qualified and
authorized engineer. These procedures must be carried out with the unit shut-down.

NOTE: During any handling, maintenance or service operations the engineers working on the unit must
be equipped with safety gloves, glasses, shoes and protective clothing.

(1) Never work on a unit that is still energized.

(2) Never work on any of the electrical components, until the general power supply to the unit has been
cut using the disconnect switch in the control box.

(3) If any maintenance operations are carried out on the unit, lock the power supply circuit in front of the
machine.

(4) If the work is interrupted, ensure that all circuits are de-energized before resuming work.

ATTENTION: Even if the unit has been switched off, the power circuit remains energized, unless the unit
or circuit disconnect switch is open. Refer to the wiring diagram for further details. Attach appropriate
safety labels.

2.2 Operating checks:

Important information regarding the refrigerant used:

 Refrigerant type: R134a

 Periodic inspections for refrigerant leaks may be required depending on local legislation. Contact
your local dealer for more information.

 During the service life of the system, inspection and tests must be carried out in accordance with
national regulations.

2.3 Safety device checks:

 The safety devices and external overpressure devices (safety valves) must be checked on site
regularly.

 At least once a year thoroughly inspect the protection devices (valves). If the machine operates
regularly carry out leak tests and immediately repair any leaks.

 Ensure regularly that the vibration levels remain acceptable and close to those at initial unit start-up.
Before opening a refrigerant circuit, purge and check the pressure gauges.

 Change the refrigerant when there are equipment failures. Follow related regulations or carry out a
refrigerant analysis in a specialist laboratory.

 If the refrigerant circuit remains open for longer than a day after an intervention (such as a
component replacement), the openings must be plugged in and the circuit charged with nitrogen
(inertia principle). The objective is to prevent penetration of atmospheric humidity and resulting

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

corrosion on the internal walls and on non-protected steel surfaces.

3. Repair safety considerations

Note: It is compulsory to wear personal protection equipment. The insulation must be removed and
warming up must be limited using a wet cloth. Before opening the unit, ensure that the circuit has been
purged.

 All installation parts must be maintained by qualified technicians, to avoid material deterioration and
injury. Faults and leaks must be repaired immediately. Authorized technician must repair faults
immediately. Each time repairs have been carried out on the unit, the safety devices must be
re-checked.

 Comply with the regulations and recommendations for the unit and installation safety standards. If a
leak occurs or the refrigerant becomes contaminated (e.g. by a short circuit in a motor) remove the
complete charge using a recovery unit and store the refrigerant in mobile containers.

 Repair the leak and recharge the circuit with the total R134a charge, as indicated on the unit name
plate. Certain parts of the circuit can be isolated. Only charge liquid refrigerant R134a at the liquid
line. Ensure that you use the correct refrigerant type before recharging the unit. Charging any
refrigerant other than the original charge type (R134a) will impair machine operation and can even
destroy the compressors. The compressors operating with this refrigerant type are lubricated with
synthetic oil.

 Do not use oxygen to purge lines or to pressurize a machine for any reason. Oxygen gas reacts
violently with oil, grease, and other common substances.

 Never exceed the specified maximum operating pressures. Verify the allowable maximum high- and
low-side test pressures by checking the instructions in this manual and the pressures given on the
unit name plate.

 Do not use air for leak testing. Use only refrigerant or dry nitrogen.

 Do not weld or flame cut the refrigerant lines or any refrigerant circuit component until all refrigerant
(liquid and vapor) has been removed from the chiller. Traces of vapor should be displaced with dry
air nitrogen. Refrigerant in contact with an open flame produces toxic gas.

 The necessary protection equipment must be available, and appropriate fire extinguishers for the
system and refrigerant type must be within easy reach.

 Do not siphon the refrigerant. Avoid spilling liquid refrigerant on your skin or splashing it into your
eyes. Use safety goggles. Wash any spills from the skin with soap and water. If liquid refrigerant
enters your eyes, immediately and abundantly flush with water and consult a doctor.

 Never apply an open flame or live steam to a refrigerant container. Dangerous overpressure can
result. If it is necessary to heat the refrigerant, use warm water only.

 During refrigerant removal and storage operations follow applicable regulations. These regulations,
permit the conditioning and recovery of halogenated hydrocarbons under optimum quality
conditions for the product and optimum safety conditions for people, property and the environment.

 Any refrigerant transfer and recovery operations must be carried out using a transfer unit. The units
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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

must never be modified to add refrigerant and oil charging, removal and purging devices. All these
devices are provided with the units. Refer to the certified dimensional drawings for the units.

 Do not re-use disposable (non-returnable) cylinders or attempt to refill them. It is dangerous and
illegal. When the cylinders are empty, evacuate the remaining gas pressure, and move the cylinders
to a place designated for their recovery. Do not incinerate.

 Do not attempt to remove refrigerant circuit components or fittings, when the machine is under
pressure or while it is running. Ensure that the pressure is at 0 kPa before removing components or
opening a circuit.

 Do not attempt to repair or recondition any safety devices when corrosion or build-up of foreign
material (rust, dirt, scale, etc.) is found within the valve body or mechanism.

 If necessary, replace the device. Do not install safety valves in series or backwards.

ATTENTION:

No part of the unit must be used as a walkway, rack or support. Periodically check and repair or if
necessary replace any component or piping that shows signs of damage. The refrigerant lines can break
under weight and release refrigerant, causing injury. Do not climb on a machine. Use a platform, or
staging to work at higher levels.

 Use mechanical lifting equipment (crane, hoist, winch, etc.) to lift or move heavy components. For
lighter components, use lifting equipment when there is a risk of slipping or losing your balance.

 Use only original replacement parts for any repair or component replacement.

 Do not drain water circuits containing industrial, brine without informing the technical service
department at the installation site or a competent body first.

 Close the entering and leaving water shut off valves and purge the unit water circuit, before working
on the components installed on the circuit (screen filter, pump, water flow switch, etc.).

 Do not close the water box bolts until the water boxes have been completely drained.

 Periodically inspect all valves, fittings and pipes of the refrigerant and hydronic circuits to ensure
that they do not show any corrosion or any signs of leaks. ,

 Wear ear defenders, when working near the unit and the unit and when the unit is running.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

II. Product

1. General Information
1）Product Line Up
Cooling Capacity Quantity of
Series Model Power Supply
(kW) Compressors

LSBLG340/MCF 380V/3Ph/50Hz 340 1

LSBLG440/MCF 380V/3Ph/50Hz 440 1

LSBLG540/MCF 380V/3Ph/50Hz 540 1

Single
LSBLG720/MCF 380V/3Ph/50Hz 720 1
compressor

LSBLG805/MCF 380V/3Ph/50Hz 805 1

LSBLG890/MCF 380V/3Ph/50Hz 890 1

LSBLG1055/MCF 380V/3Ph/50Hz 1055 1

LSBLG1200/MCF 380V/3Ph/50Hz 1200 2

LSBLG1300/MCF 380V/3Ph/50Hz 1300 2

Dual
LSBLG1410/MCF 380V/3Ph/50Hz 1410 2
compressors

LSBLG1620/MCF 380V/3Ph/50Hz 1620 2

LSBLG1780/MCF 380V/3Ph/50Hz 1780 2

2）Nomenclature

LS BLG 340 M C F

F: Flooded evaporator
C: R134a; omit for R22
Design sequence code
340: Nominal cooling capacity (kW)
BLG: Semi-hermetic screw compressor
LS: Water cooled chiller

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
3). External appearance

Single head (LSBLG340/MCF~LSBLG1055/MCF)

Dual heads (LSBLG1200/MCF~LSBLG1780/MCF)

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

2. Features

High efficiency

 The high efficiency inner grooved copper pipe enhances the heat-exchange process,
improves heat exchange efficiency and makes the evaporator more compact saving
installation space.

 Significantly improves the evaporating temperature and reduces the heat

transfer temperature difference, which directly improves heat-exchange
efficiency, and provides the most cost effective and reliable solutions to all
customers.

 Supreme efficiency in partial loads.

Green chiller

 R134a environmental-friendly refrigerant

Refrigerant of the Chlorine-free HFC’s ODP (Ozone Depletion Potential) is zero. R134a
GWP (Global Warming Potential) is very low.

High reliability and excellent serviceability

Advanced twin-rotor screw compressor
Capacity adjustable valve Refrigerant discharge
Four stage capacity adjustable or Exhaust cavity with check valve, it
stepless adjustable. can avoid compressor to reversal
cause of stopping for long time. Twin screw rotor
Patent type line design, high
volumetric efficiency, smooth
Built-in oil separator operation.
High precision filter, the oil
separation efficiency up to Hermetic motor
99.5%.
Cool motor with refrigerant, no
heat send out in room.
Motor direct drive
High mechanical efficiency, low Semi- hermetic structure
speed of compressor, low
noise. Semi-hermetic compressor,
moveable bolts, easy to
maintain.

High efficiency heat exchange technology

Gas refrigerant inlet
Gas refrigerant Filter Filter Cooling
Chilled water outlet
water outlet

Chilled
water inlet
Cooling
Liquid water inlet
EXV Liquid refrigerant outlet
refrigerant Tube

Orifice

High efficiency shell and tube heat exchanger, 2 pass, straight water pipe, easy to clean. The end covers
can be exchanged to meet customers’ requirements for condenser.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

 The flooded evaporator makes cleaning the inside of pipes possible, and guarantees high reliability.

 The discharge cut-off valve and liquid line angle valve simplify maintenance.

 Simplified field wiring for easy installation.

Optimized, user-friendly operating Interface

 Midea chiller adopts Midea Microprocessor which

provides advanced algorithms and reliable control.

 Graphical display of the operating state, operation

scheduling, malfunction inquiry, help menu for easy
trouble shooting and other user-oriented functions.

Compressor bearing

High-precision large-sized axial and radial bearings

are selected to support the male and female rotors for a long service life. With an effective
lubrication system, the bearing service life can be further extended. While the compressor is running,
lubricant is injected into all bearings due to the pressure difference.

SKF brand industry use bearing guarantees 60,000 hours of continuous working
Advanced twin-rotor screw compressor

Midea® Screw Chiller is equipped with the 3rd generation industrial Semi-hermetic Screw
compressor, which has the latest advanced 5-6 asymmetry dentiform rotors. The rotors are
processed by high-precision CNC and each part is well-proportioned and non-gap matched, which
minimizes friction and clearance loss, guaranteeing quiet running and long duration.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

 High-precision machining and measurements make the rotor clearance μm-class, reducing leaks
between high and low pressure. Under continuous operations, the rotors maintain optimal clearance
for the highest efficiency.

 The semi-hermetic compressor with low running noise is well cooled by the refrigerant, giving a low
temperature, and no leakage compared with an open compressor.

 Patented motor-cooling design in the ducts of the refrigerant flow encompass stator optimizes heat
dissipation and does not require computer room AC.

 To reach high operation efficiency, the casing is manufactured by precise machining centers and
inspected by a coordinating measuring machine to ensure the requested precision and quality can
be retained in the compressor.

Three stages oil separation

 The built-in oil separator utilizes three-stage filter mechanism with high-density filter elements to
optimize the oil separation effect an efficiency higher than 99.7%.Two oil separators work together
to optimize the best oil separating effect.

 Detachable demister for cleaning.

 Oil is supplied by pressure difference and there is no need an oil pump.

Dual compressors (Min. 1200 ~ Max.1780kW)

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

 Large cooling capacity chillers have two truly independent refrigerant circuits, a compact outline and
superior partial load efficiency. If one breaks down, the other can work independently. So the chiller
can provide much higher reliability and minimize losses to the user.

Flooded-type evaporator

 The evaporator is the flooded type designed for 1 MPa working pressure on the chilled water side
(Higher pressure vessels can be customized). Replaceable integral finned copper tubes are
mechanically bonded to steel tube sheets. The evaporator has been
tested under extreme conditions. The 20 mm thick insulation covers
all low temperature surfaces, including the evaporator, water boxes,
oil return lines, and chilled water flow switch piping.

 Midea heat exchangers are designed by professional design

software engineers and pass rigorous tests. Double-grooved holes
at tube support for tube expansion are designed to prevent leakage
and increase the durability of heat exchanger.

Condenser

 Midea condenser has a specially designed baffle, in the condenser’s entrance to prevent
high-velocity refrigerant gas hitting the tube surface, eliminating the related vibration and noise. It
has been tested under extreme conditions. Water side working pressure is designed for 1.0 Mpa
(Higher pressure vessels can be customized).

Throttling device

The orifice baffle has no moving parts guaranting high reliability. It

works with EXV （Danfoss）to throttle high-pressure liquid refrigerant
from the condenser to the evaporator. EXV is controlled by EVD
module and provides high-precision adjustment matching the
compressor load，both full and partial.

Advanced oil system

As the diagram shows, the low

temperature and low pressure gas enters
the compressor through the suction port.
Then refrigerant gas that enters the
compressor is compressed to a high
temperature, high pressure gas that
enters the condenser to release heat to
cooling water. The condensed liquid
passes the throttling device, enters a
mixed state and enters the lower part of
the evaporator. It is then spread into a
wider surface by distributor. Finally the
distributed refrigerant evaporates by taking the heat from the chilled water inside the evaporator tube
and repeats the cycle.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Lubrication cycle

Three stages of oil separation ensure excellent compressor lubrication. One is integrated inside the
compressor and the other is a built-in oil separator located inside of the condenser. The refrigerant and
oil mixture is separated in the internal oil separator for the first time, and then is sent to the condenser oil
separator where separating efficiency can reach 99%. Oil returns to the compressor through the oil
return pipe due to the pressure difference. A small amount of oil which remains in the evaporator will be
sucked up by the Venturi tube and returns to the compressor after the gas evaporates. This is the third
stage of oil separation. These three oil return circuits can guarantee reliable oil return efficiency.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

3. Specifications
LSBLG***/MCF 340 440 540 720 805 890 1055
Cooling capacity kW 336.6 435.7 534.5 712.7 797.2 881.5 1045
Power input kW 59.77 76.71 93.65 127.0 143.7 154.4 185.9
COP kW/kW 5.631 5.679 5.707 5.611 5.547 5.709 5.621
Semi-hermetic screw compressor
Circuit A Quantity 1 1 1 1 1 1 1
Circuit B Quantity -- -- -- -- -- -- --
Oil charge
Circuit A L 18 20 23 28 40 40 40
Circuit B L -- -- -- -- -- -- --
Refrigerant Type R134a
Circuit A kg 130 145 160 230 230 250 360
Circuit B kg -- -- -- -- -- -- --
Control Type EXV+ Orifice
Evaporator Type Shell and Tube Flooded
Water flow m³/h 52.17 67.55 82.83 110.5 123.6 136.7 162.0
Pressure drop kPa 24.4 26.2 26.2 22.0 27.0 26.9 26.2
Max. pressure kPa 1000 1000 1000 1000 1000 1000 1000
Connection type Victaulic coupling
Water inlet/outlet pipe dim. mm 150 150 150 200 200 200 200
Condenser Type Shell and tube
Water flow m³/h 65.18 84.42 103.6 138.1 154.5 170.8 202.5
Pressure drop kPa 30.9 32.3 32.7 30.1 32.6 34.8 30.7
Max. pressure kPa 1000 1000 1000 1000 1000 1000 1000
Connection type Victaulic coupling
Water inlet/outlet pipe dim. mm 150 150 150 200 200 200 200
Unit length mm 3496 3496 3496 3521 3521 3521 3588
Unit width mm 1200 1200 1200 1400 1400 1400 1500
Unit height mm 1716 1768 1848 1928 2026 2026 2250
Packing length mm 3950 3950 3950 3950 3950 3950 3950
Packing width mm 1340 1340 1340 1560 1560 1560 1660
Packing height mm 1950 2020 2120 2220 2240 2240 2470
Running weight kg 2515 2560 2935 3800 4210 4300 5470
Shipping weight kg 2525 2540 2875 3580 3980 4060
5210
The following safety devices are equipped as standard.
High pressure protection(High pressure switch & high pressure sensor).
Low pressure protection(Low pressure switch & low pressure sensor).
Compressor thermal protection.
High discharge temperature on the compressor.
Phase monitor; Star/Delta transition failed.
Safety protection device
Low-pressure ratio; Low oil level protection.
Interrupter protection; Overload compressor protection.
Over-voltage & low- voltage protection.
Sensor malfunction protection.
Contactor malfunction protection.
Freeze protection.

Note:
The paramters above are given according to the AHRI550/590-2015.
Cooling condition:chilled water outlet temp.is 6.67℃(44℉),water flow is based on cooling capacity x 0.1550 m (h•kW);
3

Cooling water inlet temp.is 29.44℃(85℉),water flow is based on cooling capacity x 0.1938 m (h•kW).
3

2 2 2
The design fouling factor for evaporator is 0.0176 m ℃/kW(0.0001 ft F.hr/Btu) and for condenser is 0.044 m •℃/kW
2
(0.00025 ft F.hr/Btu).

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

LSBLG***/MCF 1200 1300 1410 1620 1780

Cooling capacity kW 1186 1286 1396 1600 1759
Power input kW 205.2 230.7 248.7 290.3 304.8
COP kW/kW 5.779 5.574 5.613 5.512 5.771
Semi-hermetic screw compressor
Circuit A Quantity 1 1 1 1 1
Circuit B Quantity 1 1 1 1 1
Oil charge
Circuit A L 28 28 28 40 40
Circuit B L 28 28 28 40 40
Refrigerant Type R134a
Circuit A kg 165 165 170 200 200
Circuit B kg 165 165 170 200 200
Control type EXV +Orifice
Evaporator Type Shell and tube flooded
Water flow m³/h 183.8 199.3 216.4 248.0 272.7
Pressure drop kPa 51.0 57.6 52.7 57.4 62.4
Max. pressure kPa 1000 1000 1000 1000 1000
Connection type Victaulic coupling
Water inlet/outlet pipe dim. mm 200 200 200 200 200
Condenser Type Shell and tube
Water flow m³/h 229.6 249.2 270.5 310.0 340.8
Pressure drop kPa 58.6 66.3 66.7 68.0 69.8
Max. pressure kPa 1000 1000 1000 1000 1000
Connection type Victaulic coupling
Water inlet/outlet pipe dim. mm 200 200 200 200 200
Unit length mm 4593 4593 4593 4611 4611
Unit width mm 1500 1500 1500 1600 1600
Unit height mm 2191 2241 2241 2343 2343
Packing length mm 5050 5050 5050 5050 5050
Packing width mm 2080 2080 2080 2180 2180
Packing height mm 2411 2461 2461 2563 2563
Running weight kg 6482 6582 6680 8250 8400
Shipping weight kg 6262 6362 6410 7730 7850
The following safety devices are equipped as standard.
High pressure protection(High pressure switch & high pressure sensor)
Low pressure protection(Low pressure switch & low pressure sensor)
Compressor thermal protection
High discharge temperature on the compressor
Phase monitor; Star/Delta transition failed
Safety protection device
Low-pressure ratio; Low oil level protection
Interrupter protection; Overload compressor protection
Over-voltage & low- voltage protection
Sensor malfunction protection
Contactor malfunction protection
Freeze protection

Note:
The paramters above are given according to the AHRI550/590-2015.
3
Cooling condition:chilled water outlet temp.is 6.67℃(44℉),water flow is based on cooling capacity x 0.1550 m (h•kW);
Cooling water inlet temp.is 29.44℃(85℉),water flow is based on cooling capacity x 0.1938 m3(h•kW).
2 2 2
The design fouling factor for evaporator is 0.0176 m •℃/kW(0.0001 ft F.hr/Btu) and for condenser is 0.044 m •℃/kW
2
(0.00025 ft F.hr/Btu).
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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

4. Outline dimension
Single head (LSBLG340~1055/MCF)

Chilled
Cooling water inlet
water outlet
Chilled

C
Cooling
water inlet water outlet
G

K
L
F

H
J D
E A
B

Unit: mm
Water
Model Ａ Ｂ Ｃ Ｄ Ｅ Ｆ Ｇ Ｈ J K L
inlet/outlet

LSBLG340/MCF 3496 1200 1716 2850 1100 411 260 300 600 260 541 DN150
LSBLG440/MCF 3496 1200 1768 2850 1100 411 260 300 600 260 541 DN150
LSBLG540/MCF 3496 1200 1848 2850 1100 411 260 300 600 260 541 DN150
LSBLG720/MCF 3521 1400 1928 2850 1300 441 300 350 700 300 591 DN200
LSBLG805/MCF 3521 1400 2026 2850 1300 441 300 350 700 300 591 DN200
LSBLG890/MCF 3521 1400 2026 2850 1300 441 300 350 700 300 591 DN200
LSBLG1055/MCF 3588 1500 2250 2850 1400 443 350 375 750 375 618 DN200

Dual heads (LSBLG1200~1780/MCF)

Cooling Chilled
water outlet water inlet
C

Chilled
Cooling water outlet
water inlet
G

K
L
F

H J D
E A
B

Unit: mm
Water
Model Ａ Ｂ Ｃ Ｄ Ｅ Ｆ Ｇ Ｈ J K L
inlet/outlet

LSBLG1200/MCF 4593 1500 2191 3850 1400 443 350 375 750 350 618 DN200
LSBLG1300/MCF 4593 1500 2241 3850 1400 443 350 375 750 350 618 DN200
LSBLG1410/MCF 4593 1500 2241 3850 1400 443 350 375 750 350 618 DN200
LSBLG1620/MCF 4611 1600 2343 3850 1500 468 350 400 800 350 643 DN200
LSBLG1780/MCF 4611 1600 2343 3850 1500 468 350 400 800 350 643 DN200

NOTE: Drawings are not contractually binding. Before designing an installation, consult the certified dimensional drawings
supplied with the unit or that are available on request.
For the positioning of the fixing points, weight distribution and center of gravity coordinates, refer to the dimensional
drawings.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

5. Refrigeration system
For single compressor (LSBLG340~1055/MCF)

For dual compressors (LSBLG1200~1780/MCF)

17
Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

6. Major system components

6.1 Advanced twin screw compressor

 Midea screw chiller is equipped with the 3rd generation industrial compressor, which has the latest
advanced 5-6 Asymmetry Dentiform Semi-hermetic Screw Rotors. The rotors are processed by
high-precision CNC and each part is well-proportioned and no-gap matching, which minimizes
friction and clearance lost, guaranteeing quiet running and service life.

