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Unit Startup
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.
☐ Turn the field supplied disconnect switch, located
upstream of the rooftop unit, to the "Off" position.
☐ Turn the 115 volt control circuit switch 1S2 to the "Off"
position. .
☐ Turn the 24 volt control circuit switch 1S3 to the "Off"
position. It is located in the secondary of the 1T2 - 1T5
transformers.
☐ Turn the "System" selection switch (at the Remote
Panel) to the "Off" position and the "Fan" selection
switch (if Applicable) to the "Auto" or "Off" position.
☐ Check all electrical connections for tightness and "point
of termination" accuracy.
☐ Verify that the condenser airflow will be unobstructed.
☐ Check the compressor crankcase oil level. Oil should
be visible in the compressor oil sight glass. The oil level
should be 1/2 to 3/4 high in the sight glass with the
compressor "Off".
☐ Verify that all refrigerant service valves are back seated
on each circuit.
NOTICE
Compressor Damage!
Excessive liquid accumulation in the suction lines
could result in compressor damage.
Do not allow liquid refrigerant to enter the suction
line.
Do not start the unit in the cooling mode if the ambient
temperature is below the following minimum recommended
operating temperature:
Standard unit with or without HGBP — +45°F
Note: See for minimum outside air temperature.
☐ Check the supply fan belts for proper tension and the
fan bearings for sufficient lubrication. If the belts require
adjustment, or if the bearings need lubricating, refer to
the Service/Maintenance section of this manual for
instructions.
☐ Inspect the interior of the unit for tools and debris.
Install all panels in preparation for starting the unit.
Electrical Phasing
Scroll compressors are phase sensitive. Proper phasing of
the electrical supply to the unit is critical for proper
operation and reliability. The compressor motor is internally
92
connected for clockwise rotation with the incoming power
supply 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.
Important: HIGH VOLTAGE IS PRESENT AT TERMINAL
BLOCK OR UNIT DISCONNECT SWITCH.
☐ Turn the field supplied disconnect switch that provides
power to terminal block or to the unit-mounted
disconnect switch to the "Off" position.
☐ Connect the phase sequence indicator leads to the
terminal block or unit-mounted disconnect switch as
follows:
Phase Sequence Leads
Black (phase A)
Red (phase B)
Yellow (phase C)
☐ Close the disconnect switch or circuit protector switch
that provides the supply power to the unit terminal block
or the unit mounted disconnect switch.
☐ 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.
☐ 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.
Voltage Supply
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.
Unit Power Terminal
L1
L2
L3
RT-SVX073A-EN
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