Electrical Phasing (Three-Phase Motors); Compressor Crankcase Heaters - Trane Horizon OADG Series Installation, Operation And Maintenance Manual

The percentage of Imbalance equals:
226 - 221
100 X = 2.2%
226
The 2.2 percent imbalance in this example exceeds the
maximum allowable imbalance of 2.0 percent. This much
imbalance between phases can equal as much as a
20 percent current imbalance with a resulting increase in
motor winding temperatures that will decrease motor life.
If the voltage imbalance is over 2.0 percent, notify the
proper agencies to correct the voltage problem before
operating this equipment.

Electrical Phasing (Three-Phase Motors)

WARNING
Live Electrical Components!
Failure to follow all electrical safety precautions when
exposed to live electrical components could result in
death or serious injury. When necessary to work with
live electrical components, have a qualified licensed
electrician or other individual who has been properly
trained in handling live electrical components perform
these tasks.
AVERTISSEMENT
Composants électriques sous tension!
Le non-respect de toutes les consignes de sécurité lors
de la manipulation de composants électriques sous
tension peut entraîner des blessures graves, voire
mortelles. S'il est nécessaire de travailler avec des
composants électriques sous tension, demandez à un
électricien qualifié et agréé ou à une autre personne
ayant la formation nécessaire pour manipuler des
composants électriques sous tension d'exécuter ces
tâches.
The compressor motor(s) and the supply fan motor are
internally connected for the proper rotation when the
incoming power supply is phased as A to L1, B to L2, and
C to L3.
Proper electrical supply phasing can be quickly
determined and corrected before starting the unit by using
an instrument such as an Associated Research Model 45
Phase Sequence Indicator and following these steps:

Turn off the main source feeding power to the unit
field-supplied or factory-installed main disconnect
device (switch or circuit breaker).

Close the unit disconnect device cover, leaving
disconnect switch in the off position, and turn main
source power on.
OAU-SVX006C-EN

Observe the ABC and CBA phase indicator lights on
the face of the sequencer. The ABC indicator light will
glow if the phase is ABC. If the CBA indicator light
glows, turn main source power off and then open the
unit main disconnect device cover and reverse any
two power wires.

Restore the main source power and recheck the
phasing. If the phasing is correct, turn main source
power off then open the unit main disconnect device
cover, remove the phase sequence indicator, reinstall
disconnect device cover and, leaving disconnect
device in the off position, turn main power source to
unit on.

Compressor Crankcase Heaters

WARNING
Live Electrical Components!
Failure to follow all electrical safety precautions when
exposed to live electrical components could result in
death or serious injury. When necessary to work with
live electrical components, have a qualified licensed
electrician or other individual who has been properly
trained in handling live electrical components perform
these tasks.
AVERTISSEMENT
Composants électriques sous tension!
Le non-respect de toutes les consignes de sécurité lors
de la manipulation de composants électriques sous
tension peut entraîner des blessures graves, voire
mortelles. S'il est nécessaire de travailler avec des
composants électriques sous tension, demandez à un
électricien qualifié et agréé ou à une autre personne
ayant la formation nécessaire pour manipuler des
composants électriques sous tension d'exécuter ces
tâches.
To prevent injury or death from electrocution, it is the
responsibility of the technician to recognize this hazard
and use extreme care when performing service
procedures with the electrical power energized.
Each compressor shall be equipped with a crankcase
heater. The proper operation of the crankcase heater is
important to maintain an elevated compressor oil
temperature during the "Off" cycle to reduce oil foaming
during compressor starts. Oil foaming occurs when
refrigerant condenses in the compressor and mixes with
the oil. In lower ambient conditions, refrigerant migration
to the compressor could increase.
When the compressor starts, the sudden reduction in
crankcase pressure causes the liquid refrigerant to boil
rapidly causing the oil to foam. This condition could
damage compressor bearings due to reduced lubrication
and could cause compressor mechanical failures.
Installation
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