 LSBLG/MCF Series units come with a high efficiency oil separator to maximize oil extraction.

 Compressors have infinitely variable control down to 25% of their total capacity. This control is made
by capacity slides controlled by microprocessors.

 Standard starter is star-delta type. Infinite capacity control type is available (as an option).

 With 5-6 asymmetry dentiform, the screw rotor patent is based on improving the shape of German
rotor GHH. It is proven to have good balance, low vibration, and low noise after balance testing by
special machines. Compared with the normal screw rotor with 4-6 dentiform, the heat efficiency of
the rotor with male and female rotor and 5-6 dentiform has increased by 10%-12% and uses 25%
energy. The rotor also gained British and American patent.

 The bearing of compressor is from SKF, Sweden, the long lifespan of which ensures screw-type
main unit can run continuously for more than 50,000 hours.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

 Lubricant:
The lubricant is supplied automatically by pressure difference inside the compressor. It is
unnecessary to add an extra lubricant pump.

The compressor is approved for use with the following lubricant:

HBR-B04 for R134a unit

 The Oil Separator has reliable qualification. The oil content can be controlled to below 3ppm (the oil
content treated by oil-gas separator of common like screw-type air compressor is least 8-10ppm).
The oil-gas separator amount is double that of same kind of other products. The large oil filter area
reduces refrigerant flux speed, and has a better separating affect and longer lifespan than the
secondary reflux technology.

 Oil filter

The screw compressor has an independent oil filter.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

6.2 Pressure vessels

6.2.1 General

Monitoring during operation, re-qualification, re-testing and re-testing dispensation:

 Follow the regulations for monitoring pressurized equipment.

 The user or operator should set up and maintain a monitoring and maintenance file.

 Follow the control programs.

 If they exist follow local professional recommendations.

 Regularly inspect the condition of the coating (paint) to detect blistering from corrosion. Check a
non-insulated section of the container or the rust formation at the insulation joints.

 Regularly check for possible presence of impurities (e.g. silicon grains) in the heat exchange fluids.
These impurities may cause wear or corrosion by puncturing.

 Filter the heat exchange fluid check and carry out internal inspections as described in EN 378-2,
annex C.

 In case of re-testing please refer to the maximum operating pressure given on the unit nameplate.

 The reports of periodical checks by the user or operator must be included in the supervision and
maintenance file.

6.2.2 Repair

Any repairs or modification, including the replacement of moving parts:

 Must follow local regulations and be performed by qualified operators in accordance with authorized
procedures, including changing the heat exchanger tubes.

 Must be made in accordance with the instructions of the original manufacturer. Repairs and
modifications that necessitate permanent assembly (soldering, welding, expanding etc.) must be
performed under the correct procedures and by qualified operators.

 Any modification or repairs must be recorded in the monitoring and maintenance file.

6.2.3 Corrosion allowances:

Gas side: 0 mm

Heat exchange fluid side: 1 mm for tubular plates in lightly alloyed steels, 0 mm for stainless steel plates
or plates with copper-nickel or stainless steel protection.

6.2.4 Operating life

The evaporator and condenser are designed for prolonged usage of 20 years using high-quality
materials.

6.2.5 Security

The unit is equipped with safety valves. A ball valve connects the safety valve to condenser (evaporator).
The ball valve maintains full-state. It is closed only when the safety valve is open or replaced.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

The ball valve can protect life and property because it can prevent refrigerant from flowing into the air
when the safety valve is open or replaced.

6.2.6 Evaporator

Gas refrigerant
Chilled
water outlet

Chilled
water inlet

EXV Liquid
refrigerant Tube

Orifice

Flooded shell and tube evaporator operates with refrigerant in shell and water in tubes. Replaceable
water tubes are fabricated from integral finned cooper and mechanically bonded to steel tube sheets.
The evaporator is GB/T151-2014 (Chinese standard) designed, constructed, inspected and stamped.
Water side working pressure is designed for 1.0 Mpa. Shell and non-connecting water head are
insulated with 3/4” closed cell insulation.

6.2.7 Condenser

Shell and tube operates with refrigerant in shell and Gas refrigerant inlet
Filter Filter Cooling
water in tubes. Replaceable water tubes are fabricated water outlet
from integral finned cooper and mechanically bonded
to steel tube sheets. The condenser is GB/T151-2014
Cooling
(Chinese Standard) designed, constructed, inspected water inlet
Liquid refrigerant outlet
and stamped. Water side working pressure is designed
for 1.0 Mpa.

The condenser adopts high-efficient tubes to enhance transfer performance. The system's COP can be
greatly increased by adding the sub-cooler.

6.2.8 Oil separator

The oil separator has a unique structure to separate oil from refrigerant very efficiently. It solves the oil
recycle problem by ensuring that oil returns to compressor normally.

6.2.9 Throttle parts

The unit achieves high-efficiency under full and partial loads by parallel connecting orifice and EXV.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

7. Water flow

Balance the chilled water flow through the evaporator and the condenser water flow through the
condenser. The flow rates must fall between the minimum and maximum values shown in the table
below. Flow rates below the minimum values shown will result in laminar flow which will reduce
efficiency, cause erratic operation of the electronic expansion valve and cause low temperature cutouts.
On the other hand, flow rates exceeding the maximum values shown can cause erosion on the heat
exchanges water connections and tubes, even piping breaking.

Variable chilled water flow through the heat exchanges while the compressor(s) are operating is not
recommended. The chiller control set points are based upon a constant flow and variable temperature.
3 3
Evaporator water flow rate m /h Condenser water flow rate m /h
Model
Rated Minimum Maximum Rated Minimum Maximum
LSBLG340/MCF 58 29 64 73 37 80
LSBLG440/MCF 76 38 83 95 47 104
LSBLG540/MCF 93 46 102 116 58 128
LSBLG720/MCF 124 62 138 155 74 173
LSBLG805/MCF 138 69 152 173 87 190
LSBLG890/MCF 153 77 168 191 96 210
LSBLG1055/MCF 182 91 200 227 113 250
LSBLG1200/MCF 206 103 227 258 129 284
LSBLG1300/MCF 224 112 246 280 140 308
LSBLG1410/MCF 243 122 267 303 152 333
LSBLG1620/MCF 279 142 312 348 177 390
LSBLG1780/MCF 306 153 337 383 191 421
Pressure drop
Evaporator

Water pressure drop curve(evaporator)

60
Water pressure drop(KPa)

50
LSBLG340/MCF
40 LSBLG440/MCF
30 LSBLG540/MCF

20 LSBLG720/MCF
LSBLG805/MCF
10
LSBLG890/MCF
0
LSBLG1055/MCF
0.0 50.0 100.0 150.0 200.0 250.0
Water flow(m3/h)

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Water pressure drop curve(evaporator)

120
Water pressure drop(KPa)

100

80 LSBLG1200/MCF
60 LSBLG1300/MCF

40 LSBLG1410/MCF
LSBLG1620/MCF
20
LSBLG1780/MCF
0
0.0 100.0 200.0 300.0 400.0
Water flow(m3/h)

Condenser

Water pressure drop curve(condenser)

70

60
Water pressure drop(KPa)

LSBLG340/MCF
50
LSBLG440/MCF
40
LSBLG540/MCF
30
LSBLG720/MCF
20
LSBLG805/MCF
10 LSBLG890/MCF
0 LSBLG1055/MCF
0.0 50.0 100.0 150.0 200.0 250.0 300.0
Water flow(m3/h)

Water pressure drop curve(condenser)

140
Wayer pressure drop(KPa)

120
100
LSBLG1200/MCF
80
LSBLG1300/MCF
60
LSBLG1410/MCF
40
LSBLG1620/MCF
20 LSBLG1780/MCF
0
0.0 100.0 200.0 300.0 400.0 500.0
Water flow(m3/h)

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

System minimum water volume

A set water volume is necessary for stable operation. It is often necessary to add a buffer water tank to
the circuit to achieve the required volume. The tank must be internally baffled to ensure the liquid (water
or brine ) is properly mixed. Water tank volume is larger than the whole system water volume at least
10%.

Refer to the examples below.

How to calculate minimum volume in pipeline system:

W=QgT/CP▽t

W — Minimum water volume（kg）；

Qg — Total cooling/heating capacity of the terminal（kW）；

T — Thermal stability time requirement，Take（8～10）×60s；

CP — Water specific heat at constant pressure，4.187kj/（kg·℃）；

▽t — Water temperature fluctuation required value，take 5℃.

For system, Qg is calculated according to the lowest load so that it operates stably.

It can be also calculated according to 0.5Q(50%). T takes 8 minutes, the shortest time that the unit run
for..

That is 480 s. Cp=4.18kj/kg, ▽t =5℃

According to the above formula, the result is as follows:

W=0.5Q*480/（4.18*5）=11.48Qkg

Note:

The above formula is only for reference. Different dimensions can be adopted to suit for different
condition.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

8. Operating range
Content Running range
Chilled Leaving Water Temperature 5℃～15℃
Cooling Entering water Temperature 25℃~35℃
Water flow volume Flow volume rating±20%
Max inlet/outlet water Temp. difference 8℃
Voltage tolerance Rating Voltage ±10%
Phase tolerance ±2％
Power supply frequency Rating frequency±2%
Evaporator max working pressure on water side 1.0MPa
Compressor max. start count 4 times/h 8 times/day
Highly corrosive environments and high
Environment quality
humidity should be avoided.
The height of water drainage should not be
Drainage system
higher than the base of the unit on the spot
Normal operation ambient temperature -10℃~45℃
Storage and transport temperature -25℃～50℃
Applicable altitude range： Less than 1000m

LSBLG/MCF evaporator Minimum Maximum

Entering temperature at start-up 8°C 25°C
Leaving temperature during operation 5°C 15°C
Entering/leaving temperature difference at full load 3.8°C 8°C

LSBLG/MCF condenser Minimum Maximum

Entering temperature at start-up 19°C 35°C
Leaving temperature during operation 22°C 42°C
Entering/leaving temperature difference at full load 3.8°C 8°C

Note:
(1) For low-temperature applications, where the leaving water temperature is below 4°C, the anti-freezing protection switch
will stop the unit stop from running.
(2) If the temperature leaving the condenser is below 19°C,the unit will stop and give a warning
(3) Ambient temperatures: During storage and transport of the LSBLG/MCF units. Including by container) the minimum
and maximum permissible temperatures are -20°C ~ 46°C(R134a);

Changes water temperature curve in the operation

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

9. Accessories
Standard accessories
NO. Name Quantity

1 User manual 1

2 Water pressure difference switch 1

3 Packing list 1

Optional Accessories

NO. Name Model Instructions Picture Qty

Installed on evaporator
Water flow WFS-1001-H
1 outlet pipe to prevent heat
2
switch (Honeywell) exchange pipe from frost
cracks.

SHA-2600
(340/440/540kW) To avoid vibration and noise,
Vibration
2 use between base and
4
damper foundation when installing
SHA-3200 the unit.
(720~1780kW)

Can be installed in the control

room. Through the cable
Remote connected to the unit touch
3 control GX03501 screen, it can display all
1
states information and
cabinet complete all the operations of
unit (startup/shutdown, error
confirm, etc.)

Q235-B,150-10
Flange connection can be
(340/440/540kW) chosen for water pipe
4 Flange connection. Customer can
8
choose water side
Q235-B,200-10 pressure 1.6 MPa
（720~1780kW） according to requirement.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

III. Control

1. Control flow chart

2 Compressors
380VAC
Double-Head
3P+N+PE

M M
~ ~
Phase Sequence

Compressor Compressor
Protector

Miniature Thermo relay Thermo relay

Circuit
Breaker
Compressor Compressor
Contactor Contactor
Star-Delta Start Star-Delta Start

Main base controller

Terminal for Terminal for

HMI External Signal Output Action
e.g. Temp. e.g. Solenoid
Pressure Valve

Main base controller gathers signals through input terminals, such as pressure,
temperature and the state of protection switches and ensures unit’s current
condition. At the same time, according to input signal from HMI, such as starting
signal, controller performs the logical operations and outputs signals. These
signals act on components, time relay, contactors and so on.
HMI+ Main base controller:

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

2. Energy adjustment

The unit adjusts capacity by chilled water. The control logic references picture.

Energy adjustment is districted when starting high pressure is too high.

High pressure
unloading

19Bar

18Bar Normal adjusting

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

3. Start/stop process
1).Cooling start
Power on

Detect YES Clear failure

NO

Start on

Chilled pump on
Cooling pump on
Cooling tower on

Water flow
YES Stop clear failure
switvh

NO

Water temp is OK
Oil heating time is enough NO Stand
Stop time is enough

YES

Compressor 25% SV ON

Compressor Y-△ start

Compressor 75% SV on
50% SV off

Loading Energy adjust Unload

Stand Water temp. is OK

Stop

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

2).Cooling stop

Stop

Running time is
NO Stop
enough

YES

Unload to 50% step

Unload to 25% step

Compressor OFF

Compressor 25% SV OFF

Cooling tower off

Cooling pump off

Chilled pump off

4. Sensors
1).Temperature sensors
The temperature sensors that unit users are all NTC thermistors, including chilled leaving water
temperature, chilled entering water temperature, discharge temperature, EXV discharge temperature.
NO. Name Type Remark
1 Chilled entering water temp. NTC,10k@25℃ Emerson
2 Chilled leaving water temp. NTC,10k@25℃ Emerson
3 Cooling entering water temp. NTC,10k@25℃ Emerson
4 Cooling leaving water temp. NTC,10k@25℃ Emerson
5 Discharge temp. 50k@25℃
6 EXV discharge temp. NTC,50k@25℃ CAREL
7 Pipe temp. Emerson
Thermistors
For PTC thermistors, resistances vary with various temperatures.
 Location
Motor thermistor are located in the motor winding and are connected to the compressor protection
module which will cut off the main power when motor winding temperature exceeds 110 °C. Water

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

temperature thermistors are installed in wells on chilled water inlet/outlet and cooling water inlet/outlet.
Refer to the electric control wiring diagram for detailed connection information.

 Thermistor replacement
To Replace Thermistors RT1, RT2, RT3, RT4, RT5, or RT6 (Entering/Leaving chilled Water;
Entering/Leaving cooling Water; Discharge Temperature; Oil temperature) — Disconnect appropriate
connector from the PCB controller. New thermistors should be spliced to existing wiring close to the
connector unless new connectors are required. Remove thermistor cable from harness. Remove and
discard original thermistor from well. Insert new thermistor in well body to its full depth. Add a small
amount of thermal conductive grease to thermistor probe and well. Tighten the screw to prevent
thermistors from slipping out of the well.
 To Service Compressor Motor Thermistors
A thermistor is factory installed in each compressor. Connections for the thermistors are located in the
compressor wiring box. 2 terminals are reserved for the thermistor: S1 and S2. Motor temperature is
measured by leads connected to S1 and S2 terminal. The thermistors are not serviceable in the field. If
the compressor motor thermistor fails, replace the compressor.

2).pressure sensors
The pressure sensors are pressure transmitters. Danfoss AKS3000 are used.

Water temp. thermistor suction temp. thermistor pressure transmitter AKS3000

5. Parts control
1). Oil heater control
If the unit is in standby modes and, the oil heater is energized to keep normal oil temperature. When
the unit starts, the oil heater it is turned off.
Oil heating time limits:
 When cooling water inlet temperature≥ 35°C (real time value), oil heating time for first startup
is 0.5h. If power down happens when the unit is running and downtime is less than 8hrs, no
heating time delay is needed when unit restarts. If it exceeds 8hrs, 0.5h heating time is needed.
 When cooling water inlet temperature ≥ 30°C (real time value), oil heating time for first startup
is 1h. If power down happens when the unit is running and downtime is less than 5hrs, no
heating time delay is needed when unit restarts. If it exceeds 5hrs, 1h heating time is needed.
 When cooling water inlet temperature ≥ 25°C (real time value), oil heating time for first startup
is 2hrs. If power down happens when the unit is running and downtime is less than 3hrs, no
heating time delay is needed when unit restarts. If it exceeds 3hrs, 1h heating time is needed. If

31
Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

it exceeds 5hrs, 2hrs heating time is needed.

 When cooling water inlet temperature ≥ 20°C (real time value), oil heating time for first startup
is 4hrs. If power down happens when the unit is running and downtime is less than 1hrs, no
heating time delay is needed when unit restarts. If it exceeds 1hrs, 2h heating time is need. If it
exceeds 5hrs, 3hrs heating time is needed. If it exceeds 8hrs, 4hrs heating time is needed.
 When cooling water inlet temperature < 20°C (real time value), oil heating time for first startup is
8hrs. If power down happens when the unit is running and downtime is less than 1hrs, no
heating time delay is needed when unit restarts. If it exceeds 1hrs, 3h heating time is need. If it
exceeds 5hrs, 5hrs heating time is needed. If it exceeds 8hrs, 8hrs heating time is needed.

2). Pressure sensor Control

High-pressure control

High pressure
50% stop
13Bar
12Bar

>50% unloading

Normal adjusting

3). Discharge temp. Control

Discharge temp.

80℃ stop

12Bar
45℃
on
12Bar

4). Return oil solenoid valve Control

Compressor

50%
50%
on 25% 25%

12Bar
off stop
SV
on 10min 2min 2min 3min
12Bar
off
12Bar 12Bar 12Bar 12Bar 12Bar
32min 32min
12Bar
12Bar 12Bar

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

a. When compressor starts, the return oil solenoid valve is open, and it will close after 10 minutes.
b. When compressor is running, from compressor starting at 50%, every 30 minutes open for return oil
solenoid valve for 2 minutes.
c. When compressor shuts down, with the compressor unloaded to 50% return oil solenoid valve open
3 minutes.
d. When oil level protection starts, the return oil solenoid valve will open and then closed after recovery.

5). EXV controller Control

a. EXV controller wiring principle
24V DC

Alarm output
to controller

CAREL EXV controller EVD

Discharge pressure Start/stop relay

transmitter From controller

Discharge temp. EXV

thermistor

EXV controller is started by the main base controller. It detects discharge pressure, and temperature and
calculates discharge superheat. Then it controls EXV opening depending on the superheat. If it is
incorrect, EXV will output alarm signal to main base controller.
b. Controller display
The interface of EXV controller cannot display and set the parameter on unit, It can only display running
status.

LED Light Extinguish Flicker

Can connect to Not Communication
NET
the network connected failure
OPEN Open the valve - Disable the drive
CLOSE Close the valve - Disable the drive
Activate the
- -
alarm
The drive is
not connected
Drive power -
to power
supply

If the parameters need to be displayed and set, change the interface..

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

1 Display suction superheat

2 Display EXV opening
3 Relay output status
4 Alarm
5 Start of the protection
6 Control state

Remove cover

Change display

Display

Button Function
Prg Open the display screen, and enter the password to enter programming mode
• In the alarm state, the display alerts the queue;
• When the "producer" level is under the rolling parameters, the display shows the
interface
• To exit the programming (maintenance / producer) and display mode;
Esc
• set a parameter, then exit without saving changes
• Display screen navigation;
UP/DOWN • Increase / decrease the value
• from the parameter setting mode, the display switches to
Enter • Confirm the list of parameters and return the value

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Running display status display all status

Press

Press Esc button

c. Controller parameter checking and changing.

Checking or changing repair parameters step:
①Press one or more Esc to switch to the standard display interface;
②Press Prg: Display the interface input password;
③Press ENTER input repair level password: 22, starting from the rightmost digit, each input a digital and
confirm with ENTER;

④If the password is correct, the first parameter that can be modified: Network address;
⑤Press UP/DOWN to select parameters to set up;
⑥Press ENTER to move to the parameter value;
⑦Press UP/DOWN to modify the parameter value;
⑧Press ENTER to save the new parameter values;
⑨Repeat the above 5, 6, 7, 8 step change other parameters;
⑩Press Esc to exit the repair parameters modify the program.

