Thanks, Blue Streak, this is exactly the kind of answer I was looking for.
aegrotatio Interesting, I didn't think of feeding it back to the utility. I wonder if the hydro dams on the NEC feed their surplus to the utility. But hold on, at least with the NEC, do they really feed 25 Hz back to the utility? Doesn't that need a dedicated set of converters?
Interesting, I didn't think of feeding it back to the utility. I wonder if the hydro dams on the NEC feed their surplus to the utility.
But hold on, at least with the NEC, do they really feed 25 Hz back to the utility? Doesn't that need a dedicated set of converters?
The way regenerative braking is handled is simple in concept but takes some high power management and now electronics. 25Hz 12Kv is the nominal power settings for the NEC. Any train "A" load on the system (actually various segments) will lower the voltage. The regenerative braking system on train "B" will try to increase the voltage back to 12Kv +. If the voltage goes above ( some value that I've forgotten maybe 12.9Kv) the regenerative eases off and dynamic brakes on the loco or even dynamics on Silverliner Vs and other EMUs take over. Then when CAT voltage goes down -- back to regenerative. This switching back and forth can be almost instantaneous.
Some power converter stations (use motor generator sets or solid state TRs) and also the hydro generator stations can also feed power back to the 60Hz grid when the voltage goes up.
The ebb and flow of load and regenerative power of many different trains is a management nightmare especially on the out of date PRR NEC electric grid. It takes a deft hand and lots of electronics. The NH-BOS section is probably much easier to manage.
If you think loco dispatch is hard imagine a power desk if things do not go as planned or programed when something in the grid breaks!! And Amtrak has to co-operate with SEPTA as well even though the 2 systems are mainly separate. NJ Transit's 25KV is separate but can have the same problems. One Amtrak Power desk is at 30th St.
Recall that electric railroads use purchased power, and that if there is no train on the line the power can be returned to the grid for general use.
Where does the energy dissipate when fed back into the catenary?
I recently learned that the WMATA Metro dynamic braking feeds into wayside battery cabinets but I understand that to be capacitor cabinets, as there was no real way to feed the energy back into the third rail. Either that or super-powerful fans blowing on resistor grids under the rail cars.
I'd really like to know the reality of dynamic braking into catenary and third rail. It sounds untrue for energy saving.
Link to the same fella's 'Southwest Railfan' web page on the Black Mesa & Lake Powell, which is another operation that uses 6,000 HP GE E60-type electric locomotives, but at 50 KV instead. At something like 78 miles, it's also much longer than any of the others referenced above:
http://www.trainweb.org/southwestshorts/bmlp.html
Thanks for those links, Sam - I'd seen some of these photos of the BM&LP before, but I don't know that I ever saw the whole web page and description, etc. He also has a list of several other webpages on misc. rail operations, at -
http://www.trainweb.org/southwestshorts/home.html
- Paul North.
Link is to an E60C running at TXU's Martin Lake Tx Line: http://www.trainweb.org/southwestshorts/txue60.html
They have three of these former NdeM RR electrics which were for an electric line in Mexico whic was never built. They also are reported to have GE U23B's for Ash Train Duty, and maybe even some former BNSF C30-7's on the property.
At the Montecello, Tx plant and Lignite mine they have some E25B's running as well:
http://www.trainweb.org/southwestshorts/txue25bmonticello.html
As one of the previous posters pointed out, a European practiced mirrored in these electric operations is the use of single electric motors on their trains. their operations run 24/7 and apparently enjoy a high reliability on their utilizations.
