background image

17

sYsteM design RecoMMendations

Refrigerant charge 
limit and compressor 
protection

crankcase heater

liquid line solenoid valve 
(llsV)

pump-down cycle

suction accumulator

A  suction  accumulator  offers  protec-
tion  against  refrigerant  floodback  at 
start-up,  during  operation,  or  after 
heat pump defrosting. Sustained and 
repeated  liquid  slugging  and  flood-
back  can  seriously  impair  the  oil’s 
ability  to  lubricate.  The  suction  line 
accumulator  also  protects  against 

off-cycle migration by providing addi-
tional internal free volume on the low 
side  of  the  system.  The  accumulator 
should be sized for not less than 50% 
of the total system charge. Tests must 
be conducted to determine the actual 
refrigerant-holding  capacity  needed 
for the application.

Performer®  scroll  compressors  incor-
porate  internal  safety  devices  such 
as  motor  temperature  protection, 
reverse  rotation  protection,  and  a 
discharge gas check valve. Additional 
safety devices or system components, 

however,  may  be  required  to  en-
sure  adequate  protection  of  the 
compressor. Depending on the system 
configuration  and  application,  one 
or  several  of  the  following  methods 
should be considered.

When  the  compressor  is  idle,  the  oil 
temperature  in  the  sump  must  be 
at  least  18

o

F  above  the  saturation 

temperature of the refrigerant on the 
low  pressure  side.  This  ensures  that 
liquid refrigerant does not accumulate 
in  the  sump.  A  crank case  heater  is 
only effective if capable of sustaining 
a  temperature  difference  of  18°F 
or  more.  Tests  must  be  conducted 
to  ensure  that  the  appropriate  oil 
temperature  is  maintained  under  all 
ambient conditions (temperature and 
wind). 
Below 23°F ambient temperature with 
wind  speed  above  11  mph,  however, 
we  recommend  thermal  insulation 
of  crankcase  heaters  in  order  to  limit 
the  energy  losses  to  the  surrounding 
air. Since the total system charge may 
be  undefined,  a  crankcase  heater  is 

recommended  on  all  stand-alone 
compressors  and  split  systems.  In 
addition,  any  system  containing  a 
refrigerant  charge  in  excess  of  the 
maximum  recommended  system 
charge  for  compressors  requires  a 
crankcase  heater.  A  crankcase  heater 
is also required on all reversible cycle 
applications. 

notes

:  Belt-type  crankcase  heater 

accessories 

are 

available 

from 

Danfoss  (see  page  34).  The  heater 
must be energized for a minimum of 
12  hours  before  initial  start-up  (with 
compressor service valves open), and 
must remain energized whenever the 
compressor  is  off.  Provide  separate 
electrical supply for the heaters so that 
they remain energized even when the 
machine is out of service (eg. seasonal 
shutdown).

An  LLSV  may  be  used  to  isolate  the 
liquid  charge  on  the  condenser  side, 
thereby preventing charge transfer or 
excessive migration to the compressor 
during off-cycles. 

The  quantity  of  refrigerant  on  the 
low  pressure  side  of  the  system  can 
be further reduced by using a pump-
down  cycle  in  association  with  the 
LLSV.

A  pump-down  cycle  is  one  of  the 
most effective ways to protect against 
the  off-cycle  migration  of  liquid 
refrigerant.  Once  the  low  pressure 
cut  off  is  activated,  a  solenoid  valve 
closes  on  the  condenser  outlet. 
The  compressor  then  pumps  the 
majority of the system charge into the 

condenser,  and  the  system  stops  on 
the low pressure switch. This reduces 
the amount of charge on the low side 
and  prevents  off-cycle  migration. 
Recommended  settings  for  the  low 
pressure  switch  can  be  found  in  the 
table  on  p.  22.  For  suggested  wiring 
diagrams, please see p. 14-15.

Summary of Contents for Performer SM Series

Page 1: ...selection application guidelines Performer scroll compressors SM SY SZ 50 60 Hz R 22 R 407C R 134a R 404A R 507A MAKING MODERN LIVING POSSIBLE REFRIGErATION AIR CONDITIONING...

