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Motors
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WE2703
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Motors
 
« on: Mar 22nd, 2005, 7:27pm »
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How many volts does a motor on a locomotine use?
 
How many volts would a SW unit use?
 
How many would a SD use?
 
Thanks
 
William


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CHESSIEMIKE
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Re: Motors
 
« Reply #1 on: Mar 23rd, 2005, 5:30am »
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Most stickers I've seen say "Caution 600 Volts!".  Specs for the SD60 with a 710G3 engine and a AR11A alternator has a Max of 1350 volts DC.
CHESSIEMIKE


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Re: Motors
 
« Reply #2 on: Mar 23rd, 2005, 5:36am »
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But don't Amps move the weight?
 


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Cody
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Re: Motors
 
« Reply #3 on: Mar 23rd, 2005, 11:30am »
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Horsepower is what pulls on the freight cars.   Volts and Amps have a relationship to each other that cannot exist in separation.   You can have many volts and few amps, or many amps and few volts to accomplish the same task.  
 
Volts x Amps = Watts  
Watts x 746 = Horsepower  
 
One horse can theoretically do 746 Watts of work.
 
If you had a 600V alternator, with traction motors and wiring rated for 1000 amps you would have 600kilowatt locomotive rated at 805hp.   Likewise, if you had a 1000V rated alternator that put out 600 amps, the result would be the same.
(If it were a three-phase AC locomotive the power output would have an additional mutliplier of 1.73 for the three phase component.)
 
A 4400 horsepower locomotive is in fact a 3.28 megawatt powerplant.   In Europe I believe they no longer bother with the stupid "horsepower" step and rate their locomotives and their cars in watts.  I know many old-timers like their horsepower ratings, but I say be done with it......go metric already!!   I have never seen 4400 horses in one place and I have no idea what they could pull.    


« Last Edit: Mar 23rd, 2005, 11:30am by Cody » Logged
WE2703
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Re: Motors
 
« Reply #4 on: Mar 26th, 2005, 5:38pm »
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How many volts would one motor on one axle use?
 
Thanks
 
William


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Pennsy
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Re: Motors
 
« Reply #5 on: Mar 26th, 2005, 6:11pm »
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Hi,
 
The voltage doesn't vary too much, running around 660 to 750 volts. What varies considerably with the load, speed, is the current going through the motors, the Amperage. The heavier the load and speed the more current the motors will draw and demand from the generator and the Diesel engine. Diesel engines attempt to maintain a constant RPM, irrespective of the load, and so the difference in the sound of the diesel and the amount of smoke it spews through its exhausts. So, as you notch up the throttle, up goes the Amperage, to an extent the voltage, and we won't even mention what happens to the fuel consumption and economy. And of course, the sound level of the engine climbs as well. If you want to see this in action, camp out at Cajon Pass for a while, and watch diesels really wind up the decibels climbing the mountain. The ground feels like an earthquake is going on.


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Cody
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Re: Motors
 
« Reply #6 on: Mar 26th, 2005, 9:47pm »
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We need a locomotive electrician out there to answer in more detail.  My question is how do they accelerate?....what is the throttle lever connected to?.... does it adjust the field of the motor with the genset being a governed, "constant speed" variety?   or does it just increase the frequency of the genset by giving it more fuel?


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Cody
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Re: Motors
 
« Reply #7 on: Mar 26th, 2005, 10:16pm »
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From the specs I downloaded here for an SD40, it does not appear that the diesels on locomotives attempt a constant speed situation as you have suggested Pennsy, as the specs seem to show a range of speeds.  
 
I would guess that with DC locomotives frequency (RPM) change must be converted into a voltage change on the DC side of the recitifiers for more speed or power at the motors.   With AC locomotives the frequency change (RPM) of the genset could be converted directly into a speed change.
 
I know this is a bunch of eletro-babble, but it is a great and fundamental question:  what makes the darn things move?   We all know it aint a driveshaft with a U-Joint.  
 
