Wacky idea for dual modes - third rail HEP?

I know that the third rail dual modes on all three railroads (MNRR, Amtrak, and LIRR) run off the third rail "where required" instead of "where available" like the ALP45s and future Amtrak catenary dual modes do and will. There are a number of disadvantages running on the third rail which is why they run only where required, but I was wondering, what's stopping the dual mode engines from using the third rail where available for HEP? I'm sure none of the current engines are wired to allow such, but would that even be a technical possibility that would have advantages? Mostly I'm thinking that the engine could put its full horsepower to the rail instead of having to use some for HEP which should also lower emissions and fuel use. But I admit, I know how much lower those would be.

Well, third rail is Direct Current.... HEP is Alternating Current.

Not sure how much you'd lose in the conversion of single phase 600V DC to three phase 480V AC.

(corrected to remove reference to catenary being DC)

Mod Note: Passed around from LIRR, Amtrak, Metro North and settled into the NYC cross agency forum.

fun fact: similar systems were used in germany via wiring to lower power requirements on intensive coaches (such as diners w/kitchens)

The Rhaetian Railway has pantographs on bicycle/baggage cars, not because they have a large a power draw, but because 1 of those cars will be on every longer train so the HEP draw is not too much on the locomotive.

@eolesen catenary is AC

You're correct, Rohr. Catenary on the NEC is single phase AC. The Metra Electric and South Shore are both 1500v DC still, and that's what I'm most familiar with.

Regardless, with NEC catenary being single phase, there's still the issue of having to convert that into 480v three-phase.

eolesen wrote: ↑Tue Feb 22, 2022 5:46 pm Well, third rail is Direct Current.... HEP is Alternating Current.

Not sure how much you'd lose in the conversion of single phase 600V DC to three phase 480V AC.

(corrected to remove reference to catenary being DC)

I don't think the conversion is the issue, they have to convert when they're running fully on third rail.

nomis wrote: ↑Tue Feb 22, 2022 6:03 pm Mod Note: Passed around from LIRR, Amtrak, Metro North and settled into the NYC cross agency forum.

Haha! Good call, sorry, I was inspired to write this after seeing a picture of an LIRR locomotive.

ConstanceR46 wrote: ↑Tue Feb 22, 2022 6:08 pm fun fact: similar systems were used in germany via wiring to lower power requirements on intensive coaches (such as diners w/kitchens)

I was thinking of these too.

eolesen wrote: ↑Tue Feb 22, 2022 9:29 pm You're correct, Rohr. Catenary on the NEC is single phase AC. The Metra Electric and South Shore are both 1500v DC still, and that's what I'm most familiar with.

Regardless, with NEC catenary being single phase, there's still the issue of having to convert that into 480v three-phase.

It gets converted anyways somehow, I don't think conversion is the issue here.

Ah, got it @eolesen. I'm not familar with Chicago electrification. And yes you're correct on the single-phase to 3-phase issue.

The PRR kept demand on the GG-1s steam system by having a few diners equipped with PANs to provide the high loads to the diner. Does anyone know what happened to them and when?

do photos of this system exist?

MattW wrote: ↑Tue Feb 22, 2022 12:18 pm I know that the third rail dual modes on all three railroads (MNRR, Amtrak, and LIRR) run off the third rail "where required" instead of "where available" like the ALP45s and future Amtrak catenary dual modes do and will. There are a number of disadvantages running on the third rail which is why they run only where required, but I was wondering, what's stopping the dual mode engines from using the third rail where available for HEP? I'm sure none of the current engines are wired to allow such, but would that even be a technical possibility that would have advantages? Mostly I'm thinking that the engine could put its full horsepower to the rail instead of having to use some for HEP which should also lower emissions and fuel use. But I admit, I know how much lower those would be.

It would require conversion no matter what to the voltage/amperage the HEP system uses, possibly through an inverter. Most of the time it's being done anyway, even it it's through the engine's diesel or catenary system.... so nothing new.

Doing diesel and electric at the same time? Now that's asking for trouble, IMHO, but we have the technology since they did have catenary-powered HEP on diners.

Albany to NYP is somewhere in the 225 to 285 gallon range if memory serves me correctly for a one way trip. How much fuel could you save? The real savings is in keeping them shut down in the summer when not in use and making sure the auto starts are working correctly in the winter.
Amtrak and MNRR run on two different systems for the third rail shoes. Over running LIRR Amtrak. Under running NYCRR MNRR. When we were going into GCT, MNRR wanted the shoes in the down in the locked position from the jump which caused Amtrak a few issues with crossings and platforms and broken shoes. Going into NYP we can raise and lower the shoes as needed.
The back of a dual mode has a block of inverters to change DC to AC as they use AC for traction. If anyone has ever been stuck in a light powdery snow on a broken down dual mode powered train it is because snow can sometimes get into those inverters then its game over.

single phase can be converted to 3 phase, they do the conversion when the waveform passes through zero volts,so it doesnt require as heavy a "switchgear"( mosfets or other transistors) as would be the case with higher voltages.
Inverters convert power to d.c anyway , and chop it up to the required a.c hz and voltage , so starting with d.c actually saves a step . Pretty much anything is possible with modern electronics.
Sounds more like the under /over rail difference is more of a problem, and politics.
however Amtrak will want to improve its carbon footprint , currently not much better than the private auto , and higher than a bus ) , so small gains such as this may become desirable.

David Benton wrote: ↑Tue Mar 01, 2022 4:59 am single phase can be converted to 3 phase, they do the conversion when the waveform passes through zero volts,so it doesnt require as heavy a "switchgear"( mosfets or other transistors) as would be the case with higher voltages.
Inverters convert power to d.c anyway , and chop it up to the required a.c hz and voltage , so starting with d.c actually saves a step . Pretty much anything is possible with modern electronics.
Sounds more like the under /over rail difference is more of a problem, and politics.
however Amtrak will want to improve its carbon footprint , currently not much better than the private auto , and higher than a bus ) , so small gains such as this may become desirable.

I have a big question.

Why diesel for motive power and electric third rail for the rest if you're concerned about emissions? Why not electric all over the place? Can't they run catenary all the way up?

Of course, there's one problem with the Empire service: the swing bridge north of Penn. But you may be able to get away with it if there's a battery system on it.