Page 2: ...oft start controller 15 SYSTEM DESIGN RECOMMENDATIONS 17 Refrigerant charge limit and compressor protection 17 Crankcase heater 17 Liquid line solenoid valve LLSV 17 Pump down cycle 17 Suction accumul...

Page 3: ...Compressor sound radiation 27 Mechanical vibrations 27 Gas pulsation 27 INSTALLATION 28 Compressor handling 28 Mounting 28 Removing connections shipping plugs 29 System cleanliness 29 Tubing 29 Filter...

Page 4: ...once the power has been switched off The figure below illustrates the entire compression process Therearetwoscrollelements anorbiting scroll and a fixed scroll The center of the orbiting scroll trace...

Page 5: ...or protection type Applies to Description For trio assemblies please contact Danfoss 5 Model SM SZ 084 090 100 110 120 148 161 SM SZ 115 125 160 175 185 SY SZ 240 300 SY SZ 380 Version V R C MA MB AA...

Page 6: ...s and capacity tables refer to Online Datasheet Generator www danfoss com odsg SM SY compressors SZ compressors Refrigerant R 22 R 407C Frequency 50 Hz 50 Hz Standard rating conditions ARI standard co...

Page 7: ...Online Datasheet Generator www danfoss com odsg SM SY compressors SZ compressors Refrigerant R 22 R 407C Frequency 60 Hz 60 Hz Standard rating conditions ARI standard conditions Evaporating temperatu...

Page 8: ...re indicated by a double line The solid line represents the limit when the su perheat is 20o F or less The dotted line shows the limit when the superheat is 54o F Interpolate for superheat values betw...

Page 9: ...110 120 130 140 150 160 10 0 10 20 30 40 50 60 Evaporating temperature F Condensing temperature F Condensing temp limits S H 20o F S H 54o F SUPERHEAT 10 0 10 20 30 40 50 60 Evaporating temperature F...

Page 10: ...e application envelopes Dew temperature Mean temperature Example for SZ 084 to 185 Example for SZ 084 to 185 Refrigerant R 407C is a zeotropic mix ture with a temperature glide in both evaporator and...

Page 11: ...ion 1 5 8 2 1 4 1 3 8 Discharge 1 1 8 1 3 4 7 8 SY SZ 240 Suction 1 5 8 2 1 4 1 5 8 Discharge 1 1 8 1 3 4 1 1 8 SY SZ 300 Suction 1 5 8 2 1 4 1 5 8 Discharge 1 1 8 1 3 4 1 1 8 SY SZ 380 Suction 2 1 8...

Page 12: ...230V 3 60 Hz 460V 3 60 Hz 575V 3 60 Hz 380 3 60 Hz Voltage range 60 Hz 180 253 V 414 506V 517 632V 342 418 V Electrical connections The terminal box is provided with a 1 1 29 mm hole for the power su...

Page 13: ...or 115 230 vac 13 ELECTRICAL CONNECTIONS AND WIRING The motor protection module is factory installed in the terminal box and has both phase sequence protection and pre wired thermistor connections The...

Page 14: ...KS BP HP DGT TH 180 s T1 T2 M T3 KA KA A1 A2 A3 Wiring diagram without pump down cycle Suggested wiring diagrams Compressor models SM SZ 115 125 160 175 185 Wiring diagram with pump down cycle CONTRO...

Page 15: ...starter MCI soft starters are designed to reduce the starting and stopping current of 3 phase AC motors MCI soft starters can reduce in rush current by up to 40 thereby eliminating the detrimental ef...

Page 16: ...erated by the MCI As the contactor always switches in no load condition it can be selected on the basis of the thermal current AC 1 Contacts 13 14 are not applicable with MCI 25C When control voltage...

Page 17: ...wind Below 23 F ambient temperature with wind speed above 11 mph however we recommend thermal insulation of crankcase heaters in order to limit the energy losses to the surrounding air Since the total...

Page 18: ...the table a crankcase heater must be used During operation liquid floodback may be detected by measuring either the oil sump temperature which should be at least 18 F above the saturated suction tempe...

Page 19: ...est Crankcase heater Cooling only systems with remote condensor and split system units Refrigerant migration floodback test Crankcase heater because full system charge is not definable risk of overcha...

Page 20: ...d motor protection module in the terminal box This device provides efficient reliable protection against overheating overloading and phase loss or reversal Connected to the module are PTC sensors embe...

