Dual Mode: 3rd Rail + Catenary locomotive

General discussion about locomotives, rolling stock, and equipment

Moderator: John_Perkowski

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby F-line to Dudley via Park » Tue Mar 24, 2015 5:54 pm

BandA wrote:MBTA blue line subway cars have or had catenary + 3rd rail

How big is a transformer for these electric locomotives, and how much do they weigh? I can't wrap my head around why electric locos aren't much smaller than diesel-electric which has to carry a big diesel + generator


Very different systems you're talking here.

Blue Line is the same exact 600V DC power source whether it comes from the 3rd rail or pantograph. Actually, Blue Line is same exact 600V DC power source as Red, Orange, Green, the Mattapan trolley, the Silver Line dual-mode buses, and the Cambridge trackless trolleys. It takes zero additional electrical equipment to run on any MBTA traction power other than wiring to the roof for a pantograph mount vs. wiring to the underside for 3rd rail shoe mounts. It's why the Orange Line 01200 cars came out of the same factory with the same pantograph mounting plugs on the roof as the Blue Line 0600's. Seashore Trolley Museum runs all of its ex-MBTA heavy rail cars on its trolley overhead simply by attaching a trailer to the cars with a trolley pole and jumper cables connected to the 3rd rail shoes on the car. Same voltage any which way...the difference is only in the means of physical contact: pantograph, trolley pole, or shoes.


On the RR you have 750V DC 3rd rail on Metro North and LIRR...fully electrically compatible if you have the flippable shoes like the M8's that can do under-running MNRR 3rd rail or over-running LIRR 3rd rail. But then you've got the AC overhead on the NEC. 60 Hz/12.5 kV is a transformer core completely different from the DC inputs, and it takes a lot of additional equipment to switch on-the-fly between such different power sources. That's more weight on an M8. 60 Hz/25 kV for Shore Line East running is yet another heavy transformer core on top of the 12.5 kV one. Now you've got 3 power inputs in one vehicle and pretty close to the heaviest EMU in active service. Kawasaki offered a purchase option to configure the M8's for 25 Hz/12.5 kV...but the 25 Hz transformer cores are the heaviest of them all and would've left the cars so seriously overweight they'd likely have had all sorts of other design and mechanical problems to contend with related to the excess bulk. As is, the DC + AC inputs require so many extra components on the underside of the cars that it's going to be physically impossible--at least for the next few decades--to ever design a New Haven Line EMU in MLV dimensions. They're stuck with single-levels pretty much forever, unlike NJT which is ordering its Arrow-replacement EMU's in the MultiLevel coach carbody.

It's somewhat easier to have just the AC-only cores. Every electric locomotive sold here comes out-of-the-box equipped for 25 Hz/12.5 kV, 60 Hz/12.5 kV, and 60 Hz/25 kV. As do the Silverliner V EMU's and these next-gen NJT EMU's. As do the ALP-45DP diesel dual-modes. They're all heavier than they could/should be because the NEC electrification is so fragmented. It would be a lot easier for everyone if 25 Hz got phased out and everyone could consolidate on just the two 60 Hz voltages for significant weight savings, but Amtrak made its bed with refurbing the 25 Hz infrastructure so we're stuck with it. Other fresh electrifications elsewhere in the U.S. and Canada that start from Day 1 at 60 Hz/25 kV have the advantage of being able to buy equipment with only one transformer core at all the cost and weight savings that brings. The Euros have so much continental standardization on 25 kV AC that they have it a little easier only needing to do one AC core, one [other] core, and segmenting their equipment pools. They likewise can't possibly unite every mainline electrification scheme on the continent in one vehicle only without being impractically heavy, but unlike the three-headed voltage monster on the NEC there are few routes that have a need for changing between >2 electrification schemes on the same trip. The trains that do are outliers few enough in number that an engine switch somewhere en route usually does the trick with greater efficiency than larding up the rolling stock to absurdity. It's unavoidable here because of the NEC's voltage fragmentation.


