I know AEM-7 supposedly stands for ASEA Electro Motive 7000HP but what does ALP44 stand for?
According to ABB, the "ALP" is for 'American Locomotive Passenger'; the first "4" is number of axles, and the second represents the 'power range' (nominally in kW)
While the AEM-7's 7000 hp is the maximum horsepower the ALP-44's 4.32 MW (5,790 hp) is the continous horsepower.
In Europe the maximum horsepower is usually the hourly rating, the output for one hour without overheating. I don't know if it is the same in the USA?Regards, Volker
Huh. I wonder if the ALP-46 and ALP-46A are accurate with that too.
VOLKER LANDWEHRIn Europe the maximum horsepower is usually the hourly rating, the output for one hour without overheating. I don't know if it is the same in the USA?
i am interested to see if this is so. "Historically" the 'horsepower' rating was understood to be continuous (see the nominal hp for the GG1s) with the 'hourly' and 'instantaneous' ratings provided separately.
EMD of course began to be notorious with 'marketing inflation' of numbers in unit designations with the introduction of the GP30 (which was nowhere near 3000 hp) - and I am pretty sure this was the case with the 'white wonders' in the '70s if we work backward from the published TE at speed numbers. I never remember a 'toaster' called more than a 6000hp locomotive ... and that being pretty much a short-term extreme high speed rating ... so I think the case could be made that "7" was more marketing swagger than nomenclatural veracity.
The GP30 designation was selected to showcase "30 new features" or something like that, not 3000 HP. In fact, the original designation would have been GP22.
Yes, but...
the immediately preceding numbers (GP18, SD24, etc.) reflected hp, and the general competition (Alco Centuries upstaged by GE U-boats) did, so marketing something new and turbocharged with -30 was ...
Overmod"7" was more marketing swagger
BIGMINDCREATORI wonder if the ALP-46 and ALP-46A are accurate with that too.
44, 45, 46 all follow the same general system up to that last digit, which does conform to power in kW but I think has been rationalized just a bit to give 'power class' distinctions by technological platform too (the ALP45DP is I think only rated 4400kW peak, 4000 continuous electrical, but the platform it is built on is very different from the ALP44 and perhaps for that reason the locomotive was given the next 'higher' digit.) Of course an ALP45DP makes nowhere near that power on diesel engine, either with or without HEP load included.
timzDon't recall what they said AEM7 peak short-time horsepower was-- maybe 7500 at the rail?
I don't think there was a way to measure 'peak' near-instantaneous accurately. That locomotive was remarkably adhesion-limited, especially with the original DC motors, up to comparatively high speed, where short-term acceleration would be the significant determinant. You probably know better than I what the highest permitted short-term amperage was, and the degree to which other traffic in the same power block on test might tend to pull the effective voltage at 'test distance' from the substation down.
As I noted over in the other thread, I was trained to use the continuous rating as the locomotive 'horsepower' and call out hourly and instantaneous ratings as what they were. What I think was needed for the AEM-7s was something like a '5-minute' rating, reflecting the power needed for continuous acceleration above the adhesion-limit speed to the full speed the locomotives could reach, which was somewhere above 135mph. It would be interesting to see some test graphs that showed exactly where peak hp was developed.
Overmod Yes, but... the immediately preceding numbers (GP18, SD24, etc.) reflected hp, and the general competition (Alco Centuries upstaged by GE U-boats) did, so marketing something new and turbocharged with -30 was ...
FT, F2,F3,F7,F9, GP7,GP9...which ones represent HP again? I'm not saying EMD wasn't playing marketing Shenanigans. I am saying that the days when an EMD road locomotive had a model number that directly reflected HP were extremely short and atypical.
YoHo1975FT, F2,F3,F7,F9, GP7,GP9...which ones represent HP again?
You mean like F for Fifteen hundred?
Seriously: I was talking only about the era when GM-EMD introduced the GP30 as the successor to the immediately preceding generations of general-purpose locomotive, which acquired the HP number, at the time the competition also advertised with an indication of horsepower. I don't believe any of the later EMD main-line freight-locomotive designations returned to HP thereafter; certainly the passenger locomotives in the modern F/FP series didn't. (That leaves a curious case like the GP15/15T open to discussion, though...)
This discussion has reached a Shakespearean level: Much Ado About Nothing.
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
FWIW, the HP figures that GE used were for the diesel equivalent of the continuous power rating, i.e. the E60's 5,100HP continuous rating was equivalent to a 6,000HP diesel.
The 1980 Car & Locomotive Cyclopedia claims a short term rating of 8,120HP and a continuous TE of 29,000lb @ 75MPH, which translates to 5,800 draw-bar HP. Also remember that the AEM-7 used separately excited field windings, so adhesion should have been better than an equivalent series motor equipped locomotive.
- Erik
erikem1980 Car & Locomotive Cyclopedia claims a short term rating of 8,120HP
For the AEM-7, you mean?
The Pueblo AEM-7 test report said power into the transformer peaked at 6.7 megawatts at 56 mph. That was probably under 25 kV catenary, tho. That's probably not enough for 8120 hp at the rail?
ALP ? = Another looser parked ?
timz erikem 1980 Car & Locomotive Cyclopedia claims a short term rating of 8,120HP For the AEM-7, you mean?
erikem 1980 Car & Locomotive Cyclopedia claims a short term rating of 8,120HP
Yes.
6.7 megawatts at 90.4% efficiency is 8120HP. 90% efficiency is a reasonable number for large DC traction motors. Since the transformer is a limiting factor, I would assume that HEP would cut down the peak drawbar HP. The GG-1s were good for momentary bursts of 8,000+HP, which would be on the order of 7MW.
FWIW, the GM10B electric from the 70's was essentially 1.5 AEM-7's with freight gearing and presumably frieght locomotive axle loading. These were set up to run under the PRR 11kV/25Hz catenary.
The Milwaukee Little Joes were capable of drawing 3,000 amps from the catenary - that's from one Joe. That works out to 9MW at 3,000V.
I think too that the factory has to name it SOMETHING. I doubt the engineering department at each railroad is purchasing based on the model name. They had data and specifications on the locomotives. I don't think GM was fooling anyone in the industry.
erikemMilwaukee Little Joes were capable of drawing 3,000 amps from the catenary - that's from one Joe. That works out to 9MW at 3,000V.
Thru one pantograph? 9 MW means how much power at the rail, at what speed?
Yes, with one pantograph. GE tests undertaken in July 1923 showed that 5,000+ amps could be collected for one pantograph. The test set-up at Erie used the same twin trolley contact wire arrangement that the Milwaukee used on its main-line tracks (side tracks used single contact wire). The test results were published in a 1923 issue of General Electric Review, which is available on-line (Google Books or Internet Archive).
The text commenting about the Joe's 3,000 amp draw (Noel Holley's book) did not mention speed or tractive effort, my guess that was with full shunting applied, probably 30-35MPH and 100,000+lb tractive effort. Drawbar horsepower would have been close to 10,000HP - depends on the wire voltage. Hoelley's book said that the Milwaukee electrical system was good for about 4,000A per train, which implies that these curent peaks were being seen when the Joe's were used for passenger trains.
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