Link here is to the SouthWest railfan site for the TXU Montecello Operation:
http://www.trainweb.org/southwestshorts/txumonticello.html
This link is to the same SWRF website for the TXU Martin Lake Operation:
http://www.trainweb.org/southwestshorts/txumartinlake.html
If the energy is recaptured, and there is no other train on the system to use that energy, what's the point or feeding back into the catenary besides dynamic braking? And, when there is no other load, how is the load dissipated in the catenary when going downhill?
erikemLocomotive inverters typically run off an 800VDC bus, which is too low for heavy electrification. Components are currently (pun not intended) available that would allow inverters to run directly off a 3,000VDC catenary, but that's also too low for long haul electricfications.Having said this, AC traction motor technology would make it cheaper to produce new freight electrics as the power conversion (e.g. transformer) only needs to provide a constant voltage feed to the inverter as opposed to variable voltage and current supply needed by DC traction motors.
Locomotive inverters typically run off an 800VDC bus, which is too low for heavy electrification. Components are currently (pun not intended) available that would allow inverters to run directly off a 3,000VDC catenary, but that's also too low for long haul electricfications.
Having said this, AC traction motor technology would make it cheaper to produce new freight electrics as the power conversion (e.g. transformer) only needs to provide a constant voltage feed to the inverter as opposed to variable voltage and current supply needed by DC traction motors.
The newest European electrics are using a 6Kv DC link. That is why their performance under a 3Kv DC overhead is less than on any AC overhead.
fredswain An electric motor is rated very differently than an internal combustion engine. A motor rated at "1000 hp" is rated to produce this for a certain amount of time. If it is rated at this for 1 hour, it may actually be capable of 2 or even 3 times that amount of power for shorter durations. I assure you that a traction motor rated at 1000 hp is capable of far more than that but not full time.
A few months ago I asked about this here to try to get a better handle on quantifying that overload capability, and some members were kind enough to provide detailed information. Of course, ''it all depends'' on the locomotive, motor specs, the particular service and environmental conditions = outside air temperature at the moment, etc. Nevertheless, to summarize as best as I can recall - without going back and looking it up, a doubling of the power output could not be sustained for longer than 5 or 10 minutes, and a 10 or 20 percent increase might be OK for a half-hour to an hour, but not longer.
Also, this applies to 'universal' = series-wound DC motors and similar = commutator AC motors only, I believe*. I don't believe it applies to AC induction motors, which are 'self-limiting' as I understand it.
*I'm not an electrical engineer, and have no pretensions of being one, so if I'm wrong or less than complete or correct with any of this, anyone who knows the subject better please feel free to jump in with comments and corrections, etc.
ICLandInterestingly, the modern AC traction motor diesel-electric will likely reduce the costs of Electrification if and when railroads ever get around to it, ironically by lowering the costs of the motive power and permitting the use of high voltage DC overhead instead of AC, since the inverters to take advantage of a DC supply system are already built into the off-the-shelf AC diesel-electric. The use of high voltage DC will significantly reduce the physical cost of the building the overhead.
Interestingly, the modern AC traction motor diesel-electric will likely reduce the costs of Electrification if and when railroads ever get around to it, ironically by lowering the costs of the motive power and permitting the use of high voltage DC overhead instead of AC, since the inverters to take advantage of a DC supply system are already built into the off-the-shelf AC diesel-electric. The use of high voltage DC will significantly reduce the physical cost of the building the overhead.
An electric motor is rated very differently than an internal combustion engine. A motor rated at "1000 hp" is rated to produce this for a certain amount of time. If it is rated at this for 1 hour, it may actually be capable of 2 or even 3 times that amount of power for shorter durations. I assure you that a traction motor rated at 1000 hp is capable of far more than that but not full time.