So unfortunately, all four electrification schemes under one hood is just a bridge too far. Even the spacious environs of a locomotive carbody is going to have trouble fitting the DC equipment inside and staying within weight when it has no choice but to carry at least 2-3 other AC voltage cores to adequately roam anywhere on the NEC. To do that you pretty much do have to consolidate from 3 to 2 AC cores to create the room and shed enough weight to re-load. Which means spending the $B's to convert at least one of the NEC power sources--probably the 25 Hz--to another. And even then, the possible routes where it would be worth it to consolidate power just don't exist. Amtrak can't run thru from the NEC to the Empire because the tunnels point the wrong way, and there's the diesel gap on the Empire Connection so the Metro North 3rd rail isn't a factor anyway. LIRR splits from the NEC out in open air and LIRR 3rd rail runs to the North River portal on the NJ side, so you only need one either/or type of diesel dual-mode--not both--to get from any side of Penn to any other side of Penn and anywhere on Long Island. It can be done today with a P32 or ALP45-DP, so the only thing lost vs. your hypothetical 4-input all-electric is needing to do some diesel running and picking which vehicle spends more time in E-mode: a 3rd rail dual that runs diesel from New Jersey-south or a pantograph dual that runs on diesel from Sunnyside-east onto Long Island. GCT does have the diesel layup tracks if the schedule is small enough for that limited platform space to be adequate, so you can bring an ALP-45DP in there too for special-event trains points east to Boston. And if NYSHSR electrification ever happens to Albany then the Empire Connection and Hudson Line 3rd rail past Spuytien Duyvil is going to get replaced with 60 Hz/25 kV AC overhead and Metro North is going to start running New Haven Line EMU's on the entire Hudson schedule, changing from under-running 3rd rail to 25 kV overhead at SD on GCT runs and LIRR over-running 3rd rail to 25 kV overhead on the Empire Connection to avoid the short length of 25 Hz overhead in the tunnel that they can't run on.

So not even in the future is there going to be a single route scenario that pops up where you have to unite every electrification scheme under the hood of one vehicle. The diesel dual-modes obviate that need now and forever, with Penn's overhead + 3rd rail portal-to-portal configuration making the changeovers straightforward today if you had the vehicles and ridership demand in sufficient numbers to launch such a service.
F-line to Dudley via Park
 
Posts: 7108
Joined: Fri Mar 11, 2005 7:26 pm
Location: North Cambridge

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby chrisf » Tue Mar 24, 2015 6:47 pm

BandA wrote:MBTA blue line subway cars have or had catenary + 3rd rail

In addition to both the catenary and 3rd rail being 600VDC, the motors run off that same 600VDC so there simply isn't the need for a traction transformer.
chrisf
 
Posts: 283
Joined: Sat Apr 24, 2004 9:35 pm

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby talltim » Wed Mar 25, 2015 10:41 am

There have been plenty of dual AC and DC locos and MUs out there in Europe for years and they have lower axle load limits than in the US. Not many have third rail DC, admittedly (Eurostar has already been mentioned), but the shoe gear doesn't weigh that much more than a pantograph. Many modern EMUs in the UK are built dual system and simply only have either the pantograph or pickup shoes fitted as required. If there was much a weight disadvantage to this, it wouldn't happen. Modern electronics mean that input voltage, AC or DC distribution and frequency choices have far less effect on weight than they used too.
Altering an existing loco is more complicated admittedly and I'm not that up on the ALP46a. However it is related to the TRAXX family of locos, which are available in a dual AC and DC version, to the lighter European axle loads. in fact one version the F140 MS can use four different systems; 15 kV/16.7 Hz AC, 25 kV/50 Hz AC, 1.5 kV DC, 3 kV DC
Last edited by talltim on Wed Mar 25, 2015 10:50 am, edited 1 time in total.
Tim David
User avatar
talltim
 
Posts: 173
Joined: Wed Jun 08, 2011 6:16 am
Location: Chesterfield, UK

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby DutchRailnut » Wed Mar 25, 2015 10:49 am

untill a few years back, the European locomotives were also only 1/4 of horsepower of US locomotives.
If Conductors are in charge, why are they promoted to be Engineer???

