2.2.5
Metal-Clad Switchgear Outgoing Section
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NOTE: This paragraph may also be used to specify
freestanding switchgear not directly connected to a
unit substation. This paragraph is not intended to
be used for generator control switchgear without
extensive modification and coordination with
applicable diesel engine generator guide
specifications. Specify Category A requirements
when switchgear area is subject to access by the
unsupervised general public. Category B enclosures
must be fence enclosed or in a locked room.
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NOTE: To help determine whether metal-clad
switchgear or metal-enclosed interrupter switchgear
is more appropriate for a project, consider that the
primary applications for interrupter switchgear are
where there are no instantaneous relaying and where
switching is infrequent. Also interrupter
switchgear is significantly less costly than
metal-clad switchgear.
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IEEE C37.20.2 for metal-clad medium-voltage [vacuum][SF6] circuit breaker
type, insulated for [5][15] kV for use on [_____] kV system. Each steel
unit forming part of the switchgear structure shall be self-contained and
shall house [one-high][two-high] breaker or instrument compartments, and a
full height center and rear compartment for the buses and outgoing cable
connections. For two-high breaker units, provide a removable metal barrier
to separate the two cable circuits. Equip individual circuit-breaker
compartments with drawout contacts, rails, disconnecting mechanism, and a
cell interlock to prevent moving the removable element into or out of the
"connected" position while the circuit breaker is closed. Provide a steel
door for each breaker compartment. Enclosures shall be designed for
[indoor][outdoor] location and shall conform to the Category [A][B]
requirements of Table A1 of Appendix A to IEEE C37.20.2. Design the
structure to allow for future additions. Provide laminated plastic
nameplates for each relay, switch, meter, device, and cubicle to identify
its function. Provide permanent labels for wiring and terminals
corresponding to the designations on approved shop drawings. Mount
nameplates on each circuit breaker compartment door.
a.
Phase buses and connections: Mount bus structure on insulated supports
of high-impact, non-tracking, high-quality insulating material and
brace bus to withstand the mechanical forces exerted during
short-circuit conditions when connected directly to a source having
maximum of [_____] amperes rms symmetrical available. Bus bars shall
be rated [_____] amperes and shall be high conductivity copper having
silver plated joints. Make bus bar connections from main buses to the
incoming circuit breaker studs. Equip outgoing circuit breaker studs
with mechanical clamp type cable connectors for the size of cables
shown. Provide cable supports for outgoing cables. Wire secondary
circuits, including heater circuits, to terminal blocks. Terminal
blocks shall be readily accessible for making external connections as
required.
SECTION 16361N
Page 23
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