Overmod From a copy of the ACS64 Familiarization and Orientation manual: No weight given for the main transformer (which is between the trucks) but it is p/n A2V00002028490, and using that information might get you physical parameters. It includes two 480VAC dedicated HEP transformers. The two stepdown voltages for different catenary voltages are given as 1957 VAC and 1878 VAC, "depending on the catenary input". "Voltage switching Is Done Electronically By The Primary Side Tap Changer" There is a modular "HEP Rack" (A2V00002106069) which produces 480 VAC "to locomotive as a secondary source of electricity ... it can be used during full catenary line operation". (This to me indicates that the inverter modules do not perform any HEP duty...) The traction converters are A2V00002028491. The nominal DC link voltage is 3600 V nominal. Nothing is said about having HEP-compatible outputs in these converters.
From a copy of the ACS64 Familiarization and Orientation manual:
No weight given for the main transformer (which is between the trucks) but it is p/n A2V00002028490, and using that information might get you physical parameters.
It includes two 480VAC dedicated HEP transformers.
The two stepdown voltages for different catenary voltages are given as 1957 VAC and 1878 VAC, "depending on the catenary input".
"Voltage switching Is Done Electronically By The Primary Side Tap Changer"
There is a modular "HEP Rack" (A2V00002106069) which produces 480 VAC "to locomotive as a secondary source of electricity ... it can be used during full catenary line operation". (This to me indicates that the inverter modules do not perform any HEP duty...)
The traction converters are A2V00002028491. The nominal DC link voltage is 3600 V nominal. Nothing is said about having HEP-compatible outputs in these converters.
I'm much more familiar with diesel electric locomotives with AC traction.
However, I understood that the Amtrak supply was 3 Phase AC 480 volts at 60Hz.
The overhead line supply is single phase AC at either 60Hz or 25Hz.
The only way of getting 3 phase AC from the OHL supply would be rectifying it and feeding it through an inverter.
If however the train only requires single phase 60Hz, transformers would suffice on 60Hz overhead but this would be unavailable under 25Hz supply.
Certainly the Amtrak P32s use an inverter for HEP supply and a traction inverter can be used in case of failure of the HEP inverter, the locomotive then running on three motors.
The Alaska Railroad SD70MAC can divert one inverter for HEP use on passenger trains with the remaining one powers the train.
M636C
While not really relevant to the ACS-64, Vossloh have a circuit diagram in their "UK Light" diesel locomotive, fitted with a Caterpillar C175 engine.
The circuit diagram appears on the last page:
http://www.vossloh-innotrans.com/media/downloads/pdfs/vrv/Vossloh_UKLIGHT_us.pdf
In this case there is a rectifier on the alternator, but an inverter on the dynamic brakes.
It shows that the HEP inverters are basically similar to the traction inverters.
oltmannd time speed Short time factor distance TE trn resist 4.700979 5 0 0.009794 100,000 4071 9.41684 10 0 0.026168 100,000 4379 14.14991 15 0 0.049176 100,000 4725 18.90437 20 0 0.078892 100,000 5109 23.67769 25 0 0.115354 100,000 5531 28.47435 30 0.1 0.158658 100,000 5991 33.29656 35 0.3 0.208889 100,000 6489 38.14657 40 0.5 0.266146 100,000 7025 43.50619 45 0.5 0.336863 91,733 7598 49.57122 50 0.5 0.425312 82,560 8210 56.38348 55 0.5 0.534119 75,055 8860 63.99394 60 0.5 0.666245 68,800 9548 72.46481 65 0.5 0.825073 63,508 10274 81.87237 70 0.5 1.014531 58,971 11039 92.31073 75 0.5 1.239246 55,040 11841 103.897 80 0.5 1.504765 51,600 12681 116.7786 85 0.5 1.817858 48,565 13559 131.1431 90 0.5 2.186948 45,867 14475 147.2341 95 0.5 2.622746 43,453 15429 165.3737 100 0.5 3.139218 41,280 16421 185.9987 105 0.5 3.755106 39,314 17451 209.7218 110 0.5 4.496452 37,527 18519 237.4367 115 0.5 5.401035 35,896 19625 270.519 120 0.5 6.526753 34,400 20769 311.2446 125 0.5 7.969118 33,024 21952
Assuming 100000 lb TE from 0 to 41.28 mph, then constant 11008 rail hp, and traditional Davis resistance the standing-start mile takes 92.3 seconds. The train reaches 125 mph in a bit more than 8 miles.
Overmod I was hoping we could get you out from 'under the wharf' to address this! Can you provide some specific URLs (in either English or German) that point to specific technical pages? Also: a poster on one of the other lists (the PRR catenary electrics Yahoo group) had a detailed cut of the ACS64 truck, but didn't provide any of the other information about its detail, particularly the way the torque linkage is arranged, or the specific routing of the shafts and gearboxes for final drive. Can you give us URLs that show truck mechanical detail, as well?