Retired Triebfahrzeugführer
User avatar
DutchRailnut
 
Posts: 21176
Joined: Thu Mar 11, 2004 8:02 pm
Location: released from Stalag 13

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby talltim » Wed Mar 25, 2015 10:54 am

The ALP46a is 7,500 hp, the TRAXX F140 MS is 7,500 hp (only 5,400hp on 1.5 kV DC). The ALP46a is only about 3 or four years older.
Anyway you should be a fan of the the NS ones :wink:

Edit:corrected link
Last edited by talltim on Wed Mar 25, 2015 11:18 am, edited 1 time in total.
Tim David
User avatar
talltim
 
Posts: 173
Joined: Wed Jun 08, 2011 6:16 am
Location: Chesterfield, UK

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby DutchRailnut » Wed Mar 25, 2015 11:16 am

More fan of Werkspoor class 1200's.


and the former British 1500 class

MH200112180224c.jpg
Attachments
MH200302010124.jpg
If Conductors are in charge, why are they promoted to be Engineer???

Retired Triebfahrzeugführer
User avatar
DutchRailnut
 
Posts: 21176
Joined: Thu Mar 11, 2004 8:02 pm
Location: released from Stalag 13

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby Fan Railer » Sun Mar 29, 2015 12:28 pm

BandA wrote:MBTA blue line subway cars have or had catenary + 3rd rail

How big is a transformer for these electric locomotives, and how much do they weigh? I can't wrap my head around why electric locos aren't much smaller than diesel-electric which has to carry a big diesel + generator

Define "much smaller". You can't have a significant size reduction in a locomotive and maintain tractive power at the same time. Less weight = less adhesion = poor adhesive performance. There's an optimal weight range for a given power/TE rating, and sometimes, an electric locomotive must be fitted with ballast to make that weight range.
Fan Railer
 
Posts: 2156
Joined: Wed Sep 03, 2008 9:32 pm

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby mtuandrew » Sun Mar 29, 2015 1:51 pm

Fan Railer wrote:
BandA wrote:MBTA blue line subway cars have or had catenary + 3rd rail

How big is a transformer for these electric locomotives, and how much do they weigh? I can't wrap my head around why electric locos aren't much smaller than diesel-electric which has to carry a big diesel + generator

Define "much smaller". You can't have a significant size reduction in a locomotive and maintain tractive power at the same time. Less weight = less adhesion = poor adhesive performance. There's an optimal weight range for a given power/TE rating, and sometimes, an electric locomotive must be fitted with ballast to make that weight range.

Ballast, or an exponentially expensive wheel-slip system, or AC traction, or drive wheels that are all geared together, or all of the above.

Moderator's Note: Moving this to General Discussion: Locomotives.
User avatar
mtuandrew
 
Posts: 4011
Joined: Tue Feb 20, 2007 2:59 am
Location: the Manassas Gap Independent Line

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby ex Budd man » Mon Mar 30, 2015 7:22 am

I don't see why it isn't feasble for US equipment. Europe has equipment that operates on several voltages and are AC/DC as well. They even have an engine that can change wheel spacing for going between France and Spain! I think it all comes down to need, if it is needed it can be done. At what cost and will it be worth the effort can only be determined by actually designing and building such a beast.
Just my two cents. ;-)
"I may not have a brain, but I have an idea!" BOB, benzoate ostylezene bicarbonate.
ex Budd man
 
Posts: 906
Joined: Thu Nov 13, 2008 11:17 am

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby Adirondacker » Mon Mar 30, 2015 7:00 pm

F-line to Dudley via Park wrote:
60 Hz/25 kV for Shore Line East running is yet another heavy transformer core on top of the 12.5 kV one.