http://www.northeast.railfan.net/images/gm1976a.jpg
EDIT: *"Critters" are usually small low-HP industrial locomotives by oddball, specialized, or very small volume manufacturers, such as Plymouths, Whitcombs, etc. - see http://www.railroadinfo.com/critter-definition.html The GM10 fits none of those criteria, and is pretty much the exact opposite - hence the correction. - PDN
Thomas 9011 Interesting topic.Horsepower and locomotives are often a confusing subject.Electric locomotives may have a lot of horsepower but you are always going to be limited by how much you can pull by how much your locomotive weighs.It wouldn't matter if you had a 30,000 hp locomotive.If your locomotive is going to slip the wheels trying to pull a heavy train it is useless no matter how much horsepower you have. Electric locomotives are mainly used for high speed rail passenger service.They may have very high horsepower but that does not mean they are any stronger than your average freight locomotive.I doubt a Acela could pull 40 cars up a grade.They were designed and geared for high speed.It's the same with top fuel dragsters.They average 9,000 horsepower but they couldn't pull a loaded semi trailer up a steep grade. I can't remember the locomotive name but it was made by GE in the 1970's and had a B-B-B wheel arrangement,was electric,painted white,and was rated at 10,000 hp.It was a sucessful locomotive but the railroads said they were not interested because it was too risky putting a single locomotive on a freight train in case it broke down somewhere.If you did have to have a second locomotive as a back up it might as well be running so you really only needed two 5000 hp locomotives.As a former locomotive mechanic I can tell you that the more horsepower these locomotives have the more problems you will get.Some of those higher horsepower locomotives also tend to load up much faster then your older ones.I can remember having a 6000 hp locomotive in the front of a train with 4 more locomotives behind it and it would load up so fast it was trying to pull the entire train right away while the 4 locomotives behind it was just starting to load up. The Milwaukee road was probably the best managed electric freight railroad of all time.They had the right ideas.Heavy locomotives with lots of wheels.
Interesting topic.Horsepower and locomotives are often a confusing subject.Electric locomotives may have a lot of horsepower but you are always going to be limited by how much you can pull by how much your locomotive weighs.It wouldn't matter if you had a 30,000 hp locomotive.If your locomotive is going to slip the wheels trying to pull a heavy train it is useless no matter how much horsepower you have.
Electric locomotives are mainly used for high speed rail passenger service.They may have very high horsepower but that does not mean they are any stronger than your average freight locomotive.I doubt a Acela could pull 40 cars up a grade.They were designed and geared for high speed.It's the same with top fuel dragsters.They average 9,000 horsepower but they couldn't pull a loaded semi trailer up a steep grade.
I can't remember the locomotive name but it was made by GE in the 1970's and had a B-B-B wheel arrangement,was electric,painted white,and was rated at 10,000 hp.It was a sucessful locomotive but the railroads said they were not interested because it was too risky putting a single locomotive on a freight train in case it broke down somewhere.If you did have to have a second locomotive as a back up it might as well be running so you really only needed two 5000 hp locomotives.As a former locomotive mechanic I can tell you that the more horsepower these locomotives have the more problems you will get.Some of those higher horsepower locomotives also tend to load up much faster then your older ones.I can remember having a 6000 hp locomotive in the front of a train with 4 more locomotives behind it and it would load up so fast it was trying to pull the entire train right away while the 4 locomotives behind it was just starting to load up.
The Milwaukee road was probably the best managed electric freight railroad of all time.They had the right ideas.Heavy locomotives with lots of wheels.
You are referring to the EMD ASEA GM10 which is what started this topic of in the first place...it was a b-b-b locomotive adapted from a succesful Swiss Railways locomotive design. It didn't go into production because the only US mainline electric freight operator, Conrail, wasn't in the market for new electrics at that time, and the other US railroads studying electrification in the 1970's did not go forward with putting up catenary.
Electrics are historically more reliable than diesels and in parts of the world where electrification is the norm it is common to see single units on even heavy freights. PRR and New Haven commonly ran freight trains with single electric locos back during the "golden age" of under wire operations..
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
daveklepperYou are correct that the short-time overload capacity of electrics vs diesels is much greater with older diesels, and specifically electrics vs. dc motor diesels. AC motor diesels have much the same advantage as AC motor electrics.
You are correct that the short-time overload capacity of electrics vs diesels is much greater with older diesels, and specifically electrics vs. dc motor diesels. AC motor diesels have much the same advantage as AC motor electrics.
creepycrankICLandElectrification really shines going downhill by recapturing up to 50% of energy used going uphill How do they do that? If the catenary is AC then the returned power would have to be the same voltage, the same frequency, and in phase.