I was hoping we could get you out from 'under the wharf' to address this!
Can you provide some specific URLs (in either English or German) that point to specific technical pages?
Also: a poster on one of the other lists (the PRR catenary electrics Yahoo group) had a detailed cut of the ACS64 truck, but didn't provide any of the other information about its detail, particularly the way the torque linkage is arranged, or the specific routing of the shafts and gearboxes for final drive. Can you give us URLs that show truck mechanical detail, as well?
To my disappointment, Siemens have been progressively dumbing down their website, which was one of the last to give real technical detail and most of my sources just lead to broken links on Siemens' website.
This is still better than nothing:
https://www.mobility.siemens.com/mobility/global/SiteCollectionDocuments/en/rail-solutions/locomotives/vectron/vectron-creating-corridors-technic-en.pdf
This might (just) help with explaining the truck design (assuming the ACS-64 truck is basically similar).
https://www.mobility.siemens.com/mobility/global/en/interurban-mobility/rail-solutions/locomotives/vectron/technology/modular-locomotive-concept/flexible-drive/Pages/flexible-drive.aspx
I might have some better data stored away somewhere....
I haven't even been ON a wharf in some time. I've been trapped at a desk in our Navy Headquarters trying to get projects to meet certification requirements which is much less enjoyable.
Blue Streak,
Inverters intended for variable speed drive with induction or synchronous motors are almost invariably variable voltage variable frequency. With that, the inverters should be able to handle a wide range of AC side voltages, though with a maximum set by the devices used in the inverter (this may be what sets the Silverliner 5's 13.4 kV crossover). It is entirely possible, though not necessarily optimal, that the locomotives could operate without any tap changing on either the primary or secondary side (note that this is how the locomotives could be configured, not how they actually are configured).
One advantage of using the inverters on the catenary side of the DC link is that they can do power factor correction, i.e. that the current drawn is (mostly) sinusoidal and in phase with the voltage. Rectifiers generally induce rather non-sinusoidal currents, typically slightly trapezoidal square waves when choke input filters are used. Using thyristors to control the DC link voltage also introduces a significant phase difference between the voltage and current, with consequent reduction in power factor, where the inverter can control the DC link voltage and maintain unity power factor. Anything less than unity power factor requires more current to transmit the same power and thus more conductor area.
- Erik
My acceleration calc is OK. Didn't convert mph to fps to calc time.
Here is table again. I bumped up my aero drag to something more realisitic (0.0375)
Can get to 125 mph in 8 miles if loco can do 50% over rating for 4 - 1/2 min. Have no idea if this is reasonable or not.
With aero coeff at 0.03, only need 40% short time overload
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
timz(Didn't think it would take you this long to find your error.)
Please stand by!
oltmanndAgree that F=ma
Turns out if we set the train's resistance to zero (except for inertia) it will reach 125 mph in 7 miles from the start.
timzThe 0.045 is for freight cars-- it's 0.03 for passenger.
Kinda. There really aren't "freight cars" and "passenger cars" anymore. Even 0.0005 x cross section area is an approximation.
Agree that F=ma, always. Well for speeds <0.1c anyway.
oltmanndI modified C to back into 8 miles and 125 mph (or thereabouts)
oltmannd[Davis said] R=1.3 + 29/W +0.045V +0.0005kAV^2/WN in #/ton
in #/ton
If you drop a one-ton object off a tall building it will accelerate downward at 9.80665 meters per second per second, which is 21.937 mph/sec. In other words 2000 lb will accelerate a ton at 21.937 mph/sec-- so it takes 91.171 lb per ton to accelerate at 1 mph/sec, assuming no rotational inertia.
erikem I would suspect that the there may be separate primary windings for the different voltage levels, though one way of handling 25Hz would be to use the same number of turns for 11kV/25Hz primary as for the 25kV/60Hz primary, but increase the number of secondary turns for 25Hz to maintain the same secondary voltage. This would result in about the same peak magnetic flux in the transformer core. - Erik
I would suspect that the there may be separate primary windings for the different voltage levels, though one way of handling 25Hz would be to use the same number of turns for 11kV/25Hz primary as for the 25kV/60Hz primary, but increase the number of secondary turns for 25Hz to maintain the same secondary voltage. This would result in about the same peak magnetic flux in the transformer core.
M636CSiemens are very good at providing technical detail on their website, often in English as well as German and circuit block diagrams are provided.
(As a partial defense: I was being a bit humorous about the 'inverter feeding a DC link' because of the way it was worded without comment. I thought it would have been more appropriate to say 'inverter functioning as a rectifier' (or something else similarly accurate at low word count). Same way I'd refer to the 'speaker' in a yard telephone when somebody is talking into it -- not a microphone, of course, but acting as one. On the other hand, I easily lapse into pedanticism -- hey, at least I recognize the problem!)
