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metsfan

AC vs DC, pros, cons, why!?

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What, aside from the traction motor feed current, is the difference between say a 4400 hp AC loco, and a 4400 DC loco? I understand AC can be single, dual or 3 phase (or more!), and that DC might be simpler, but i never really understood, and how does it relate to how power lashups are decided upon?

 

- A

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What, aside from the traction motor feed current, is the difference between say a 4400 hp AC loco, and a 4400 DC loco? I understand AC can be single, dual or 3 phase (or more!), and that DC might be simpler, but i never really understood, and how does it relate to how power lashups are decided upon?

 

- A

 

AC allows for higher tractive effort, and i believe they are more efficient, but they require more complicated equipment. AC locos also have the potential to regenerate the brake energy, something that DC can't do (but you know that).

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cost and easier to run but CN is the only class one not to go to ac yet

What about GO Transit and VIA Rail?

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Interesting.

 

I have a very low level of respect for CN, they seem to be the worst 'road out there, i prefer CP.

 

That aside, DC units are i guess simpler to maintain i guess?

 

- A

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What about GO Transit and VIA Rail?

 

Passenger railroads have very little use for an AC unit. Which always puzzles me as to why NJT bought them since they get nothing out of them that a DC unit would not have been able to accomplish.

 

It should be noted that when pairing an AC unit with a DC unit use loose all the extra functions the AC unit might have broughtAlso noted is that NS did not enter the AC market until last year, as the SD80MAC's were given to them they never bought them, their first AC purchase was the ES44AC, which of course all blew up on them except for I believe two and were taken out of service, so it will be interesting to see what NS prefers in the future when buying more power. Personally I hope they buy more SD70M-2's but thats just me.

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So basically AC units are simply slightly better at slowing long trains down, and slightly higher tractive effort? If those are not needed, you'd go with a DC unit?

 

- A

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You can replace two DC units with one AC unit, AC units however don't have the life expectancy of DC units, those are another point thats over looked, do you buy a fleet that you have to replace in 15-20 years or do you buy a locomotive that you will be able to keep around for the long haul, though with many companies buying service contracts from the maker its really up to what they need. AC units are great in coal and intermodal service but with a manifest where you're switching out yards you might not need all that extra effort.

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Ah, i get it now.

 

So, one last question here...

 

The EMD DD and other mega-locos, what are their power systems usually, or is there no "usually"?

 

- A

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You can replace two DC units with one AC unit, AC units however don't have the life expectancy of DC units, those are another point thats over looked, do you buy a fleet that you have to replace in 15-20 years or do you buy a locomotive that you will be able to keep around for the long haul, though with many companies buying service contracts from the maker its really up to what they need. AC units are great in coal and intermodal service but with a manifest where you're switching out yards you might not need all that extra effort.

 

Thats why CN prefers DC as they tend to run cuts of mixed freight eg cut of intermodel with cuts of autoracks and other freight. CN runs the least amount of unit trains over the rest of the Class Ones. BNSF and UP run the most Unit trains reason why they had most of the AC fleet

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I understood all that already but the point your forgetting with CN is that its not that they can't run longer trains its the fact that they choose to run shorter trains.

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I understood all that already but the point your forgetting with CN is that its not that they can't run longer trains its the fact that they choose to run shorter trains.

 

Not really they have been running a few 11500 feet long trains from Toronto to Winnipeg and they dont let the yards fill up they are a load and go railroad

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I have looked at their operating strategy, one of the thing that stood out in my mind was that their trains are routinely shorter than other class ones yet they haul the same amount of tonnage, upon talking to a friend working for CN in the Chicago area he told me they do this purposely and I was not reading wrong. I really don't like CN though, they are the worst railroad to work for.

Edited by kaback9
taking that last bit out

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Not really they have been running a few 11500 feet long trains from Toronto to Winnipeg and they dont let the yards fill up they are a load and go railroad

 

I have looked at their operating strategy, one of the thing that stood out in my mind was that their trains are routinely shorter than other class ones yet they haul the same amount of tonnage, upon talking to a friend working for CN in the Chicago area he told me they do this purposely and I was not reading wrong. I really don't like CN though, they are the worst railroad to work for.

 

After a 1.93 mile long CN train derailed going over the divide (rocky mountains) the canadian government restricted the length of their trains. They have been under close scrutiny from the transport ministry after several infrastructure incidents (bridge collapses), resulting in polluted rivers etc. They remind me of the worst parts of every railroad that ever was in north america, and i'm betting they will be taken over by the government if they don't shape up a lot really soon. :tdown:

 

As for the locos they use, i don't like the new mostly black livery, thats about it as far as opinion. They do have a large number of yard slugs, which i see as kinda weird, why not just get smaller more useful yard switchers?

 

My favorite aspect of CN as far as power: 2459-CNIC.jpg

 

Oh wait, it's IC.... :eek: :cool::):)

 

- A

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That is almost to the exact word the thing I read from CN! Thanks for clearing that info up.

 

As for power nothing beats an IC SD70 with the IC Logo at least they are keeping them and repainting them though not like what they did to those WC SD45's:cry:

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There are luckily two survivors from their fleet one in Illinois in WC paint and one in Minnesota going to be painted back into Northern Pacific. I'm glad its going back to its colors, it makes me glad to know Conrail turned their 45-2's into 40-2's otherwise I think they all may have gone to the scrapper. Instead 8 soldier on(6 NS, 2 CSX)!

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After a 1.93 mile long CN train derailed going over the divide (rocky mountains) the canadian government restricted the length of their trains. They have been under close scrutiny from the transport ministry after several infrastructure incidents (bridge collapses), resulting in polluted rivers etc. They remind me of the worst parts of every railroad that ever was in north america, and i'm betting they will be taken over by the government if they don't shape up a lot really soon. :tdown:

 

As for the locos they use, i don't like the new mostly black livery, thats about it as far as opinion. They do have a large number of yard slugs, which i see as kinda weird, why not just get smaller more useful yard switchers?

 

My favorite aspect of CN as far as power: 2459-CNIC.jpg

 

Oh wait, it's IC.... :eek: :cool:B):)

 

- A

 

 

They will not be taken over and thats when CN was trying to run 13000 ft trains in the west now they are run 11000 feet trains in Northern Ontario. On a side note CN is trying to buy Ontario Northland from the Ontario Government

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Yeah CN is pretty stable, if they were being taken over there probably would have been some uproar in the US about having a Canadian railroad making a profit in the US while under the control of a foreign in this case the Canadian government. Also I'm sure the STB would have blocked their relatively recent purchase of the EJ&E.

 

Joe you would know more about this than I do but hasn't CN been trying to buy Ontario Northland since earlier in the decade?

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Yeah CN is pretty stable, if they were being taken over there probably would have been some uproar in the US about having a Canadian railroad making a profit in the US while under the control of a foreign in this case the Canadian government. Also I'm sure the STB would have blocked their relatively recent purchase of the EJ&E.

 

Joe you would know more about this than I do but hasn't CN been trying to buy Ontario Northland since earlier in the decade?

 

Yes CN tired to buy ONR in the past but it didnt work out and btw CN is publicly traded company since 1995 when the Canadian Government had a public stock offering. Even tho CN is based in Montreal more the 60% of its shareholders are Americans. The EJ&E was a good fit for CN as it connected CN's GTW,IC and WC lines.

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