Proper compressor motor electrical
phasing can be quickly determined
and corrected before starting the
unit. Use a quality instrument, such
as the Associated Research Model 45
Phase Sequence Indicator, and
follow this procedure.
1 Press the STOP key on the UCM-
CLD.
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 Terminal
Black (Phase A) L1
Red (Phase B) L2
Yellow (Phase C) L3
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 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 switch two line
leads on the line power terminal
block(s) (or the unit mounted
disconnect). Reclose the main
power disconnect and recheck the
phasing.
CAUTION! 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 indicator.
Water System Flow Rates
Establish a balanced chilled water
flow through the evaporator. The
flow rates should fall between the
minimum and maximum values
given on the pressure drop curves.
Chilled water flow rates below the
minimum values will result in
laminar flow, which reduces heat
transfer and causes either loss of
EXV control or repeated nuisance,
low temperature, cutouts. Flow rates
that are too high can cause tube
damage in the evaporator.
Water System Pressure
Drop
Measure water pressure drop
through the evaporator at the field-
installed pressure taps on the
system water piping. Use the same
gauge for each measurement. Do
not include valves, strainers fittings
in the pressure drop readings.
Pressure drop readings should be
approximately those shown in the
pressure drop charts in the
Installation - Mechanical section.
70 RTAD-SVX01F-E4
Pre-Start Checkout
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