Operating conditions
Motor supply
MLZ / MLM scroll compressors can be operated
at nominal voltages as indicated in table section
“Motor voltage”. 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 define the envelope within
which reliable operations of the compressor are
guaranteed:
• Maximum discharge gas temperature: +135°C
• A suction superheat below 5 K is not
recommended due to the risk of liquid flood
back
• Minimum and maximum evaporating and
condensing temperatures as per the operating
envelopes.
MLZ / MLM compressors can be applied from
-35°C to 55°C 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 internal
compressor overload protection the compressor
must cool down to about 60°C 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
Compressor ambient
temperature
High ambient temperature
Low ambient temperature
MLZ - R404A / R507
RGT: +20°C
Max. superheat: 10K
Condensing t
emp
er
atur
e (°C
)
Evaporating temperature (°C)
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
5
10
15
20
25
30
35
40
45
50
55
60
65
28
FRCC.PC.015.A8.02
Application Guidelines
