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| Transportation
-> Rail
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| New Technically-Advanced Locomotives Rely on More
Copper |
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Copper is helping the railroads gain market share
from long-haul truckers. More than eight tons of copper in each of
the latest, most-powerful locomotives enables them to pull longer
trains faster up steeper grades.
The latest advance in this use of copper is the substitution of AC-induction
drive motors for DC drive motors. To gain higher efficiency and tractive
effort, fabricated copper conductor bars are specified for the rotors
of these three-phase motors instead of aluminum. (The rotors of the
vast majority of induction motors for all uses are made by die casting
aluminum.) The stators (stationary part) of all motors are wound with
copper wire.
These technically advanced locomotives are also more reliable, more
efficient and more resistant to environmental extremes than the prior
generation of locomotives with DC drive motors. America's two manufacturers
of locomotives, General Electric and General Motors, developed AC-induction
drive motors several years ago. Today, this technology is enabling
them to introduce units with six drive motors that will generate 6,000
or more horsepower, 50% more powerful than prior models with DC drive
motors. GE still offers smaller locomotives with DC propulsion systems.
AC Motors Last Longer. Besides ensuring greater tractive power
on the order of 30% and more, the new AC-induction drive motors are
expected to last much longer than DC drive motors, according to N.
Richard Dunteman, general director, Advance Technologies & Locomotive
Systems, GM Electro-Motive Division, LaGrange, Illinois. The six one-hp
AC-Induction motor in the latest GM locomotives are powered by big
AC alternator in turn driven by a single 16-cyclinder diesel, which
also drives a smaller auxiliary generator. All the copper in GE's
and GM's drive motors, main and auxiliary generators and cabling is
high purity, electrolytic tough pitch copper, C11000. In the GM locomotives,
each rotor contains 150 kilograms (330 pounds) of copper and each
stator uses 185 kilograms (410 pounds). The copper in the main generator
weighs 1150 kilograms (2,550 pounds) while that in the auxiliaries
weighs 236 kilograms (525 pounds).
Eight Kilometers of Copper Cable. In addition to all the copper
in the propulsion system, there's more than 8,100 meters (27,000 feet)
of copper power and communications cable in each GM locomotive, including
the heavy duty cables linking the induction motors to the braking
system. About the same amount is in GE's largest locomotives, according
to Bruce Colton, product planner for GE Transportation Systems, Erie,
Pennsylvania. The crew compartments are equipped with refrigerators,
hot plates, air conditioning and heating, which require more copper
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