Specifications

92 Catalog WSC/WDC-4
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.
Low Voltage (200 through 600 volts) 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.
All Low Voltage starters shall:
6. 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.
8. The main contactors shall have a normally open and a normally closed auxiliary
contact rated at 125VA pilot duty at 115 VAC. An additional set of normally open
contacts shall be provided for each MCR.
9. There shall be electronic overloads in each phase set at 107% of the rated load
amps of each motor. Overloads shall be manual reset and shall de-energize the
main contactors when the overcurrent occurs. The overloads shall be adjustable
and selected for mid-range. Overloads shall be adjusted for a locked rotor trip
time of 8 seconds at full voltage and must trip in 60 seconds or less at reduced
voltage (33% of delta LRA).
10. Each starter shall have a current transformer and adjustable voltage dropping
resistor(s) to supply a 5.0 VAC signal at full load to the unit control panels.
11. Each starter shall be equipped with a line to 115 VAC control transformer, fused
in both the primary and secondary, to supply power to the control panels, oil
heaters and oil pumps.
12. Each starter shall include the following protective devices:
a) Phase failure and reversal protection
b) Stall protection
-OR-
F. Variable Frequency Drive
1. The chiller shall be equipped with a Variable Frequency Drive (VFD) to
automatically regulate each compressor speed in response to cooling load and
compressor pressure lift. The chiller control shall coordinate compressor speed
and guide vane position to optimize chiller efficiency.