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Recommendations for maintenance and cleaning of MCHE
(microchannel) condenser coils
•
Regular cleaning of the coil surface is essential for
correct unit operation.
•
Eliminating contamination and removal of harmful
residue will increase the operating life of the coils and
the unit.
•
The maintenance and cleaning procedures below are
part of the regular maintenance and will prolong the life
of the coils.
•
Specific recommendation in case of snow: For long term
storage, regularly check that no snow has accumulated
on the unit coils.
Products qualified as suitable for cleaning untreated MCHE
coils are available from the Carrier spare parts network.
After cleaning, rinsing of the coil is mandatory (see Carrier
standard RW01--25). The use of any other cleaning product
is strictly prohibited.
•
Remove all foreign objects or fragments/debris attached
to the coil surface or wedged between the chassis and
the supports.
•
Use a low-pressure dry air jet to remove all traces of
dust from the coil.
•
Wear the personal protection equipment, including
safety glasses and or mask, waterproof clothes and safety
gloves. It is recommended to wear clothing that covers
the whole body.
WARNING: Never use pressurised water without a large
diffuser. Concentrated and/or rotating water jets are strictly
forbidden.
Never use a fluid with a temperature above 45°C to clean
the air heat exchangers.
Correct and frequent cleaning (approximately every three
months) will prevent 2/3 of the corrosion problems. Protect
the control box, the motorized ball valve and the VFD
during cleaning operations. Don't forget to remove
protections after cleaning operations.
11.7 - Evaporator maintenance
Check that:
•
The insulating foam is intact and securely in place.
•
The cooler heaters are operating, secure and correctly
positioned.
•
The water-side connections are clean and show no sign
of leakage.
11.8 - Compressor maintenance
11.8.1 - Oil separator
Check the correct operation of the heaters and check that
they are properly attached to the oil separator shell.
11.8.2 - Integral oil filter change
As system cleanliness is critical to reliable system operation,
there is a filter in the oil line at the oil separator outlet.
The oil filter is specified to provide a high level of filtration
(5 μm) required for long bearing life.
The filter should be checked after the first 500 hours of
operation, and every subsequent 2000 hours. The filter should
be replaced at any time when the pressure differential across
the filter exceeds 200 kPa (2 bar).
The pressure drop across the filter can be determined by
measuring the pressure at the filter service port and the oil
pressure port. The difference in these two pressures will be
the pressure drop across the filter, check valve, and solenoid
valve. The pressure drop across the check valve and solenoid
valve is approximately 40 kPa (0.4 bar), which should be
subtracted from the two oil pressure measurements to give
the oil filter pressure drop.
11.8.3 - Compressor rotation control
Correct compressor rotation is one of the most critical
application considerations. Reverse rotation, even for a very
short duration, damages the compressor.
The reverse rotation protection scheme must be able to
determine the direction of rotation and stop the compressor
within 300 ms. Reverse rotation is most likely to occur when-
ever the wiring to the compressor terminals is disturbed.
To minimise the opportunity for reverse rotation, the following
procedure must be applied. Rewire the power cables to the
compressor terminal pin as originally wired.
For replacement of the compressor, a low pressure switch is
included with the compressor. This low pressure switch should
be temporarily installed as a hard safety on the high pressure
part of the compressor. The purpose of this switch is to protect
the compressor against any wiring errors at the compressor
terminal pin. The electrical contact of the switch would be
wired in series with the high pressure switch. The switch will
remain in place until the compressor has been started and
direction of rotation has been verified; at this point, the switch
will be removed.
The switch that has been selected for detecting reverse
rotation is Carrier part number HK01CB001. This switch
opens the contacts when the pressure falls below 7 kPa. The
switch is a manual reset type that can be reset after the
pressure has once again risen above 70 kPa. It is critical that
the switch be a manual reset type to preclude the compressor
from short cycling in the reverse direction.
11.9 - Variable frequency drive maintenance
CAUTION: Before any work on the VFD ensure that the
circuit is isolated and there is no voltage present. Note that
it may take 5 minutes for the circuit capacitors to fully
discharge after isolating the circuit. Only appropriately
qualified personnel are authorised to work on the VFD.
In case of any alarm or persistent problem related to the
VFD, contact Carrier Service.
The VFDs fitted with 30XAV units do not require an
insulation test, even if being replaced; they are systematically
verified before delivery. Moreover, the filtering components
installed in the VFD can falsify the measurement and may
even be damaged. If there is a need to test the insulation of
the unit components (fan motors and pumps, cables, etc.),
the VFD must be disconnected at the power circuit.
Содержание AquaForce 30XAV 1050
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