bubbajustin Oh yah, I guess that NS did enter the 21st century and buy the ES44AC. I wish I had something moer inteligant to say. I just try to absorb as mutch info as I can. Ac is still more expensive but I think we still might see evan CN buy some AC's in the future. It seems from what you guy's are telling me that AC is more efficiant in some apps.
Oh yah, I guess that NS did enter the 21st century and buy the ES44AC. I wish I had something moer inteligant to say. I just try to absorb as mutch info as I can. Ac is still more expensive but I think we still might see evan CN buy some AC's in the future. It seems from what you guy's are telling me that AC is more efficiant in some apps.
I thought NS bought ES44DC locomotives. Besides they've had GP38AC units on the roster for a long time.
NS does have ES44AC's on the roster. http://www.nsdash9.com/rosters/8000.html
In reply to rrnut, no NS did finnaly buy the ES44AC. I wonder what made them decide to finnal buy a AC locomotive? Probbably just to see how thay would function on coal service. To the service in witch theay are assighned I think. I saw a ES40DC Last weekend. Thay are nice looking locomotives. I belive, however, that the 40DC's are equipped with a button witch you push so the engine puts-out 4400 hp. Probably a nice feature if you begin to stall out on a grade!
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To the service in witch theay are assighned I think.
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BigJim To the service in witch theay are assighned I think.Justin,Big guy, remember Glenda the Good Witch? Maybe she can help you with your spelling before you graduate and go out to apply for a job.
Sorry Big Jim, I will have to get better at that if I wish to become an engineer! I take it by youre' avatar you are an engineer for NS? I wat to work for NS. Is this how you spell that... wich uhhh
Justin -- Dude, RE: " . . . a button witch you push . . . " It's which, and your spell-checker probably won't spot that as an error since the two words sound the same. .
More on topic: This has been touched on before, but the latest big diesel-electric locomotives out of EMD and GE are very complicated beasts. Some of the newest even have three levels of power generation...they generate "dirty" AC power (meaning out-of-phase, I think), transform that into DC, then convert THAT to "clean" AC to actually power the transmission (if that's even the right word).
Short story long, DC's may be down but not out. I don't see the new kind of AC getting cheaper due to economies of scale in the very near future. I do see the two "bigs" that have held out the longest for DC loco's to go for AC's if the price difference isn't that great. But in this economic climate, innovation has to take a back seat to soldiering on, and major purchases or leases may have to be deferred. So Justin, I guess you are "justified"? - a.s.
al-in-chgoMore on topic: This has been touched on before, but the latest big diesel-electric locomotives out of EMD and GE are very complicated beasts. Some of the newest even have three levels of power generation...they generate "dirty" AC power (meaning out-of-phase, I think), transform that into DC, then convert THAT to "clean" AC to actually power the transmission (if that's even the right word).
Modern "AC" locomotives use an alternator to generate a more or less constant voltage variable frequency alternating current. The alternating current is then rectified to produce DC power that is fed into the inverters. The inverters then convert the DC to a variable voltage variable frequency AC power that is fed to the traction motors. The reason that the AC from the traction alternator can't be fed directly to the traction alternator is that it would fix the ratio of prime mover speed to traction motor speed - where the whole point of the electric transmission on a locomotive is to allow a continuously variable ration between prime mover speed and traction motor speed, e.g. allowing run 8 at 10 MPH and run 4 at 70 MPH.
The advantage of this complexity is that the AC transmission is significantly more efficient than the DC transmission and approaches the efficiency of direct gearing. The AC transmission has most of the advantages of a hydraulic transmission (i.e. high adhesion, ruggedness and braking to near zero speed) and is a lot more efficient.
WHICH Ok O made a postit on my PC screen to remind me. I don't have a spell checker. Like asid before Al the power is produced in AC then is sent to the tractoin motors to a inverter I think and then put to the wheels.
The improvements and lowering of cost for AC is a steady slope downward. Example: SEPTA will have AC propulsion on their Silverliner Vs. The transformer on the car provides either 25Hz 11Kv(nominal) or 60Hz 12.5 Kv (doesn't matter which no switching required) directly to 4 wave rectifiers that supply various inverters (traction, passenger convience, emergency, battery charger, signals, communications, etc. The AC traction motors can supply regenerative braking first to all the above car electrical and then to the CAT (if it can take the power) or to dynamic brakes. The specs require a MTBF(mean time between failure rate) of 50,000hr service for the traction motors. AC will be the only way to go.
bubbajustinI don't have a spell checker
Say, Justin, do you have a word processor such as Word or, better yet, WordPerfect, on your computer? Sometimes I write my post in WordPerfect, use the spell checker, then copy the post and paste it on the thread. A spell checker will catch most misspelled words, and it will also catch the error if you don't leave a space between words. There are some words that we use on these threads that the creator of the spell checker did not know and so did not put in, but if you are sure that the word is right, you can add it to your spell checker.
