A
PPLICATION
GUIDELINES
O
PERATING
CONDITIONS
Motor supply
MLZ / MLM scroll compressors can be operated at
nominal voltages as indicated on page 14. 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 and start assist for
single-phase compressors may be required.
The operating envelopes for MLZ/MLM 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 MLZ compressors with refrigerants R404A/507,
R134a and R22. The operating limits serve to de-
fine the envelope within which reliable operations
of the compressor are guaranteed:
• Maximum discharge gas temperature: 275°F
• A suction superheat below 10°F is not recom-
mended due to the risk of liquid flood back
• Minimum and maximum evaporating and con-
densing temperatures as per the operating en-
velopes.
MLZ / MLM compressors can be applied from
-31°F to 122°F ambient temperature. The com-
pressors are designed as 100 % suction gas cooled
without need for additional fan cooling. Ambient
temperature has very little effect on the compres-
sor performance.
In case of enclosed fitting and high ambient tem-
perature it’s recommend to check the temperature
of power wires and conformity to their insulation
specification.
In case of safe tripping by the internal compres-
sor overload protection the compressor must cool
down to about 140°F before the overload will re-
set. A high ambient temperature can strongly de-
lay this cool-down process.
Although the compressor itself can withstand low
ambient temperature, the system may require
specific design features to ensure safe and reli-
able operation. See section ‘Specific application
recommendations’.
Application envelope
Compressor ambient
temperature
High ambient temperature
Low ambient temperature
21
FRCC.PC.016.A1.22
MLZ - R404A / R507
RGT: 65°F
Transient conditions
C
ondensing temper
a
tur
e (°F)
Evaporating temperature (°F)
40
60
80
100
120
140
160
-30
-20
-10
0
10
20
30
40
50
60
