GE Industrial Solutions Evolution Switchboards - Manuel (Page 10)

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Chapter 2- Installing the Switchboard
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The ground bus is bolted to the uprights of the rear frame
structure. It is arranged so that connections to the station
ground can be made in any unit. A ground lug is included in
each complete equipment for tying the switchboard to the
station ground. Ground-sense relays are recommended for
protection of the switchboard.
W WAARRN NIIN NG G:: The equipment must be adequately
grounded to insure that all parts of the
equipment, other than live parts, are at ground
potential. Failure to observe this precaution can
result in serious injury or death.
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Before any installation work is performed, study all drawings
furnished by the supplier for the particular installation. These
include arrangement drawings (front, end, and plan view),
connection diagrams, and schedule of equipment. Any
material exterior to the equipment that may be required to
meet any local codes (such as railings) is not furnished.
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Align the conduit holes linearly directly over or as close as
possible to the braces. Consider installing any conduits or
sleeves that may be required for future connections.
Run and bend the main cable in the most convenient
orientation, insuring that the main cable has been located
directly up against the cable braces before it connects to
the main cable terminals. Lash the main cable as shown in
Figure 11, using a 3/8-inch nylon rope or a polyester braided
rope having a minimum tensile strength of 2000 lb. Make six
revolutions around the A- and B-phase main cables and six
revolutions around the B- and C-phase main cables.
Continue wrapping the cord around the main cable lashing
and around the cable braces (if applicable), between the
phases. Tie a knot to the cable brace or cable as you
complete the last revolution. All revolutions must be as tight
as possible to prevent whipping during short circuits. For
GenTowerTM connections it is recommended that all cables
outside the equipment be secured together with at least six
revolutions and a span of 15” between secured lengths. The
rope is not provided.
FFiigguurree 1111.. Tying the main cables to the cable brace.
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Observe the following rules about cable installation:
• To prevent heating, there must be no closed loops of
steel around a single conductor or group of conductors
that does not include all the conductors of the circuit,
including the neutral.
• If the conductors must pass through separate holes in a
piece of steel, cut slots between the holes.
• Do not allow cables carrying high currents to come near
instruments or meters, as this may affect their
accuracy.
• Use the minimum length of cable necessary to make
the connections. The increased resistance of longer
cables generates unnecessary heat.
• Check main cable lashing annually.
Cable Brace
15"
Maximum
Main Cable Terminals