81
14.8.2 - Integral oil lter change
As system cleanliness is critical to reliable system operation, there
is a lter in the oil line at the oil separator outlet. The oil lter is
specied to provide a high level of ltration (5 µm) required for long
bearing life.
The lter should be checked after the rst 500 hours of operation,
and every subsequent 2000 hours. The lter should be replaced at
any time when the pressure dierential across the lter exceeds
200 kPa (2 bar).
The pressure drop across the filter can be determined by
measuring the pressure at the lter service port and the oil pressure
port. The dierence in these two pressures will be the pressure
drop across the lter, 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 lter pressure drop.
14.8.3 - 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 veried; 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.
14.9 - 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
xing rivet of the contact block.
Connection of the contactor or current transformer
2
2
1 Power supply bus bar with riveted contact block
2 Contactor or current transformer connection zone
14.10 - Check of power factor correction
capacitors
The commissioning and periodical verication of the capacitor is
mandatory to insure safe operation. It includes the verication of
the current, voltage, capacitance and voltage distortion.
The procedure for these checks is described in a document that
is dedicated for this purpose.
14 - STANDARD MAINTENANCE
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