Overmod Just what an 'input inverter' that feeds a 'DC link' might be is a mystery. I suspect they meant 'rectifier' in this context (see here for an example feeding a motor directly) ... but got lost in translation without a proofreader who understood the technology.
Just what an 'input inverter' that feeds a 'DC link' might be is a mystery. I suspect they meant 'rectifier' in this context (see here for an example feeding a motor directly) ... but got lost in translation without a proofreader who understood the technology.
Siemens are very good at providing technical detail on their website, often in English as well as German and circuit block diagrams are provided. The ACS-64 is basically a standard European locomotive adapted for Amtrak's voltages.
Both input and output inverters are basically the same. The input inverters under power, as you imply, operate as rectifiers and feed their intermediate DC to the output inverters. Under power two of the output inverters feed the motors with variable voltage, variable frequency AC while the third provides 60Hz power at constant voltage to the train.
When in regenerative braking the "output" inverters take three phase power at variable voltage and frequency and convert it to DC which they feed to the "Input" inverters which convert it to single phase AC at the line voltage and frequency.
The input and output inverters are basically the same. The three output inverters are identical, and if the train HEP inverter fails, one of the traction inverters takes its place and the train proceeds on half traction power.
To address one point by the original poster, there are two major overhead line frequencies used in Europe, 50Hz (25kV) and16.66Hz (15kV). These are equivalent to the two voltages and frequencies used by Amtrak and many locomotives are built for the two AC systems. Generally, the transformer is built to take the lower frequency and will operate correctly at the higher frequency. Amtrak's 25Hz transformer will be smaller and lighter than a German 16.66Hz transformer of the same power which would be installed in the equivalent standard locomotive.
For those new to this, 50Hz and 60Hz are unsuitable for direct use in commutator motors of high power so lower frequency current of 16.66Hz or 25Hz was used for rail traction purposes. The catenary of the Pennnsylvania and New Haven was 25Hz and Amtrak only adopted 60Hz after only rectifier locomotives or inverter locomotives were in use.
timz If we assume traditional Davis resistance, then train resistance in pounds is A + BV + (C times V squared) where V is speed in miles/hour and A = 3653.5 B = 33.45 C = 1.0344
If we assume traditional Davis resistance, then train resistance in pounds is A + BV + (C times V squared) where V is speed in miles/hour and
A = 3653.5
B = 33.45
C = 1.0344
Yes, except I modified C to back into 8 miles and 125 mph (or thereabouts)
I didn't the "bearing" and "flange/wheel" parts of Davis would differ much.
R=1.3 + 29/W +0.045V +0.0005kAV^2/WN
where k is my fudge factor.
oltmannd timzStill some sort of big error in your calculation-- 100000 lb TE won't accelerate an 1100-ton train at 1.6 mph/sec, even with zero rolling resistance. Probably units in my accel calc.
timzStill some sort of big error in your calculation-- 100000 lb TE won't accelerate an 1100-ton train at 1.6 mph/sec, even with zero rolling resistance.
Probably units in my accel calc.
Looks okay to me. But units are ft/s^2. No reason engineer can't start a stretched train at that rate after a few seconds. It's much slower than the 0.1g rate for some transit equipment.
timzTraditional-Davis says the train needs 2763 rail horsepower to maintain 80 mph. Think it actually needs less than that?
Has to be. C is what I had to vary to back into the performance. There is no published info I could find on a modified Davis Eq. for Amfleet.
I ignored the mass of the locomotive - which isn't a terrible thing to do in the freight world, but matters a bit more here. I should add it in...it's easy to do. Adding in rotational inertia? Meh. It's less than passenger load (or my error in actual train weight) Let's just call this a one and a half significant digit exercise!
Overmod Erikem is admirably suited to answer this in full detail. It is a bit difficult to extract the sense from what I think is translated German, but it would appear that the setup is heavier because there are separate transformer windings for each of the three powers, presumably stepping down to a standard (unspecified) voltage going to the 'cubicles'. It woud have been interesting to see a block or circuit diagram showing more precisely how Siemens designed this. Just what an 'input inverter' that feeds a 'DC link' might be is a mystery. I suspect they meant 'rectifier' in this context (see here for an example feeding a motor directly) ... but got lost in translation without a proofreader who understood the technology.
Erikem is admirably suited to answer this in full detail.
It is a bit difficult to extract the sense from what I think is translated German, but it would appear that the setup is heavier because there are separate transformer windings for each of the three powers, presumably stepping down to a standard (unspecified) voltage going to the 'cubicles'. It woud have been interesting to see a block or circuit diagram showing more precisely how Siemens designed this.
