GE AKD-10 Application Manual page 57

<auxiliary relays> <primary and control circuit fuse blocks>
<potential transformers> <control power transformer>. The
section(s) shall have hinged doors over each compartment.
Rear cable and terminal compartment for cable installation
and termination shall be provided. The cable bending space
shall meet the requirements of the National Electrical Code.
Outdoor switchgear
Outdoor switchgear shall be similar to indoor, except that it
shall be fully weatherproof, housed in a factory assembled
outdoor enclosure, have lifting plates at the base of the
structure, hinged aisle doors with rubber gaskets and pad-
locking provisions, asphalt base undercoating on the exterior
bottom, interior lights, space heater in each vertical section,
ground-fault circuit interrupter receptacle, light switch, and
space heater switch. Provide walk-in enclosure to include
front aisle space for breaker maintenance and inspection
running the full length of the equipment, sloping roof, rear
bolted hinged doors, breaker lifting device and storage pro-
vision for the hoist operation crank <hinged rear doors with
lockable T-handle and three point latch>. Front doors shall
be provided at each end of the walk-in enclosure. The aisle
access door at one end shall be the width of two adjacent
sections to allow easy installation or removal of power circuit
breakers from the enclosure. This "double wide" opening shall
have two doors that are hinged on opposite sides. One of
the doors shall be equipped with a panic latch mechanism.
All front doors shall be capable of being padlocked. Provide
<wire mesh over louvers and rodent guards> <thermostat>
<humidistat> <[3/5/7.5/10] kVA control power transformer>.
Bus bars
Main bus and riser bus will be fully isolated from the breaker,
instrument and auxiliary compartments. The bus bar material
shall be copper, fully [tin-plated/ silver plated] after fabrica-
tion, bolted at the connections between the vertical bus and
horizontal bus, and at the point of connection on the vertical
bus where the bus bars supply power to the circuit breaker
compartments. All bolted joints for bus, interconnections and
external connections to the equipment shall be [tin-plated/
silver plated] copper. The bus arrangement shall be designed
to permit future additions.
The vertical bus shall be held rigid in a support structure
of non-hygroscopic and flame retardant molded glass
reinforced polyester.
<An insulated / isolated bus system, which fully insulates the
horizontal main bus with a fluidized epoxy coating and isolates
each phase of the vertical riser bus with molded polyester
glass barriers, shall be provided. Main bus joints shall be
accessible through removable / replaceable covers. No live
connections shall be accessible from the rear except the
breaker load side terminals.>
(Note — Vertical bus in 4000A breaker sections is either
furnished as bare bus or with bus compartment barriers.)
56
<Vertical and horizontal buses shall be isolated from the
cable compartment by glass reinforced polyester barriers.
No live connections shall be accessible from the rear except
the breaker load side termination.>
Continuous current rating will be determined by temperature
rise and limited by ANSI standards and will be demonstrated
by design tests. If a main circuit breaker, bus tie circuit
breaker, or an incoming bus duct or cable is provided, the
continuous rating of the bus shall be equivalent to the frame
size rating of the main breaker, bus tie breaker or incoming
bus duct or cable. All line and load side bussing shall be rated
to carry the full frame size continuous current rating of the
breaker to which they are connected. In addition, breaker
load side bars shall be insulated.
Breaker primary connections shall be silver-plated copper-
to-copper. The bus bars of the main bus are to be braced to
withstand mechanical forces exerted during a short circuit of
[65kA/100kA/150kA/200kA] RMS symmetrical. Other buswork
shall be braced to withstand mechanical forces exerted during
a short circuit equivalent to the maximum interrupting
capacity of the associated circuit breakers, or the maximum
let-through current in the case of the load side of a fused
circuit breaker.
Where a bus sectionalizing breaker is present, the buses on
the two sides of that breaker will be isolated from each other.
Where an incoming line or main breaker is present, the
incoming line conductors shall be isolated from the main bus.
Breaker compartment
Each low voltage power circuit breaker will be mounted in
an individual compartment with grounded metal barriers at
the top, bottom, front and sides and with flame retardant,
track resistant glass reinforced polyester base barrier at the
rear. Each compartment shall be equipped with drawout
rails, stationary breaker contacts, mechanical interlocks, and
necessary control and indicating devices. A guiderail system
shall be used to ensure accurate alignment of the breaker
primary and secondary disconnects during drawout operation.
The drawout mechanism shall retain the removable element
in the connected position and shall overcome the mechanical
resistance of making and breaking the contacts of the self
coupling primary and secondary disconnects. Positive
mechanical interlocks shall prevent the breaker from being
racked in or out unless the breaker is open, and shall prevent
the breaker from being closed while it is being racked in or out.
The circuit breaker cannot be closed except in the connected
or test positions.
The drawout mechanism shall provide for four distinct positions
of the circuit breaker: CONNECT, TEST, DISCONNECT, and
WITHDRAWN. The drawout mechanism shall be capable of
being operated without opening the cubicle door and an
indicator shall be provided on the front of the breaker to show
the position of the circuit breaker. Breaker doors shall be pro-
vided without ventilation slots and shall be able to be closed
when the breaker is in any of the above mentioned positions.