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is of oil or refrigerant - is capable of doing damage
resulting in compressor failure.
Unbrazing System Components
WARNING
Before attempting to braze, it is important to recover
all refrigerant from both the high and low side of the
system.
If the refrigerant charge is removed from a scroll-
equipped unit by evacuating the high side only, it is
possible for the scrolls to seal, preventing pressure
equalization through the compressor. This may leave
the low side shell and suction line tubing pressurized.
Removing Compressors
WARNING
Before attempting to cut copper tubing, it is
important to recover all refrigerant from both the
high and low side of the system.
Instructions should be provided in appropriate product
literature and assembly (line repair) areas. If a
compressor removal is required, the compressor should
be cut out of system rather than unbrazed. See Figure
2 for the proper compressor removal procedure.
Pressure Testing
Never pressurize the compressor to more than 475
psig (33 bar) for leak checking purposes. Never
pressurize the compressor from a nitrogen
cylinder or other pressure source without an
appropriately sized pressure regulating and relief
valve.
The pressure used on the line to meet the U.L. burst
pressure requirement must not be higher than 475 psig
(33 bar). Higher pressure may result in permanent
deformation of the compressor shell and possible
misalignment, bottom cover distortion and/or shell
rupture.
Assembly Line System Charging Procedure
Systems should be charged with liquid on the high side
to the extent possible. Most of the charge should be
pumped in the high side of the system to prevent low
voltage starting difficulties, hipot motor test failures, and
bearing washout during the first-time start on the
© 2020 Emerson Climate Technologies, Inc.
assembly line. If additional charge is needed, it should
be added as liquid to the low side of the system with the
compressor operating. Pre-charging on the high side
and adding liquid on the low side of the system are both
meant to protect the compressor from operating with
abnormally low suction pressures during charging. Do
not operate the compressor without enough system
charge to maintain at least 55 psig (3.8 bar) suction
pressure. Do not operate the compressor with the low
pressure cut-out disabled. Do no operate with a
restricted suction or liquid line.
Depending on the discharge pressure, allowing
pressure to drop below 55 psig (3.8 bar) for more than
a few seconds may overheat the scrolls and cause early
drive bearing damage.
CAUTION
Do not use the compressor to test the opening set
point of a high pressure cutout.
Bearings are susceptible to damage before they have
had several hours of normal running for proper break in.
'Hipot' (AC High Potential) Motor Testing
CAUTION
Use caution with high voltage and never hipot test
when compressor is in a vacuum.
Copeland scroll compressors are configured with the
motor down and the pumping components at the top of
the shell. As a result, the motor can be immersed in
refrigerant
to
a
reciprocating compressors when liquid refrigerant is
present in the shell. In this respect, the scroll is more like
semi-hermetic compressors that have horizontal motors
partially submerged in oil and refrigerant. When
Copeland scroll compressors are hipot tested with liquid
refrigerant in the shell, they can show higher levels of
leakage current than compressors with the motor on top.
This phenomenon can occur with any compressor when
the motor is immersed in refrigerant. The level of current
leakage does not present any safety issue. To lower the
current leakage reading, the system should be operated
for a brief period to redistribute the refrigerant to a more
normal configuration and the system hipot tested again.
See
AE4-1294
for megohm testing recommendations.
Under no circumstances should the hipot test be
performed while the compressor is under a vacuum.
11
AE4-1486 R1
greater
extent
than
hermetic
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