I'll give it my best shot...
An H-bridge inverter will gladly transfer power from the AC side to DC side (i.e. acting like a rectifier) as well as transferring power for the DC side to AC side (traditional inverter). In fact, many low output voltage (1V or less) DC-DC converters use FET's operated as synchronous rectifiers instead of diodes, as it is easy to make the I*Rdson voltage drop less than the forward voltage drop of a diode. Having the inverter capability to feed regenerated power back to the catenary also saves in not having to carry the DB resistor grids around.
Paul MilenkovicBut isn't 120+ tons of total weight on what, four axles, a bit much for the kind of speeds contemplated?
No. (Assuming the period and damping of the secondary suspension is correct). The low unsprung mass, especially with respect to low inertia of the wheel in all axes of rail interaction, is far more significant for high speed.
Weight distribution across those four axles is of course important, and there *might* be a case made for 'taper loading' (a bit less weight on the outer axles) but at those speeds you will not have a problem with primary deflection, or (with any sensible type of track curvature and transition spiraling) high rates of lateral acceleration of heavier mass requiring sudden high flange forces. So the actual weight of the carbody is of less significance, up to the point the primary springing has to become too 'hard' to give short-period following of rail-level anomalies. (I do not think this is the case for 30-ton axle load, per se)
If you look at the Siemens drawing of the truck frame, the secondary suspension is four springs, arranged laterally (two and two) right on the lateral centerline of the truck frame. I presume the torque link is decoupled from the suspension (as it is for the Flexi-Floats) so there is no particular weight transfer on acceleration, and therefore no weird loading of the primary suspension.
I am presuming that Siemens knows where any critical speeds are, and has designed the truck masses and suspension characteristics accordingly.
DeggestyYou really need a copy editor who understands the technology;
You are completely right. I *think* I was attributing fact checking to proofreading, but that's no excuse. I would note in my own defense that when I proof galleys, fact checking is inherently part of the exercise; I don't just limit it to correcting typographical mistakes.
Writer didn't recognize (or perhaps didn't care about) the difference, and editor didn't or couldn't catch it. Not a good thing all around for a technical publication... but then again I'm too much of a perfectionist when it comes to printed media...
Quoting overmod: "Just what an 'input inverter' that feeds a 'DC link' might be is a mystery. I suspect they meant 'rectifier' in this context (see here for an example feeding a motor directly) ... but got lost in translation without a proofreader who understood the technology."
You really need a copy editor who understands the technology; a copy editor has the authority to make changes in text; a proofreader only ascertains that what is going to be printed is what the author wrote and has no authority to correct the original manuscript/text (my wife worked in both capacities for two book publishers--and I gave her assistance when she was copy editing books that had mention of railkroads).
Johnny
Still some sort of big error in your calculation-- 100000 lb TE won't accelerate an 1100-ton train at 1.6 mph/sec, even with zero rolling resistance.
That's assuming 125 US tons for the engine-- zat right?
And you're assuming 7338-2/3 rail horsepower at all speeds, except a 100000-lb TE ceiling up to 27.52 mph. Tonnage 1115 actual and I'll guess 1159 effective inertial tons (the increase for rotational inertia).
The 18 cars are 1530 ft long; in that distance the train accelerates to 40.37 mph in 48.5 seconds. The standing-start mile takes 97.75 seconds; speed 61.6 mph at that point.
Five miles takes 273.8 seconds; speed there 96.1 mph; it reaches 100 mph in 31688 ft and 310.5 seconds. After ten miles they're at 109.7 mph.
In reality the train won't accelerate to 40 mph in its own length-- none of us knows what it could do if the engineer didn't bother starting smoothly.
Traditional-Davis says the train needs 2763 rail horsepower to maintain 80 mph. Think it actually needs less than that?
What has me scratching my head is this. Amtrak is just going to ask for a whole bunch of money to upgrade the cat (and speeds) on the south end of the NEC. Why not buy a loco that can take advantage of the speed?
I have no idea what the thing weighs. I Mighty Mouse is about 100 tons. This thing is bigger and stronger, so roughly P42 weight?
CSSHEGEWISCH I will proceed to throw a monkey wrench into the above calculations: Since the ACS-64 is a straight electric, have short-term ratings been considered in calculating acceleration rates?
I will proceed to throw a monkey wrench into the above calculations: Since the ACS-64 is a straight electric, have short-term ratings been considered in calculating acceleration rates?
Nope. But I can take a swag at them. What would be a good guess...+20% for 2 minutes?
Another question:
So this thing has Cardan shaft drive instead of "nose suspended" traction motors for reduced unsprung mass and less pounding of the track at high speeds.
But isn't 120+ tons of total weight on what, four axles, a bit much for the kind of speeds contemplated?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
corrected numbers
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