The following shows the detailed settings: 13 pages

Drive hardware configuration 1/13 Drive hardware configuration 2/13
Refrigerant type
Network address 198 R134a
Valve type
Danfoss ETS 250

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

Drive hardware configuration 3/13 Drive hardware configuration 4/13

Type of probe S1 Type of probe S1
User-defined NTC Carel
Unit type Auxiliary control type
Fin coil evaporator air-conditioner Disabled

Drive hardware configuration 5/13 Drive hardware configuration 6/13

Type of probe S3 Type of probe S4
Unused Unused
Relay configuration DI1 configuration
Generate alarms Start/stop SH control

Drive hardware configuration 7/13 Control parameter settings 8/13

Language Overheat degree 6.0K
Chinese Valve opening upon start 50%
DI2 configuration Pre-positioning duration 30s
Disabled

Control parameter settings 10/13

Control parameter settings 9/13 Low SH 2.0K
Hot air by-pass temperature --- LOP -50°C
Hot air by-pass temperature --- MOP 50°C
EPR back pressure ---

Control parameter settings 11/13 Control parameter settings 12/13

Enable manual valve positioning 0 HiTcond threshold 80.0°C
Manually set the valve position 0stp Constant temperature
adjustment point 0°C
Constant temperature
adjustment variance 0.1K

Control parameter settings 13/13

DC power supply mode 1

Checking or changing manufacturer parameters step:

①Press one or more Esc to switch to the standard display interface;
②Press Prg: Display interface input password;
③Press ENTER input manufacturer password, starting from the rightmost digit, input a digit for each
confirm with ENTER;
④If the password is correct, the following parameter type list will be displayed:
- Configuration parameters
- Sensor parameters
- Control parameters
- The special parameters
- Alert configuration parameters
- Valve parameters

36
MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

⑤Press UP/DOWN button to select the category, and then press ENTER to enter the first number
⑥Press UP/DOWN to select parameters to set, and then press ENTER to move to the parameter value;
⑦Press UP/DOWN to modify the parameter value;
⑧Press ENTER to save the new parameter values;
⑨Repeat the above 6, 7, 8 step change other parameters;
⑩Press Esc to exit the manufacturer parameter modification program.

340,440,540,720,805,890,1055,
Unit type Remarks
1200,1300,1410,1620,1780
Selected based on the
Refrigerant R134a refrigerant type of the unit
Valve Danfoss ETS250
Automatically brought out by
Sensor S1 4-20 mA; 0-10.0 V
subsequently set parameters
Control mode shell-and-tube unit
Setting
Overheat degree 6
parameters
Valve opening upon start 50%
Pre-positioning delay 6
Valve opening in standby state 0
Available values include: (1)
Power supply mode 1 0: 24 V AC (2) 1: 24 V DC;
default value: 0

Enable manual valve positioning 0

Manually set the valve position 0
Auxiliary control Invalid
Relay settings Alarm relay
DI2 settings Invalid
Variable 1 on the display Overheat degree
Variable 2 on the display Valve opened
Sensor S1 alarm management Valve at a fixed position
Sensor S2 alarm management Valve at a fixed position
S1: calibration offset 0
S1: calibration gain, 4–20 mA 1
Set based on the actual
Pressure sensor S1: minimum value
0 sensor
Check
parameters Pressure sensor S1: maximum Set based on the actual
value 30 sensor
Pressure sensor S1: minimum value Set based on the actual
for alarms 0 sensor
Pressure sensor S1: maximum Set based on the actual
value for alarms 30 sensor
Sensor S2 CAREL NTC
Language English
Measurement unit °C (K), barg
PID: proportional gain 80
PID: integration time 40
PID: derivation time 1.5
Minimum number of valve steps 350
Maximum number of valve steps 3810

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

Number of steps for valve closing 3970

Valve rate 250
Low SH protection: threshold 1
Low SH protection: integration time 2.5
LOP protection: threshold -50
LOP protection: integration time 4
MOP protection: threshold 50
MOP protection: integration time 10
Low overheat degree alarm delay
300
(Low SH, 0 = no alarm)
Low evaporation temperature alarm
300
delay (LOP, 0 = no alarm)
High evaporation temperature alarm
600
delay (MOP, 0 = no alarm)
Low air suction temperature alarm
-50
threshold
Low air suction temperature alarm
300
delay (0 = no alarm)

38
MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

6. Operation part
6.1 Unit operation flow chart

Welcome page
Note: use the user password (58806) or administrator
password (40828) to enter the white window

Main page Use the administrator password (40828) to enter the

purple window.

Parameter setting Mode Alarm information Status

(input password) selection information

Alarm Alarm record

record history
User Time Touch Timer
history inquiry
parameter setting screen on/off
setting setting

Condition Temperature Input Output

display of and status status
unit start pressure
display

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 Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

6.2 Operation part

The control system adopts touch screen for all operations. Take the unit with dual compressors and step
control as an example. The actual display of different products may have a little difference, but the
operations are basically the same.
 Welcome page
The first welcome page as the figure 6.1

Delete

Clear

Main control
board and
HMI program
version
number

Figure 6.1

When you press Enter button, the password keyboard will be displayed. User input 58806/40828 and
press Enter button to enter the main page.
The Indicators on the right are as follows:
Yellow indicator is the power indicator. It stays on under normal conditions, if it is not, check the power
supply wiring.
Green indicator is the touch screen operation indicator. It normally flashes slowly.
Red indicator is the communication indicator. It normally flashes quickly. If it is not, check if the
communication wire connected with the main control board is connected properly and tightly.
 Main page

Display
when unit is
fault

Display when
compressor
start condition
is not met

Function
button

Figure 6.2
The main page displays the current status, control mode and operating mode of the unit.
Press LOCK button at the bottom right of the screen, and the machine enter the initial screen. Input the
password again to enter.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Refers to the table below for the current status display and explanation of the unit:
Standby Machine is not operating, it can start normally.
Machine has malfunction and it cannot start. Please check from malfunction query page and
Malfunction
confirm if the malfunction has been solved.
Operating Machine is operating normally
Starting Machine starts to normal operation
Unload, stop the compressor and stop the water pump are the necessary process during
shutting down. If the minimum running time is not reached, it needs to wait until the minimum
Shutting downrunning time has been reached. Please inspect in the first page of status information if the
minimum running time is satisfied. The shutting down process will be continued when
minimum running time is satisfied.
The compressor startup conditions are not satisfied. The compressor startup condition
includes:
1. Water temperature does not satisfy compressor startup conditions;
2. Water temperature needs to be higher than compressor startup temperature in cooling
mode, Water temperature needs to be lower than compressor startup temperature in
Pause heating mode, this temperature can be modified in the parameter settings page;
3. Oil temperature of compressor does not satisfy startup conditions;
4. The pausing time is too short, and does not meet the requirements of the compressor starts
intervals;
The above information can be check on the first page of status information. The unit
starts automatically when startup conditions are satisfied.
1) Mode setting
Press MODE to display the mode settings window, as shown below:

Figure 6.3
Set control mode(Local, remote, timer),operating mode(cooling, heating, pumping) and single or dual

compressor(dual stage, 1#、2#) in the pop-up window. After configuring the setting, click "X" in the top

right to close the window.

② Only the control mode can be switched during operating, other mode selection is invalid.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

② The control mode is used as an on/off mode choice. "Local” control mode can only be realized
through the touch screen "on / off" button; "Remote” control mode can only be realized through the
"remote start / remote stop" hardware interface; "the timer control mode", can only be realized by setting
the timer.
③ Heating mode is only available for the heat pump unit.
Note: under the "local” control mode, remote control and timer control are invalid; under the "remote”
control mode, local control and timer control are invalid; under the "timed” control mode, local control and
remote control are invalid.

2）Startup operation

The following need to be confirmed before startup:

① The mode setting is correct. Operation mode (cooling, heating, pumping) and single/dual compressor

（dual stages、1#、2#）cannot be set after startup.

② Current status of machine is standby, it cannot start in fault status.

③ Please confirm if the oil heating is completed. If not, machine may stay in a pause state for a long
time and compressor cannot start.
Press “start” button at bottom left of screen, pop-up window will appear. If startup is confirmed, press
“confirm”; if not, click "X" at the top right corner of the window to cancel startup.

Figure 6.4
If the startup conditions are not satisfied, press "Start" button and a prompt will display at the top of the
pop-up boot window. It will show that "compressor start conditions are not met, please check status
information". The compressor startup conditions include: temperature of oil temperature sensor, interval
time of restart, and the startup temperature of compressor. The startup can be confirmed right now, but
unit will start until the compressor startup conditions are met. The main page will keep displaying
"compressor start conditions are not met, please check status information". Refer to the detailed
explanation in the “4” for explanation of status information.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Figure 6.5
Startup operation: Press “startup” is not valid if unit is in malfunction state.
Press START button, and confirm in the window, then unit can start.
If the compressor startup conditions are not met, the unit will pause after running the water pump. The
interface display "compressor start conditions are not satisfied, please check state information".
Shutdown operation:
Press the STOP button, and the shutdown confirmation window will display. Press Confirm button, then
unit status display "stop". After the unit meets stop condition, it will carry out the shutdown process.
Standby status: machine is powered on, it will display “standby status” normally.
① Unit operation: the start-up of the unit is finished.
② Pause state: Control water temperature will be lower than water temperature in paused state.
The unit enters “pause state” and compressor stops operating. Control water temperature will
be higher than water temperature of compressor, when it starts. The compressor will start and
enter “operating state”.
③ Shutting down：the unit enters “shutting down” state when carry out operation of shutdown to
the unit. After shutdown is finished, unit enters “standby state”.
④ Unit protection：A fault alarm will cause the unit to enter “unit protection” state, and a prompt on
the top of the screen will inform user.
Note:
Cooling mode: water temperature in paused state = setting chilled water temperature- temperature
control range. When unit is in paused state, if temperature controlling is higher than compressor starting
temperature, compressor starts.
Heating mode: water temperature in paused state= setting chilled water temperature+ temperature

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

control range. When unit is in paused state, if temperature controlling is lower than compressor starting
temperature, compressor starts.

 Status information- operation query

Press status in the figure 6.5 and enter figure 6.6.

Displaying the unit without oil temperature sensor

Displaying the unit with oil temperature sensor

Figure 6.6
Displaying contents of status information includes the following:
① Display refrigerant type;
② Display operating time of compressor and water pump;
③ Display times that compressor starts;
④ You can check which state the unit operates in（25%、50%、75%、100%）;
⑤ Display whether the unit has a set limit for maximum load;
⑥ Display whether the unit gives an alarm, and which unit head gives the alarm exactly;
⑦ Display whether the compressor oil heating is finished. If compressor starts, It needs to be satisfied
that oil heating time is ‘０’or oil temperature satisfies the compressor start is ‘YES’;
⑧ Display if the starting temperature is satisfied, when compressor starts, water temperature
conditions must be met and “compressor start” must be‘YES’;
⑨ Display if delay restart conditions are satisfy, when compressor starts, “delay restart” must be‘NO’;

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

⑩ Display if the minimum operation time is satisfied, when compressor stops, “Min. Running Time
Elapsed” must be ‘YES’.
Note: when the compressor has oil temperature sensor, the oil temperature conditions must be satisfied
so the compressor can start. When it has no oil temperature sensor, the remaining time for oil heating is
displayed. It depends on the unit
It displays the refrigerant type in the top left of the screen.
To start the unit must meet the following conditions:
① “Delaying Restart” needs to be “NO”, if it is “YES”, the delay time to start the unit is not reached.
② “Water Temperature Allow Compressor Start” needs to be “YES”, if it is “NO”, the current water
temperature does not meet the startup conditions of compressor.
③ “Oil Temp. Allow Compressor Start” needs to be “YES”, if it is “NO”, the current oil temperature does
not meet the startup conditions of compressor.
Shutdown must meet the following conditions:
“Min. Running Time Elapsed” needs to be “YES”, “NO” indicates the delay time for shutdown is not
reached.
1) Status information- display of temperature and pressure

Figure 6.7

2) Status information-input status:

Input status page: “ON” means the input point is closed, OFF means the input point break. “Compressor
overload protection switch”, when the machine is overloaded, “compressor overload protection switch”
input state switches to “ON” and unit enters fault protection state. Normal state of compressor overload
protection switch is “OFF”. Protection on standby is “ON”.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

Figure 6.8 (Remark: subject to the actual principle diagrams)

① “Remote start/stop” displays the status of remote start or remote stop. User needs to install the
point contact type control switch.
② “Chilling/Chilled water flow switch” outputs is OFF if water does not flow. If it does, it outputs ON.
③ “Contactor protection”, the output switches from OFF to ON when the compressor operates and
contactor has action.
3) Status information-output status
Output status page: ON means the output point is powered on, OFF means the input point is powered
off.
When the unit is in shutdown state, all state displays are OFF. According to the startup / shutdown
command, the relative switch action is activated.

Figure 6.9 (Remark: subject to the actual principle diagrams)

 User parameter setting- password interface

Press Parameter setting in the main page to display the password input interface. Input the password
（40828）and enter the user parameter setting interface. Password input interface is shown as figure
6.10.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Figure 6.10
Dialog box like figure 6.11 appears if user inputs wrong password. Press Confirm to return to the input
interface, then input password again.

Figure 6.11

 User parameter setting-temperature setting

Input the password （40828）and enter the page as figure 6.12 shows below:

Manual
input is
possible

Figure 6.12

“MAX” at the top left of setting window is upper limit of parameter setting, and “MIN” is lower limit of
parameter setting (out of range is not accepted). Press Enter button to confirm input. Press CLR
button to cancel input. The keyboard for number input will disappear.
Noun explanation

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 Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

① The temperature adjustment cycle represents each execution cycle of the judgment of load or
unload. If it is set to be 60s, then system judges the unit temperature and checks if it needs to load or
unload every 60 seconds. If it is necessary, system will execute it immediately. After 60 seconds, system
judges it again, and repeats the process;
② Temperature control range: it means the precision of temperature control, for example, the
factory setting is 2℃,if temperature is within ±0.5℃ of control temperature, the unit does not execute the
loading/unloading action;
③ The target value of temperature control: it represents the target value of water temperature
control;
④ Temperature of compressor startup: it represents the control water temperature need to meet
one condition when compressor starts;
⑤ In cooling mode, when control water temperature is higher than startup temperature, the
compressor can start; in heating mode, when control water temperature is lower than startup temperature,
the compressor can start;
⑥ Limit of load: the maximum load of unit can be set. 0-without limit of maximum load, 1-
maximum load is up to 75%, 2- maximum load is up to 50%.
Timer setting of startup or shutdown It will only display when control mode is “timer”.
1) User parameter setting-mode selection
Press Clock and enter the clock setting page as figure 6.13.
Click the setting numerical keyboard, the input numerical keyboard will appear. Input the clock and press
“ENT” to save the setting. “CLR” means the input is canceled.
Press Confirm button after the settings are completed. Check if the setting clock is the same as the
current time. If it is different, press Confirm again.

Manual input
is possible

Figure 6.13

Note: when setting date and clock, please note the non-existent date and clock cannot be set, otherwise
we are not responsible for any consequences.
2) User parameter setting-touch screen setting
User setting- press touch screen setting in the mode setting interface, then the following figure 6.14 will

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

appear.

Press
and
adjust

Figure 6.14

3) User parameter setting- Automatic On/Off

If user wants to use timer function for start or shutdown, choose “timer” in control mode of the figure 2
and enter user setting. Press AUTOMATIC ON/OFF and enter figure 6.15 as below:
Manual
input is
possible

Press
and
switch

Figure 6.15

The timer for start and shutdown can be set for one week, and unit will start or shutdown according to the
timer setting. If the unit needs to continue running for a period of time, for example: staringt from
Tuesday 10:00 and shutdown at 16:00 Thursday, user can set as 10:00 and switch the button from
Invalid to Valid in the timer starting setting of Tuesday, then set as 16:00 and switch the button from
Invalid to Valid in the timer shutdown setting for Thursday, rest timer buttons are set as Invalid .
Check the system time when using the timer function correspond to the system time.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

 Alarm window
Press Alarm button in the main page to enter real-time alarm window, as figure 6.16 shows.

Figure 6.16

If an alarm occurs, the unit executes response according to the fault program. After fault recovery, press the
“reset” button, and the system will return to normal state. When there are more faults, click the slide bar or
arrow keys to check for faults. Red means the fault has not been eliminated, green means the fault has been
eliminated.
Note:
①High pressure protection does not resume automatically, so the user needs to find reset the switch
manually.
②Over load protection does not resume automatically, so the user needs to find the thermal relay in the
control cabinet and reset it manually.
1) Alarm history
Press the Detailed and enter record page to record the alarms when compressor is running. As shown in
figure 6.17 below, the alarm record can keep 5 pieces at most, it will update automatically if there are
more than five. Check the real-time status including temperature, pressure, and status of input and
output point.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Figure 6.17

Please refer to the actual operation interface. It is subject to change without notice.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

7. Safety protection
Name Code Brand Setting Range Location

ON 0.10Mpa
Low-pressure YK-0.3/0.20-
JUNLE OFF 0.20Mpa
Switch O-R-7000

ON 1.4Mpa
High-pressure YK-1.4/0.9-C-
JUNLE OFF 0.9Mpa
Switch 1 R-7000

Note: Manual reset is needed for high-pressure switch.

Safety Devices
 Compressor protection module
The units are equipped with compressor protection modules built in the wiring cabinet of compressor.
INT69 HBY and JTX-A module is designed to detect the motor winding temperature, phase sequence
and phase loss. The detecting signal of JTX-A is voltage type. When motor winding temperature
reaches set point, the module will cut off control circuit immediately. The module with phase
sequence control can prevent motor reversal due to the adverse consequences. When any one
phase lost, the module will cut off main power after a short delay to protect the motor from burning.
When phase imbalance happens, the power cuts immediately. To avoid interference and discriminate
between false voltage drop and malfunction as phase loss or phase imbalance when motor is
operating, JTX-A will cut off main power after 3-5s delay.

 Thermal overload relay

Each compressor is equipped with one thermal overload relay to protect the compressor against
overcurrent. Bypassing the current transducers or make any changes to the factory default set points is
forbidden. The configuration of the module defines the Must Trip Amps (MTA) at which the thermal
overload relay will turn the compressor off.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

 High/low pressure switch

All compressors have factory-installed high/low-pressure switches. See Table.6.1
Table – High/low-pressure switch settings
High-pressure switch setting Low pressure switch setting
UNIT
Protection value Reset Value Protection value Reset Value
LSBLG***/MCF 14bar 9bar 1bar 2bar
Table.6.1
If the high pressure switch is continuously open for 3s during operation, the compressor will shut down. A
manual reset of the control is required to restart the compressor. If the low pressure switch is
continuously open for 1s during operation, the compressor will shut down. It will reset automatically
when the fault is solved and cleared on the fault record page of touch screen. Sometimes if the
malfunction cannot be solved by resetting, consider replacing the pressure switches.

 Evaporator protection: Low Chilled Leaving Water Temperature

PCB is programmed to shut the chiller down if the leaving water temperature drops below 4 °C. When
water temperature rises to 10℃, the safety resets and the chiller restarts. The chillers are equipped with
an antifreeze switch on the outlet of chilled water. If leaving water temperature is continuously lower than
3 °C for 3s during operation, the chiller will shut down. When water temperature rises to 10 °C, the chiller
resets, it needs manually reset on the touch screen.
IMPORTANT: If unit is installed in an area where ambient temperature may fall below 32 F (0°C), a
suitable corrosion-inhibited antifreeze solution or auxiliary electric heater must be used in the chilled
water circuit.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

IV. Electrical control

1. Electrical data

LSBLGW ***/MCF 340 440 540 720 805 890 1055 1200 1300 1410 1620 1780

Power supply / 380V 3Ph 50Hz

Voltage range V 340~420
Max. running current A 141 169 206 281 332 367 406 455 562 562 664 734

Max. power consumption kW 84 101 123 168 193 214 242 272 337 337 381 429

Rated current A 103 130 163 219 255 270 331 356 396 429 515 532
Compressor A
Locked rotor Amps. A 810 875 1340 1990 2260 2260 3090 1430 1990 1990 2260 2260
Max. allowed current A 141 169 206 281 332 367 406 227 281 281 332 367
Rated current A 103 130 163 219 255 270 329 178 198 215 257 266
Rated power kW 60 77 94 128 144 155 187 103 116 125 146 153
Compressor B
Locked rotor Amps. A -- -- -- -- -- -- -- 1430 1990 1880 2260 2260
Max. allowed current A -- -- -- -- -- -- -- 227 281 281 332 367
Rated current A -- -- -- -- -- -- -- 178 198 215 257 266
Rated power kW -- -- -- -- -- -- -- 103 116 125 146 153
Crankcase heater
Voltage V 220 220 220 220 220 220 220 220 220 220 220 220
Total input kW 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.6 0.6 0.6 0.6 0.6
Total Amps. A 1.36 1.36 1.36 1.36 1.36 1.36 1.36 2.72 2.72 2.72 2.72 2.72

Note:
1. Customer to specify the exact nominal power supply available at site so that electrical components are selected
accurately.
2. Main power must be supplied from a single field supplied and mounted fused circuit breaker.
3. The compressor crankcase heaters must be energized for hours before the unit is initially started or after a prolonged
power disconnection.
4. All field wining must comply with local standards.
5. Neutral line required on 380V-3Ph-50Hz(5 wires) power supply.
6. Rated load Amps values are on nominal conditions.
7. A ±10% voltage variation from the nominal conditions is allowed temporarily only.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

2. Electrical components

1) Power protector

This module detects power supply and protects if phase loss, phase sequence, and under voltage of
incoming line power, occurs. It prevents damage to the compressor or other components if there is a
power failure. Some models also provide protection for overvoltage and three phase imbalance.