Page 21: ...a single direction and the motor is wound so that if the connections are correct the rotation will also be correct Compressor models SM SZ 084 to 185 incorporate an internal reverse vent valve which w...

Page 22: ...e motor terminals must lie within these table limits during both start up and normal operations The maximum allowable voltage imbalance is 2 Voltage imbalance causes high amperage on one or more phase...

Page 23: ...e compressor from draining back to the discharge side of the compressor during off cycle The upper loop also helps avoid condensed liquid refrigerant from draining back to the compressor when stopped...

Page 24: ...nsing temperature shown in the application envelopes Under very low ambient conditions in which testing has revealed that the above procedures might not ensure satisfactory condensing and suction pres...

Page 25: ...compressor to draw vapor from on the suction side The compressor can then quickly enter into a vacuum condition it is therefore important that the expansion device be sized correctly and that a suffi...

Page 26: ...ure switch cut outs and may place excess strain on both bearings and motor To prevent such problems it is important to allow a 3 ft minimum discharge line length between the compressor discharge port...

Page 27: ...and code numbers Mechanical vibrations Vibration is most effectively controlled by isolation Performer scroll compressors are designed to produce minimal vibration during operation Rubber isolaters on...

Page 28: ...erminal box with the intention of moving the compressor as the force placed upon the terminal box will cause extensive damagetoboththeboxandthemotor protection module component inside Lock washer HM 8...

Page 29: ...nsables and system contaminants such as metal shavings solder and flux have a negativeimpactoncompressorservice life Many of these contaminants are small enough to pass through a mesh screen and can c...

Page 30: ...age internal components Using a heat shield a heat absorbing compound or both is recommended Due to the relatively large tubing and fitting diameters used for larger scrolls a double tipped acetylene...

Page 31: ...the table below Never use other gasses such as oxygen dry air or acetylene as these may form an inflammable mixture Pressurize the system on HP side first then LP side Leak detection compressor Use a...

Page 32: ...ng device operation and desired superheat readings Suction and discharge pressure within acceptable levels Correct oil level in compressor sump indicating proper oil return Low foaming in sight glass...

Page 33: ...daptator not available rotolock valve set not available Discharge 1 3 8 Solder sleeve adaptator set Rotolock valve set 33 Connectors and valves ACCESSORIES Compressor model Oil type Oil name Code no S...

Page 34: ...mark UL SM SZ175 185 6 7773108 Belt type crankcase heater 75 W 230 V CE mark UL SM SZ175 185 6 7973005 Belt type crankcase heater 75 W 230 V CE mark UL SM SZ175 185 50 7773118 Belt type crankcase heat...

Page 35: ...ble for code 3 version compressors Discharge gas temperature must not exceed 275 F The discharge gas thermostat acces sory kit includes all components required for installation as shown below The ther...

Page 36: ...lock T SM175 3RM SM175 4RM SM175 7RM SM175 9RM SM185 Single Brazed T SM185 3CAM SM185 4CAM SM185 7CAM SM185 9CAM Rotolock T SM185 3RM SM185 4RM SM185 7RM SM185 9RM SY240 Single Brazed M24 SY240A3AAM S...

Page 37: ...e Brazed T SZ125 3CAM SZ125 4CAM SZ125 7CAM SZ125 9CAM Rotolock T SZ125 3RM SZ125 4RM SZ125 7RM SZ125 9RM SZ148 Single Brazed Int SZ148 3VAM SZ148 4VAM SZ148 7VAM SZ148 9VAM SZ160 Single Brazed T SZ16...

Page 38: ...75 185 6 48 4 37 4 33 0 1444 2 24 0 24 0 37 0 248 SY SZ 240 4 44 9 37 4 36 25 1413 2 20 1 18 3 30 7 344 SY SZ 300 4 44 9 37 4 36 25 1413 2 20 1 18 3 30 7 355 SY SZ 380 4 44 9 37 4 37 2 1440 2 20 1 18...

Page 39: ......

Page 40: ...n Controls for Industrial Refrigeration Industrial Automation Household Compressors Commercial Compressors Thermostats Sub Assemblies Electronic Controls Sensors We are a single source for the widest...

Reviews: