Emerson Copeland Screw SCA2 Applications Manual Download

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Copeland Screw

™

Compressors

Semi-Hermetic Compact

Semi-Hermetic Compact Application Manual

Application Manual

1 General

2 Design and functions

2.1

Design features

2.2

Compression process Vi control

2.3

Capacity control and start unloading

2.4

Hydraulic control

2.5

Starting the compressor

2.6Infinite capacity control

Oil circulation

3 Lubricants

4 Integration into the refrigeration circuit

1.1

Mounting the compressor

1.2

System layout

1.3

Guide lines for special system
variations

1.4

Additional cooling by liquid injection

1.5

Additional cooling by external oil
cooler

5 Economizer operation

5.1

General

5.2

Operation principal

5.3

ECO operation with subcooling circuit

5.4

ECO operation with intermediate
pressure receiver

5.5

Layout and selection
recommendations

5.6 Additional components
5.7

Control

6 Electrical connections

6.1

Motor design

6.2

Selection of electrical components

6.3

Compressor protection system

6.4

Schematic wiring diagrams

AE4-1322

April 2002

SCH2 & SCA2

High Temp Compressors

35 – 140 Horsepower

Contents

™

Summary of Contents for Copeland Screw SCA2

Page 1: ...tegration into the refrigeration circuit 4 Integration into the refrigeration circuit 4 Integration into the refrigeration circuit 1 1 Mounting the compressor 1 2 System layout 1 3 Guide lines for special system variations 1 4 Additional cooling by liquid injection 1 5 Additional cooling by external oil cooler 5 Economizer operation 5 Economizer operation 5 Economizer operation 5 Economizer operat...

Page 2: ... Minimal space requirements and convenient piping design piping design piping design piping design piping design Shortest installed length in its performance category shut off valves connections within compressor dimensions Suction and discharge gas connections can be rotated in 90 increments Terminal box accessible from top wire access from underneath Universal applications Universal applications...

Page 3: ...process V 2 2 Compression process V 2 2 Compression process V 2 2 Compression process Vi i i i i control control control control control With screw compressors suction compression and discharge occur in one flow direction With this process the suction gas is pressed into the profile hollows by the profile peaks The volume is steadily reduced and it is thereby compressed The compressed gas is then ...

Page 4: ...ecreases The slide is controlled by a hydraulic piston If the valve CR4 is opened the oil pressure in the pressure chamber increases The slide is moved to the suction side The cooling capacity increases If the valve CR1 CR2 or CR3 is opened the pressure on the hydraulic piston decreases By means of the discharge gas the slide is pressed to the discharge side The cooling capacity is reduced 2 5 Sta...

Page 5: ...g 10 secs on 10 secs off Solenoid Coil Pulsing 10 secs on 10 secs off Solenoid Coil Pulsing 10 secs on 10 secs off Decreased cooling demand Decreased cooling demand Decreased cooling demand Decreased cooling demand Decreased cooling demand A decreased cooling demand falls below the lower set point operating point C The solenoid valve CR3 now opens for short intervals till the actual value is withi...

Page 6: ...ing and the rotors The oil then flows together with the compressed vapor into the reservoir vessel Here oil and vapor are separated in a highly efficient process The oil collects in the lower part of the separator vessel and flows back into the compressor either direct or via an external oil cooler Depending on the operating conditions the circulating oil must be cooled with liquid injection or an...

Page 7: ...e in extended systems is also possible for example with remotely installed condenser Systems with multiple compressors should preferably be designed with individual circuits Parallel compound is possible but requires a special oil equalizing system by means of oil level control 4 1 Mounting the compresso 4 1 Mounting the compresso 4 1 Mounting the compresso 4 1 Mounting the compresso 4 1 Mounting ...

Page 8: ... espe cially in discharge and economizer lines Therefore critical pipe lengths 15 with their natural fre quencies being in resonance with the compressor pulsations must be avoided Among other things the operating conditions and the refrigerant sonic speed as well as the compressor s pulsation frequency must be considered in the calcula tion The base frequency of the compressor is approx 250Hz 50Hz...

Page 9: ... systems with long pipelines suchas a remote evaporator and or con denser In addition the compressor must be equipped with an oil level switch accessory For electrical connection see Section 6 4 Systems with reverse cycling and hot gas defrost Systems with reverse cycling and hot gas defrost Systems with reverse cycling and hot gas defrost Systems with reverse cycling and hot gas defrost Systems w...