2) Time Relay and Intermediate Relay

The time relay is an automatic switch device that performs delayed control based on electromagnetic or
mechanical principles. It controls the star delta switching time for the compressor contactor. The preset
time is the start operation time (6s). The coil voltage is AC 220V. The rated contact current is usually low
and is only used for controlling the loop.

The intermediate relay delivers intermediate signals among control circuits to increase the number and
capacity of contacts. Normally, the main control board output controls starting and stopping of loads such
as motor and water pump by using the intermediate relay to drive the contactor coil. The coil power
supply can be DC or AC. Our standard screw compressor model uses the AC220V coil.

3) Compressor thermal overload relay

The thermal overload relay works are based on heating effect of electric current. With inverse time limit
action feature which is similar to the permissible overload feature of the motor, it provides overcurrent
protection for the compressor and fan. For compressor overload protection, the major loop current of the
motor is converted to an AC 0-5 A current signal by the current mutual inductor. Then the thermal
overload relay performs overload protection. For fan overload protection, the thermal overload relay is
connected in series with the major loop.

4) Current transformer and Transducer

The current transformer transforms primary current with a larger value to secondary current with a
smaller value for protection or measurement. A current transformer with transformation ratio of 400/5 can
transform 400A current to 5A.

A transducer transduces the measured current to DC voltage or DC current. After the current transformer
transforms the current to AC 0-5 A current signals, the transducer outputs 4-20 mA analog signasl based
on the linear scale to the main control board.

5) Electronic Expansion Valve

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

The electronic expansion valve is equipped with a stepping motor which controls the valve status. A
special-purpose electronic expansion valve control module is required to drive the electronic expansion
valve.

6) Solenoid Valve

When the solenoid valve is energized, the electromagnetic coil generates electromagnetic force to pull
up the closed component from the valve seat and open the valve. When the solenoid valve is powered
off, the spring pushes the closed component to the valve seat once the electromagnetic force disappears
and the valve is closed. Voltage of the solenoid valve washer is AC220V, and it is driven directly by the
main control board output.

3. Electrical parts parameter setting

1) Power protector

U： 380V

T： 6S

＜ U ：
-10%
Power LED ，on lighting

Running LED
Normal lighting;
fault off

Power protector use Schneider RM17TU type.

① Select the voltage class. For standard units, the voltage is 380 V.

① Set the delay to 6s.

② Set the under voltage value to 10%.

Note: Set the processing parameters only when the system is powered off.

2) Time Relay

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Time’s up LED
Up display green
Power LED
On display red
T： 6S

Time relay use Omron H3Y type.

3) Compressor and fan thermal overload relay

Thermal overload relay takes advantage of heating effect to protect the compressor and fans.

TEST key: to press to test whether the

overload relay is normal in stop condition

Reset key: to press to reset the overload

relay if there is compressor overload
protection

Current setting panel: to set the

protection current value.

Note：Compressor overload relay, only apply to 3UA series of Siemens brand

Compressor thermal relay value:

The calculation of compressor overload value (transformation ratio of current mutual inductor is A/B) is as
follows:

(Maximum running current of compressor/current mutual inductor A) x B = Thermal relay value of compressor

For example, if the maximum running current of compressor is 250 A, and the transformation ratio of current
mutual inductor is 300/5, Thermal relay value = (250/300) x 5 = 4.17

Note: Use a value that is smaller than the calculated one. For example, in the preceding calculation, the calculated
value is 4.17; in practice, set the value to 4.15.
Maximum Running Transformation Ratio of Thermal Relay Value of
Unit Type
Current of Compressor Current Transformer Compressor
340 141.4 200/5 3.5
440 169.4 250/5 3.3
540 206.1 300/5 3.4
720 241.2 400/5 3.5
805 331.7 500/5 3.3
890 366.8 600/5 3.0
1055 203.0x2 300/5 3.3
1200 277.4x2 300/5 3.8
1300 281.2x2 400/5 3.5
1410 281.2x2 400/5 3.5
1620 331.7x2 500/5 3.3
1780 366.8x2 500/5 3.0

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

4. Field wiring
1) Wiring diagram
Power supply wiring diagram

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Water Pump Wiring Diagram

M
3～

Recommended external wiring cable

2 2
Unit Model External wiring cable (mm ) Unit Model External wiring cable (mm )
LSBLG340/MCF 4×AWG1+AWG3 LSBLG1055/MCF 4×AWG400+AWG4/0
LSBLG440/MCF 4×AWG1/0+AWG3 LSBLG1200/MCF 4×AWG500+AWG250
LSBLG540/MCF 4×AWG3/0+AWG1 LSBLG1300/MCF 4×AWG500+AWG300
LSBLG720/MCF 4×AWG4/0+AWG1/0 LSBLG1410/MCF 4×AWG600+AWG300
LSBLG805/MCF 4×AWG300+AWG4/0 LSBLG1620/MCF 4×(2×AWG300)+AWG300
LSBLG890/MCF 4×AWG400+AWG4/0 LSBLG1780/MCF 4×(2×AWG400)+AWG500

Notice: The given wire length limits voltage drop to < 2%. If the length cannot be reduced, the power cord should be
bolder.
If the cable is installed in pipe or the ambient temperature is above 40℃, enlarge the wire section. Refer to relevant
electrical code according to the max. running current.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

2) Remote control wiring

The wiring ports for remote start/stop, flow switch, water pump linked control, alarm indication, and so
on,. are reserved in the electrical cabinet of the unit, with the numbers shown in the diagram below.

Only double head

Customer wiring terminal
Inside electric control cabinet

1 2 3 4 5 6 7 8 Inside electric 13 14 15 16 17 18 19 20 21 22 23 24
control cabinet
2

Pump intermediate relay

1

Refrigeration lamp

2# alarm lamp
1# alarm lamp
Remote Stop

Flow switch
Remote Start

Remote start/stop switch needs to use inching switch.

Lamp input 220VAC.

3) PC connection

Nowadays PC system (such as BMS) is becoming more and more popular. Midea water-cooled screw
chiller has reserved a RS485 interface using the MODBUS protocol.
(1) PLC units PC connection
PC connection wiring

Computer data collection port

Notes for PLC unit PC communication:

Bit rate: 19200 Transmission bit：8 Stop bits: 1 Parity check: even
(2) MIC units PC connection
PC connection wiring

Computer data collection port

Notes for MIC unit PC communication

Bit rate: 9600 Transmission bit：8 Stop bits: 1 Parity check: no

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

5. Wiring Diagrams
LSBLG340~1055/MCF

L1
L2
L3
N

QF1
L11 SB
L1 L2 L3
L15 L15
KR 1/G2
2/F2
12 11 14
KA
222 202
105
TA1 TA2 1 3
2/B9 2/B9 FR FR

QF2 107
5 KM1
HMI
101 103
KM3 KM1 KM3 KM2 N L
KM1 KM2
X:23 ～ 220V 24V 0V

111 115 UR1

24V
EV M EH +V -V
KT KM2 KT
X:24 117
W
V
U

L1 L2 L3
109 113
JTX-A M RS485 Communication Line

3/B10
3/E12
1SF KM1 KM2 KM3 KT
3～ 3/F2
L N S1 S2 M1 M2 N 1/G2
L15

202
216

2/F2
N

Z
Y
X
X:26
X:25

KM3
1/C12
1/F12

2/B7
2/B7

ST1 ST2

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Flooded type water cooled screw chiller(MIC) MCAC-CTSM-2018-1

X:39 X:13 X:14 X:42 X:45 X:47

SB1 SB2 SL SF SP2 SP1 KR FR

X:40 X:12 X:15 X:41 X:43 X:44 X:46 X:48

202 204 206 208 202 214 216 218 220 202 222 224 226

301 303 307 309 311 313 315

X:27 X:1 X:4 X:31 X:33 X:35 X:5
SV5 YV3 YV2 YV1

X:28 X:2 X:3 X:32 X:34 X:6

3/E2
1/F12 N 3/A5
L15
1/C12 3/F2
3/A5

Note: It indicates the field wiring in the dotted box

62
MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

2/F11
2/F11
N L15

N L
X:17 X:18 X:20 ～220V X:50 X:51 X:54 X:55 X:58 X:62

1/E10
232 UR2
SQ1 SQ2 SQ3 12V
+V -V

RT2

RT1

RT5

RT3

RT4

RT7
X:16 X:19 X:21 12V 0V X:49 X:52 X:53 X:56 X:57 X:61
202 230 234 402 404 406 408 410 404 0V 412 404 416

317 319 321 504 502

X:8 X:9

X:66

X:64
X:65

X:63
KA 24V

1/E10
I I
L15 BP2 BP1
X:7 X:10 P P
2/F11
N
2/F11
RS485 Communication Line
1/F11

Note: It indicates the field wiring in the dotted box S3 code setting:
code 1: ON indicates single head, OFF indicates dual heads
code 2: ON indicates there is not oil temperature sensor, OFF
indicates there is.

63
Flooded type water cooled screw chiller(MIC) MCAC-CTSM-2018-1

TC FU
L15 L17 L19
1/C12

N N1
1/F12

611 613 615 617

X:74
X:73
X:72
X:71
EVD

Green
White
Black

Red
605 603 601 607 609
X:69 X:68 X:67 X:70

BP P KA
I RT

64
MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)
LSBLG1200~1780/MCF

L1
L2
L3
N

L1 L2 L3 QF1
KR
SB
12 11 14

202 232 L11 L15

1/G2
1/G4
1 3 7 9 2/B2
3/B9 3/B9 1TA1 1TA2 2TA1 2TA2
1FR 2FR QF2 1KM1 2KM1 N L
～220V HMI
5 11 101 103 105 UR1
24V
X:29 X:32 +V -V 24V 0V
0V
24V
1KM1 1KM2 2KM1 2KM2 EV M 1EH 2EH
RS485 Communication Line

4/E12
4/B10
X:30 X:31 4/F2
N 1/G2
1W
1V
1U

1/G4

2U
2V
2W
L1 L2 L3 L1 L2 L3
2/E2
1SF JTX-A M 2SF JTX-A M
L N S1 S2 M1 M2
3～ L N S1 S2 M1 M2
3～
X:33 L15

222
202

L15

202
236
X:34 N

N
1Y
1X

2Y
1Z

2X
2Z
X:34
X:33

1KM3 2KM3
1/C11
1/E11
1/E11
1/C11

3/B10
3/B10
3/B7
3/B7

1ST1 1ST2 1ST1 1ST2

65
Flooded type water cooled screw chiller(MIC) MCAC-CTSM-2018-1

L15
1/C11 3/F2
4/A5
5/B1
1KA 2KA
107 121

1FR 2FR
109 123

1KM3 1KM1 1KM3 1KM2 2KM3 2KM1 2KM3 2KM2

113 117 127 131

1KT 1KM2 1KT 2KT 2KM2 2KT

119 133
111 115 125 129
1KM1 1KM2 1KM3 1KT 2KM1 2KM2 2KM3 2KT
N
1/E11 3/F2
4/A5
5/B1

66
MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

X:53 X:18 X:19 X:56 X:59 X:62 X:65

SB1 SB2 1SL 1SF 1SP2 1SP1 2SP2 2SP1 KR 1FR 2SF

X:52 X:54 X:17 X:20 X:55 X:57 X:58 X:60 X:61 X:63 X:64 X:66
202 204 206 208 210 202 220 222 224 226 202 228 230 232 234 236 238

301 303 305 307 309 311 313 319 321 323 325 327 329
X:35 X:37 X:1 X:4 X:38 X:40 X:42 X:5 X:8 X:49 X:48 X:46 X:9
2SV5 1SV52YV3 2YV1 2YV2 2YV3 1YV1 1YV2 1YV3

X:36 X:2 X:3 X:39 X:41 X:6 X:7 X:50 X:47 X:10
N 4/F2
2/E12
2/B12 L15 4/E2

Note: It indicates the field wiring in the dotted box

67
Flooded type water cooled screw chiller(MIC) MCAC-CTSM-2018-1

2/E12
2/B12
N L15

N L
X:22 X:23 X:25 X:67 ～220V

1/E10
X:70 X:71 X:74 X:75 X:78 X:79 X:82 X:83
242 UR2
SQ1 SQ2 2FR SQ3 2SL 12V
+V -V

RT7

RT8
RT6
RT2

RT1

RT5

RT3

RT4
X:21 X:24 X:26 X:68 12V 0V X:69 X:72 X:73 X:76 X:77 X:80 X:81 X:84
202 240 248 246 402 404 406 406 410 404 OV 412 406 404 416 418
244

331 333 335 337 508 506 504 502

X:12 X:13

X:92

X:90

X:88

X:86
X:91

X:89

X:87

X:85
2KA 1KA 24V

1/E10
I I I I
L15 2BP2 1BP2 2BP1 1BP1
X:11 X:14 P P P P
3/F11
N
3/F11 RS485 Communication Line
1/E11

Note: It indicates the field wiring in the dotted box S3 code setting:
code 1: ON indicates single head, OFF indicates dual heads
code 2: ON indicates there is not oil temperature sensor, OFF
indicates there is.

68
MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

TC FU
L15 L17 L19
2/B12

N N1
2/E12

611 613 615 617 629 631 633 635

X:100

X:108
X:107
X:106
X:105
X:99
X:98
X:97
1EVD 2EVD

Green

Green
White

White
Black

Black
Red

Red
605 603 601 607 609 623 621 619 625 627
X:95 X:94 X:93 X:96 X:103 X:102 X:101 X:104

P 1KA P 2KA
1BP 2BP
I 1RT I 2RT

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

V. Installation

Safety considerations
Only authorized personnel should maintain the unit. The access limitation device must be installed by
the customer.

After the unit has been received, when it is ready to be installed or reinstalled, and before it starts up, it
must be inspected for damage. Check that the refrigerant circuit(s) is (are) intact, especially that no
components or pipes have shifted. If in doubt, carry out a leak tightness check and verify with the
manufacturer that the circuit integrity has not been impaired. If damage is detected upon receipt,
immediately submit a claim with the shipping company.

Arrange for a specialist company to unload the machine.

Safety is only guaranteed, if these instructions are followed carefully. If this is not the case, there is a risk
of damage or injury..

1. Unit installation

1).Lifting

○
1 When transporting the unit, avoid collision between the unit and other objects.

○
2 Move the unit by placing a roller at the bottom of the unit to avoid damage.

○
3 Choose a suitable crane according to the unit’s weight（Purchase insurance if possible）；Lift the unit
according to the following chart strictly. The steel rope winds the lifting hook in one circle to prevent steel
rope slipping when the weight is unbalanced. Set up a security perimeter during hoisting and follow local
regulations. Prohibit non-staff from entering the job site or from staying under the unit or the hoisting
crane.

Any person is not allowed to stand below the unit when sling it.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)
2) Foundation

① Consider the construction of installation foundation. Attention should be especially paid to the
intensity of the floor and noise elimination when installing the unit in interlayer or on the top floor.
It is suggested to consult the building designer before installation.

② For convenient drainage, a gutter should be made around the basement.

③ To eliminate the vibration and noise, put an absorber between the unit and basement and keep
the unit balanced. Install a shockproof foundation when necessary.

④ Vibration isolators are recommended for all roof mounted installations or wherever vibration
transmission is a consideration. Neoprene Isolation is optional, it is recommended for normal
installations and provides good performance in most applications for the least cost. Spring
isolator is level adjustable, spring and cage type isolators for mounting under the unit base rails.
1” nominal deflection may vary slightly by application.
Typical Isolation:
Anchor Bolt

Chiller Leg

RubberegPad
Steel Base Plate

Concrete Base

Foundation Dimensions

71
Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
Foundation Bolt Installation Dimension Table

LSBLG***/MCF
Model
Dimension 340 440 540 720 805 890 1055 1200 1300 1410 1620 1780
D(mm) 2850 2850 2850 2850 2850 2850 2850 3850 3850 3850 3850 3850
E(mm) 1100 1100 1100 1300 1300 1300 1400 1400 1400 1400 1500 1500

3) Vibration isolators
Put the absorbers under unit saddles before finally positioning the unit. The quantity of absorbers
used for each unit is decided by the elasticity or durometer value of the absorber. Refer to the typical
isolation pad and vibration isolator below during selection.

Typical isolation pad Typical vibration Isolator

Expected load bearing values are listed below:

Isolation pad Vibration Isolator

Running
Model Minimum load Minimum Minimum load
Quantity weight(kg)
bearing (kg/EA) Quantity bearing (kg/EA)

LSBLG340/MCF 900 4 900 4 2515

LSBLG440/MCF 1000 4 1000 4 2560
LSBLG540/MCF 1200 4 1200 4 2935
LSBLG720/MCF 1400 4 1400 4 3800
LSBLG805/MCF 1800 4 1800 4 4210
LSBLG890/MCF 1800 4 1800 4 4300
LSBLG1055/MCF 2000 4 2000 4 5470
LSBLG1200/MCF 2200 4 2200 4 6482
LSBLG1300/MCF 2200 4 2200 4 6582
LSBLG1410/MCF 2200 4 2200 4 6680
LSBLG1620/MCF 2200 4 2200 4 8250
LSBLG1780/MCF 2200 4 2200 4 8400

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)
Note:
(1) Pads must extend the full length of the saddle when an isolation pad is used.
(2) Level the unit to within 5mm of its length and width after absorbers are installed.

4).Spaces
Ensure sufficient space for maintenance:

 Place without the interference of sunlight or other kind of heat source.

 Place close to electrical source for wiring.
 Place on a solid base to prevent vibration and noise.
 Position in a clean, bright and well ventilated place.
 Place where it is convenient for piping and water drainage with the least influence on the
surroundings caused by noise, cold or hot wind.

2. Water pipeline system installation

1) Water quality control

When industrial water is used as chilled water, a little furring may occur; however, well water or river
water, when used as chilled water, may cause much sediment, such as furring, sand, and so on.
Therefore, well water or river water must be filtered and softened using softening water equipment
before it enters into chilled water system. Sand and clay in the evaporator may block the circulation
of chilled water , and lead to freezing. If the hardness of chilled water is too high, furring may occur
easily, and corrode the devices. Therefore, the quality of chilled water should be analyzed, including
PH value, conductivity, and the concentration of chloride and sulfide ions.
1. Avoid NH4+ ammonium ions in the water, as they are very damaging to copper. This is one of the
most important factors for the service life of copper pipes. A content of several tenths mg/l will badly
corrode copper over time.
2. Cl- Chloride ions are damage, corrode and can perforate copper. If possible, keep below <50 ppm.
3. SO2-4 sulphate ions can cause perforation corrosion. If possible, keep below <50 ppm.
4. No fluoride ions (<0.1 mg/l).
5. If possible keep Calcium ion below <50 ppm.
6. No Fe2+ and Fe3+ ions with non-negligible levels of dissolved oxygen must be present. Dissolved iron
< 5 mg/l with dissolved oxygen < 5 mg/l. If possible, keep below <0.3 ppm.
7. Dissolved silicon: silicon is an acidic element of water and can lead to corrosion. Content <30 ppm
8. Water hardness: Total hardness <50 ppm is recommended. This will facilitate scale deposits that can
limit corrosion of copper. A total alkalimetric titer (TAC) below 100 is desirable.
9. Dissolved oxygen: Avoid any sudden change in water oxygenation conditions. Do not deoxygenate

73
Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
the water by mixing it with an inert gas as it will over-oxygenate it by mixing it with pure oxygen.
Altering oxygenation conditions destabilizes copper hydroxides and enlarges particles.
10. Specific resistance – electric conductivity: Higher specific resistance, shows corrosion. Conductivity
<20μV/cm (25℃) is desirable. A neutral environment favors maximum specific resistance values. For
electric conductivity values of 200-6000S/cm are recommended.
11. PH: Ideal case pH neutral at 20-25°C 7 < pH < 8.5. If the water circuit must be emptied for longer
than one month, the complete circuit must be placed under nitrogen charge to avoid any risk of
corrosion by differential aeration. Charging and removing heat exchange fluids should be done with
devices included in the water circuit by the installer. Never use the unit heat exchangers to add heat
exchange fluid. Piping systems must be properly vented, with no stress on water box nozzles and
covers. Use flexible connections to reduce the transmission of vibrations. Water flowing through the
cooler and condenser must meet site requirements. Measure the pressure drop across cooler and
condenser, and compare it with the nominal values .If pump out storage tank and/or pump out
equipment are installed, ensure the pump out condenser water has been piped in. Check for
field-supplied shutoff valves and controls as specified in the job data. Check for refrigerant leaks on
field-installed piping.
2). Performance adjustment factors

Ethylene and Propylene Glycol Factors

A glycol solution is required when the unit in the mentioned condition. The use of glycol will reduce
the performance of the unit depending on concentration.
Ethylene Glycol
Evaporator side

Quality of Cooling Freezing

Power Water flow Water
capacity
glycol（%） modification modification resistance point ℃
modification
30 0.972 0.99 1.013 1.215 -16
35 0.971 0.984 1.04 1.267
40 0.965 0.977 1.074 1.325 -23
Ethylene 45 0.96 0.967 1.121 1.389
glycol 50 0.946 0.955 1.178 1.458 -35
Condenser side
30 0.991 1.02 1.013 1.164 -16
35 0.989 1.027 1.04 1.212
40 0.986 1.032 1.074 1.261 -23
45 0.984 1.037 1.121 1.309
50 0.98 1.044 1.178 1.362 -35
Note: the freezing point is not shown here. Please calculate it according to the interpolation method.

