A.C. Technology in Modern Locomotives

[Anonymous]

Can anyone give me a general overview of how A.C. technology is put to use in moder locomotives such as General Electric AC4400's, or AC6000's?

How is A.C. better then D.C.?

C. Santiago

[spekarik]

AC is better for a few reasons. AC allows the engine to operate a lower speed while exerting its full amount of tractive effort for the train. LIke an AC4400 can produce 150,000 lbs of tractive effort at around 9 mph where as an SD40-2 can only go as slow as 12 mph to produce about 70,000 lbs of tractive effort. The reason DC can't go slower is that the traction motors over heat. The AC units can hall more frieght at a slower speeed, which is great for loading a coal train or running on steep grades. AC units also have fewer engine parts. So maitenence is also cheaper.

[Anonymous]

In regards to your response to A.C. Technology :
AC units also have fewer engine parts. Can you explain that one. A 16-710G3 for DC is the same as for an AC locomotive. Or are you talking about other systems on the locomotvie?

[spekarik]

Actually I don't really know. I remember it in Trians Magazine. It was in one of their "motive power review" issues. But I think the article pertains more to GE than GM. Look in their back issues about two years and you'll find the issue.

[Anonymous]

Actually AC units are a bit more complex internally. They still have the same number of main components. Diesel prime mover, alternator, air compressor, electrical gear, etc. They are actually more complicated and therefore expencsive to maintain. However, they are more reliable and efficient under the right circumstances. I suggest that you get a hold of the November 1998 issue of Trains and read the article on page 62.