e.
Necessary motor-alarm and interlock switches.
f.
One-pole or two-pole thermal-magnetic molded-case circuit breakers
suitable for the operating voltage for control, heater, and light
circuits.
g.
A minimum of eight spare circuit breaker auxiliary contacts, four
normally open (52a) and four normally closed (52b), wired to
interface terminals.
h.
Terminal facilities wired for devices installed in the cabinet,
and to permit corresponding connections of incoming conductors
from remote items of equipment.
i.
A key interlock if indicated.
j.
A switch-operating handle with provisions for locking in either
the open or closed position.
k.
Safety devices as necessary to ensure that the load interrupter
switch is in the open position whenever unit doors are in the open
position.
l.
An interface terminal block wired for required exterior
connections.
m.
Devices specified under specific unit requirements below.
2.5.1.3
Sulfur Hexaflouride (SF6) Interrupter Switchgear
SF6 interrupters shall be of the puffer type where the movement of the
contact plunger will initiate the puff of SF6 gas across the contact to
extinguish the arc. Switchgear shall be provided with a loss-of-pressure
alarm remote as shown on the drawings. Before the pressure in the
interrupter drops below the point where the interrupter cannot open safely
without damage, the switchgear shall activate the loss-of-pressure alarm,
open automatically, and remain in the locked open position until repaired.
The SF6 shall meet the requirements of ASTM D 2472, except that the maximum
dew point shall be minus 60 degrees C minus 76 F (corresponding to 11 ppm
water by volume), with only 11 ppm water by volume, and the minimum purity
shall be 99.9 percent by weight. Switchgear shall have provisions for
maintenance slow closing of contacts and have a readily accessible contact
wear indicator. Tripping time shall not exceed [3] [5] [8] cycles.
2.5.1.4
Vacuum Circuit Interrupter Switchgear
**************************************************************************
NOTE: See IEEE 37.04 for preferred ratings.
**************************************************************************
Vacuum interrupters shall be hermetically-sealed in a high vacuum to
protect contacts from moisture and contamination. Switchgear shall have
provisions for maintenance slow closing of contacts and have a readily
accessible contact wear indicator. Tripping time shall not exceed [3] [5]
[8] cycles.
SECTION 16311A
Page 25
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