The specs:
 
http://www.alleged.com/info/sd40/


« Last Edit: Mar 26th, 2005, 10:32pm by Cody » Logged
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Re: Motors
 
« Reply #8 on: Mar 26th, 2005, 10:28pm »
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An excerpt from the spec/manual:  http://www.alleged.com/info/sd40/
 
 
"Each running notch on the throttle increases locomotive power by increasing generator excitation or engine speed or both. At time of locomotive start each notch provides a fixed and immediate level of generator excitation. This level brings about an immediate and fixed response to throttle position during starting."
 
 
So to answer my own question:   The throttle controls engine speed and generator excitation depending upon the situation to make the locomotive pull harder.


« Last Edit: Mar 26th, 2005, 10:33pm by Cody » Logged
CHESSIEMIKE
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Re: Motors
 
« Reply #9 on: Mar 27th, 2005, 6:57am »
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on Mar 26th, 2005, 5:38pm, WE2703 wrote:       (Click here for original message)
How many volts would one motor on one axle use?
 
Thanks
 
William
Think about it this way.  Does the voltage in your house change every time you turn on another light?  Now, let's think about your car.  The voltage does change somewhat depending on load & engine speed.  If you checked you would see about 10.5 volts available to run other things while the starter is cranking over the engine and about 13.8 volts available at 1500rpm with no load on the alternator.  So, in your car you have a more limited supply of electricity and can see a voltage change depending on load.  In your house you have a larger supply in comparison to the amount of load so you don't see a large change.  Does that comparison help?  
Another change that the locomotive goes through is "Transition".  The amount of effective voltage at the traction motor can change depending on the electrical circuit it is in & this can change under normal operation.  They can be hooked up in Series-Series, Series-Parallel, or Parallel-Parallel The change in circuit is called Transition.  Are you confused yet?  
CHESSIEMIKE


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Pennsy
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Re: Motors
 
« Reply #10 on: Mar 27th, 2005, 10:18am »
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Hi Chessie 2-8-2;
 
Actually the voltage in your walls does vary, by as much as 5 %. Nominal line voltage is 117 VAC @ 60 hz. People normally regard it as 110 VAC or 120 VAC. It can fluctuate depending on the time of day, ie. how many amps, total, the city or area being served by the powerplant has to deliver. Come summertime, good luck, hence the term "brown out".  What is held very constant, within a fraction of a percent, is the frequency of the power, 60 hz. (cycles per second). That is because many industrial, commercial, clocks and timepieces depend on that for their accuracy.  
 
In the Physics lab we once had to calculate how much of a load the line could take to maximize current demand, amperage. It turned out to be about 57 VAC. Can you imagine loading down a 117 VAC line to that level The amperage delivered would blow you away. An interesting exercise in "reduction to absurdity". (Reducio ad absurdum).


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Cody
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Re: Motors
 
« Reply #11 on: Mar 27th, 2005, 12:32pm »
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I had no idea they could series-parralel and vice versa the motors.  That makes a lot of sense.   It would be similar to having "gears" and would allow a much greater range of loading capabilities.

« Last Edit: Mar 27th, 2005, 12:33pm by Cody » Logged
Knightwolf2102
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Re: Motors
 
« Reply #12 on: Mar 29th, 2005, 3:39pm »
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A little something to make it easier to understand
 
think of a garden hose......
 
the water is comprised of two things...volume and pressure
 
pressure would be like the voltage in an electric cable....
 
current or amperage would be the volume.
 
the higher the voltage the higher the pressure
 
the higher the amperage the higher the volume or power.


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Pennsy
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Re: Motors
 
« Reply #13 on: May 26th, 2005, 10:40am »
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Hi AceyDeucey;
 
The bottom line here is WATTS. Or, more appropriately, Kilowatts. This directly translates into Horsepower. As you draw more current, Amperes, from your source, it loads down, and the voltage, the driving pressure, drops. Accordingly, the current rises dramatically. You see the same phenomenon when you start your car. You get a momentary voltage drop, a tremendouse increase in amperage, and the starter motor turns over.