ICLandElectrification really shines going downhill by recapturing up to 50% of energy used going uphill
With something called an inverter...
Inverters for tying solar cell arrays to the electric grid have been available for more than a decade, though electric locomotive service has at leas a few -um- features not typically found in solar power installations.
Also bear in mind that the phase converter locomotives used by the N&W and the VGN along with the MG locomotives used by the GN and VGN were capable of regenerative braking.
Paul_D_North_JrRight you are. Thanks for that example, too - for intellectual honesty, I've also been trying to think of a long, really long and heavy grade situation, where an electric locomotive can't really rely upon or use its short-time motor overload capability to out-perform an equivalent diesel. On that one, it's several hours to make that climb, so they're both going to be limited to their continuous ratings.
Right you are. Thanks for that example, too - for intellectual honesty, I've also been trying to think of a long, really long and heavy grade situation, where an electric locomotive can't really rely upon or use its short-time motor overload capability to out-perform an equivalent diesel. On that one, it's several hours to make that climb, so they're both going to be limited to their continuous ratings.
Time/motion studies have consistently shown that a key advantage of electric locomotion isn't particularly in having the overload capacity available for grades. Older electric types did have a pretty hefty overload rating; these days, using identical off-the-shelf traction motors, the advantage over a comparable diesel-electric isn't that great. It's there, maybe about 10% (1 hr rating), and that could offer a couple mph advantage, if that's of any particular significance.
The real operating advantage however is in using the higher short-term (10-20 min) overload capacity in and out of sidings. The time/motion studies show that Electrification offers a significant advantage, but this is at the very low speeds involved, and so it may be fairly said that a key advantage gets back to the TE available, and not the HP. As a "for instance," reducing siding time by a mere two minutes, by being able to accelerate out quicker, can increase line capacity on a division by two trains per day. It makes that much difference.
In that context, the operating advantage of Electrification translates into a significant revenue productivity.
Of course, in the long, heavy grade scenario, Electrification's big advantage in any case is not in going uphill.
Electrification really shines going downhill by recapturing up to 50% of energy used going uphill.
timz ddechamp71As it appears that north american railroads using 6000hp diesel units are dropping them (UP, CSX, CP with GE AC6000 or SD90MACS, I mean SD90 and not SD9043), I hardly imagine that electric units of the same power could be used one of these days in the USI'm guessing US RRs would love a 6000 hp diesel if it were reliable. An AC44 with full tonnage is making maybe 8 mph; 10-11 mph from an AC60 would be a help. A US main line freight RR that electrified today would want 9000+ rail hp per unit. (By the way, the E60C on BM&LP etc is 5100 continuous rail hp.)
ddechamp71As it appears that north american railroads using 6000hp diesel units are dropping them (UP, CSX, CP with GE AC6000 or SD90MACS, I mean SD90 and not SD9043), I hardly imagine that electric units of the same power could be used one of these days in the US
(By the way, the E60C on BM&LP etc is 5100 continuous rail hp.)
I've read here and there that the primary concern with 6000 hp diesel units for railroads using them was unspread power. I mean, when a railroad needs to move a freight train it needs what we could call a "block of power", ie total horsepowers and tractive effort. Translating this into models, we could say that 3 AC4400s roughly equal 2 AC6000s. As far as I remember, the concern was: if one unit fails, the bi-unit consist loses 50% of its power, as the 3-unit consist loses 1/3 of its power, and so on.
But maybe I'm not aware of the latest issues dealing with these powerful 6000 hp diesels. What about BHP Billiton in Australia, the only other railroad that operates them?
Dom
beaulieu Yes, but your thinking Eastern, while I am thinking Western. Specifically the BNSF eastbound from the Colorado River bridge to the top of the Arizona Divide going from 456ft. above sea level to 7,322 ft. above sea level in about 220 miles, very few speed restrictions lower than 40 mph, 70 mph top speed for Intermodals. I can't find my copy of the relevant Trains Magazine to be more exact. Not a helper grade since steam days, but a long slog at full throttle.
