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32
Installation
01.4IB.51000C
PowlVac® Metal-Clad Switchgear
5kV & 15kV
o. c
ontrol
c
ABleS
Space is provided for control cables to enter
the switchgear from either the top or the
bottom of the units. See drawings furnished
with the switchgear for detailed dimensions
and location of the control cable entry space.
When control conduits enter the unit from
below, entry space is located on each side of
the unit near the front inside the secondary
enclosure. The conduit should not extend
more than 1 inch above the floor. The control
cables may be pulled through the conduits
before or after the switchgear is installed,
whichever is more convenient. However, if
the cables are pulled before the switchgear is
installed, they must be threaded through the
opening in the switchgear floor plate when
setting the switchgear in place.
All control wiring that passes through an area
designated as high voltage (part of the primary
circuit) must be shielded or run through a
wireway to maintain the metal-clad isolation
requirements.
Connect the cables to the terminal blocks in
accordance with the wiring diagrams furnished
for the specific job.
If the control conduits enter from above, drill
the top cover plate of the front enclosure to
suit the conduits, being careful not to damage
existing wire bundles. The top cover may
be removed temporarily to facilitate drilling.
Fasten the conduits to the cover with locknuts.
The cables from the control power source to
the switchgear should be large enough to
avoid excessive voltage drop when the circuit
breakers are operated.
Where units have been split for shipment, any
control or other secondary leads that must
connect across the split will be arranged with
terminal blocks in a convenient location so that
the wires can be reconnected. The wires will be
cut to length and formed before being folded
back so that a minimum time will be required
for reconnecting them.
p. S
urGe
p
rotectIon
It will be the responsibility of the purchaser
to provide suitable surge arrestors to protect
the switchgear from damage due to lightning
or other surges. When surge arrestors are
furnished as part of the switchgear, the primary
cable termination will be insulated at the
factory unless it must be disconnected for
shipment. When this connection is completed
in the field, it will be necessary to insulate the
primary connection before the switchgear is
energized. Insulating boots will normally be
supplied to insulate connections.
Q. r
oof
e
ntrAnce
B
uShInG
When furnished, roof entrance bushings are
frequently removed from the switchgear for
shipment, and the mounting openings covered
with shipping covers. To install the roof
entrance bushings, remove and discard the
shipping covers and install the roof entrance
bushings in their place. Use the gasket
materials furnished with the roof entrance
bushings to ensure a weather proof installation.
If the bushings have fixed terminals, which
cannot be rotated in the field, be sure that the
bushing terminal is aligned properly before
bolting the bushing in place. The mounting
flanges of roof entrance bushings typically
have six or more evenly spaced bolt holes,
allowing adjustment every 60° or less.