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  • Marc Electrics

  • Discussion related to DC area passenger rail services from Northern Virginia to Baltimore, MD. Includes Light Rail and Baltimore Subway.
Discussion related to DC area passenger rail services from Northern Virginia to Baltimore, MD. Includes Light Rail and Baltimore Subway.

Moderators: mtuandrew, therock, Robert Paniagua

 #1337885  by dowlingm
 
Aren't some of those already earmarked for SEPTA to bridge them until they get their new ones?
 #1337890  by F-line to Dudley via Park
 
dowlingm wrote:Aren't some of those already earmarked for SEPTA to bridge them until they get their new ones?
Not decided yet. Amtrak hasn't made any decisions on long-term leases for the Remans, so these random appearances on MARC trains are the extent of it for now. 6 to SEPTA was the rumor quoted by AMTK employees on the forums, but that was awhile ago and it's a fluid rumor. Sprinters gotta have the kinks worked out before it's prudent to let them start taking 'dibs' on formal leasers, so whether there's been any discussions with SEPTA or more or less agreed-upon number of leasers...they obviously can't say anything, transact anything, or pin a calendar date on such a transaction until Amtrak's more or less finished the fleet replacement to its own satisfaction. And I'm sure that's well-understood by SEPTA.


Seeing as how they have 28 units, and even if you take the most pessimistic assumption that "best of the rest" will only net maybe half that many good-condition units, it's more than SEPTA and MARC both would ever need for the rest of the decade run in relatively light-duty/light-mileage commuter rail. Amtrak's probably going to have a bunch of extras fully up-to-task that it has no means of getting rid of or milking a little lease revenue out of. Vanishingly unlikely that finding decent-condition leaser bodies for both CR agencies to use indefinitely as bridge fleets is ever going to be an issue. There's a legitimate glut of Remans, and "a little beat-up" for Boston-D.C. duty on Amtrak means "this is like-new compared to the crap we're running!" when you're only talking SEPTA a few peak hours per day, 3+ dozen short-distance MARC runs between D.C.-Baltimore per day, and a dozen MARC pokes beyond Baltimore to/from Perryville per day. That's like a lazy Sunday drive compared to what work most of the Reman fleet is still up for doing.
 #1337907  by realtype
 
Backshophoss wrote:At times,Amtrak has "borrowed" MARC's Hippo's for service across the NEC,it might be in Amtrak's interest to Lend/Lease
some the "stored serviceable" AEM-7's(or the stored Hippo's) to MARC to get the "Rush Hour" trains on the motors
instead of the MP-36's that can't keep up.
Yep #925 (AMTK AEM-7AC) was on a MARC consist today.
 #1340102  by farecard
 
Which, if any of the new electrics out there are AC? When I was last reading up on the topic, it looked like the vendors were still (Edison would be proud....) pushing DC-motored units....
 #1340167  by F-line to Dudley via Park
 
farecard wrote:Which, if any of the new electrics out there are AC? When I was last reading up on the topic, it looked like the vendors were still (Edison would be proud....) pushing DC-motored units....
All of them.

There hasn't been a DC-motor electric loco produced for domestic consumption since the ALP-44 (first orders 1989-93, one tiny subsequent order by NJT '95-97). And those are more or less an "AEM-7DC Version 2.0" in terms of being lightly-updated old tech. Haven't been any DC-motor EMU's produced since the Metro North M6's in 1994. Same for new diesel purchases; last passenger DC's were late-90's vintage. Only places you still see DC-anything being bought new is freight diesels because that's still optimal traction performance for some freight needs. But even that market is shrinking big now that Tier 4 air quality standards are squeezing them out for AC's. Only place "kinda"-new DC's are thriving are with remanufacturings of old DC diesels--like the latest F40PH-3C passenger spec--since those kinds of overhauls aren't bound to nearly as tight air quality restrictions as brand new vehicles.

It's an AC traction world now. And on the electrics side parts availability for DC's is a bigger constraint than actually finding someone offering them in a product catalog. It's not hard to find replacement parts for an AEM-7AC; the AC guts they were remanufactured with are pretty generic. It's brutally difficult to find parts for an AEM-7DC; Amtrak was having a lot of trouble near the end scraping up bits and pieces to keep their fleet running.
 #1340380  by mtuandrew
 
I'm coming into this discussion late, so sorry if this has been asked & answered, but...

Let's say MARC is bluffing Amtrak about converting to full diesels, and wants some electrics to hold it over before they go shopping for new motors. So far, this thread is talking up AEM-7ACs for good reason. What else is out there? Does NJT have any spare ALP-46 1st-gens it could lease to MARC?

(I'd kind of love to see ALP-44s rebuilt in the spirit of the AEM-7AC rebuilds, but this is both unrealistic and out of the scope of this thread.)
 #1340410  by farecard
 
F-line to Dudley via Park wrote:

Only places you still see DC-anything being bought new is freight diesels because that's still optimal traction performance for some freight needs. But even that market is shrinking big now that Tier 4 air quality standards are squeezing them out for AC's.

