Unit Voltage Power Supply; Unit Voltage Imbalance; Unit Voltage Phasing - Trane CGAM Installation & Operation Manual

Unit Voltage Power Supply

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. Measure each leg of the supply voltage at the unit's
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.
NOTICE:
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:
1V x
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 percent.

Unit Voltage Phasing

It is important that proper rotation of the compressors be established before the unit is started.
Proper motor rotation requires confirmation of the electrical phase sequence of the power supply.
The motor is internally connected for clockwise rotation with the incoming power supply phased
A, B, C.
Basically, voltages generated in each phase of a polyphase alternator or circuit are called phase
voltages. In a three-phase circuit, three sine wave voltages are generated, differing in phase by 120
electrical degrees. The order in which the three voltages of a three-phase system succeed one
another is called phase sequence or phase rotation. This is determined by the direction of rotation
of the alternator. When rotation is clockwise, phase sequence is usually called "ABC" , when
counterclockwise, "CBA" .
CG-SVX17D-EN
WARNING
= phase with greatest difference from V (without regard to sign)
ave
Pre-Start Checkout
143