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AGL_Ref_ST_YBK1E_EN_Rev01
caused by operating three-phase Copeland scroll compressors in the reverse direction for a short
period of time (under one hour) but oil may be lost. Oil loss can be prevented during reverse rotation
if the tubing is routed at least 15 cm above the compressor. Af ter several minutes of operation in
reverse, the compressor protection system will trip due to high motor temperature. The operator will
notice a lack of cooling. However, if allowed to repeatedly restart and run in reverse without correcting
the situation, the compressor will be permanently damaged.
All three-phase scroll compressors are identically wired internally. Theref ore, once the correct
phasing is determined for a specific system or installation, connecting properly phased power leads
to the identified compressor terminals will ensure proper rotation direction.
5.9
Starting sound
During the very brief start-up, a clicking sound resulting f rom the initial contacting of the spirals is
audible and is normal. Due to the design of the Copeland scroll compressors, the internal
compression components always start unloaded even if system pressures are not balanced. In
addition, since internal compressor pressures are always balanced at start -up, low voltage starting
characteristics are excellent for Copeland scroll compressors.
5.10 Deep
vacuum
operation
WARNING
Operation below ambient pressure! Fire hazard!
For applications with A2L
ref rigerants, a flammable mixture can form inside the system during operation
below ambient pressure. Make sure that air does not enter the system and
that the pressure never falls below atmospheric pressure.
CAUTION
Vacuum operation! Compressor damage!
Copeland Scroll compressors
should never be used to evacuate ref rigeration or air-conditioning systems.
Operating scroll compressors in deep vacuum could damage internal motor
parts and lead to unacceptable high temperatures in the compressor housing.
5.11 Shell
temperature
During normal operation, the discharge gas as well as the compressor top shell and discharge line
can reach temperatures up to the maximum discharge gas temperature of 130 °C
– see
section 3.7
"Discharge gas temperature protection"
.
In a f ailure mode, the discharge gas temperatures can even get higher. Care must be taken to ensure
that wiring or other materials that could be damaged by these temperatures do not touch the shell.
5.12 Pumpdown cycle
WARNING
Operation below ambient pressure! Fire hazard!
For applications with A2L
ref rigerants, a flammable mixture can form inside the system during operation
below ambient pressure. Make sure that air does not enter the system and
that the pressure never falls below atmospheric pressure.
CAUTION
Vacuum operation! Compressor damage!
Compressor operation outside
the operating envelope is not allowed.
A pumpdown cycle to control ref rigerant migration may have to be used for several reasons, for
example when the compressor is located outdoors without any housing so that cold air blowing over
the compressor makes the crankcase heater ineffective.
If a pumpdown cycle is used, a separate external check valve must be added
. The scroll
discharge check valve is designed to stop extended reverse rotation and prevent high-pressure gas
f rom leaking rapidly into the low side after shut-off. The check valve might in some cases leak more
than reciprocating compressor discharge reeds, normally used with pumpdown, causing the scroll
compressor to recycle more f requently. Repeated short cycling of this nature can result in a low oil
situation and consequent damage to the compressor. The hysteresis of the low-pressure control
dif ferential has to be reviewed since a relatively large volume of gas will re-expand f rom the high side
of the compressor into the low side after shutdown.
