- REPAIR - FABRICATION - DESIGN - MODIFICATION
With CURRENT-CARRYING ARMS,
the arm body becomes the conductor between the cables and contact
pad and thus conventional bus tubes are eliminated. Regardless of
the design, current carrying arms are lighter in weight than conventional
mast arms and have decreased maintenance requirements due to the
exclusion of tubes, supports, structures and many insulated areas.
Electrically, hot arms reduce resistance and reactance in
the secondary circuit.
Both copper clad-steel and aluminum
mast arms are repairable by a competent specialist. And while maintenance
requirements are decreased, these arms do tend to accumulate sludge
in much the same way as conventional arms. With this design it is
particularly important to keep the internal chambers clean so the
arms can be properly cooled... as excessive heating might cause
problems to the dissimilar metals and weld seams.
Plates are cut to size and welded together - steel
on the inside to form a water-tight box and copper on the outside
to make the entire outer surface a single, uniform conductor. Thus
the rectangular arm bodies are designed to perform all necessary
structural and electrical functions.
These Copper Clad-Steel arms,
fabricated at Erie Copper Works’ plant, are made from a carbon steel
plate with explosion-bonded copper cladding.
arms are fabricated from flat or formed plates of a specific
alloy. In addition to the required mechanical and structural properties,
the aluminum alloy must have chemical properties, which impedes
corrosion sometimes caused by contact with water. The main advantage
aluminum has over copper is its light weight and strength. The
disadvantage with aluminum compared to copper is the lower electrical
conductivity. Alloy 5083 aluminum is about 30% IACS whereas
or OFHC coppers have electrical conductivities ranging between
94 and 100% IACS.
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