Propylene Glycol
Evaporator side
Quality of Cooling
Power Water flow Water Freezing
glycol capacity
modification modification resistance point ℃
（%） modification
Propylene 30 0.968 0.969 1.01 1.16 -13
glycol 35 0.964 0.955 1.028 1.287
40 0.955 0.937 1.05 1.4 -21
45 0.945 0.914 1.078 1.502
50 0.929 0.89 1.116 1.604 -33

74
MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)
Condenser side
30 0.969 1.023 1.01 1.227 -13
35 0.959 1.029 1.028 1.276
40 0.944 1.039 1.05 1.329 -21
45 0.923 1.054 1.078 1.388
50 0.896 1.078 1.116 1.453 -33

Note: the freezing point is not shown here. Please calculate it according to the interpolation method.
Units operating with glycol solutions are not included in the AHRI Certification Program.
Altitude correction factors
Performance tables are based on sea level. Elevations other than sea level affect the performance of
the unit. The decreased air density will reduce condenser capacity and reduce the unit’s
performance. For performance at elevations other than sea level, refer to below table. The maximum
allowable altitude is 1,800 meters.

Evaporator temperature drop factors

Performance tables are based on a 5℃ temperature drop through the evaporator. Adjustment
factors for applications for temperature range from 3℃ to 6℃ in follow table. Temperature drops
outside this range can affect the control system’s capability to maintain acceptable control and are
not recommended.
Fouling Factor

2 2 2 2
Difference between 0.018m ℃ /kW 0.044m ℃ /kW 0.086m ℃ /kw 0.172m ℃ /kw
Height
water inlet and outlet
(m)
temp.(℃) C P C P C P C P

3 1.020 1.021 1.014 1.014 0.988 0.992 0.962 0.990

Sea 4 1.032 1.023 1.021 1.016 0.993 0.998 0.968 0.992
level 5 1.041 1.028 1.028 1.021 1.000 1.000 0.976 0.996
6 1.048 1.030 1.036 1.023 1.007 1.003 0.985 0.998
3 1.018 1.031 0.998 1.024 0.972 1.004 0.948 0.999
4 1.020 1.034 1.006 1.026 0.978 1.006 0.956 1.001
600
5 1.026 1.037 1.013 1.029 0.986 1.009 0.964 1.004
6 1.033 1.039 1.020 1.032 0.993 1.012 0.972 1.007
3 0.999 1.042 0.980 1.035 0.958 1.015 0.935 1.010
4 1.005 1.046 0.992 1.039 0.965 1.018 0.943 1.013
1200
5 1.014 1.050 1.001 1.041 0.973 1.021 0.951 1.016
6 1.021 1.052 1.008 1.043 0.981 1.024 0.959 1.019
3 0.969 1.054 0.975 1.046 0.946 1.025 0.923 1.020
4 1.000 1.057 0.980 1.050 0.953 1.028 0.931 1.023
1800
5 1.002 1.060 0.988 1.052 0.960 1.031 0.938 1.024
6 1.005 1.062 0.995 1.054 0.967 1.034 0.950 1.025

C--Cooling capacity
P—Power

75
Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
3).Design of the store tank in the system
a. kW is the unit for cooling capacity, L is the unit for (G) minimum water flow volume in the formula.
Comfortable type air conditioner
G= cooling capacity×2.6L
Process type cooling
G= cooling capacity×7.4L
b. In certain occasion (especially in the manufacturing cooling process), to comply with the system’s
water content requirement, mount a tank equipped with a cut-off baffle in the system to avoid water
short-circuit, Please see the following schemes:

Error Recommendation
Error Recommendation

Error
Error Recommendation
Recommendation
Fig.4-4
Fig.4-4
4).Water pipeline installation

Due to the variety of piping practices, it is advisable to follow the recommendations of local authorities.
The installation and insulation of the water pipelines of the air conditioning system shall be designed and
guided by design professionals, and confirm to the corresponding provisions of the HVAC installation
specifications.

Basically, the piping should be designed with a minimum number of bends and changes in elevation to
keep system cost down and performance up.
1) Condenser and cooling water piping: suggested piping as follows：
d e g
a c Cooling
h j tower

Cond return water

condenser

Condenser inlet water

Chiller

k
i
WS

Cond outlet
Condenser water
outlet water
（Condenser, cooling water hose connection diagrammatic sketch）

76
MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)
a Flexible connection k Flow switch
c Butterfly valve d Pressure gauge
e Thermometer f Platinum resistance thermometer
g Air vent h Water pump
I Drain valve j Y- shape strainer

Note: All water pipe accessories and flow switches must be provided by user.
2) Chilled water piping: suggested piping as follows：

e g expansion make-up water

c d tank
h j

Cooler return
Cooler inlet water Return
Chiller

water k Inlet
waterwater
cooler

b i
WS

Cooler outlet water Outlet

water
(Chiller cooler piping diagrammatic sketch）
c Flexible connection b Pressure type temperature controller
e Pressure gauge d Butterfly valve
g Air vent h Water pump
i Drain valve j Y- shape strainer
k Flow switch

Note: All of water pipe accessories and flow switch is provide by user.
Users must install flow switch in the outlet pipe of cooler and evaporator, the two sides must be level straight pipe
with a length longer than five times the pipe diameter.

3) The water inlet pipeline and drain pipeline must be connected according to the requirements of
markings on the unit. Generally, the refrigerant pipe side of the evaporator is the chilled water
outlet side.

4) The chilled water pipeline system must be provided with the soft connection, thermometer,
pressure gauge, water filter, electronic scale remover, check valve, target flow controller,
discharge valve, drain valve, stop valve, expansion tank, etc.

5) The water system must be fitted with the water pump with appropriate displacement and head to
ensure normal water supply to the unit. The soft connection must be used between the water
pump, unit and water system pipelines, and the bracket must be provided to avoid stress on the
unit. Welding work for installation must avoid damage to the unit.

(1) Determination of water pump flow:

Flow (m3/h) = (1.1 ~ 1.2) * Unit Cooling Capacity (kW)/5.8

(2) Determination of water pump head:

Head (m) = (Unit Resistance (see product parameters) + Resistance at Maximum End of
Pressure Drop (see product parameters) + Pipeline Resistance (length of the least favorable loop
pipe * 0.05) + Local Resistance (length of the least favorable loop pipe * 0.05 * 0.5)) * (1.1 ~ 1.2)

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

6) The flow switch must be arranged on the drain pipe of the evaporator. The flow switch must be
interlocked with the input contact in the control cabinet. Its installation requirements are as
follows:

(1) The flow switch must be installed on the pipe vertically.

(2) The straight pipe section on each side of the flow switch must be at least 5 times longer than
the pipe diameter; do not install it near the elbow, orifice plate or valve.

(3) The direction of the arrow on the flow switch must be consistent with the direction of water
flow.

(4) To prevent vibration of the flow switch, remove all air in the water system.

(5) Adjust the flow switch to keep it open state when the flow is lower than the minimum flow
(the minimum flow is 70% of the design flow). When the water flow is satisfied, the flow
switch will stay in closed state.

7) The water filter must be installed before the water inlet pipeline of the unit, and include a
25-mesh screen. This will stop foreign material from entering into and decreasing the
performance of the evaporator.

8) A strainer should be placed for enough upstream to prevent cavitation at the pump inlet (consult
pump manufacturer for recommendations). The use of a strainer will prolong pump life and help
maintain high system performance levels

9) Flushing and insulating the water piping must be done before it is connected to the unit to
prevent dirt from damaging the unit.

10) The design water pressure of the water chamber is 1.0 Mpa. Use of the water chamber must
not exceed this pressure to avoid damaging the evaporator.

11) Do not load the weight of water pipe onto the unit. When water inlet/outlet are connected to
corresponding water pipe, soft connections such as rubber joints should be used to avoid the
transmitting vibration indoors .

12) In a close loop water system, to diminish the impact on water pipe because of the expansion or
contraction of water volume and avoid impact from supplementing water pressure, water return
side should be fitted with an expansion water tank. The expansion tank should be installed
1~1.5m higher than the system, and its capacity accounts about 1/10 of the water in the whole

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

system.

13) The drain connection is arranged on the evaporator cylinder. The drain outlet has been
equipped with a 1/2’’ plug.

14) To expel the air from water system, install an automatic discharge valve at the highest point of
local water pipe and the horizontal pipe should be tilted up for about 1/250 degrees.

15) The thermometer and pressure gauge are arranged on the straight pipe sections of the water
inlet pipeline and drain pipeline, and they should be installed far away from the elbows. The
pressure gauge installed must be vertical to the water pipe. The installation of the thermometer
must ensure that its temperature probe can be inserted into the water pipe directly.

16) Each low point must be fitted with a drain connection to drain the remaining water in the system.
Before operating the unit, connect the stop valves to the drain pipeline, near the water inlet
connection and drain connection. The by-pass pipeline must be installed between the water
inlet pipe and drain pipe of the evaporator, so it is convenient for cleaning and maintenance.
Flexible connections can reduce vibration transfer.

17) Insulate the chilled water pipeline and expansion tank. Leave enough room for valve
connections.

18) After the air-tightness test is carried out, and the insulation layer is applied on the pipeline,
avoid heat transfer and surface condensation by covering the insulation layer with a
moisture-proof seal.

19) Any water piping to the unit must be protected to prevent freezing. There are reserved
terminals for the auxiliary electrical heater. Logic in PCB will transmit an ON/OFF signal by
checking the leaving evaporator water temperature.

Note: The unit only supplies the ON/OFF signal, but not the 220V power. If a separate
disconnect is used for the 220V supply to the cooler heating cable, it should be clearly marked
so that it does not accidentally shut off during cold seasons.

20) If the unit is used as a replacement chiller on a previously existing piping system, the system
should be thoroughly flushed prior to unit installation. Regular chilled water analysis and
chemical water treatment is recommended immediately on equipment start-up.

21) Power on the chilled water pump, and inspect its rotation direction. The correct rotation
direction must be clockwise; if not, re-inspect the wiring of the pump.

22) Start the chilled water pump to circulate water flow. Inspect the water pipelines for water
leakage and dripping.

23) Commission the chilled water pump. Observe whether the water pressure is stable. Observe
the pressure gauges at the pump inlet and outlet, and the readings of the pressure gauges and
the pressure difference between the inlet and outlet change slightly when the water pressure is
stable. Observe whether the operating current of the pump is within the range of rated
operating current; inspect whether the resistance of the system is too large if the difference
between the operating current and rated value is too big; eliminate the system failures until the

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 Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

actual operating current is satisfactory.

24) Inspect whether the water replenishing device for the expansion tank is smooth, and that the
auto discharge air valve in the water system enables auto discharge. If the discharge air valve
is a manual type, open the discharge valve of the chilled water pipeline to discharge all air in
the pipeline.

25) Adjust the flow and inspect whether the water pressure drop of the evaporator meets the
requirements of the unit’s normal operation. The pressure at the chilled water inlet and outlet of
the unit must be kept at least 0.2 MPa.

26) The total water quantity in the system should be sufficient to prevent frequent “on-off” cycling. A
reasonable minimum quantity allows for a complete water system turnover in at least 15
minutes.

3. Wiring installation

WARNING: To prevent any accidents during wiring, cut the power before connecting the unit.

Wiring must comply with all applicable codes and ordinances. Warranty is voided if wiring is not in
accordance with specifications. An open fuse indicates a short, ground, or overload. Before replacing a
fuse or restarting a compressor, find and correct any faults

Copper wire is required for all supply lines in field connections to avoid corrosion and overheating at the
connection of terminals. The lines and control cables must be separately paved and equipped with
protective pipes to avoid intervention of supply lines in control cable.

Power section: Connect the power supply cable to the control cabinet, when it arrives at the jobsite. The
power supply cable is connected to the terminals of L1, L2, L3, N and PE and the terminals need to be
fixed again after 24h running (the minimum allowed time). Please seal the entering wiring hole after
users installed the main power wires, in order to avoid the dust entering into electric control cabinet.

Caution: it is suggested that to use appropriate tools to make sure that a enough height to install the
main power wires if the basement is higher than 200 mm. Breaking isolation switches should be added
between the power cord of users and the unit. The capacities of the breaking isolation switches
recommended are electric control.

(1) Attention: refrigerant selection: the previous software settings are replaced by the current hardware
settings to avoid a software error wrongly selecting refrigerant and damaging the unit.

(2) To avoid incorrect control in field connection, the liquid control circuit (24 V) must not be in the same
conduit with the lead wire with a voltage higher than 24 V.

(3) The control circuits of various units are all 220 V. For the wiring of the control circuits, refer to the wiring
diagrams supplied with the units.

(4) A unit consists of a master compressor and slave compressor communicating via shield wire protected
by sleeve and paved separately from supply line.

(5) The control output cable to be connected on site shall be AC250V-1mm2, and 0.75mm2 shield wire (24 V)
must be used for control signal line.

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 MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

(6) Attentions: Connect the wires strictly according to the wiring terminal diagram. Use three-core shield
cable (3×0.75mm2) to connect to the temperature sensor. Use common two-core cable (2×0.75mm2) to
connect the flow switch to connect to the NO contact of the switch, i.e. the opening point when waterless.
Two buttons can be connected to the external remote start and stop.

(7) If the customer wants linked control of the water pump, connect the water pump as shown in the diagram,
where an intermediate relay is required. If the function of linked control of water pump is not needed,
ensure that the water pump starts before starting the machine.

CAUTION: An independent power supply box needs to be equipped with the power supply of the water
pump.

(8) The wiring ports for remote start/stop, flow switch, cool/warm switch, water pump linked control, alarm
indication are reserved in the electrical cabinet of the unit.

(9) Passive inching button is used for remote start and stop, and the flow switch must be connected to the
NO contact, or the machine cannot be started.

Passive holding switch is used for cool/warm switch, e.g. common selection switch. Controls of large
power electrical appliances such as water pump and user electric heating must be interfaced with a relay,
or the PCB might burn out. Other outputs can be directly connected to indicator lamps or alarms.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

VI. Commissioning

1. Pre start-up

(1) Electrical System Inspection

1) Inspect whether power distribution capacity complies with the power of the unit before the first start-up,
and whether the diameter of the selected cable can bear the maximum working current of the master
compressor.

The max economical conveying distance:

The max loading time in a year（h） Copper core length(m)

<3000 h 264
3000～5000 h 294
>5000 h 331

2) Inspect whether the electricity mode is compliant with that of the unit, three-phase five-line (three
phase lines, one zero line and one earth wire, 380V±10%).

3) Inspect whether the maximum phase voltage imbalance complies with the requirement, 2% for the
maximum permissible phase voltage imbalance and 5% for the phase current balance. The machine
must not be started up when the phase voltage imbalance exceeds 2%. If the measured imbalance% is
excess, the power supply sector must be notified immediately.

4) Inspect whether the supply circuit for the compressor is firmly and properly connected, and tighten it if
there is any looseness. The screws might be loose due to factors such as long-distance transport and
hoisting of the master compressor. Or, the electrical elements (e.g. air switch, AC contactor, etc.) in the
control cabinet of the master compressor and the compressor might be damaged.

5) Carefully inspect all the electrical lines with a multimeter, and check that all connections are properly
installed. Carry out measurement in mega ohm and ensure that there is no short circuit at the shell.
Inspect whether the earth wire is properly installed, and whether the insulation resistance to ground
exceeds 2MΩ. And inspect whether the supply line meets capacity requirements.

6) Inspect whether the disconnection switch is installed in the supply line of the supply unit.

7) Complete all connections of the main circuit in the control cabinet and all external connections of the
control circuit before power connection (e.g. oil heater, compressor electronic protection, circulatory
water temperature sensor, target-type flow switch connection, water pump linked control, communication
line connection); inspect the bolts of the wiring terminal for looseness. Inspect whether various electric
meters and appliances are properly installed, complete and available. Inspect the interior and exterior of
the electrical cabinet, especially various wiring ports, for cleanness. If the communication lines of the
PCB and control screen are damaged, refer to the diagram below.

8) After the inspection for all the above items is completed, connect the control cabinet and the supply
indication lamp will light up, indicating that the oil heater is working. Observe whether the phase loss
protection is normal, if it is (green light on), close the single-pole switch in the control cabinet, then the
control circuit will begin working, and the touch screen and PCB control will be put into operation.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

9) Before starting up the machine, inspect whether the external system of the unit meets the conditions
for start-up (e.g. whether the water cooling pump of the system is externally controlled or interlocked with
the master compressor, and whether the water pump must be started before starting up the master
compressor via external control).

10) Inspect whether the compressor overload protection value, which must not exceed the maximum
compressor permissible current value indicated in the nameplate on the compressor, is set correctly. The
compressor overload protection value generally equals the set value of heat relay multiplied by the
variable ratio of current inductor, which is (250/5)50 in the following case.

11) Inspect whether the value of phase loss and reversal protection is set correctly. The
over-/under-voltage protection value shall be ±10% of the rated voltage.

(2) Refrigeration System Inspection

1) The discharge line valve and suction line valve of the compressor must be fully open (turn
anticlockwise to open). The cores must be tightly locked to prevent refrigerant leaks.

The discharge line

valve and suction line The discharge line
valve shall be open valve and suction line
(both valves in the valve shall be open
figure are closed, and (both valves in the
shall be opened before figure are closed, and
start-up). shall be opened
before start-up).

2) Inspect whether moisture content of the system exceeds the limit

Excessive moisture content in the refrigerant system of the unit might cause ice blocks, copper plating, etc. that
will seriously affect the safety of the unit. Therefore, the dryness of the refrigerant system of the unit must be
inspected with the sight glass before and when the unit is running. Purple indicates dry and pink moist, as shown
in the figure on the right. When the color turns red, replace the filter core in the unit shall be replaced with a dry
one.

The color is indicated in the

center and compared with
the color card around it to
reflect the moistness in the
system.

3) Sufficient lubricating oil in the oil tank (not lower than 1/2 of the oil level in the high oil immersion
lens), and no deterioration (blackness).

Inspect the oil level and quality before start-up, as both directly impact performance and reliability.
There must be sufficient lubricating oil in the unit. During shutdown, the high oil immersion lens must

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

be full of oil.

The oil must be full in stop

status of the unit, and above
the 1/2 position in stable
operation.

When the unit is running stably, the oil level in the high oil immersion lens should be at least above the
1/2 position. There must be no deterioration (blackness) in the lubricating oil, or else, qualified lubricating
oil must be changed before operating the unit.

6) Inspect whether the pressure sensor stop valve, dry filter front/rear angle valve and liquid/air sampling
stop valve are all open.

When the unit stops, the high and low voltages must be almost the same. After start-up, the low voltage
decreases, and the high voltage increases. If there is no voltage change a certain time after start-up,
inspect whether the liquid/air sampling stop valve is open.

7) After the unit is installed and before it is connected, tighten the connections in the electrical cabinet of
the unit one by one.

8) Inspect the bolts of the unit for looseness.

After the unit is transported and installed, inspect whether the fixing bolts of the unit (e.g. fixing bolts at
compressor base angle, at post and beam of the unit, and at pipe clamp, etc.) and of the electrical
elements (e.g. fixing bolts of PCB and insulating transformer, and connection bolts of upper/lower
terminals of AC contactor, etc.) are firmly fixed.