.....

It's an AC traction world now. And on the electrics side parts availability for DC's is a bigger constraint than actually finding someone offering them in a product catalog. It's not hard to find replacement parts for an AEM-7AC; the AC guts they were remanufactured with are pretty generic. It's brutally difficult to find parts for an AEM-7DC; Amtrak was having a lot of trouble near the end scraping up bits and pieces to keep their fleet running.

Thinking back, it must have been a freight diesel thread I read not an electric one. I still don't grasp why an AC motor delivers less traction than a DC one; if it's a weight difference, add ballast. And I agree re: the electronics availability. But the big issue is no %&$%^&$ DC motors to maintain.
 #1340414  by F-line to Dudley via Park
 
mtuandrew wrote:I'm coming into this discussion late, so sorry if this has been asked & answered, but...

Let's say MARC is bluffing Amtrak about converting to full diesels, and wants some electrics to hold it over before they go shopping for new motors. So far, this thread is talking up AEM-7ACs for good reason. What else is out there? Does NJT have any spare ALP-46 1st-gens it could lease to MARC?

(I'd kind of love to see ALP-44s rebuilt in the spirit of the AEM-7AC rebuilds, but this is both unrealistic and out of the scope of this thread.)
NJT has to substitute its dual-mode ALP-45DP's it has too few all-electrics to go around. They're in no position to lease out their ALP-46's. It's pretty much the AEM-7AC's as short-term reliable power available in the very near future. The "reliable" part being why MARC--or anyone--will never ever look at AMTK's stored HHP-8's. That would just be masochism.
 #1340657  by sammy2009
 
Yeah NJT isn't leasing any of those dual-mode alp's no time soon. Hell they even use the dual-mode locomotives on the NorthEast Corridor Line which is all electric.
 #1341133  by dt_rt40
 
924 was pulling the MARC 6:40 to Baltimore tonight. That is one sad looking loco, what happened to the exterior of it? The lower half of it looks like it was attacked by an army of angle grinders.
 #1341895  by mtuandrew
 
farecard wrote:Thinking back, it must have been a freight diesel thread I read not an electric one. I still don't grasp why an AC motor delivers less traction than a DC one; if it's a weight difference, add ballast. And I agree re: the electronics availability. But the big issue is no %&$%^&$ DC motors to maintain.
Short answer: it's a power curve issue.

Long answer: DC motors provide maximum torque at 0 rpm, while AC motors provide max torque at a higher range (I forget exactly what though.) It'd be perfect, except that you burn up your DC motors' brushes and have to limit the power. AC doesn't have that limitation, so you can start at Notch 8 and dump as many amperes into the motors as your cooling system can handle.

F-line: I'm looking forward to the HHP-8 line by Gillette. :P
 #1341998  by farecard
 
mtuandrew wrote:
Short answer: it's a power curve issue.

Long answer: DC motors provide maximum torque at 0 rpm, while AC motors provide max torque at a higher range (I forget exactly what though.) It'd be perfect, except that you burn up your DC motors' brushes and have to limit the power. AC doesn't have that limitation, so you can start at Notch 8 and dump as many amperes into the motors as your cooling system can handle.

F-line: I'm looking forward to the HHP-8 line by Gillette. :P
Well, series-wound DC motors provide 0-rpm torque. That's how your car starter works. I guess locomotive motors would also be, to a major extent.

Are the AC motors geared down or many-poled?
 #1345120  by Fan Railer
 
farecard wrote:
mtuandrew wrote:
Short answer: it's a power curve issue.

Long answer: DC motors provide maximum torque at 0 rpm, while AC motors provide max torque at a higher range (I forget exactly what though.) It'd be perfect, except that you burn up your DC motors' brushes and have to limit the power. AC doesn't have that limitation, so you can start at Notch 8 and dump as many amperes into the motors as your cooling system can handle.

F-line: I'm looking forward to the HHP-8 line by Gillette. :P
Well, series-wound DC motors provide 0-rpm torque. That's how your car starter works. I guess locomotive motors would also be, to a major extent.

Are the AC motors geared down or many-poled?
The typical phrase I've seen with AC motor specs is "3-phase; 4-pole"
 #1345144  by farecard
 
Fan Railer wrote: The typical phrase I've seen with AC motor specs is "3-phase; 4-pole"

A 4-pole motor spins at 1800 RPM on 60 Hz. {Well, at sync speed; 1725 is the usual running spec.}

I have no idea what frequency range the VFD's cover but in fixed applications it is in the 10-150 Hz realm; higher frequencies have too much inductive reactance. It sounds as if the motors are geared down within the truck. We could work backwards from top speed and wheel diameter to make a guess as to the ratio.