York YK Manual page 110

FORM 160.75-EG1 (519)
Guide Specifications (Cont'd)
Programmable
• Local Motor Current Limit
• Pulldown Demand Limit
• Pulldown Demand Time
Other features include: low line voltage; 115-volt control transformer; three-leg sensing
overloads; phase rotation and single-phase failure protection; high temperature safety
protection; motor current imbalance and under voltage safeties; open and close SCR
protection; momentary power interruption protection. The Solid-State Starter is cooled by
a closed loop, fresh water circuit consisting of a water-to-water heat exchanger and cir-
culating pump. All interconnecting water piping is factory-installed and rated for 150 psig
(10.3 barg) working pressure.
(Optional) Unit-mounted circuit breaker includes ground fault protection and provides
65,000 amps. Short circuit withstand rating in accordance with UL Standard 508. A non-
fused disconnect switch is also available. Both options have keyed locks for safety.
FACTORY-INSTALLED COMPRESSOR MOTOR STARTER (2300V & 4160V/3/60HZ
OR 3300V/3/50HZ- UNIT MOUNTED FOR H9 COMPRESSOR OR LARGER ONLY)
The chiller manufacturer shall furnish a reduced-volt-age, Medium Voltage Solid-State
Starter, in accordance with the chiller manufacturer's starter specifications. The starter
shall be of modular construction with complete access to all parts. The starter shall be
tested and the design starting current and overload settings adjusted at the factory. The
starter shall provide, through the use of six in-line (not inside the Delta) silicon controlled
rectifiers (2 per phase), a smooth acceleration of the motor without current transitions or
transients.
The following protective devices and convenience items shall be factory mounted and
wired to the starter:
A. 3-leg sensing electronic overloads – shuts unit down if current exceeds 105% of FLA
to protect the motor windings.
B. Phase rotation protection circuit – denies start-up when detecting incorrect power wir-
ing phase sequence to the starter which could cause reverse motor rotation and dam-
age the equipment.
C. Single-phase failure protection circuit – ensures against motor burnout by shutting the
unit down if power loss occurs in any of the incoming lines during start-up.
D. High temperature safety protection system – temperature activated switches on heat
sinks will shut the unit down if the SCR temperature exceeds acceptable limits.
E. 3-phase digital ammeter and digital voltmeter readout via control center – easily cross-
check design current and voltage limitations against supply characteristics.
F. Starter mounted load break rated input disconnect switch with interlocked lockable
handle. Positive disconnecting means shall be visible from outside the enclosure, in
operator area. All doors shall be interlocked with the disconnecting means.
G. Open/Shorted SCR Protection – Failed semiconductor devices are automatically de-
tected and reported via the Control Center.
110 JOHNSON CONTROLS