RT-SVX070B-EN
43
Pre-Start
Use the checklist provided below in conjunction with the
“General Unit Requirements” checklist to ensure that the
unit is properly installed and ready for operation.
WARNING
Hazardous Voltage w/Capacitors!
Failure to disconnect power and discharge capacitors
before servicing could result in death or serious
injury.
Disconnect all electric power, including remote
disconnects and discharge all motor start/run
capacitors before servicing. Follow proper lockout/
tagout procedures to ensure the power cannot be
inadvertently energized. Verify with a CAT III or IV
voltmeter rated per NFPA 70E that all capacitors have
discharged.
•
Check all electrical connections for tightness and “point
of termination” accuracy.
•
Verify that the condenser airflow will be unobstructed.
WARNING
Rotating Components!
Failure to disconnect power before servicing
could result in rotating components cutting and
slashing technician which could result in death or
serious injury.
During installation, testing, servicing and
troubleshooting of this product it may be
necessary to work with live and exposed rotating
components. Have a qualified or licensed service
individual who has been properly trained in
handling exposed rotating components, perform
these tasks.
•
Verify that the condenser fan and indoor blower turn
freely without rubbing and are properly tightened on the
shafts.
•
Verify that a condensate trap is installed and the piping
is properly sized and pitched.
•
Verify that the correct size and number of filters are in
place.
•
Inspect the interior of the unit for tools and debris and
install all panels in preparation for starting the unit.
Voltage Imbalance
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 percent.
Measure and record the voltage between phases 1, 2, and
3 and calculate the amount of imbalance as follows:
% Voltage Imbalance =
where;
100 x AV - VD
AV
AV (Average Voltage) =
Volt1 + Volt2 + Volt3
3
•
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 + 221
3
= 226 Avg.
VD (reading farthest from average) = 221
The percentage of Imbalance equals:
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:
