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Multiple fans move air through the coils. They are dy-
namically and statically balanced, direct-drive with cor-
rosion-resistant, glass-fiber-reinforced composite blades
molded into low noise, full airfoil cross section, pro-
viding vertical air discharge from extended orifices for
efficiency and low sound. Each fan is located in a sepa-
rate compartment to prevent cross flow during fan cy-
cling. Guards of heavy gauge, PVC-coated galvanized
steel are provided.
The fan motors are high-efficiency, direct-drive, 6-pole,
3-phase, Class - "F", current-overload-protected, totally
enclosed (TEAO) type with double-sealed, permanently
lubricated ball bearings.
Oil Separator / System
The external oil separator, with no moving parts and
designed for minimum oil carry-over, is mounted in the
discharge line of the compressor. The high pressure dis-
charge gas is forced around a 90 degree bend. Oil is
forced to the outside of the separator through centrifu-
gal action and captured on wire mesh where it drains to
the bottom of the oil separator and into the compressor.
The oil (YORK "L" oil – a POE oil used for all refrig-
erant applications), which drains back into the com-
pressor through a replaceable 0.5 - 3.0 micron oil filter,
and oil supply solenoid, is at high pressure. This high
pressure "oil injection" forces the oil into the compres-
sor where it is gravity fed to the gears and bearings for
lubrication. After lubricating the gears and bearings, it
is injected through orifices on a closed thread near the
suction end of the rotors. The oil is automatically in-
jected because of the pressure difference between the
discharge pressure and the reduced pressure at the suc-
tion end of the rotors. This lubricates the rotors as well
as provides an oil seal against leakage around the ro-
tors to assure refrigerant compression (volumetric effi-
ciency). The oil also provides cooling by transferring
much of the heat of compression from the gas to the oil
keeping discharge temperatures down and reducing the
chance for oil breakdown. Oil injected into the rotor
cage flows into the rotors at a point about 1.2x suction.
This assures that a required minimum differential of at
least 2.0 bar (30 PSID) exists between discharge and
1.2x suction, to force oil into rotor case, a minimum of
0.6 bar (10 PSID) is all that is required to assure pro-
tection of the compressor. Oil pressure is measured as
the difference between suction pressure and the pres-
sure of the oil entering the rotor case.
Maximum working pressure of the oil separator is 31
bar (450 PSIG). A relief valve is installed in the oil
YORK INTERNATIONAL
separator piping. This will soon be incorporated into
the oil separator. Oil level should be above the mid-
point of the "lower" oil sight glass when the compres-
sor is running. Oil level should not be above the top of
the "upper" sight glass. Oil temperature control is pro-
vided through liquid injection activated by the micro-
processor, utilizing a discharge temperature sensor, and
a solenoid valve.
Oil Cooling
Oil cooling is provided by routing oil from the oil sepa-
rator through several rows of the condenser coils and
back to the compressor.
Capacity Control
The compressors will start at the minimum load posi-
tion and provide a capacity control range from 10% -
100% of the full unit load using a continuous function
slide valve. The microprocessor modulates the current
signal to a 3-way pressure regulating capacity control
valve which controls compressor capacity independent
of system pressures and balances the compressor ca-
pacity with the cooling load.
The automatic spring return of the capacity control valve
to the minimum load position will ensure compressor
starting at minimum motor load.
Loading is accomplished by varying pressure through
the capacity control valve to move the slide valve against
the spring pressure to provide stable, smooth loading.
Power and Control Panel
All controls and motor starting equipment are factory
wired and function tested. The panel enclosures are de-
signed to IP55 and are manufactured from powder
painted galvanized steel.
The Power and Control Panel are divided into power
sections for each compressor and associated fans, a con-
trol section and an electrical options section. The power
and control sections have separate hinged, latched, and
gasket sealed doors equipped with wind struts.
Each power compartment contains:
Compressor and fan starting contactors, fan motor ex-
ternal overloads, control circuit serving compressor ca-
pacity control, compressor and fan contactor coils and
compressor motor overloads.
FORM 201.18-NM8
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