Electrical Phasing (Three-Phase Motors) - Trane Horizon OABD Series Installation, Operation And Maintenance Manual

Installation
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.
Three phase electrical power to the unit must meet stringent
requirements for the unit to operate properly. Measure each leg
(phase-to-phase) of the power supply. Each reading must fall
within the utilization range stamped on the unit nameplate. If
any of the readings do not fall within the proper tolerances,
notify the power company to correct this situation before
operating the unit.
Excessive three phase voltage imbalance between phases will
cause motors to overheat and eventually fail. The maximum
allowable voltage imbalance is 2.0 percent. Measure and
record the voltage between phases 1, 2, and 3 and calculate
the amount of imbalance as follows:
% Voltage Imbalance = 100 X
AV (Average Voltage) =
V1, V2, V3 = Line Voltage Readings
VD = Line Voltage reading that deviates the farthest from the
average voltage.
Example: If the voltage readings of the supply power
measured 221, 230, and 227, the average volts would be:
221 + 230 + 227
= 226 Avg.
3
VD (reading farthest from average) = 221
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
86
AV - VD
where;
AV
Volt 1 + Volt 2 + Volt 3
3
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 it is 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.
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.
OAU-SVX007A-EN