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13 -STANDARD MAINTENANCE
- Specific recommendation in case of snow: For long term
storage, regularly check that no snow has accumulated on
the coil.
- Clean the surface of the coil by spraying the coil regularly
and uniformly from bottom to top, orienting the water jet at
right angles to the surface. Do not exceed a water pressure
of 6200 kPa (62 bar) or an angle of 45° to the coil. The nozzle
must be at least 300 mm away from the coil surface.
- Clean and scrub the entire coil connections with a soft Nylon,
PolyPro® or Tynex
brush and low pressure tap water.
®
13.6.1 - Level 1 cleaning:
- 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.
13.6.2 - Level 2 cleaning:
- Carry out the level 1 cleaning operations.
- Clean the coil using suitable products.
Use appropriate PPE including safety glasses and/or mask,
waterproof clothes and safety gloves. It is recommended to
wear clothing that covers the whole body.
Specific products approved by the manufacturer for cleaning
coils are available from the manufacturer's spare parts
network. The use of any other product is strictly prohibited.
After the cleaning product is applied, rinsing with water is
mandatory (see manufacturer's standard RW01-25).
IMPORTANT: Never use a pressure water spray 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 electrical cabinets, the motorised ball valve and the VFDs
during cleaning operations. Don't forget to remove protections
after cleaning operations.
13.7 - 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.
13.8 - Compressor maintenance
13.8.1 - Oil separator
Check the correct operation of the heaters and check that they
are well attached to the oil separator ring.
13.8.2 - 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.
13.8.3 - Compressor rotation control
Correct compressor rotation is one of the most critical appli-cation
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 minimize the opportunity for reverse rotation, the follow-ing
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.
13.9 - Precaution for compressor power supply
bus bar connection
This note applies to units using power supply bus bars with riveted
contact block at the level of the connection cages in the control
box. During re-connection it is imperative to:
- Engage each bus bar in the cage up to the stop
- Ensure visually that the bus bars have good contact at the
connection areas: There must not be any free move-ment
between the bus bar and the connection area created by the
fixing rivet of the contact block.
Connection of the contactor or current transformer
1
1
Power supply bus bar with riveted contact block
2
Contactor or current transformer connection zone
13.10 - Check of power factor correction
capacitors
The commissioning and periodical verification of the capacitor is
mandatory to insure safe operation. It includes the verification of
the current, voltage, capacitance and voltage distortion.
The procedure for these checks is described in a document that
is dedicated for this purpose.
2
2
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