9) Inspect the connections in the electrical cabinet for looseness, especially the electric part in the
cabinet. The parts connected by bolts might become loose due to transportation. If there is any
looseness, tighten them to avoid burnout of circuit or element caused by poor contact.

Inspect the terminals for looseness and poor contact caused by vibration and collision during
transportation and installation (especially electric parts; ensure the connection points of all terminals are
firm and reliable before electrification).

Inspect all terminals All connection points

for firmness and of terminals must be
reliability before firm and reliable.
electrification.

Inspect whether there is poor contact and short circuit caused by dust, moisture, etc. in the electrical

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

cabinet, and whether the values of all temperature sensors are normal. During shutdown, the indicated
temperatures for discharge, fin, and the environment must be almost the same, and the entering and
leaving chilled water temperatures shall be almost the same.

10) Before the unit leaves the factory, the control cabinet is pre-connected with main motor, electrical
actuator, and sensor elements of pressure temperature, so wiring on site is very simple. Only the chilled
water flow switch line and chilled water pump linked control line (control contact is active) needs to be
connected. For the detailed connection method refer to the circuit wiring diagram in the operation
manual for the unit. (The attached circuit diagram represents the case of air-cooled heat pump unit for
user’s reference. For details, the operation manual supplied with the unit is final.)

11) Target-type flow control is set on the chilled water pipeline and must be installed at the chilled water
outlet of the unit. The NO contact of the target-type flow control in the chilled water system must be
connected to the control circuit as per the wiring diagram.

Note: Disordered water flow may lead to wrong action of the flow switch; therefore, the control cabinet
will command the unit to stop after receiving continuous disconnection signals over 10 s.

12) The tube where the temperature sensing probe is installed must be filled with lubricating oil or other
grease that will not freeze at the temperature of the leaving chilled water for the convenience of heat
transfer. Thermostatic insulation and enclosing measures must be taken for the temperature sensing
device.

Inspect whether there is temperature deviation for the entering and leaving water temperature sensor
caused by insufficient heat transfer oil in the thermostatic pipe.

For later armored dip-type temperature sensor, no lubricating oil is required for heat transfer.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

2. Start-up
Before starting the unit, the following performance parameters need to be inspected:

(1) High/low voltage value of the system. If the unit will be shut down and waterless for a long time, the
liquid and gas of the system must be equivalent and close to the saturation pressure corresponding
to the current ambient temperature. The correlation of saturation temperatures and pressures (the
pressures in the list are gauge pressures, of which atmospheric pressure is 0.1MPa) of R22 and
R134a refrigerant is shown in table 1:

In shutdown status, the high and

low voltages shall be the same and
equal to the saturation pressure
corresponding to the current
temperature.

In the pressure gauge scale, taking the right figure for example: the values outside of the black circle are
pressure values (unit: bar), and the values of the red, blue and green circles indicate saturation
temperatures of refrigerants R404A, R22 and R134a respectively under relative pressure. The types of
refrigerants indicated in different pressure gauges might differ.
[Table 1]
Refrigerant R134a Refrigerant Pressure (Gage
Temperature ℃ Pressure) MPa
0 0.19
5 0.25
10 0.32
15 0.39
20 0.47
25 0.57
30 0.67
35 0.79
40 0.92

If the high/low voltage deviates much from the saturation pressure corresponding to the current
temperature (more than 2bar), leakage or insufficient refrigerant is likely in the system.
(2) Inspect the unit for normal heating
Before start-up, inspect whether the oil heating in the unit is available, and whether the oil heater does
not work when there is oil for heating but no power supply. It is particularly important in winter when the
temperature is low and a failure in oil heating might lead to poor lubrication of the unit. The optimum
working temperature for current types of lubricating oil is generally around 40℃.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Compressor oil
heater begins to
work when the
unit is electrified.

(3) Inspect whether there is an alarm on the display screen. If there is, correct the fault.

(4) Inspect the electronic expansion valve control module for alarms.

(5) Inspect whether the temperature points displayed on the screen are within the normal range.

Before running the unit, the temperatures for the discharge and fin and the ambient temperature need to
be close to the current actual ambient temperature, and the entering and leaving water temperatures
close to the water temperature at the user side. If there is any obvious deviation of the above
temperatures, inspect whether the temperature sensor is working normally and whether the connection
is firm and reliable.

Values of various
temperature and
pressure points
showed in the main
page of the unit.

(6) Inspect whether the flow in the water pump meets the requirements of the unit.
(7) Inspect whether the power supply of the unit is stable.
2) Parameters Inspections during Start-up and Operation
(1) The maximum range of parameters for normal operation of R134a refrigerant unit
See table 2 for the maximum range of performance parameters of R134a refrigerant:
[Table 2]
Refrigeration
Working Condition
Discharge temp. ℃ 40~50℃
Suction temp. ℃ 5~9℃
Suction super-heating degree ℃ 1~3℃
Discharge super-heating degree ℃ 10~15℃
Discharge pressure MPa 0.8~0.9MPa
Suction pressure MPa 0.2~0.25MPa

(2)Keep full records of unit data during commissioning.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

VII.Maintenance

ATTENTION:

All installation parts must be maintained by personnel in charge, to avoid material deterioration and
injuries to people. Faults and leaks must be repaired immediately. Authorized technician must repair
faults immediately. Each time repairs have been carried out on the unit, the safety devices must be
re-checked.

Do not use oxygen to purge lines or to pressurize a machine for any reason. Oxygen gas reacts violently
with oil, grease, and other common substances.

The necessary protection equipment must be available, and appropriate fire extinguishers for the system
and refrigerant type must be within easy reach.

Do not siphon the refrigerant. Avoid spilling liquid refrigerant on your skin or splashing it into your eyes.
Use safety goggles. Wash any spills from the skin with soap and water. If liquid refrigerant enters your
eyes, immediately and abundantly flush the eyes with water and consult a doctor.

Never let an open flame or live steam come close to a refrigerant container. Dangerous overpressure
can result. If it is necessary to heat refrigerant, only use warm water.

Do not re-use disposable (non-returnable) cylinders or attempt to refill them. It is dangerous and illegal.
When the cylinders are empty, evacuate the remaining gas pressure, and move the cylinders to a place
designated for their recovery. Do not incinerate.

Ensure that you use the correct refrigerant type before recharging the unit. Charging any refrigerant
other than the original charge type (R-22) will impair machine operation and can even destroy the
compressors. The compressors operating with this refrigerant type are lubricated with a synthetic

Do not climb on a machine. Use a platform, or staging to work at higher levels. Use mechanical lifting
equipment (crane, hoist, winch, etc.) to lift or move heavy components. For lighter components, use
lifting equipment when there is a risk of slipping or losing your balance. Use only original replacement
parts for any repair or component replacement. Consult the list of replacement parts that correspond to
the specification of the original equipment.
1. Daily maintenance

Annual Startup

This is a good time to check all the motor winding resistance to ground. Semi-annual checking and
recording of this resistance will provide a record of any deterioration of the winding insulation. All new
units have well over 100 MΩ resistances between any motor terminal and ground.

1. The control circuit must be energized at all times, except during service. If the control circuit has been
powered off and the oil is cool, energize the oil heaters and allow 8 hours for heater to remove
refrigerant from the oil before starting.

2. Check and tighten all electrical connections.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

3. Replace the drain plug in the cooling tower pump if it was removed at shutdown time the previous
season.

4. Install fuses in the main disconnect switch (if removed).

5. Reconnect water lines and turn on the supply water. Flush the condenser and check for leaks.

Annual Shutdown

Where the chiller can be subject to freezing temperatures, the condenser and chiller must be drained of
all water. Dry air blown through the condenser will help force all the water out and decrease the
corrosion. Water permitted to remain in the piping and vessels can rupture these parts in freezing
temperatures.

If the chiller is used in areas where the ambient temperature will fall below 0℃, forced circulation of
antifreeze through the water circuits is one method of avoiding freeze up.

1. Take measures to prevent the shutoff valve in the water supply line from being accidentally turned on.

2. If a cooling tower is used, and if the water pump will be exposed to freezing temperature, be sure to
remove the pump drain plug and leave it out so any water that can accumulate will drain away.

3. Open the compressor disconnect switch, and remove the fuses.

4. Check for corrosion and clean and paint rusted surfaces.

5. Clean and flush water tower for all units operating on a water tower. It should be recognized that
atmospheric air contains many contaminants that increase the need for proper water treatment. The
use of untreated water can result in corrosion, erosion, sliming, scaling or algae formation. Use a
reliable water treatment company.

6. Remove the condenser heads at least once a year to inspect the condenser tubes and clean if
required.

Recommended maintenance schedule

This chapter describes the preventive maintenance of Midea screw chiller. Correct maintenance and
timely service will keep the chiller in the best condition and give the best performance, and prolong its
service life.

The customer must appoint an equipment management engineer and specially-assigned operator to
perform the daily and scheduled maintenance. The repair work should be done by large maintenance
company that is qualified to do the job. It is better to make a maintenance agreement with the local
Midea service center when the warranty guarantee reliable operations.

Note: Repair work caused by incorrect maintenance within warranty will lead to extra charges.

Daily maintenance

The basic work of unit maintenance is to accurately record the operation parameters of the unit at certain
intervals (e.g. 2 hours) everyday. Fill the operation parameter table which contains such key parameters
such as high/low pressure, suction/discharge temperature, degree of sub-cooling/overheat degree. True
and complete records of operating parameters are useful for analyzing and forecasting the trend of unit

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

operation. It’s good for finding and forecasting the problem that may occur and taking measures in time.

For example, by analyzing the record of a whole month, you may find that the temperature difference
between the condensing temperature and leaving cooling water temperature may become bigger. It
means that the cooling water is dirty or the water is hard, and it is scaling constantly. So it is compulsory
to perform a softening process or clean the tubes.

Note: Keeping the normal operation parameters of the initial unit’s commissioning is very useful. It can
be used for comparative analysis to find out problem trends.

Scheduled maintenance

General

Take notice of the noise at any time by standing 1m from the unit. Watch the vibration amplitude at all
times to see whether it is with in the allowable range. Check whether the power supply is within ±10% of
the rated voltage at any time.

 Visual inspection

Keep the unit clean. If there is rust, do scaling with iron brush and cover it with antirust paint. Pay
attention to oil traces (sign of a refrigerant leak) and water traces on pipeline. Check the threaded
connection joints carefully, fasten any loose screws in time. If the insulating material flakes off, stick it
with adhesive.

 Compressor

Check insulation resistance yearly. It should be over 5 MΩ when measuring with a DC 500V ohmmeter .
When touching the shockproof rubber, it should be elastic, or the rubber will age. Every 3,000 hours,
inspect vibration and oil. Every 6,000 hours, check the safety device and protective device to guarantee
normal operations.

Important: The normal oil level is in the middle of sight glass. Add lubricating oil if the oil level declines
noticeably. Inspect the oil quality monthly to see if there is dirt or deterioration. Replace the oil and filter
core if necessary by specialized technicians. Make chemical analysis of the lubricating oil. If
emulsification phenomenon occurs, change the oil with the same brand.

 Heat exchangers

Adjust the water flow to keep the high/low pressure within a normal range (high pressure
0.6~1.2MPa/low pressure 0.1~0.4),If the temperature difference between the leaving cooling water
temperature and refrigerant temperature in the condenser is more than 6 °C, the condenser is scaling
and cleaning is needed. When the chiller is not used for a long time, fully drain the water in heat
exchangers and pipe system. For newly installed chiller, the filters in water system should be cleaned
after running for 24 hours and then clean the filters quarterly.

 Valves and pressure controllers

▲ Safety valves

Inspect the integrity and performance of valves every year. Maintenance ON safety valves should be
performed by specialized technicians. Take apart the connecting pipe of the safety valve, and check it to

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

see whether there is corrosion, rust, scaling, leakage phenomenon internal (if necessary, replace the
safety valve). Check the other valves to see whether they open and close smoothly.

▲ High/low pressure switch

Check whether they are in good condition according to “performance of protection device”, every month
and change broken ones in time. Or the chiller may get damaged when over high pressure or too low
pressure happens.

 Chilled water cycling

Check for leaks on the unit and the pipe joint with leak detector. Expel the water from the condenser and
evaporator to see whether there are leaks on the water inlet and outlet. Leaks can be found with an
electronic detector, torch detector or soap water. The work looking for refrigerant leaks should be carried
out at least once/month.

 Electrical control system

Check insulation resistance monthly. It should be over 1MΩ when measuring with a 500VDC ohmmeter.
Check the running current and compare with the rated value (refer to Table.9). Check the conductibility
of wire and verify whether it is intact and well connected. Tighten loose bolts. Check other components
each month, including the electromagnetic contactor, rotary switch, auxiliary relay, time relay and
thermostat.

Training User Operator

The commissioning process includes training user operators in the following aspects:

1) Stress safety in shutdown and operation processes.

2) Require users to carefully read the operation manual of the unit.

Explain to users that the operation of the unit must be carried out strictly as per the steps and
methods specified in the operation manual. If anyone has any problems about descriptions in the
manual, consult after-sale personnel or professionals in the factory and carry out the operation only
with full understanding. Any deviation in the installation of the unit from the requirements in the
manual must be pointed out to the party responsible for installation. The after-sales factory
personnel will determine whether a change is necessary.

3) Short-connection is forbidden when all protection functions of the unit are normal. Ensure all
protection functions are available and reliable.

Various protection switches in the unit are for the safety of the unit or user, and are not permitted to
be short connected in principle. If short-connection is required for commissioning, after-sales or
factory personnel must do so on site. After commissioning, connect the protection switches to the
system before starting up the unit for long-term running.

4) Open the water pump and wait until the water flow is stable before starting up the master
compressor. For shutdown, the water pump must be closed after a delayed time. Do not forcibly
close the water pump when the master compressor is still running. If the water pump fails, and the
flow switch does not jump, the unit must be immediately shut down.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

5) Disconnect the unit from the power supply during inspection or replacement of the lines.

Tighten the line bank screw or replace the wire and element in the electrical cabinet during
commissioning and maintenance, only when the power supply is disconnected. Similar operations
in subsequent maintenance and servicing must also be done when the power supply is
disconnected.

6) Do not change non-user parameters on the touch screen of the unit and electronic expansion valve
control module.

Relate to the performance and reliability of the unit, and must not be changed. Even if it is required
to adjust some parameters due to special local climate, it must be done by or under the instructions
of after-sales or factory personnel.

7) If the unit behaves unexpectedly, do not forcibly start up the unit unless under the instructions of
professionals.

Exceptional temperature, pressure, sound, or vibration, etc. of the unit when it is running must be
clearly recorded in details, and reported to after-sales or factory personnel. Do not forcibly start up
the unit unless permitted.
2. Maintenance

If the problem is serious, contact your local Midea office or your local representative for assistance.

Cleaning Heat Exchangers

Check the chiller tightness and whether there’s leak in the heat exchange tubes. It is necessary to do
nondestructive inspection for the principal weld (longitudinal and circumferential weld of
evaporator/condenser barrel) of the pressure vessel. Inspect and clean cooler tubes at the end of the
first operating season. Tube conditions in the exchanger will determine the scheduled frequency for
cleaning, and will indicate whether water treatment is adequate in the water circuit. Too much scale will
cause a big loss in capacity and efficiency.

Refer to the following pressure-temperature curve for the condition of heat exchangers:

High pressure-cooling water temperature (high pressure outside of 0.6~1.2MPa is abnormal)

Fig.26 High pressure at full load (standard unit)

Low pressure-chilled water temperature (low pressure outside of 0.14~0.37MPa is abnormal)

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Fig.27 Low pressure at full load (standard unit)

Cleaning work must be done a lot of scale is found. Physical and chemical cleaning can be chosen
according to the device you have. Generally, chemical cleaning is much easier to carry out. Methods are
as below. Arrange for a qualified water treatment specialist to develop and monitor a treatment program.
a) Cycle under normal temp. (A):
(Volume of condenser+ volume of pipes+ volume of container)×1/3
Note: concentration of detergent ——33%
b) Cycle under normal temp. (B):
(Volume of cooling tower flume + volume of condenser+ volume of pipes)×1/10
Note: concentration of detergent ——10%
Warning: When you do cleaning while the unit stops, the volume of the cooling tower flume can be 1/2
or 1/3 of rated value. The volume of cooling tower flume should keep at the rated value if cleaning is
performed when the unit is running. Midea assumes no responsibility for pressure vessel damage
resulting from untreated or improperly treated water.
Requirement for cleaning and maintenance
Water quality Scale Corrosion Remark
1 PH≤6 Acid water Hard Strong Generates insoluble CaSO4
Soft fluid deposit may be
2 PH≥8 Alkali water Soft —— caused by ions iron or
aluminum
Water with much Ca2+ and
3 Hard —— Easily generates hard scale.
Mg2+
Corrosive to copper and
4 Water with much Cl- Dirt Ultra-strong
iron.
Water with much SO42- and Generates hard CaSO4 and
5 Hard Strong
SiO22- CaSiO2
Large quantity, Generates deposits Fe(OH)3
6 Water with much Fe3+ Strong
hard and Fe2O3
Generates sulfide, ammonia
7 Odorous water Large quantity Ultra-strong and marsh gas, especially
H2S which corrodes copper.
Water with organic
8 Large quantity —— Easily generates scale
substances
Exhaust gas from auto, Strong Copper tubes of condenser
9
chemical factory, plating may be eroded and

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
factory, sewage plant, perforated.
ammonia refrigeration plant
and fiber factory
Dusty places such as plastic
10 Large quantity
plant
11 Sulfurous gas in the air Ultra-strong
Natural pollution such as
damp air near the coast or Strong
12 Large quantity
insects get into the cooling
tower.
Cycle under normal temp. (A):
(Capacity of condenser+ Capacity of pipe+ Capacity of container)×1/3(Thickness of detergent 33%)
Cycle under normal temp. (B):
(Capacity of flume of cooling tower+ Capacity of condenser+ Capacity of pipe)×1/10(Thickness of
detergent 10%)
When cleaning after the unit stops, the capacity of the cooling tower flume can be 1/2 or 1/3 of rated
value. When you do cleaning during running, the capacity should achieve the rated value.
Precautions on using detergent
When cleaning, wear rubber gloves and do not expose your skin or your clothes to detergent. If you
touch the detergent, wash it off with clean water.
The container for detergent should be made of plastic or glass and not lead. The used detergent should
be neutralized with lime or soda before draining
Detergent is harmful. Keep it away from children.
Turn on the unit after cleaning to ensure it is clean, clean it again.

c) Precautions for chemical cleaning

 When you clean, wear rubber gloves and do not expose your skin or your clothes to detergent. If
you touch the detergent, wash with it off clean water immediately.
 The container for detergent should be made of plastic or glass and not lead.
 Used detergent should be neutralized with lime or soda before draining.
 Detergent is harmful, keep it away from children.
 Turn on the unit to check the effect after cleaning. If necessary, clean it again.

Water Treatment
Before every start-up, clean and flush the cooling water circuit. Make sure the tower blow-down or
bleed-off is operating. Atmospheric air contains contaminants that increase the need for proper water
treatment. The use of untreated water can result in corrosion, erosion, sliming, scaling or algae formation.
Midea assumes no responsibility for the results of untreated or improperly treated water.
See appendix 1 for water quality requirements.

Refrigerant Circuit
 Leak testing

Units are factory-charged with refrigerant R134a (Refer to the Physical Data tables supplied in the IOM

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

manual book). Leak testing must be done under sufficient pressure. Charge enough refrigerant into the
system to build the pressure up to approximately 70 kPa and add sufficient dry nitrogen to bring the
pressure up to a maximum of 850 kPa. Leak test with an electronic leak detector. Water flow through the
vessels must be maintained anytime refrigerant is added or removed from the system. If any leaks are
found in welded or brazed joints, or it is necessary to replace a gasket, relieve the test pressure in the
system before proceeding. Brazing is required for copper joints. After leaks are repaired, the system
must be evacuated and dehydrated.

 Evacuation

After it has been determined that there are no refrigerant leaks, the system must be evacuated using a
vacuum pump with a capacity that will reduce the vacuum to at least 130Pa (=1mmHg). A mercury
manometer, or an electronic or other type of micron gauge, must be connected at the farthest point from
the vacuum pump. For readings below 130 Pa, an electronic gauge or other micron gauge must be used.
The triple evacuation method is recommended and is particularly helpful if the vacuum pump is unable to
obtain the desired 130Pa of vacuum. The system is first evacuated to approximately 660Pa (=5mmHg).
Dry nitrogen is then added to the system to bring the pressure up to zero.
Then the system is once again evacuated to approximately 230 Pa(=2mmHg). This is repeated three
times. The first pull down will remove about 90% of the non-condensable, the second about 90% of that
remaining from the first pull down and, after the third, only 0.2% non-condensable will remain.

