Specifications

8
MOTOR AND OIL COOLING CYCLE
The motor and the lubricating oil are cooled by liquid refriger-
ant taken from the bottom of the condenser vessel (Fig. 3).
Refrigerant flow is maintained by the pressure differential that
exists due to compressor operation. After the refrigerant flows
past an isolation valve, an in-line filter, and a sight glass/mois-
ture indicator, the flow is split between the motor cooling and
oil cooling systems.
Flow to the motor cooling system passes through an orifice
and into the motor. Once past the orifice, the refrigerant is di-
rected over the motor by a spray nozzle. The refrigerant col-
lects in the bottom of the motor casing and is then drained back
into the cooler through the motor refrigerant drain line. An ori-
fice (in the motor shell) maintains a higher pressure in the mo-
tor shell than in the cooler. The motor is protected by a temper-
ature sensor imbedded in the stator windings. An increase in
motor winding temperature past the motor override set point
overrides the temperature capacity control to hold, and if the
motor temperature rises 10 F (5.5 C) above this set point, the
PIC II controls close the inlet guide vanes. If the temperature
rises above the safety limit, the compressor shuts down.
Refrigerant that flows to the oil cooling system is regulated
by thermostatic expansion valves (TXVs). The TXVs regulate
flow into the oil/refrigerant plate and frame-type heat exchang-
er (the oil cooler in Fig. 3). The expansion valve bulbs control
oil temperature to the bearings. The refrigerant leaving the oil
cooler heat exchanger returns to the chiller cooler.
VFD COOLING CYCLE
The unit-mounted variable frequency drive (VFD) is cooled
in a manner similar to the motor and oil cooling cycle (Fig. 3).
If equipped with a unit-mounted VFD, the refrigerant line
that feeds the motor cooling and oil cooler also feeds the heat
exchanger on the unit-mounted VFD. Refrigerant is metered
through an orifice. The refrigerant leaving the heat exchanger
returns to the cooler.
LUBRICATION CYCLE
Summary —
The oil pump, oil filter, and oil cooler make
up a package located partially in the transmission casing of the
compressor-motor assembly. The oil is pumped into a filter
assembly to remove foreign particles and is then forced into an
oil cooler heat exchanger where the oil is cooled to proper op-
erational temperatures. After the oil cooler, part of the flow is
directed to the gears and the high speed shaft bearings; the re-
maining flow is directed to the motor shaft bearings. Oil drains
into the transmission oil sump to complete the cycle (Fig. 4).
Details — Oil is charged into the lubrication system through
a hand valve. Two sight glasses in the oil reservoir permit oil
level observation. Normal oil level is between the middle of the
upper sight glass and the top of the lower sight glass when the
compressor is shut down. The oil level should be visible in at
least one of the 2 sight glasses during operation. Oil sump tem-
perature is displayed on the ICVC (International Chiller Visual
Controller) default screen. During compressor operation, the
oil sump temperature ranges between 125 and 150 F (52 and
66 C).
OPTIONAL
UNIT
MOUNTED
VFD
(VARIABLE
FREQUENCY
DRIVE)
HEAT
EXCHANGER
THERMOSTATIC
EXPANSION
VALVE
(TXV)
ORIFICE
FITTING
MOISTURE/
FLOW
INDICATOR
FILTER
DRIER
FLOAT VALVE
CHAMBER
REFRIGERANT
COOLING
ISOLATION VALVE
MOTOR
CONDENSER ISOLATION VALVE (OPTION)
ORIFICE FITTING
TRANSMISSION
DIFFUSER
GUIDE VANE
MOTOR
GUIDE
VANES
IMPELLER
FLASC CHAMBER
CONDENSER
CONDENSER
WATER
STATOR
ROTOR
OIL
PUMP
COMPRESSOR
COOLER ISOLATION
VALVE (OPTION)
DISTRIBUTION
PIPE
REFRIGERANT
LIQUID
REFRIGERANT
VAPOR
REFRIGERANT
LIQUID/VAPOR
OIL
CHILLED
WATER
OIL
COOLER
OIL
FILTER
VFD COOLING
ORIFICE
Fig. 3 — Refrigerant Motor Cooling and Oil Cooling Cycles
a19-1851