It's the same one. There's more than one way to skin the cat but it involves relatively cheap and uncomplicated switches. Or since it's not 1913 any more, sophisticated software massaging the whiz bang power supply that supplies the polyphase motors with polyphase electricity. Part of the same software that lets the whiz bang power supply create polyphase electricity from the DC third rail.
Adirondacker
 
Posts: 601
Joined: Wed Jul 01, 2009 9:00 pm

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby amtrakowitz » Wed Apr 08, 2015 12:39 am

ex Budd man wrote:I don't see why it isn't feasble for US equipment. Europe has equipment that operates on several voltages and are AC/DC as well. They even have an engine that can change wheel spacing for going between France and Spain! I think it all comes down to need, if it is needed it can be done. At what cost and will it be worth the effort can only be determined by actually designing and building such a beast.
Just my two cents. ;-)

Europe has been historically more tolerant of higher frequency of maintenance for power and rolling stock than the USA; the US stance was most likely due to the far longer distances trains had to travel across the contiguous 48 states, needing to keep in good working order for extended periods of time, but this culture worked (and works) well for local commuter traffic. The less you standardize, the more that can go wrong and the fewer spare parts are available.

Take note that NJ Transit's ALP-45DPs cost 2-3 times more than a straight diesel-electric. These did not have a prototype to boot. There are also extra operating costs associated with it.
User avatar
amtrakowitz
 
Posts: 1104
Joined: Mon Nov 24, 2008 6:33 pm

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby FRN9 » Wed Apr 08, 2015 4:45 pm

IPEMU battery technology seems like a much better choice than Diesel/Electric hybrid technology.

amtrakowitz wrote:
ex Budd man wrote:I don't see why it isn't feasble for US equipment. Europe has equipment that operates on several voltages and are AC/DC as well. They even have an engine that can change wheel spacing for going between France and Spain! I think it all comes down to need, if it is needed it can be done. At what cost and will it be worth the effort can only be determined by actually designing and building such a beast.
Just my two cents. ;-)

Europe has been historically more tolerant of higher frequency of maintenance for power and rolling stock than the USA; the US stance was most likely due to the far longer distances trains had to travel across the contiguous 48 states, needing to keep in good working order for extended periods of time, but this culture worked (and works) well for local commuter traffic. The less you standardize, the more that can go wrong and the fewer spare parts are available.

Take note that NJ Transit's ALP-45DPs cost 2-3 times more than a straight diesel-electric. These did not have a prototype to boot. There are also extra operating costs associated with it.
FRN9
 
Posts: 337
Joined: Sun Jan 18, 2009 1:29 pm

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby docsteve » Tue Apr 28, 2015 7:24 pm

Adirondacker wrote:
F-line to Dudley via Park wrote:
60 Hz/25 kV for Shore Line East running is yet another heavy transformer core on top of the 12.5 kV one.


It's the same one. There's more than one way to skin the cat but it involves relatively cheap and uncomplicated switches. Or since it's not 1913 any more, sophisticated software massaging the whiz bang power supply that supplies the polyphase motors with polyphase electricity. Part of the same software that lets the whiz bang power supply create polyphase electricity from the DC third rail.


Are you saying that banks of GTOs replace the transformer cores?
Steve Sconfienza, Ph.D.
http://railroad.docsteve.com/
User avatar
docsteve
 
Posts: 113
Joined: Fri Apr 15, 2005 8:48 am
Location: Albany & Caroga Lake, N.Y.

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby Allen Hazen » Tue Apr 28, 2015 8:14 pm

docsteve--
He MAY have been saying that, but my guess was that a single transformer could be used for more than one voltage: different "taps," so output current can be drawn off after different numbers of turns around the cores.
(But now that we've demonstrated that different things could have been suggested by his words, maybe he will post a more specific description!)
Allen Hazen
 
Posts: 2332
Joined: Fri Mar 12, 2004 10:14 pm
Location: Edmonton, Canada (formerly Melbourne, Australia)

Re: Dual Mode: 3rd Rail + Catenary locomotive

Postby Adirondacker » Wed Apr 29, 2015 10:51 pm

People stopped using GTOs. IGBTs are easier to control. I seem to remember they are more efficient too.
There's at least three ways to skin the cat. Taps on the tranformer, switching the inverters between serial and parallel operation and designing the AC-DC-AC magic to operate on a variety of voltages. I'm sure there are others. It's not 1915 anymore.
Adirondacker
 
Posts: 601
Joined: Wed Jul 01, 2009 9:00 pm

PreviousNext

Return to General Discussion: Locomotives, Rolling Stock, and Equipment

Who is online

Users browsing this forum: No registered users and 2 guests