I believe that Trains article might be the one by Richard Steinheimer in the 1970's - 1980's time frame - perhaps titled "Arizona Divide" or similar. However, I was just shocked to see that Kalmbach has removed the "Index to Magazines" tool/ application due to obsolescence and security concerns, which is understandable, so I no longer have my easy and fun way to look up that kind of thing.
beaulieuPaul_D_North_Jrtimz [snip] An AC44 with full tonnage is making maybe 8 mph; 10-11 mph from an AC60 would be a help. A US main line freight RR that electrified today would want 9000+ rail hp per unit. [snip] Interesting discussion. timz's "9,000 rail HP per unit" [emphasis added for at the rail] - that's around 10,000 HP / 7,460 kw = 7.5 MW power input. Taking a "unit" to be a C-C with the usual 'loading gauge' limits of around 70,000 lb. axle loading/ 420,000 lb. gross weight, at 35 % adhesion = 147,000 lbs. Tractive Effort likewise at the rail, implies a typical speed of about 23 MPH or better in order to fully utilize that HP. That's a little higher than is currently typical for some mountain grades - such as the East Slope/ Horse Shoe Curve, where around 16 MPH seems to be the norm - but those are about the only places all that TE and HP could be put to use for a sustained time, so it might lead to slight speed-ups there. Otherwise, the low 20's is a typical average train speed for most unit and general freight trains (non-intermodal). Perhaps there too the power and TE available from such a unit and needed by the train could be closely matched to the service so as to maximize the usage of all of the unit's capabilities; or else they could be used in intermodal service where the average speed is in the upper 30 MPH range, which therefore needs much more HP. - Paul North. Yes, but your thinking Eastern, while I am thinking Western. Specifically the BNSF eastbound from the Colorado River bridge to the top of the Arizona Divide going from 456ft. above sea level to 7,322 ft. above sea level in about 220 miles, very few speed restrictions lower than 40 mph, 70 mph top speed for Intermodals. I can't find my copy of the relevant Trains Magazine to be more exact. Not a helper grade since steam days, but a long slog at full throttle.
Paul_D_North_Jrtimz [snip] An AC44 with full tonnage is making maybe 8 mph; 10-11 mph from an AC60 would be a help. A US main line freight RR that electrified today would want 9000+ rail hp per unit. [snip] Interesting discussion. timz's "9,000 rail HP per unit" [emphasis added for at the rail] - that's around 10,000 HP / 7,460 kw = 7.5 MW power input. Taking a "unit" to be a C-C with the usual 'loading gauge' limits of around 70,000 lb. axle loading/ 420,000 lb. gross weight, at 35 % adhesion = 147,000 lbs. Tractive Effort likewise at the rail, implies a typical speed of about 23 MPH or better in order to fully utilize that HP. That's a little higher than is currently typical for some mountain grades - such as the East Slope/ Horse Shoe Curve, where around 16 MPH seems to be the norm - but those are about the only places all that TE and HP could be put to use for a sustained time, so it might lead to slight speed-ups there. Otherwise, the low 20's is a typical average train speed for most unit and general freight trains (non-intermodal). Perhaps there too the power and TE available from such a unit and needed by the train could be closely matched to the service so as to maximize the usage of all of the unit's capabilities; or else they could be used in intermodal service where the average speed is in the upper 30 MPH range, which therefore needs much more HP. - Paul North.
timz [snip] An AC44 with full tonnage is making maybe 8 mph; 10-11 mph from an AC60 would be a help. A US main line freight RR that electrified today would want 9000+ rail hp per unit. [snip]
Interesting discussion. timz's "9,000 rail HP per unit" [emphasis added for at the rail] - that's around 10,000 HP / 7,460 kw = 7.5 MW power input. Taking a "unit" to be a C-C with the usual 'loading gauge' limits of around 70,000 lb. axle loading/ 420,000 lb. gross weight, at 35 % adhesion = 147,000 lbs. Tractive Effort likewise at the rail, implies a typical speed of about 23 MPH or better in order to fully utilize that HP.
