Trane Axiom GWS Series, Инструкция по установке, эксплуатации и обслуживанию

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WSHP-SVX015C-EN 45
Measure each leg (phase-to-phase) of the power
supply. Each reading must fall within the utilization
range stamped on the unit nameplate. If any of the
readings do not fall within the proper tolerances, notify
the power company to correct this situation before
operating the unit.
Excessive three phase voltage imbalance between
phases will cause motors to overheat and eventually
fail. The maximum allowable voltage imbalance is 2%.
Measure and record the voltage between phases 1, 2,
and 3 and calculate the amount of imbalance as
follows:
% Voltage Imbalance =
where Average Voltage (AV);
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:
VD (reading farthest from average) = 221
The percentage of Imbalance equals:
The 2.2% imbalance in this example exceeds the
maximum allowable imbalance of 2.0%. This much
imbalance between phases can equal as much as a
20% current imbalance with a resulting increase in
motor winding temperatures 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.
Electrical Phasing (Three Phase
Motors)
The compressor motor(s) and the supply fan motor are
internally connected for the proper rotation when the
incoming power supply is phased as A, B, C.
Proper electrical supply phasing can be quickly
determined and corrected before starting the unit by
using an instrument such as an Associated Research
Model 45 Phase Sequence Indicator and following the
steps below:
• Turn the field supplied disconnect switch that
provides power to the main power terminal block or
to the “Line” side of the optional factory mounted
disconnect switch to the “Off” position.
• Connect the phase sequence indicator leads to the
terminal block or to the “Line” side of the optional
factory mounted disconnect switch as follows;
– Black (phase A) to L1
– Red (phase B) to L2
–
Yellow (phase C) to L3
• Close the field supplied main power disconnect
switch or circuit protector switch that provides the
supply power to the unit.
• 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.
Compressor Crankcase Heaters
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Each compressor is equipped with a crankcase heater.
The proper operation of the crankcase heater is
important to maintain an elevated compressor oil
temperature during the “Off” cycle to reduce oil
foaming during compressor starts. Oil foaming occurs
when refrigerant condenses in the compressor and
mixes with the oil. In lower ambient conditions,
refrigerant migration to the compressor could increase.
When the compressor starts, the sudden reduction in
crankcase pressure causes the liquid refrigerant to boil
rapidly causing the oil to foam. This condition could
damage compressor bearings due to reduced
lubrication and could cause compressor mechanical
failures.
Before starting the unit in the “Cooling” mode, set the
system switch to the “Off” position and turn the main
power disconnect to the “On” position and allow the
crankcase heater to operate a minimum of 8 hours.
Before closing the main power disconnect switch,
insure that the “System” selection switch is in the
“Off” position and the “Fan” selection switch is in the
“Auto” position.
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