A
PPLICATION
GUIDELINES
E
LECTRICAL
DATA
,
CONNECTIONS
AND
WIRING
The compressor will only operate properly in a
single direction. Use a phase meter to establish
the phase orders and connect line phases L1, L2
and L3 to terminals T1, T2 and T3, respectively.
For three-phase compressors, the motor will run
equally well in both directions. Reverse rotation
results in excessive noise; no pressure differential
between suction and discharge; and suction line
warming rather than immediate cooling. A service
technician should be present at initial start-up to
verify that supply power is properly phased and
that compressor and auxiliaries are rotating in the
correct direction.
MLZ/MLM015-038 scroll compressors are de-
signed to operate for a maximum of 150 hours in
reverse, but as a reverse rotation situation can go
unnoticed for longer periods, phase monitors are
recommended.
For compressors MLZ/MLM048 and larger, phase
monitors are required. The selected phase moni-
tor should lock out the compressor from opera-
tion in reverse.
At brief power interruptions, reverse rotation can
occur with single phase compressors. In this case
the internal protector will stop the compressor. It
will have to cool down and will restart safely af-
terwards.
For three-phase applications the voltage meas-
ured at the compressor terminals for each phase
should be within ± 2% of the average for all phas-
es.
Phase sequence and re-
verse rotation protection
Voltage imbalance
Internal motor protection
MLZ/MLM scroll compressors are equipped with
an internal line break protector mounted on the
motor windings. The protector is an automatic
reset device, containing a snap action bimetal
switch.
Internal protectors respond to over-current and
overheating. They are designed to interrupt motor
current under a variety of fault conditions, such as
failure to start, running overload, and fan failure.
If the internal overload protector trips out, it must
cool down to about 140°F to reset. Depending on
ambient temperature, this may take up to several
hours.
18
FRCC.PC.016.A1.22
