Operating conditions
SM084 to 185
SY185 to 380
R22
Motor supply
SM / SY / SZ scroll compressors can be operated
at nominal voltages as indicated on page 18.
Under-voltage and over-voltage operation is
allowed within the indicated voltage ranges. In
case of risk of under-voltage operation, special
attention must be paid to current draw.
The operating envelopes for SM / SY / SZ
scroll compressors are given in the figures
below, where the condensing and evaporating
temperatures represent the range for steady-
state operation. Under transient conditions, such
as start-up and defrost, the compressor may
operate outside this envelope for short periods.
The figures below show the operating envelopes
for SM / SY compressors with refrigerants R22
and for SZ compressors with R407C, R134a,
R404A and R507C.
The operating limits serve to define the
envelope within which reliable operations of the
compressor are guaranteed:
• Maximum discharge gas temperature: 275°F
• A suction superheat below 9°F (18°F for R407C)
is not recommended due to the risk of liquid
flood back
• Maximum superheat of 54°F
• Minimum and maximum evaporating and
condensing temperatures as per the operating
envelopes.
SM / SY / SZ compressors can be applied from
-31°F to 145.4°F (for SM/SZ084 to 185) and 127.4°F
(for SY/SZ 240 to 380) ambient temperature. The
compressors are designed as 100 % suction gas
cooled without need for additional fan cooling.
Ambient temperature has very little effect on the
compressor performance.
In case of enclosed fitting and high ambient
temperature it’s recommend to check the
temperature of power wires and conformity to
their insulation specification.
In case of safe tripping by the compressor
overload protection the compressor must cool
down to about 140°F before the overload will
reset. A high ambient temperature can strongly
delay this cool-down process.
Although the compressor itself can withstand
low ambient temperature, the system may
require specific design features to ensure safe
and reliable operation. See section ‘Specific
application recommendations’.
Application envelope at dew
temperatures
Compressor ambient
temperature
High ambient temperature
Low ambient temperature
80
90
100
110
120
130
140
150
160
-10
0
10
20
30
40
50
60
C
ondensing t
emper
atur
e (°F)
Evaporating temperature (°F)
S.H. = 54°F SUPERHEAT
S.H. = 20°F
S.H. = 9°F
Application guidelines
26
FRCC.PC.003.A5.22