Trane RTAA-100, Installation & Maintenance Manual

Page: 105 / 178

RTAA-SVX01A-EN 105
Pre-Start Checkout
Unit Voltage Power Supply
WARNING
Live Electrical Components!
During installation, testing, servicing and troubleshooting of this
product, it may be 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. Failure to follow all
electrical safety precautions when exposed to live electrical
components could result in death or serious injury.
Voltage to the unit must meet the criteria given in Table 10 . Measure each leg
of the supply voltage at the unit main power fused-disconnect. If the
measured voltage on any leg is not within specified range, notify the supplier
of the power and correct the situation before operating the unit.
CAUTION
Equipment Damage!
Inadequate voltage to the unit may cause control components to
malfunction and shorten the life of relay contact, compressor
motors and contactors.
Unit Voltage Imbalance
Excessive voltage imbalance between the phases of a three-phase system
can cause motors to overheat and eventually fail. The maximum allowable
imbalance is 2 percent. Voltage imbalance is determined using the following
calculations:
= phase with greatest difference from V
ave
(without regard to sign)
For example, if the three measured voltages are 221, 230, and 227 volts, the
average would be:
The percentage of imbalance is then:
This exceeds the maximum allowable (2%) by 0.2%.
% Imbalance
V
x
V
ave
–
( )
x 100
V
ave
------------------------------------------ =
V
ave
V
1
V
2
V
3
+ +
( )
3
-------------------------------------- =
1V
x
221 230 227 + +
3
---------------------------------------
226 =
100 221 226 –
( )
226
--------------------------------------
2.2% =