Pre-Start
RT-SVX39B-EN
27
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.
•
Check all electrical connections for tightness and
“point of termination” accuracy.
•
Verify that the condenser airflow will be unobstructed.
•
Verify that the condenser fan and indoor blower turn
freely without rubbing and are properly tightened on
the shafts.
•
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 maintenance section of this manual for
instructions.
•
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%. Measure
and record the voltage between phases 1, 2, and 3 and
calculate the amount of imbalance as follows:
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:
VD (reading farthest from average) = 221
The percentage of Imbalance equals:
The 2.2% imbalance in this example exceeds the
maximum allowable imbalance of 2.0%. This much
imbalance between phases can equal as much as a 20%
current imbalance with a resulting increase in motor
winding temperatures that will decrease motor life. If the
voltage imbalance is over 2%, 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.
Table 5.
Temperature versus resistance (temperature vs.
resistance is negative)
Temperature
Degrees F° Degrees C°
Nominal
Resistance
-20°
-28.9°
170.1 K - Ohms
-15°
-26.1°
143.5 K - Ohms
-10°
-23.3°
121.4 K - Ohms
-5°
-20.6°
103.0 K - Ohms
0°
-17.8°
87.56 K - Ohms
5°
-15.0°
74.65 K - Ohms
10°
-12.2°
63.80 K - Ohms
15°
-9.4°
54.66 K - Ohms
20°
-6.7°
46.94 K - Ohms
25°
-3.8°
40.40 K - Ohms
30°
-1.1°
34.85 K - Ohms
35°
1.7°
30.18 K - Ohms
40°
4.4°
26.22 K - Ohms
45°
7.2°
22.85 K - Ohms
50°
10.0°
19.96 K - Ohms
55°
12.8°
17.47 K - Ohms
60°
15.6°
15.33 K - Ohms
65°
18.3°
13.49 K - Ohms
70°
21.1°
11.89 K - Ohms
75°
23.9°
10.50 K - Ohms
80°
26.7°
9.297 K - Ohms
85°
29.4°
8.247 K - Ohms
90°
32.2°
7.330 K - Ohms
95°
35.0°
6.528 K - Ohms
100°
37.8°
5.824 K - Ohms
WARNING
Hazardous Voltage!
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.
% Voltage Imbalance =
100 X AV - VD
where;
AV
AV (Average Voltage)
Volt 1 + Volt 2 + Volt 3
3
221 + 230 + 227
= 226 Avg.
3
100 X 226 - 221
= 2.2%
226
