C6.2.15/0815/E
25
pressure is present in the compressor before it runs. The majority of the charge should be
placed in the high side of the system to prevent bearing washout during first-time start on the
assembly line.
5.5
Initial start-up
CAUTION
Oil dilution! Bearing malfunction!
It is important to ensure that new
compressors are not subjected to liquid abuse. Turn the crankcase heater on
12 hours before starting the compressor.
CAUTION
High discharge pressure operation! Compressor damage!
Do not use
the compressor to test opening set point of high-pressure cut-out. Bearings
are susceptible to damage before they have had several hours of normal
running in.
Liquid and high pressure loads could be detrimental to new bearings. It is therefore important to
ensure that new compressors are not subjected to liquid abuse and high-pressure run tests. It is
not good practice to use the compressor to test the high-pressure switch function on the
production line. Switch function can be tested with nitrogen prior to installation and wiring can be
checked by disconnecting the high-pressure switch during the run test.
5.6 Rotation direction
Copeland Scroll compressors, like several other types of compressors, will only compress in one
rotational direction. The direction of rotation is not an issue with single-phase compressors since
they will always start and run in the proper direction. Three-phase compressors will rotate in
either direction depending upon phasing of the power. Since there is a 50-50 chance of
connecting power in such a way as to cause rotation in the reverse direction
, it is important to
include notices and instructions in appropriate locations on the equipment to ensure
proper rotation direction when the system is installed and operated
.
Observing that suction pressure drops and discharge pressure rises when the compressor is
energized allows verification of proper rotation direction. There is no negative impact on
durability caused by operating three-phase Copeland Scroll compressors in the reversed
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. After several
minutes of operation in reverse, the compressor's 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. Therefore, 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.
5.7 Pressure fluctuations
During the normal operation of the Digital Scroll compressor, there is a fluctuation in the suction
and the discharge pressures. This fluctuation will be in the range of 2 to 3.5 bar. During the
unloaded state, discharge pressure will start to drop and suction pressure will start to rise. This is
normal. This pressure fluctuation has no effect on the reliability of any system components.
NOTE:
Models ZRD42K* to ZRD81K* and ZPD34K* to ZPD91K* require a minimum of
3.5 bar differential between the suction pressure and the discharge pressure to unload
properly.
5.8 Starting sound
During the very brief start-up, a clicking sound is audible, resulting from initial contacting of the
spirals 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.
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