 Check on the refrigerant charge

To verify that the unit is operating with the correct refrigerant charge, perform the following checks.
1. Run the unit at maximum operating load.
2. Check that the leaving chilled water temperature is between 6~8°C.
3. Check that the entering cooling water temperature is between 25 ~ 32°C.
4. Under the above conditions, verify the following items.
a) The sub-cooling is between 4 and 6°C
b) The difference between the leaving water temperature and evaporating temperature is 4~6°C.
c) The difference between condensing temperature and condenser leaving water temperature to is
0.2~3°C.
e) The evaporator refrigerant level slightly laps the last tubes row by checking the sight glass installed on
each evaporator for a visual inspection.
f) The condenser refrigerant level is included between the condensing and the sub-cooling sections by
checking the sight glass installed on each condenser for a visual inspection.
5. Verify the sight glass on the liquid piping is fully charged. If one of the above parameters exceeds the
limits, the unit may require an additional refrigerant charge.
Note: Refrigerant removal and draining must be performed by qualified personnel using the correct tools.
Inappropriate maintenance could lead to refrigerant or pressure loss. Do not discharge the refrigerant or
the lubricant oil into the environment. Always use a proper recovery system.
Refer to Physical Data tables supplied in the IOM manual book). Immediately in front of the orifice baffle
(see Fig.) is a factory-installed liquid line service angle valve. Each angle valve has a1 5/8-in. threaded
connection for charging liquid refrigerant. Connect the refrigerant drum to the gauge port on the liquid
line shutoff valve and purge the charging line between the refrigerant cylinder and the valve. Then open

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

the valve to the mid-position.

Turn on both the cooling tower water pump and chilled water pump and allow water to circulate through
the condenser and the chiller.
IMPORTANT: When adding refrigerant to the unit, circulate water through the evaporator continuously to
prevent freezing and possible damage to the evaporator. Do not overcharge, and never charge liquid
into the low-pressure side of system.

If the system is under a vacuum, stand the refrigerant drum with the connection up, and open the drum
and break the vacuum with refrigerant gas to a saturated pressure above freezing.

For system gas pressure that is higher than the equivalent of a freezing temperature, invert the charging
cylinder and elevate the drum above the condenser. With the drum in this position, if the valves are open,
and the water pumps operating, liquid refrigerant will flow into the condenser. Approximately 75% of the
total requirements estimated for the unit can be charged in this manner.

After 75% of the required charge has entered the condenser, reconnect the refrigerant drum and
charging line to the service valve on the bottom of the evaporator. Purge the connecting line, stand the
drum with the connection up, and place the service valve in the open position.

Before replacing the electronic expansion valve or thermal expansion valve of the system, pressure
sensor sampling shut valve, low pressure pipeline, etc. force the refrigerant in the liquid part of the
system.
The particular steps are: (Be careful when performing the following steps)`
a Close the dry filter angle valve of the system.
b Start the unit, and immediately stop when the gas in the system is below 0.5 bar.
c Close the liquid/air valve of the compressor.
d Discharge the residual refrigerant in the gas system.
e Carry on replacing parts in the system.
f After the replacement, extract vacuum in the gas part.
g After vacuum extraction, keep the negative voltage until the resumed vacuum meets requirements.
h Open the angle valve of liquid system and compressor liquid/air stop valve to ensure the loop of the
entire system is unobstructed.
i Add proper amount of refrigerant, generally 5~10k.

Compressor Oil System

Each compressor/circuit has its own oil system that includes an oil filter, oil solenoid valve, Venturi tube,
oil separator heater, and an oil shut-off valve. A typical oil system is shown in Fig. 34. See Table 33 for oil
charge Quantities.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

Fig. 34.
Each screw compressor is connected to a tank (oil separator) that separates and collects the oil from the
discharge gas. The discharge gas pressure pushes the oil back into the compressor for compressor seal
and lubrication of all moving parts. During compression, the oil joints the discharge gas before it is
conveyed again into the oil separator and restarts the cycle. The oil flow is enabled by the pressure
difference created between the condenser and the evaporator. This difference depends on the cooling
water and evaporator water temperatures. During startup, it is vital to quickly establish the appropriate
temperature difference, by checking the right cooling water temperature. The head of the cooling water
pump at zero flow rate should not exceed the maximum working pressure of condenser and plant water
side.

Oil recovery system

Each compressor includes a system to recover the oil accumulated inside the evaporator during normal
operations. This system consists of a jet pump that continuously collects all the oil from the evaporator,
preventing accumulation due to the low speed of the refrigerant gas. The high-pressure discharge gas
feeds the jet pump that creates a depression, which allows the suction of the oil refrigerant mixture from
the evaporator into the compressor to re-establish the oil level inside the lubrication system. On the oil
recovery piping, a sight glass allows users to check the oil-gas mixture flow to the compressor. If flow is
insufficient or the unit stops for s “Low Oil Level” alarm, verify the correct operation of the corresponding
circuit.

Oil Charging/Low Oil Recharging

 Precautions for changing oil

1. Use only the permitted oil and do not mix different brands of oil together. Different kinds of refrigerant
should match different kinds of oil, note that some synthetic oil is incompatible with mineral oil.
2. When using the synthetic oil in the chiller system, do not expose the oil to the atmosphere for a long
time, it is also necessary to vacuum the system completely when installing the compressor.
3. To ensure no moisture collects inside the system, clean the system by charging it with dry Nitrogen
and then vacuum the system repeatedly for as long as possible.
4. Change with new oil especially after the motor burns out; the acidity debris still remains inside the
system so cleaning must be done to overhaul the system. Check the oil acidity after 72 hours of
operation and then change it again until the oil acidity is in the standard range.
5. Contact the local distributor/agent concerning the oil to use.

 Oil change

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

1. Change oil periodically: Check the lubrication oil after every 10,000 hours of continuous running.
When the compressor first runs, change the oil and clean the oil filter after running for 2,000 hours.
Check whether the system is clean and change the oil every 20,000 hours or after 3 years of continuous
running when the system has been running normally.
2. Avoid debris or swarf clogging oil filter as this may cause the bearings to fail. The oil pressure
differential switch will trip when the oil pressure differential reaches the critical point (default: 150 kPa).
The compressor will automatically shut down to prevent the bearings from being damaged by a lack of
lubricating oil.

Caution

Compressor oil is pressurized. Take safety precautions when relieving pressure.

 Oil Filter Maintenance

Each compressor has its own internal oil filter and each circuit also has an in-line external filter located
under the external oil separator. The internal oil filter pressure drop should be checked and filter
changed (if necessary) after the initial 2,000 hours of compressor operation. Oil line pressure loss is
monitored by the control and reported for each compressor as the oil filter pressure drop.
Normally the pressure differential (discharge pressure minus oil pressure) is typically less than 150kPa
for a system with clean internal and external filters. To determine the oil pressure drop due to the oil lines
and external filter only, connect a gauge to the oil pressure bleed port. Compare this value to the
discharge pressure read at the touch screen. If this value exceeds 150 kPa, replace the external filter.

Moisture-Liquid Indicator

Clear flow of liquid refrigerant indicates sufficient charge in the system. Note, however, that bubbles in
the sight glass do not necessarily indicate insufficient charge. Moisture in the system is measured in
parts per million (ppm), changes of color of indicator are:
Green—moisture is below 80 ppm;
Yellow-green (chartreuse)—80 to 225 ppm (caution);
Yellow (wet)—above 225 ppm.
Change filter drier at the first sign of moisture in the system.
IMPORTANT: The unit must be in operation for at least 12 hours before the moisture indicator can give
an accurate reading. With the unit running, the indicating element must be in contact with liquid
refrigerant to give a true reading.

Relief Devices
 Pressure relief valves

Relief valves are installed on the evaporator, condenser and oil separator. These valves are designed to
provide relief if an abnormal pressure condition arises. Relief valves on the condenser start at 2.07MPa.
These valves should not be capped. If a valve relieves, it should be replaced. If it is not replaced, it may
relieve at a lower pressure compared to the set point, or leak due to trapped dirt from the system which
may prevent resealing.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

VIII.Troubleshooting

1. Protection items

Midea screw chiller has many protection measures and devices. There’re many features to aid in
troubleshooting. By using the alarm information, DI/O, AI/O and operating conditions of the chiller during
chiller operation, it’s convenient to find the possible problem. Verify that the chiller is properly configured,
including options and/or accessories.
Protection items:
Protection Purpose
High pressure / low pressure Ensures the compressor runs in a normal range and
protection of compressor guarantees its service life.
Converse phase, lack of phase Protects the compressor from damage because of a
protection converse phase or lack of phase of power.
Protects key components such as the evaporator,
Anti-freezing protection during
condenser and water pipe from damage because of
refrigeration
the expansion caused by water freeing into ice
Protects the compressor from burning due to overload
Overload protection
running.
Protects the compressor from burning due to over
Over current protection on the compressor
current running under bad conditions.
Enables the compressor to run safely under permitted
Internal protection
conditions.
Protects the compressor from burning because of
Anti-overheating protection of the system
running a lack of refrigerant or lubricating oil.
Protects the compressor and the water pump motor
Water flow switch protection from burning because there is lack of cooling water or
chilled water.
Ensures the data from the sensor is correct to prevent
Protection of the sensor fault
the system from wrong action.
Oil level and oil pressure difference protection Ensures the compressor can run normally.
Enables the compressor to run safely under permitted
High discharge temperature protection
conditions.

 Phase reversal/phase loss (phase protection)

Power supply A/B/C should exist simultaneously and differ from each other by a 120°phase angle.
If not, Phase reversal or phase loss fault will occur and be displayed on screen. Before the unit
starts when phase reversal or phase loss fault occurs, the chiller won’t start; when Phase reversal or
phase loss fault occurs during chiller operations, the chiller will stop according to the protective stop
program. Both compressors are shut down and water pumps and cooling tower fans stop in
accordance with normal shutdown procedures. When the fault record is cleared and both
temperature and time conditions are satisfied, the chiller can restart.

 Water flow failure (both chilled water and cooling water)

PCB controller begins to detect chilled/cooling a water flow switch after the water pumps get
energized 180s. The switch will disconnect if water flow is less than a set point and the water flow
loss signal will occur if it lasts for more than 5s. During chiller operations (including dual heads unit),
any flow switch that disconnects for 5s continuously, Unit stops according to protective stop
program.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

If chilled water flow fails, chilled water pump stops after 30s delay; cooling water pump and cooling
tower stops after 60s delay.

If cooling water flow fails, the cooling water pump and cooling tower stops after a 60s delay; the
chilled water pump stops after 600s delay.

Note: The fault can be cleared after power is re-energized and it needs to be confirmed manually,
then when both temperature and time condition gets satisfied, the chiller can restart.

 Temperature sensor failure

Entering the chilled water temperature sensor short circuit/open circuit will display the entering
chilled water temperature fault, and the chiller will stop according to the abnormal shutdown
program. After the sensor resets, faults on the screen must be cleared manually; when both
temperature and time conditions are satisfied, the chiller can restart.

Leaving chilled water temperature sensor short circuit/open circuit will display the leaving chilled
water temperature fault, and chiller will stop according to the abnormal shutdown program. After the
sensor resets, faults on the screen must be cleared manually; when both temperature and time
conditions are satisfied, the chiller can restart.

Entering cooling water temperature sensor short circuit/open circuit will display the entering cooling
water temperature fault, and chiller will stop according to abnormal shutdown program. After the
sensor resets, faults on the screen must be cleared manually; when both temperature and time
conditions are satisfied, the chiller can restart.

Leaving cooling water temperature sensor short circuit/open circuit, display leaving cooling water
temperature fault and chiller stops according to abnormal shutdown program. After the sensor reset,
fault on screen must be cleared manually; when both temperature and time condition gets satisfied,
the chiller can restart.

Discharging the temperature sensor short circuit/open circuit will display the discharge temperature
fault, and chiller will stop according to abnormal shutdown program. After the sensor resets, faults
on the screen must be cleared manually; when both temperature and time conditions are satisfied,
the chiller can restart.

Oil temperature sensor short circuit/open circuit will display oil temperature fault, and chiller will stop
according to abnormal shutdown program. After the sensor resets, faults on screen must be cleared
manually; when both temperature and time conditions are satisfied, the chiller can restart.

 Over/under voltage

When power supply voltage is less than 90% or more than 110%, the corresponding alarm over
voltage or under voltage will occur. The chiller will stop immediately according to the abnormal
shutdown program. Faults on screen must be cleared manually; when both temperature and time
conditions are satisfied, the chiller can restart.

 High/low pressure protection

As alarm as soon as the high-pressure switch trips and will stop the chiller immediately according to
abnormal shutdown program. This is one kind of NC switch that needs to be manually reset via the

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

red reset button when a fault happens. Faults on screen must be confirmed and cleared manually;
when both temperature and time conditions are satisfied, the chiller can restart.

When suction pressure is lower than the protective low pressure set point (effective for a time delay),
the system will stop according to the abnormal shutdown program. After the switch reset, faults on
screen must be confirmed and cleared manually. When both temperature and time conditions are
satisfied, the chiller can restart.

 Anti-freezing protection

When the leaving chilled water temperature becomes lower than 4°C, perform low water
temperature protection and stop the unit according to abnormal protective shutdown program.
Cooling water pump/chilled water pump/cooling tower fan will keep on running. When leaving chilled
water temperature exceeds 10°C, the unit will reset. When both the temperature and time conditions
are satisfied, the chiller can restart.

 Mechanical antifreeze switch

The switch will trip when leaving chilled water temperature is ≤ 3°C and chiller will stop according
to abnormal protective shutdown program. Reset at 10°C and fault on screen must be cleared
manually; when both temperature and time conditions are satisfied, the chiller can restart.

 Compressor motor protection

Alarm when compressor protection module trips. Execute the abnormal protective shutdown
program immediately. Faults on screen must be confirmed and cleared manually; when both
temperature and time conditions are satisfied, the chiller can restart.

 Compressor overload protection

Thermal overload relay trips when heat storage reaches the tripping point. Faulted compressor will
stop immediately to abnormal protective shutdown program and other normal system will keep on
running. After the switch reset, fault on screen must be confirmed and cleared manually; when both
temperature and time conditions are satisfied, the chiller can restart.

 Oil level protection

When the unit is running, if the oil level stays lower than the set point for 30s, the unit will stop
immediately via the protective shutdown program. After resetting the switch, faults on screen must
be confirmed and cleared manually; when both the temperature and time conditions are satisfied,
the chiller can restart

 High cooling leaving water temperature protection

When the leaving cooling water temp. is higher than 45°C when the unit is operating, the chiller will
stop immediately via the protective shutdown program. Resetting at 38°C needs to be confirmed
and cleared manually; when both temperature and time conditions are satisfied, the chiller can
restart.

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

2. Troubleshooting

No. Alarm Trouble Description Action Reset Type Possible Cause

Compressor cannot work. The

Power Failure Phase sequence relay Reset it manually on the touch The power quality is poor due to phase inversion,
1 compressor stop running
Protection switches OFF screen lacking phase or phase imbalance.
immediately

Power off the unit and 1 The power of motor is poor due to phase
Compressor cannot work. The
Compressor Motor Compressor motor module re-power up the electricity, inversion, lacking phase, over-voltage,
2 compressor stop running
Protection switches OFF reset manually on the touch under-voltage
immediately
screen 2. The motor overheats

Excessive current and 1,The compressor continues running in bad

Compressor Overload The compressor will stop Reset it manually on the touch
3 cumulated energy cause the conditions like over-current.
Protection running immediately screen
thermal relay to trip 2,The setting value of thermal relay is too low

1.The suction of the contactor is abnormal when

The coil of the contactor
The compressor will stop Reset manually on the touch Y type switches to △ type
4 Contactor Protection does not perform suction
running immediately screen 2.The vibration during operations cause the
normally
contact to loosen

1,The chilled water flow falls sharply, the water

The compressor will stop Reset it manually on the touch temperature too low
5 Anti-freezing Protection Anti-freezing switch OFF
running immediately screen 2,Anti-freezing switch is damaged or wiring
connection is abnormal

1.The compressor cannot work.

The compressor stops running
immediately ；
2. Chilled water flow failure: The
chilled water pump stops
Power off the unit and 1,The water pump fails and the water flow is too
The water flow switch working after 30s delay; Cooling re-power up the electricity, small
6 Water Flow Fault disconnects for more than water pump and cooling tower reset manually on the touch 2,Water flow switch fails or the wiring connection
5s shut down after 120s delay
screen is incorrect
3.Cooling water flow failure: The
cooling water pump and cooling
tower shut down after 30s delay;
chilled water pump stops
working after 180s delay.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

1,The cooling water quality is poor and the heat

exchange of condenser is abnormal
2,There is too much non-condensable gas in the
The compressor for protection Press the red reset button, and system
High-pressure
7 High pressure switch OFF stops running. Other reset manually on the touch 3,The cooling water flow is too small or the
Protection
compressors continue running screen temperature is too high
4,Too much refrigerant
5,Wrong refrigerant type
6,The discharge shutoff valve does not fully open

1,The refrigerant is not enough

2,EXV fails and cannot work normally
1.The compressor for protection 3,The delay time of low pressure switch alarm is
stops running immediately. too short
Other compressors continue 4,There is plugging in the filter
The low pressure switch
Low-pressure running. Reset it manually on the touch 5,Some water enters the refrigerant system in
8 disconnects for more than 3s
Protection 2.If protection occurs before the screen evaporator
(can be set)
unit starts to work, all 6,Poor system matching(the evaporator is too
compressors in the unit cannot small or the compressor is too large)
run. 7,There is too much oil in the system
8,Chilled water flow is too small or the
temperature is too low

1, The oil temperature is too low when starting so

the pressure difference is too low and return oil is
abnormal
The compressor for protection 2,Return oil solenoid valve fails or the filter is
The oil level switch
Low Oil Level stops running immediately. Reset it manually on the touch blocked
9 disconnects for more than
Protection Other compressors continue screen 3,Different oil types have been mixed so the
60s (can be set)
running return oil system is abnormal
4,Oil level switch failure or wrong wiring
connection
5. The oil volume is not enough

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

1,The superheat is too high( the refrigerant is not

enough, EXV fails)
The protection is relieved once 2,The discharge pressure is too high
The compressor discharge The compressor for protection the discharge temperature is 3,The oil level is too low and the oil volume in the
High Discharge
10 temperature is greater than stop running immediately; Other lower than the setting value system too small
Temperature Protection
the setting value compressors continue running and reset manually on the 4,Running in poor conditions, the compression
touch screen ratio is too high , and there is no auxiliary cooling
5,Beartings or screws are damaged
6,Poor system matching

No display. Reset
Low Chilled Leaving The chilled water 1,The chilled water flow is not enough
The compressor will stop automatically when the water
11 Water Temperature temperature is lower than the 2,The unit continues running under load
running immediately temperature is greater than the
Protection setting value condition
setting value
No display. Reset
High Cooling Entering The cooling water
The compressor will stop automatically when the water 1,The cooling tower can not work normally
12 Water Temperature temperature is greater than
running immediately temperature is greater than the 2,The cooling water flow not enough
Protection the setting value
setting value

Chilled entering water 1.The temperature sensor fails

Chilled Entering Water
temperature sensor is The compressor will stop Reset it manually on the touch 2.The wiring connection is not correct
13 Temperature Sensor
abnormal (open circuit or running immediately screen 3.The wiring line is abnormal, or has been
Failure
short circuit) damaged

Cooling leaving water 1.The temperature sensor fails

Cooling Leaving Water
temperature sensor is The compressor will stop Reset it manually on the touch 2.The wiring connection is not correct
14 Temperature Sensor
abnormal (open circuit or running immediately screen 3.The wiring line is abnormal, or has been
Failure
short circuit) damaged

Cooling entering water 1.The temperature sensor failure

Cooling Entering Water
temperature sensor is The compressor will stop Reset it manually on the touch 2.The wiring connection is not correct
15 Temperature Sensor
abnormal (open circuit or running immediately screen 3.The wiring line is abnormal, has been
Failure
short circuit) damaged

Chilled leaving water 1.The temperature sensor fails

Chilled Leaving Water
temperature sensor is The compressor will stop Reset it manually on the touch 2.The wiring connection is not correct
16 Temperature Sensor
abnormal (open circuit or running immediately screen 3.The wiring line is abnormal, or has been
Failure
short circuit) damaged

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

IX.Appendix

1. Temperature-Resistance specifications sheet for the discharge temperature

sensor
NTC sensor characteristic sheet Unit：Temp:℃--K.Ratio:KΩ，5K@90℃
Temp. Ratio Temp. Ratio Temp. Ratio Temp. Ratio
-20 542.7 20 68.66 60 13.59 100 3.702
-19 511.9 21 65.62 61 13.11 101 3.595
-18 483 22 62.73 62 12.65 102 3.492
-17 455.9 23 59.98 63 12.21 103 3.392
-16 430.5 24 57.37 64 11.79 104 3.296
-15 406.7 25 54.89 65 11.38 105 3.203
-14 384.3 26 52.53 66 10.99 106 3.113
-13 363.3 27 50.28 67 10.61 107 3.025
-12 343.6 28 48.14 68 10.25 108 2.941
-11 325.1 29 46.11 69 9.902 109 2.86
-10 307.7 30 44.17 70 9.569 110 2.781
-9 291.3 31 42.33 71 9.248 111 2.704
-8 275.9 32 40.57 72 8.94 112 2.63
-7 261.4 33 38.89 73 8.643 113 2.559
-6 247.8 34 37.3 74 8.358 114 2.489
-5 234.9 35 35.78 75 8.084 115 2.422
-4 222.8 36 34.32 76 7.82 116 2.357
-3 211.4 37 32.94 77 7.566 117 2.294
-2 200.7 38 31.62 78 7.321 118 2.233
-1 190.5 39 30.36 79 7.086 119 2.174
0 180.9 40 29.15 80 6.859 120 2.117
1 171.9 41 28 81 6.641 121 2.061
2 163.3 42 26.9 82 6.43 122 2.007
3 155.2 43 25.86 83 6.228 123 1.955
4 147.6 44 24.85 84 6.033 124 1.905
5 140.4 45 23.89 85 5.844 125 1.856
6 133.5 46 22.89 86 5.663 126 1.808
7 127.1 47 22.1 87 5.488 127 1.762
8 121 48 21.26 88 5.32 128 1.717
9 115.2 49 20.46 89 5.157 129 1.674
10 109.8 50 19.69 90 5 130 1.632
11 104.6 51 18.96 91 4.849
12 99.69 52 18.26 92 4.703
13 95.05 53 17.58 93 4.562
14 90.66 54 16.94 94 4.426
15 86.49 55 16.32 95 4.294
16 82.54 56 15.73 96 4.167
17 78.79 57 15.16 97 4.045
18 75.24 58 14.62 98 3.927
19 71.86 59 14.09 99 3.812

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1

2. Temperature-Resistance specifications sheet for the water temperature sensor,

ambient temperature sensor, oil temperature sensor.

