Taut-band suspension shall be provided where this design is available.
Zero adjustments accessible from the front without removal of covers shall
be provided for instruments with spring control. AC instruments shall be
designed and calibrated for use on 60-Hz circuits and for operation from
120-volt secondaries of voltage transformers and 5-ampere secondaries of
current transformers, as shown. AC instrument potential coils shall be
designed for continuous operation at 150-volts, and AC instrument current
coils shall be capable of withstanding 40 times rated current for two
seconds. Instrument identification legends shall be neatly printed on the
dials or on separate legend plates inside the cases. Instrument scales
shall be as specified, or as approved if scales are not specified, and
appropriate for the application.
2.5.13.2
Rectangular Switchboard Instruments
Instruments shall be 108 mm 4-1/4 inch minimum rectangular type with
nominal 250-degree scale angle and zero-left scales
2.5.13.3
AC Voltmeters
AC voltmeters shall be provided with expanded type scales.
2.5.14
Nameplates
Each item of equipment mounted on the switchgear which does not have a
suitable designation included as an integral part of the device shall be
provided with an engraved nameplate or with other approved suitable means
of identification. Nameplates shall be made of laminated sheet plastic or
of anodized aluminum approximately 3 mm 1/8 inch thick, engraved to provide
white letters on a black background. Equipment of the withdrawal type
shall be provided with nameplates mounted on the removable equipment in
locations visible when the equipment is in place. The nameplates shall be
fastened to the panels in proper positions with black finished roundhead
screws.
2.6
METAL-ENCLOSED BUS
2.6.1
General
The electrical connections between the 480-volt terminals of the station
service transformers and the power supply air circuit breakers in the main
480-volt station service switchgear shall consist of 3-phase,
nonventilated, nonsegregated-phase, metal-enclosed bus conforming to the
applicable requirements of NEMA SG 6 and [IEEE C37.20.1][IEEE C37.20.2][
IEEE C37.20.3]. The bus shall be rated 600 volts AC [1,600] [_____]
amperes continuous current carrying capacity, and the momentary current
rating shall be not less than [25,000] [50,000] rms asymmetrical amperes.
The metal-enclosed bus shall be fabricated in sections to suit the
arrangement shown. Necessary frames and flange sections required at the
bus terminals at the transformers and switchgear, and all required
structural supports for the bus structures shall be provided. Expansion
sections shall be provided wherever the bus crosses a contraction joint in
the building. All electrical and mechanical connections at the station
service transformers shall be coordinated with the station service
transformer manufacturer. Flexible connections shall be provided at the
switchgear and transformer connections. Connections at the switchgear
shall be coordinated with the design of the 480-volt station service
switchgear.
SECTION 16404A
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