That's a little higher than is currently typical for some mountain grades - such as the East Slope/ Horse Shoe Curve, where around 16 MPH seems to be the norm - but those are about the only places all that TE and HP could be put to use for a sustained time, so it might lead to slight speed-ups there. Otherwise, the low 20's is a typical average train speed for most unit and general freight trains (non-intermodal). Perhaps there too the power and TE available from such a unit and needed by the train could be closely matched to the service so as to maximize the usage of all of the unit's capabilities; or else they could be used in intermodal service where the average speed is in the upper 30 MPH range, which therefore needs much more HP.
Yes, but your thinking Eastern, while I am thinking Western. Specifically the BNSF eastbound from the Colorado River bridge to the top of the Arizona Divide going from 456ft. above sea level to 7,322 ft. above sea level in about 220 miles, very few speed restrictions lower than 40 mph, 70 mph top speed for Intermodals. I can't find my copy of the relevant Trains Magazine to be more exact. Not a helper grade since steam days, but a long slog at full throttle.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
ddechamp71 beaulieu Rainhilltrial Even if there was a freight railroad in the US with 25,000 or 50,000 volt AC overhead power ... May I take this to mean you are unaware of the Black Mesa & Lake Powell RR, and the Deseret & Western RR, both of which are freight only and are electrified at 50Kv? I do agree with you that a 15,000hp electric is highly unlikely for US railroads if they electrified, but I could readily see them bump the current 4400hp up to say the 6000hp range. This would be useful on Intermodal trains, particularly with DPU. As it appears that north american railroads using 6000hp diesel units are dropping them (UP, CSX, CP with GE AC6000 or SD90MACS, I mean SD90 and not SD9043), I hardly imagine that electric units of the same power could be used one of these days in the US, had the electrified freight railroads (BM&LP, Deseret & Western) the need to renew their fleet. Dom
beaulieu Rainhilltrial Even if there was a freight railroad in the US with 25,000 or 50,000 volt AC overhead power ... May I take this to mean you are unaware of the Black Mesa & Lake Powell RR, and the Deseret & Western RR, both of which are freight only and are electrified at 50Kv? I do agree with you that a 15,000hp electric is highly unlikely for US railroads if they electrified, but I could readily see them bump the current 4400hp up to say the 6000hp range. This would be useful on Intermodal trains, particularly with DPU.
Rainhilltrial Even if there was a freight railroad in the US with 25,000 or 50,000 volt AC overhead power ...
Even if there was a freight railroad in the US with 25,000 or 50,000 volt AC overhead power ...
May I take this to mean you are unaware of the Black Mesa & Lake Powell RR, and the Deseret & Western RR, both of which are freight only and are electrified at 50Kv?
I do agree with you that a 15,000hp electric is highly unlikely for US railroads if they electrified, but I could readily see them bump the current 4400hp up to say the 6000hp range. This would be useful on Intermodal trains, particularly with DPU.
As it appears that north american railroads using 6000hp diesel units are dropping them (UP, CSX, CP with GE AC6000 or SD90MACS, I mean SD90 and not SD9043), I hardly imagine that electric units of the same power could be used one of these days in the US, had the electrified freight railroads (BM&LP, Deseret & Western) the need to renew their fleet.
The coal haulers you mention currently operate 6,000 HP GE E60C locomotives (with DC traction motors). The heavy haul electric freight locomotive offerings on the market currently (From Bombardier and Alstom) are considerably more powerful than that, were they in the market for replacement power, I would imagine it would be something like the Bombardier IORE locomotives operating in Sweden, which are 7,200 HP six axle units with AC traction motors..
Our community is FREE to join. To participate you must either login or register for an account.