NTC sensor specifications sheet Unit：Temp:℃--K . Ratio:KΩ，10K@25℃

Temp. Ratio Temp. Ratio Temp. Ratio Temp. Ratio
-20 103.882 20 12.598 60 2.383 100 0.623
-19 97.868 21 12.023 61 2.296 101 0.605
-18 92.246 22 11.478 62 2.213 102 0.587
-17 86.987 23 10.961 63 2.134 103 0.570
-16 82.065 24 10.470 64 2.057 104 0.553
-15 77.457 25 10.005 65 1.984 105 0.537
-14 73.106 26 9.564 66 1.913 106 0.521
-13 69.031 27 9.146 67 1.846 107 0.506
-12 65.211 28 8.749 68 1.781 108 0.492
-11 61.629 29 8.372 69 1.718 109 0.478
-10 58.270 30 8.013 70 1.659 110 0.464
-9 55.099 31 7.669 71 1.601
-8 52.123 32 7.342 72 1.546
-7 49.328 33 7.031 73 1.492
-6 46.703 34 6.735 74 1.441
-5 44.235 35 6.453 75 1.392
-4 41.896 36 6.183 76 1.346
-3 39.697 37 5.927 77 1.301
-2 37.628 38 5.683 78 1.258
-1 35.682 39 5.450 79 1.217
0 33.849 40 5.228 80 1.177
1 32.115 41 5.016 81 1.139
2 30.483 42 4.813 82 1.101
3 28.944 43 4.620 83 1.066
4 27.494 44 4.436 84 1.031
5 26.126 45 4.261 85 0.998
6 24.833 46 4.092 86 0.966
7 23.613 47 3.932 87 0.935
8 22.461 48 3.778 88 0.906
9 21.373 49 3.632 89 0.877
10 20.344 50 3.492 90 0.850
11 19.365 51 3.357 91 0.823
12 18.438 52 3.229 92 0.798
13 17.563 53 3.106 93 0.773
14 16.734 54 2.989 94 0.749
15 15.950 55 2.876 95 0.727
16 15.205 56 2.769 96 0.704
17 14.500 57 2.666 97 0.683
18 13.831 58 2.568 98 0.662
19 13.198 59 2.473 99 0.643

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)

3. Temperature-Resistance specifications sheet for the EXV temp. sensor.

NTC Sensor specifications sheet Unit：Temp:℃--K. Ratio:KΩ10K@25℃

Temp. Ratio Temp. Ratio Temp. Ratio Temp. Ratio
-20 67.74 20 12.09 60 3.02 100 0.97
-19 64.54 21 11.63 61 2.92 101 0.94
-18 61.52 22 11.20 62 2.83 102 0.92
-17 58.66 23 10.78 63 2.75 103 0.90
-16 55.95 24 10.38 64 2.66 104 0.87
-15 53.39 25 10.00 65 2.58 105 0.85
-14 50.96 26 9.63 66 2.51 106 0.83
-13 48.65 27 9.28 67 2.43 107 0.81
-12 46.48 28 8.94 68 2.36 108 0.79
-11 44.41 29 8.62 69 2.29 109 0.77
-10 42.25 30 8.31 70 2.22 110 0.75
-9 40.56 31 8.01 71 2.16
-8 38.76 32 7.72 72 2.10
-7 37.05 33 7.45 73 2.04
-6 35.43 34 7.19 74 1.98
-5 33.89 35 6.94 75 1.92
-4 32.43 36 6.69 76 1.87
-3 31.04 37 6.46 77 1.81
-2 29.72 38 6.24 78 1.76
-1 28.47 39 6.03 79 1.71
0 27.28 40 5.82 80 1.66
1 67.74 41 5.63 81 1.62
2 26.13 42 5.43 82 1.57
3 25.03 43 5.25 83 1.53
4 23.99 44 5.08 84 1.49
5 22.99 45 4.91 85 1.45
6 22.05 46 4.74 86 1.41
7 21.15 47 4.59 87 1.37
8 20.29 48 4.44 88 1.33
9 19.40 49 4.30 89 1.30
10 18.70 50 4.16 90 1.26
11 17.96 51 4.02 91 1.23
12 17.24 52 3.90 92 1.20
13 16.55 53 3.77 93 1.16
14 15.90 54 3.65 94 1.13
15 15.28 55 3.53 95 1.10
16 14.68 56 3.42 96 1.08
17 14.12 57 3.31 97 1.05
18 13.57 58 3.21 98 1.02
19 13.06 59 3.11 99 0.99

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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
Temperature-Resistance specifications sheet for the EXV temp. sensor.
NTC Sensor specifications sheet Unit：Temp:℃--K. Ratio: KΩ 50K@25℃
Temp. Ratio Temp. Ratio Temp. Ratio Temp. Ratio
-40 1630,77
-35 1178,11
-30 860,97
-25 636,08
-20 474,78
-15 357,83
-10 272,18
-5 208,83
0 161,56
5 125,97
10 98,96
15 78,29
20 62,37
25 50,00
30 40,34
35 32,73
40 26,71
45 21,92
50 18,08
55 14,99
60 12,48
65 10,44
70 8,78
75 7,41
80 6,28
85 5,34
90 4,56
95 3,91
100 3,37
105 2,91
110 2,52
115 2,19
120 1,91
125 1,67
130 1,46
135 1,28
140 1,13
145 1,00
150 0,89

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)
4. Sample selection sheet

Part 1 — General

1.01 SYSTEM DESCRIPTION

Microprocessor-controlled liquid chiller shall use a semi-hermetic Screw compressor using refrigerant
HFC-134a.

1.02 QUALITY ASSURANCE

A. Chiller performance shall be rated in accordance with AHRI Standard 550/590, latest edition.

B. Each compressor assembly shall undergo a mechanical run-in test to verify vibration levels, oil pressures,
and temperatures are within acceptable limits. Each compressor assembly shall be proof tested at a
minimum 498 psig (3,432 kPa).

C. Entire chiller assembly shall be proof tested at 181 psig (1,250 kPa) and leak tested at 167 psig (1,150
kPa) with a tracer gas mixture on the refrigerant side. The water side of each heat exchanger shall be
hydrostatically tested at 1.25 times rated working pressure.

D. Prior to shipment, the chiller automated controls test shall be executed to check for proper wiring and
ensure correct controls operation.

E. Unit-mounted compressor motor starter or VFD (variable frequency drive) shall be factory wired and
tested together to verify proper operation prior to shipment.
.
F. Chiller shall be manufactured at an ISO (International Organization for Standardization) 9001 facility.

1.03 DELIVERY, STORAGE AND HANDLING

A. Unit shall be stored and handled in accordance with manufacturer's instructions.
B. Unit shall be shipped with all refrigerant piping and control wiring factory installed.
C. Unit shall be shipped charged with oil and full charge of refrigerant HFC-134a or a nitrogen holding
charge as specified on the equipment schedule.
D. Unit shall be shipped with firmly attached labels that indicate name of manufacturer, chiller model number,
chiller serial number, and refrigerant used.
E. Unit shall be sufficiently protected from the factory against sea water corrosion to be suitable for
sea-shipment.

1.04 WARRANTY
Warranty shall include parts and labor for one year after start-up or 18 months from shipment, whichever
occurs first.

Part 2 — Products

2.01 EQUIPMENT
A. General:
Factory assembled, single piece, liquid chiller shall consist of compressor, motor, starter or variable
frequency drive, lubrication system, cooler, condenser, initial oil and refrigerant operating charges,
microprocessor control system, and documentation required prior to start-up.
B. Compressor:
1. One high performance screw compressor.

2. Compressor, motor, and transmission shall be semi-hermetically sealed into a common assembly
and arranged for easy field servicing.

3. All pressure transducers shall have quick-disconnects to allow replacement of the sensor without
replacement of the entire sensor wire. Pressure transducers and temperature sensors shall be
serviceable without the need for refrigerant charge removal or isolation.
4. Screw compressors shall be provided with a factory-installed lubrication system to deliver oil
under pressure to bearings and transmission.

Included in the system shall be:

a. Hermetic driven oil pump with factory-installed motor contactor with overload protection.
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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
b. Refrigerant-cooled oil cooler. Water-cooled oil coolers are not acceptable.

c. Oil pressure regulator.

d. Oil filter with isolation valves to allow filter change without removal of refrigerant charge.
e. Oil sump heater controlled from unit microprocessor.
f. Oil reservoir temperature sensor with main control center digital readout.
g. All wiring to oil pump, oil heater, and controls shall be prewired in the factory.
h. Compressor shall be fully field-serviceable.
C. Motor:
1. Compressor motor shall be of the hermetic, refrigerant cooled, squirrel cage, induction type
suitable for voltage shown on the equipment schedule.

2. Motors shall be suitable for operation in a refrigerant atmosphere and shall be cooled by
atomized refrigerant in contact with the motor windings.
.
3. Full load operation of the motor shall not exceed nameplate rating.

D. Unit-Mounted Wye-Delta Starter

.
The compressor motor starter shall be factory mounted, wired and tested prior to shipment by the
chiller manufacturer.
Customer electrical connection for compressor motor power shall be limited to main power leads
to the starter, and wiring water pumps and tower fans to the chiller control circuit.

a. NEMA 1 enclosure with integral fan cooling and lockable hinged doors.
b. Main power disconnect (non-fused type).
c. Capability to start and stop chiller, pumps and tower fans.

d. 1 kVA control/oil heater transformer.

e. The following are standard features:

1) Phase loss
2) Phase reversal
3) Phase imbalance
4) 3-phase ground fault
5) Phase to phase and phase to ground
6) Current overload
7) Current flow while stopped
8) 3-phase under/over voltage
9) 3-phase digital ammeter/voltmeter
10) Frequency

E. Unit-Mounted Variable Frequency Drive (VFD)

a. Design:
1) VFD shall be air-cooled, microprocessor-based, pulse width modulated design.

2) Output power devices shall be insulated gate bipolar transistors (IGBTs).

3) Converter section with full-wave fixed diode bridge rectifier shall convert incoming fixed
voltage/frequency to fixed DC voltage.

4) DC link shall filter and smooth the converted DC voltage.

5) Transistorized inverter and control regulator shall convert fixed DC voltage to a square
waveform.

b. Enclosure:
1) Pre-painted, unit mounted NEMA 1 cabinet shall include hinged, lockable doors and
removable lifting lugs.

2) Provisions to padlock main disconnect handle in the “Off” positions shall be provided.

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)
c. VFD Rating:
1) Drive shall be suitable for nameplate voltage ±10%.
2) Drive shall be suitable for continuous operation at 100% of nameplate amps and 150% of
nameplate amps for 3 seconds.
3) Drive shall comply with applicable UL, CE, and NEMA standards.
4) Drive shall be suitable for operation in ambient temperatures between 4.4 and 40 C, 95%
humidity (non-condensing) for altitudes up to 1,000 m above sea level.

d. User Interface:
Displays shall provide interface for display of VFD and chiller parameters. Viewable
parameters include:
1) Operating, configuration and fault messages

2) Frequency in Hz
3) Load side voltage and current (at the VFD)
4) kW (on the VFD interface)

e. VFD Performance:
1) VFD full load efficiency shall meet or exceed 98% at 100% VFD Rated Ampacity.
2) Displacement Input Power Factor shall meet or exceed 94% soft start, linear acceleration,
coast to stop.

3) Base motor frequency shall be either 50 or 60 Hz. Adjustable frequency range from 30 to
50 Hz or 30 to 60 Hz.

f. VFD Electrical Service (single point power):

1) VFD shall have input circuit breaker with minimum 50,000 amp interrupt capacity.

2) VFD shall have standard 1 kVA control power transformer with circuit breaker provides
power for oil heater, VFD controls and chiller controls.
3) Input power shall be 380 or 460 VAC, ±10%, 3 Phase, 50/60Hz ± 1Hz.

g. Discrete Outputs: 220-V discrete contact outputs shall be provided for:

1) Circuit breaker shunt trip

2) Chilled water pump

3) Condenser water pump

4) Alarm status.

5) Cooling tower

h. Protection (the following shall be supplied):

1) Under-voltage
2) Over voltage
3) Phase loss
4) Phase reversal
5) Ground fault
6) Phase unbalance protection
7) Programmable auto re-start after loss of power
8) Motor overload protection (NEMA Class 10)
9) Motor over temperature protection

i. VFD Testing:
VFD shall be factory mounted, wired and tested on the chiller prior to shipment.

F. Cooler and Condenser:

1. Cooler shall be of shell and tube type construction. Units shall be fabricated with
high-performance tubing, minimum 10 mm steel shell and tube sheets with fabricated steel
waterboxes.
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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
a. Waterbox shall have standard victaulic grooves.
Unit manufacturer shall insulate the cooler shell, compressor suction elbow, motor shell and
motor cooling lines. Insulation shall be 3/4 in. (19 mm) thick with a thermal conductivity not
2
exceeding 0.28 (Btu in.)/hr ft F [(0.0404 • W)/(m • °C)]
2. Condenser shall be of shell and tube type construction. Units shall be fabricated with
high-performance tubing, minimum 10 mm steel shell and tube sheets with fabricated steel
waterboxes.
a.Waterbox shall have standard victaulic grooves.
3. Waterboxes shall have vents, drains, and covers to permit tube cleaning.
A thermistor type temperature sensor with quick connects shall be factory installed in each water
nozzle.
4. Tubes shall be individually replaceable from either end of the heat exchanger without affecting
the strength and durability of the tube sheet and without causing leakage in adjacent tubes.
5. Tubing shall be copper, high-efficiency type, with integral internal and external enhancement
unless otherwise noted. Tubes shall be nominal 3/4-in. or 1 in.
6. Cooler shall be designed to prevent liquid refrigerant from entering the compressor.
7. The condenser shell shall include a flash sub-cooler which cools the condensed liquid refrigerant
to a reduced temperature, thereby increasing the refrigeration cycle efficiency.
8. A reseating type pressure relief valve shall be installed on each heat exchanger.

G. Refrigerant Flow Control:

1. To maintain optimal part load efficiency, the refrigerant expansion device to the cooler shall use a
EXV

H. Controls, Safeties, and Diagnostics:

Controls:
a. The chiller shall be provided with a factory installed and wired microprocessor control center.
The microprocessor can be configured for either English or SI units.

b. All chiller and starter monitoring shall be displayed at the chiller control panel.

c. The controls shall make use of non-volatile memory.

d. The chiller control system shall have the ability to interface and communicate directly to the
building control system.

e. The default standard display screen shall simultaneously indicate the following minimum
information:

1) date and time of day

2) 24-character primary system status message
3) 24-character secondary status message
4) chiller operating hours
5) entering chilled water temperature
6) leaving chilled water temperature
7) evaporator refrigerant temperature
8) entering condenser water temperature
9) leaving condenser water temperature
10) condenser refrigerant temperature
11) oil supply pressure
12) oil sump temperature
13) percent motor rated load amps (RLA)

f. In addition to the default screen, status screens shall be accessible to view the status of
every point monitored by the control center including:
1) evaporator pressure
2) condenser pressure
3) bearing oil supply temperature
4) compressor discharge temperature
5) motor winding temperature
6) number of compressor starts

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MCAC-CTSM-2018-1 Flooded type water cooled screw chiller (MIC)
7) control point settings
8) discrete output status of various devices
9) compressor motor starter status
10) optional spare input channels
11) current and voltage for each phase
12) frequency

g. Schedule Function:
The chiller controls shall be configurable for manual or automatic start-up and shutdown. In
automatic operation mode, the controls shall be capable of automatically starting and
stopping the chiller according to a stored user programmable occupancy schedule. The
controls shall include built-in provisions for accepting:
1) A minimum of two 365-day occupancy schedules.
2) Minimum of 8 separate occupied/ unoccupied periods per day.
3) Daylight savings start/end.
4) Minimum of 18 user-defined holidays.
5) Means of configuring an occupancy timed override.
6) Chiller start-up and shutdown via remote contact closure.

h. Service Function:
The controls shall provide a password protected service function which allows authorized
individuals to view an alarm history file which shall contain the last 25 alarm/alert messages
with time and date stamp.

i. Network Window Function:

Each chiller control panel shall be capable of viewing multiple point values and statuses from
other like controllers connected on a common network, including controller maintenance
data.

j. Chilled Water Reset:

The control center shall allow reset of the chilled water temperature set point based on any
one of the following criteria:
1) Chilled water reset based on an external 4 to 20 mA signal.
2) Chilled water reset based on a remote temperature sensor (such as outdoor air).
3) Chilled water reset based on water temperature rise across the evaporator.

k. Demand Limit:
The control center shall limit amp draw of the compressor to the rated load amps or to a lower
value based on one of the following criteria:
1) Demand limit based on a user input ranging from 40% to 100% of compressor rated load
amps.

2) Demand limit based on external 4 to 20 mA signal.

l. Controlled Compressor Shutdown:

The controls shall be capable of being configured to soft stop the compressor.

2. Safeties:
a. Unit shall automatically shut down when any of the following conditions occur: (Each of these
protective limits shall require manual reset and cause an alarm message to be displayed on
the control panel screen, informing the operator of the shutdown cause.)
1) motor overcurrent
2) over voltage
3) under voltage
4) single cycle dropout*
5) bearing oil high temperature
6) low evaporator refrigerant temperature
7) high condenser pressure
8) high motor temperature
9) high compressor discharge temperature
10) low oil pressure
11) prolonged surge
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Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
12) loss of cooler water flow
13) loss of condenser water flow
14) starter fault

b. The control system shall detect conditions that approach protective limits and take
self-corrective action prior to an alarm occurring. The system shall automatically reduce chiller
capacity when any of the following parameters are outside their normal operating range:
1) high condenser pressure
2) high motor temperature
3) low evaporator refrigerant temperature
4) high motor amps.

c. During the capacity override period, a pre-alarm (alert) message shall be displayed informing
the operator which condition is causing the capacity override. Once the condition is again
within acceptable limits, the override condition shall be terminated and the chiller shall revert
to normal chilled water control.

3. Multiple Chiller Control:

The chiller controls shall be supplied as standard with a two-chiller lead/lag and a third chiller
standby system. The control system shall automatically start and stop a lag or second chiller on a
two-chiller system. If one of the two chillers on line goes into a fault mode, the third standby chiller
shall be automatically started. The two-chiller lead/lag system shall allow manual rotation of the
lead chiller, include load balancing if configured, and a staggered restart of the chillers after a
power failure.

I. Vibration Isolation:

Chiller manufacturer shall furnish spring isolators for mounting equipment on a level concrete surface.

J. Special Features:
Automatic Hot Gas Bypass:
1. BACnet Communication:
Shall provide field-installed communication capability with a BACnet network.

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 Technical Service Manual
Water Cooled
Screw Chiller

Model:

Commercial Air Conditioner Division

LSBLG***/MCF （Flooded Type）
Midea Group
Address: Midea Headquarters Building, 6 Midea Avenue, Beijiao, Shunde, Foshan,

Guangdong, China
Midea CAC After-service Application
Postal code: 528311

Tel: +86-757-26338346 Fax: +86-757-22390205

cac.midea.com global.midea.com

Note: The data in this book may be changed without notice for further improvement on

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