Unit Voltage Imbalance; Unit Voltage Phasing; Water System Flow Rates; Water System Pressure Drop - Trane R Series Installation Operation & Maintenance

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%. Voltage imbalance is
determined using the following
calculations:
% Imbalance =
[(Vx - V ave) x 100/V ave]
V ave = (V1 + V2 + V3)/3
Vx = phase with the greatest
difference from V ave (without
regard to the sign)
For example, if the three measured
voltages are 401, 410, and 417 volts,
the average would be:
(401+410+417)/3 = 410
The percentage of the imbalance is
then:
[100(410-401)/410] = 2.2%
This exceeds the maximum
allowable (2%) by 0.2%.

Unit Voltage Phasing

WARNING
It is imperative that L1, L2, and L3 in
the starter be connected in the A-B-
C phase sequence to prevent
equipment damage due to reverse
rotation.
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.
When rotation is clockwise, the
phase sequence is usually called
"ABC;" when counterclockwise,
"CBA."
RLC-SVX02G-E4
Pre-Start Checkout
This direction may be reversed
outside the alternator by
interchanging any two of the line
wires. It is this possible interchange
of wiring that makes a phase
sequence indicator necessary if the
operator is to quickly determine the
phase rotation of the motor.
1. Press the STOP key on the
CH.530.
2. Open the electrical disconnect or
circuit protection switch that
provides line power to the line-
power terminal block(s) in the
starter panel (or to the unit-
mounted disconnect).
3. Connect the phase-sequence
indicator leads to the line power
terminal block as follows:
Phase Sequence Lead
Black (Phase A)
Red (Phase B)
Yellow (Phase C)
4. Turn power on by closing the unit
supply-power fused-disconnect
switch.
5. Read the phase sequence on the
indicator. The "ABC" LED on the
face of the phase indicator will
glow if the phase is "ABC."
WARNING
To prevent injury or death due to
electrocution, take extreme care
when performing service
procedures with electrical power
energized.
6. If the "CBA" indicator glows
instead, open the unit main-
power disconnect and
interchange two line leads on the
line-power terminal block(s) (or
the unit mounted disconnect).
Reclose the main-power
disconnect and recheck the
phasing.
Do not interchange any load leads
that are from the unit contactors or
the motor terminals. Doing so may
damage the equipment.
7. Reopen the unit disconnect and
disconnect the phase-sequence
indicator.
Water-System Flow Rates
Establish a balanced chilled-water
flow through the evaporator. The
flow rates should be between the
minimum and maximum values
given on the pressure-drop curves.
Water-System Pressure
Drop
Terminal
L1
Measure the water-pressure drop
through the evaporator at the field-
L2
installed pressure taps on the
L3
system water piping. Use the same
gauge for each measurement. Do
not include valves, strainers, or
fittings in the pressure-drop
readings.

CH.530 Set-up

Use of the TechView service tool is
required to view and adjust most
settings. Refer to the CH.530
Operation manual for instruction on
adjustment of the settings.
CAUTION
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