Voltage Supply And Voltage Imbalance - Trane IntelliPak WEHE Series Installation, Operation And Maintenance Manual

System Start-up
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.
• Turn the field supplied disconnect switch, located
upstream of the rooftop unit, to the "Off" position.
• Turn the 115 volt control circuit switch 1S1 to the "Off"
position. It is located in the secondary of the 1T1
transformer.
• Turn the 24 volt control circuit switch 1S70 to the "Off"
position. It is located in the secondary of the 1T2 & 1T3
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.
• 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
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:
• Turn the field supplied disconnect switch that provides
power to terminal block 1TB1 or to the factory mounted
disconnect switch 1S14 to the "Off" position.
• Connect the phase sequence indicator leads to the
terminal block or to the factory mounted disconnect
switch as follows:
Table 19.
Phase Sequence Unit Power
Leads Terminal
Black (phase A)
Red (phase B)
Yellow (Phase C)
74
L1
L2
L3
WARNING
Hazardous Voltage!
HIGH VOLTAGE IS PRESENT AT TERMINAL BLOCK 1TB1
OR UNIT DISCONNECT SWITCH 1S14. 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.
• Close the disconnect switch or circuit protector switch
that provides the main power supply to terminal block
1TB1 or to the factory mounted disconnect switch
1S14.
• 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 and Voltage Imbalance

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.
Voltage Imbalance
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:
% Voltage Imbalance =
AV (Average Voltage) =
V1, V2, V3 = Line Voltage Readings
VD = Line Voltage reading that deviates the farthest from
the average voltage.
100 X AV - VD where;
AV
Volt 1 + Volt 2 + Volt 3
3
RT-SVX35H-EN