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Flooded type water cooled screw chiller (MIC)
MCAC-CTSM-2018-1
110
b. Refrigerant-cooled oil cooler. Water-cooled oil coolers are not acceptable.
c. Oil pressure regulator.
d. Oil filter with isolation valves to allow filter change without removal of refrigerant charge.
e. Oil sump heater controlled from unit microprocessor.
f. Oil reservoir temperature sensor with main control center digital readout.
g. All wiring to oil pump, oil heater, and controls shall be prewired in the factory.
h. Compressor shall be fully field-serviceable.
C. Motor:
1. Compressor motor shall be of the hermetic, refrigerant cooled, squirrel cage, induction type
suitable for voltage shown on the equipment schedule.
2. Motors shall be suitable for operation in a refrigerant atmosphere and shall be cooled by
atomized refrigerant in contact with the motor windings.
.
3. Full load operation of the motor shall not exceed nameplate rating.
D. Unit-Mounted Wye-Delta Starter
.
The compressor motor starter shall be factory mounted, wired and tested prior to shipment by the
chiller manufacturer.
Customer electrical connection for compressor motor power shall be limited to main power leads
to the starter, and wiring water pumps and tower fans to the chiller control circuit.
a. NEMA 1 enclosure with integral fan cooling and lockable hinged doors.
b. Main power disconnect (non-fused type).
c. Capability to start and stop chiller, pumps and tower fans.
d. 1 kVA control/oil heater transformer.
e. The following are standard features:
1) Phase loss
2) Phase reversal
3) Phase imbalance
4) 3-phase ground fault
5) Phase to phase and phase to ground
6) Current overload
7) Current flow while stopped
8) 3-phase under/over voltage
9) 3-phase digital ammeter/voltmeter
10)
Frequency
E. Unit-Mounted Variable Frequency Drive (VFD)
a. Design:
1) VFD shall be air-cooled, microprocessor-based, pulse width modulated design.
2) Output power devices shall be insulated gate bipolar transistors (IGBTs).
3) Converter section with full-wave fixed diode bridge rectifier shall convert incoming fixed
voltage/frequency to fixed DC voltage.
4) DC link shall filter and smooth the converted DC voltage.
5) Transistorized inverter and control regulator shall convert fixed DC voltage to a square
waveform.
b. Enclosure:
1) Pre-painted, unit mounted NEMA 1 cabinet shall include hinged, lockable doors and
removable lifting lugs.
2) Provisions to padlock main discon
nect handle in the “Off” positions shall be provided.