Trane INTELLIPAK ™ ™ ™ ™ ™ Commercial Single-Zone Rooftop Air Conditioners with CV or VAV Control - Manual (Page 62)

60
Unit Start-Up (Continued)
[ ] 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 require-
ments 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 name-
plate. If any of the readings do not fall within the proper tol-
erances, notify the power company to correct this situation
before operating the unit.
WARNING
Live Electrical Components!
During installation, testing, servicing and troubleshoot-
ing of this product, it may be necessary to work with live
electrical components. Have a qualified licensed electri-
cian or other individual who has been properly trained in
handling live electrical components perform these
tasks. Failure to follow all electrical safety precautions
when exposed to live electrical components could result
in death or serious injury.
Voltage Imbalance
Excessive three phase voltage imbalance between phases
will cause motors to overheat and eventually fail. The maxi-
mum allowable voltage imbalance is 2%. Measure and
record the voltage between phases 1, 2, and 3 and calcu-
late the amount of imbalance as follows:
% Voltage Imbalance = 100 X AV - VD where;
AV
AV (Average Voltage) = Volt 1 + Volt 2 + Volt 3
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 + 227 = 226 Avg.
3
VD (reading farthest from average) = 221
The percentage of Imbalance equals:
100 X 226 - 221 = 2.2%
226
The 2.2% imbalance in this example exceeds the maximum
allowable imbalance of 2.0%. This much imbalance be-
tween phases can equal as much as a 20% current imbal-
ance with a resulting increase in motor winding tempera-
tures 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.