McQuay WDC

76 Product Manual PM WSC/WDC
3. For open motor unit, an oil reservoir shall collect any oil and refrigerant that leaks
past the seal. A float device shall be provided to open when the reservoir is full,
directing the refrigerant/oil mixture back into the compressor housing. Manufacturer
shall warrant the shaft seal, reservoir, and float valve system against leakage of oil
and refrigerant to the outside of the refrigerating unit for a period of 5 years from the
initial start-up including parts and labor to replace a defective seal and any
refrigerant required to trim the charge original specifications.
4. The starters must comply with Section 1.2 as required.
5. All controllers are to be continuous duty AC magnetic type constructed according to
NEMA standards for Industrial Controls and Systems (ICS) and capable of carrying
the specified current on a continuous basis. The starters shall be:
Autotransformer - The autotransformer starters shall be of the closed transition type and
equipped with multiple taps for 80%, 65%, 50%, and set up for the 65% tap. A clearly
marked timer shall be adjustable from 0 to 30 seconds.
-- Or --
Wye-Delta Closed Transition - The wye contactor shall be capable of handling 33% of the
delta locked rotor current and be equipped with properly sized resistors to provide a
smooth transition. The resistors shall be protected with a transition resistor
protector, tripping in a maximum of two seconds, locking out the starter, and shall be
manually reset. A clearly marked transition timer shall be adjustable from 0 to 30
seconds.
-- Or --
Solid-State Reduced Voltage - Starter shall be furnished with silicon controlled rectifiers (SCR)
connected for starting and include a bypass contactor. When operating speed is
reached, the bypass contactor shall be energized removing the SCRs from the circuit
during normal running. The starter shall be capable of across-the-line starting in an
emergency.
6. Starters shall be coordinated with the chiller package(s) making certain all terminals
are properly marked according to the chiller manufacturer’s wiring diagrams.
7. The starters shall be equipped with redundant motor control relays (MCR) with coils
in parallel. The relays interconnect the starters with the unit control panels and
directly operate the main motor contactors. The MCRs shall constitute the only
means of energizing the motor contacts.