Page 10: ...or vibration during operation Check for vibration during operation Check for vibration during operation Check for vibration during operation Calculating the cooling capacity of the liquid Calculating the cooling capacity of the liquid Calculating the cooling capacity of the liquid Calculating the cooling capacity of the liquid Calculating the cooling capacity of the liquid injection valve injectio...

Page 11: ...e oil line This is to avoid oil migration into the compressor during shutdowns The solenoid valve must be installed close to the compressor s oil inlet connec tion and its electric control should be parallel to the contactor s normally open contact Recommended additional components Sight glass to check oil flow Manual shut off ball valves in both feed and return lines for ease of service Oil filte...

Page 12: ...rature should be equal to or greater than 250 F As an example figure 11 shows a layout with a primary receiver after the condenser An alternative layout of the thermosyphon circuit as well as refrigerant circulation by means of a pump or an ejection is also possible information upon request 4 Economizer operation 1 1 General 1 1 General 1 1 General 1 1 General 1 1 General SCH2 SCA2 screw compresso...

Page 13: ...peration with sub cooling circuit 5 3 Economizer operation with sub cooling circuit 5 3 Economizer operation with sub cooling circuit 5 3 Economizer operation with sub cooling circuit 5 3 Economizer operation with sub cooling circuit With this operation mode a heat exchanger is utilized as a liquid sub cooler A part of the refrigerant mass flow from the condenser enters the sub cooler via an expan...

Page 14: ...pe diameters can be used SCH2 5000 to 9000 1 12 Rotolock SCA2 3500 to 7000 SCH2 11H0 to 14H0 1 12 Rotolock SCA2 9000 to 11H0 Pipe vibrations Due to the pulsations emitting from the profile area of the compressor critical pipe lengths must be avoided See also Section 4 2 5 6 Additional components 5 6 Additional components 5 6 Additional components 5 6 Additional components 5 6 Additional components...

Page 15: ...rt current value in star mode 1 3 of The start current value in star mode 1 3 of The start current value in star mode 1 3 of The start current value in star mode 1 3 of The start current value in star mode 1 3 of the direct on line value is generally stated the direct on line value is generally stated the direct on line value is generally stated the direct on line value is generally stated the dir...

Page 16: ...ing motors Part winding motors The following current values appear in the part wind ings PW1 PW2 50 50 Both of the contactors should be selected for at least 60 of the maximum operating current Star delta motors Star delta motors Star delta motors Star delta motors Star delta motors Calculate mains and delta contactor each to at least 60 start contactor to 33 of the maximum operating current Power...

Page 17: ...rge and a subsequent time delay The layout of correction systems for motors with direct starting is similar CAUTION CAUTION CAUTION CAUTION CAUTION It is essential to observe the general It is essential to observe the general It is essential to observe the general It is essential to observe the general It is essential to observe the general design and layout instruction of the design and layout in...

Page 18: ...and oil level controls are included CAUTION CAUTION CAUTION CAUTION CAUTION Make sure that the rotation monitoring is Make sure that the rotation monitoring is Make sure that the rotation monitoring is Make sure that the rotation monitoring is Make sure that the rotation monitoring is functioning T functioning T functioning T functioning T functioning Terminal D1 of the erminal D1 of the erminal D...

Page 19: ...nds M1 Compressor Q1 Main switch R1 Oil heater R2 Oil temperature sensor PTC R3 8 Motor PTC sensor S1 On off switch S2 Fault reset motor discharge temperature and or direction of rotation S4 Fault reset oil level U Screening unit if required such as from Murr Elektronik Y1 SV capacity control Y2 SV capacity control Y3 SV capacity control Y4 SV capacity control Y5 SV liquid line Y6 SV refrigerant i...

Page 20: ...AE4 1322 2002 Copeland Corporation Issued 4 2002 Printed in U S A 20 Figure22 Partwindingstartwith4 stepcapacitycontrol Figure23 Partwindingstartoptions ...

Page 21: ...rameters pressure levels liquid tempera tures compared with data according to intermediate temperatures used so far As a consequence this results in a lower numerical value for cooling capacity and efficiency COP Liquid sub cooling Liquid sub cooling Liquid sub cooling Liquid sub cooling Liquid sub cooling With standard conditions no no no no no liquid sub cooling is considered Therefore the rated...

Page 22: ... for ECO T T T T Technical data of a compressor echnical data of a compressor echnical data of a compressor echnical data of a compressor echnical data of a compressor Hit T Data Window Data appears in which the technical data are listed Further windows Dimensions dimensional drawing and Notes notes and legend Export all data with Print Print out at standard printer or Export asASCII file Export p...

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