Discussion in 'Amtrak Rail Discussion' started by Ryan, Dec 21, 2018.
tread is about locomotives , lets get this clear.
So now we have three Charger variants, the SC-44 for the PRIIA orders, the SCB-40 for Brightline, and the ALC-42 for Amtrak. I wonder why Amtrak went with 4200hp?
Congrats on your promotion to Moderator.
It's 4200 HP continuously. It would probably start at 4400 HP but run at 4200 continuously.
I’m thinking reliability. Being the workhorses of the LD network is not an easy job, so I guess Amtrak feels that the extra hp of a standard Charger isn’t necessary, and that reliability is more important. That’s the reason Brightline went with only 4,000 hp.
Nope, the standard Chargers are 4,400 continuous.
Brightline went with 4000 because they use theirs on both ends of short trains. Those trainsets are rockets, perhaps the highest HP/ton of any loco hauled train in regular service in America. Amtrak will be using theirs to replace P42s, presumably on a one-to-one ish basis. It might end up being a little better than that though, as P42s have 4250HP available when not in HEP mode but when providing HEP they provide a max of about 3500 and depending on HEP load can go all the way down to about 2500. With the chargers it’s way less substantial of a hit given they use modern inverters, I am not sure about the extract numbers.
Yes but reliability is the reason they specifically had them tuned down to 4,000.
Page 1-4 of the operator's manual from Siemens says differently lol.
4200 continuous, 4400 maximum short-time.
If Amtrak is going with 4200 hp only, then the software simply doesn't call for the 200 horsepower short-time boost mode. The traction motors are only rated at 978 hp anyway, so even with no HEP load, you're only getting 3900 hp to rail.
The traction motor rating isn’t completely relevant since a locomotive’s horsepower rating is at the prime mover shaft, not at the wheels. “4400 HP” freight locomotives aren’t supposed to make 4400 at the wheel either, that’s normal. And there is no such thing as “boost mode,” this is a diesel locomotive, not a Tesla Model S. AC traction motors don’t require short time ratings so I’m not sure why the software would need to kick it down to 4200. I’m interested to see what the manual actually says if you could you provide it.
There can absolutely be a “boost mode” in diesels, either as a reference to to the natural power curve of the engine or probably more likely a software setting that modifies fuel injection and/or turbocharger geometry for increased power under certain circumstances.
They’re smaller than locomotive engines, but modern FPT diesels have a little “boost” icon on the dash that supposedly corresponds to when the engine is reaching maximum power, although in my experience it comes on pretty much all the time at 1700 rpms, so I’m not exactly sure what it’s trying to say the engine is doing.
The manual is proprietary, so I'm not going to share that publicly, but if you say there's no such thing as "boost mode" on a diesel locomotive, perhaps you should tell that to Siemens lol
This is the official protest letter from EMD back when the initial locomotive contract was awarded by IDOT to Siemens instead of EMD.
On page 4:
Though this letter is written by EMD, it specifically quotes from Siemens's technical proposal portion of its bid. It's important to note, as stated above, that the boost feature is for the DIESEL PRIME MOVER, not the traction motors. Just the same way you can derate a prime mover to reduce wear and tear, you can uprate a prime mover for a short period of time over the rated continuous output.
The traction motor output is relevant for the factoring in of HEP load on the prime mover. As stated before, if there is no HEP load on the locomotive, "boost mode" accomplishes nothing, as the 4200 continuous rating at the shaft is enough to account for any transmission losses from the alternator to the traction motors and any onboard aux loads. As soon as you add an external HEP load, boost mode becomes more relevant. Factoring in a 600 kW load (800 hp), you're looking now at about a 3100-3200 hp at wheel continuous, or 3300-3400 hp with "boost mode" active. This is likely useful for a commuter application where the stops are close together and acceleration matters. For a long distance application, the cost from the additional wear and tear on the prime mover likely outweighs the minuscule time gains from the extra 200 hp, which explains why Amtrak would opt not to have the traction software do that on their long distance spec'd locomotives.
Fair enough, thanks for the info. I assumed boost mode referred to the traction motors. As far as the manual, though, do you work for Siemens? I can absolutely appreciate not wanting to share it publicly, but if you have it unofficially yourself it’s not exactly proprietary information to yourself.
The fact that someone trusted him enough to give him information doesn’t mean that he’s free to just share it with random people on the internet. (In fact the two are probably inversely related - someone share because they can trust them precisely to not do that)
Rather than be demanding of them, be thankful that they had the information necessary to answer your questions and leave it at that.
Where exactly was I demanding? I actually said that I can appreciate not wanting to share the info publicly. I thanked him for the information on EMD’s protest notice. I acknowledged that the information provided showed I was incorrect about the boost mode feature. No big deal. Not sure how you could infer any type of demand, unless you are just searching for something to call me out on. The only time I said something that wasn’t in complete agreement was when I pointed out that it’s not proprietary information to someone that got the info unofficially, it’s proprietary information to Siemens. That isn’t in order to argue “so therefore give me the information,” it’s just to point out that most of us here are railfans, not employees, so if you have something that is not intended for the public then it isn’t really “yours” either. Disrespect was neither delivered nor intended.
I never said it was proprietary to me. Yea, sure if I wanted to, I could drop it somewhere and share the link; but the point was already made as to why I wouldn't do such a thing with something like this.
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