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silver_champion
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Re: Motors
  102-2.jpg - 182192 Bytes
« Reply #14 on: Jul 17th, 2005, 8:26am »
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Hello, here is a picture of the inside of a F7 unit. 600 Volts at 1500 hp. Also please check my new Photo Shows on railroading at;
//photoshow.comcast.net/richardtrains



Image exceeds display size of 900 pixels wide. (182192 bytes, 1024x787 pixels)


Click Here to View Image 102-2.jpg - 182192 Bytes


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Knightwolf2102
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Re: Motors
 
« Reply #15 on: Jul 17th, 2005, 5:17pm »
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on May 26th, 2005, 12:25am, AC/DC wrote:       (Click here for original message)
Boy, do most of you have this wrong!
 
On D.C. locomotives the voltage can vary quite a bit--from 0 up to 1500+ volts depending on the excitation and throttle setting (engine rpm).
 
You can not compare a locomotive to the realitively steady voltage in your house...they do not work that way!
 
Locomotives do not even produce the same voltage in the same notch. For example, a locomotive in notch 8 on a slow heavy pull will be producing lower volts and high amps. A locomotive in notch 8 at 70mph will be producing its power by high volts and lower amps.
 
A.C. locomotives also vary the frequency, along with the volts and amps.
 
Most modern DC locomotives do not transition either. The are wired in permanent parallel, and reduce back EMF via circuts in the main alternator.
 
AC locomotives are always in parallel as the AC traction produces minimal back EMF.

 
who are you to tell anyone they are wrong?


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Knightwolf2102
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Re: Motors
 
« Reply #16 on: Jul 31st, 2005, 5:01am »
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I all ready know all of this........you still have not answered my question.

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jdstew
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Re: Motors
 
« Reply #17 on: Jul 31st, 2005, 5:08pm »
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Okay, time to Moderate!
 
Language is a very subtle art form, especially on the Internet. People may disagree, but please do not respond to aggressive language with the same...it will only encourage the situation. Before responding, take a step back, collect your thoughts, then disagree.  
 
Pissing Contests, Bully BS, or other toxic language will not be tolerated!
 
JE Stewart


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JE Stewart
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Re: Motors
 
« Reply #18 on: Jul 31st, 2005, 5:16pm »
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Cody-
 
As I recall, early DC Traction motors did have roughly 4 settings: Something like series-series, series-parallel, parallel-parallel.  
 
Specifically, EMDs D27 and D37 come to mind. The D37 was rated for a Max. 825Amps and the D37 900amps.
 
The Diesel Engine is the indirect actor in this case, the Gen Set is the direct controller of power output to the Traction Motors.
 
Hope this helps and Great question!
 
JE Stewart


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JE Stewart
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Re: Motors
 
« Reply #19 on: Oct 7th, 2005, 1:48am »
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I know I'm probably gonna regret this[LOL!!] But I'm pretty sure AC/DC is correct.The notches on the throttle of a locomotive merely control the throttle[engine speed] of the prime mover.Each notch simply increases the power applied to the generator.If the engine is in run 8,but the locomotive isn't moving,or is moving very slowly,the traction motors will be drawing high amperage,but at low voltage.As the locomotive accelerates,the amps will go down,and the voltage will rise,along with engine RPM's,pretty much the same as an automatic car stuck in high gear would act.To simplify it,each "notch" is simply a proportional increase in throttle opening,with each higher notch producing more engine rpm's,and more potential power,with peak voltage and amperage draw being dictated by how hard the traction motors are working. As far as parallel and series wiring,I can't really immagine reliable relays that could handle that "on the fly"[I could be wrong, it's just my opinion.] But I could see how it would be useful.Series running would allow the generator to pull a heavier train for a longer time at slower speeds,by running the power through all the traction motors,making them all act as resistors,which would decrease the load on the generator,and allow the prime mover to operate at a higher RPM,and make more horsepower.Locomotive engines don't SOUND like the RPM's change much,because the operate at a total range of [usually] less than 750 RPM's. They idle around 50 to 100 RPM's,and max out around 800.By the way,there's NO limit to how much power a DC electric motor can make,it's limited only by how much power you put into it,and how long it holds together!!!

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