Electrical Phasing; Motors); Compressor Crankcase Heaters - Trane Foundation GBC036-060 Installation, Operation And Maintenance Manual

The supply power line voltage readings (V1, V2, V3) are
221, 230, and 227 respectively.:
• AV (Average Voltage) = (221 + 230 + 227) / 3 = 226
Avg.
• VD (reading farthest from average) = 221
• % Voltage Imbalance = (100 + 226 + 221) / 226 = 2.2%
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 percent, notify the proper
agencies to correct the voltage problem before operating
this equipment.
Electrical Phasing (Three Phase Motors)
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, B, C.
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 the steps below:
WARNING
Hazardous Voltage!
Failure to disconnect power before servicing could
result in death or serious injury.
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Verify that no power is
present with a voltmeter.
1. Turn the field supplied disconnect switch that provides
power to the main power terminal block or to the "Line"
side of the optional factory mounted disconnect switch
to the "Off" position.
2. Connect the phase sequence indicator leads to the
terminal block or to the "Line" side of the optional
factory mounted disconnect switch as follows:
• Black (phase A) to L1
• Red (phase B) to L2
• Yellow (phase C) to L3
3. Close the field supplied main power disconnect switch
or circuit protector switch that provides the supply
power to the unit.
RT-SVX058G-EN
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.
4. 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, open the disconnect switch or circuit protection
switch and reverse any two power wires.
5. Restore the main electrical power and recheck the
phasing. If the phasing is correct, open the disconnect
switch or circuit protection switch and remove the
phase sequence indicator.

Compressor Crankcase Heaters

NOTICE
Compressor Failure!
Failure to follow instruction below could result in
compressor failure.
Unit must be powered and crankcase heaters
energized at least 8 hours BEFORE compressors are
started.
Each compressor can 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.
Before starting the unit in the "Cooling" mode, set the
system switch to the "Off" position and turn the main power
disconnect to the "On" position and allow the crankcase
heater to operate a minimum of 8 hours.
Before closing the main power disconnect switch, insure
that the "System"selection switch is in the "Off" position and
the "Fan" selection switch is in the "Auto" position.
Close the main power disconnect switch and the unit
mounted disconnect switch, if applicable.
Installation
21