SCXF-SVX01T-EN
73
Start-up
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.
NOTICE
Compressor Damage!
Failure to follow instructions below will cause the
compressor to operate in a vacuum and result in
compressor damage.
Never manually or automatically pump down system
below 7 psig.
NOTICE
Compressor Damage!
Failure to follow instructions could result in
compressor damage.
Keep crankcase heaters on whenever refrigerant is in
the system.
If crankcase heaters have not been on with refrigerant
in the system, turn the crankcase heaters on for a
minimum of 24 hours before starting compressors.
To start the unit, complete the following steps in order.
Review “Preliminary Refrigerant Charging,” p. , if
applicable. Confirm all steps were completed.
Note: R-410A compressors have belly band crankcase
heaters that must be energized 24 hours before
starting compressor. Power to the unit will energize
the heaters. Heaters will be energized during the off-
cycle as long as the unit has power. Failure to
perform these pre-start instructions could result in
compressor damage.
1. Verify compressor crankcase heaters have been on for
at least 24 hours.
2. Make sure all service valves are open.
3. Attach a thermocouple type temperature sensor on
liquid line close to liquid line service valve. To ensure
an accurate reading, clean line where sensor is
attached. After securing sensor to line, insulate sensor
and line to isolate it from ambient air.
4. Attach service gauges to suction and discharge ports.
5. Check low side pressure. Low pressure cutout opens
below, and closes above, values in Table 28, p. 55. If
the low side pressure is less than the open psig,
refrigerant may need to be added to the suction line
before starting the compressor(s) to close the switch.
SLOWLY meter into the suction line only as much R-
410A as needed to close the low pressure cutout. Use
the VAPOR charging connection. If possible, plan to
use this entire refrigerant bottle on the same unit in
order to minimize fractionalization. Use an accurate
scale to measure and record amount of R-410A added.
6. Switch the field supplied unit disconnect to “OFF”.
Open the unit control box and plug in the reset relay for
only the circuit being started
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.
7. Turn 115 volt control circuit switch “ON”. Close control
box and switch field supplied unit disconnect “ON”. Unit
power should be off no longer than 60 minutes to
prevent refrigerant migration to compressor sumps. If
power is off for longer than 60 minutes, allow time for
crankcase heaters to drive refrigerant from compressor
sumps before starting compressors.
8. Adjust setpoints at the HI.
Note: Sufficient cooling load must be visible to
refrigerant circuit controls for mechanical
refrigeration to operate. If necessary, temporarily
reduce the discharge air setpoint to verify the
refrigeration cycle operation.
9. Check voltage at all compressor terminals to ensure it
is within 10% of nameplate voltage.
10. Check voltage imbalance from these three voltage
readings at each compressor. Maximum allowable
voltage imbalance, phase to phase is 2%.
11. Start the first step compressor only.
12. Check amp draw at compressor terminals. RLA and
LRA are on the unit nameplate.
13. Measure amp draw at evaporator fan motor terminals.
FLA data is on the motor nameplate.
14. As soon as a compressor starts, verify correct rotation.
If a scroll compressor is allowed to run backwards for
even a very short period of time, internal compressor
damage could occur and compressor life could be
reduced. When rotating backwards scroll compressors
make a loud noise, do not pump, and draw about 1/2
expected amps, and low side shell gets hot.
Immediately shut off a compressor rotating backwards
and correct wiring.
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