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Yes I have word procesor. That's aggod idea. I saw 5 NS trains at Attica just a while ago. I gave 2 roll by's. I evan saw a -8 40c. Arent those the ones built with the convintional cabs? All DC units as always.
blue streak 1 The improvements and lowering of cost for AC is a steady slope downward. Example: SEPTA will have AC propulsion on their Silverliner Vs. The transformer on the car provides either 25Hz 11Kv(nominal) or 60Hz 12.5 Kv (doesn't matter which no switching required) directly to 4 wave rectifiers that supply various inverters (traction, passenger convience, emergency, battery charger, signals, communications, etc. The AC traction motors can supply regenerative braking first to all the above car electrical and then to the CAT (if it can take the power) or to dynamic brakes. The specs require a MTBF(mean time between failure rate) of 50,000hr service for the traction motors. AC will be the only way to go.
Similarly, several rapid transit operators (I believe that CTA is one of them) are testing AC propulsion motors in their equipment, and this is with a 600 VDC feed from a third rail.
CSSHEGEWISCH blue streak 1 The improvements and lowering of cost for AC is a steady slope downward. Example: SEPTA will have AC propulsion on their Silverliner Vs. The transformer on the car provides either 25Hz 11Kv(nominal) or 60Hz 12.5 Kv (doesn't matter which no switching required) directly to 4 wave rectifiers that supply various inverters (traction, passenger convience, emergency, battery charger, signals, communications, etc. The AC traction motors can supply regenerative braking first to all the above car electrical and then to the CAT (if it can take the power) or to dynamic brakes. The specs require a MTBF(mean time between failure rate) of 50,000hr service for the traction motors. AC will be the only way to go. Similarly, several rapid transit operators (I believe that CTA is one of them) are testing AC propulsion motors in their equipment, and this is with a 600 VDC feed from a third rail.
Aren't the units that Alstom built for NJT AC units? I might just be imaganig things though.
CSSHEGEWISCHblue streak 1 The improvements and lowering of cost for AC is a steady slope downward. Example: SEPTA will have AC propulsion on their Silverliner Vs. The transformer on the car provides either 25Hz 11Kv(nominal) or 60Hz 12.5 Kv (doesn't matter which no switching required) directly to 4 wave rectifiers that supply various inverters (traction, passenger convience, emergency, battery charger, signals, communications, etc. The AC traction motors can supply regenerative braking first to all the above car electrical and then to the CAT (if it can take the power) or to dynamic brakes. The specs require a MTBF(mean time between failure rate) of 50,000hr service for the traction motors. AC will be the only way to go. Similarly, several rapid transit operators (I believe that CTA is one of them) are testing AC propulsion motors in their equipment, and this is with a 600 VDC feed from a third rail.
According to Interurbans Special 50, which came out summer of 1970, Cleveland Transit System was proposing to test the WABCO AC drive system - the blurb on pages 130 & 131 mentioned that the drive system used pulse width modulation to supply power for AC motors. To put things into perspective, more time has passed since Special #50 was published than between the time that development of PCC car and when Special #50 was published.
IOW, AC drives for transit cars is nothing new, what is new is that the power devices capable of handling the loads for a transit car are getting cheaper - IGBT's and associated drive circuits are a lot cheaper than the thyristor circuits used in the original WABCO system. As another example, the chopper for the original BART cars needed two thyristors in series to handle the 1000V traction supply, it is now possible to buy an off the shelf three phase IGBT H-bridge module (which just needs a logic level drive signal) that will handle 1700V.
When the electricity leaves the alternator, is it converted to DC power? Or vise-versa?
The rapidly changing world of electrical equipment is staggering. When I went to college no one thought that electrical work would change much (a mature technology - ha). Now it is changing so fast that it makes a person's head swim. The new 4 wave rectifiers and the new inverters will make - in a few years AC the same price as DC. The applications that are mentioned in light rail rapid transit also leads to this. I forecast that in a few years a standard car (al-la-PCC) will be manufactured and be able to operate on any DC system electrical power standards. DC to AC may also not be far away This ability will allow systems such as METRA electric and South shore to operate on the present 3000V DC and on an AC system (lower construction costs) on any expansions done on these systems. That way when any section of the DC CAT and power supplys get to the end of its useful life in various sections it can be replaced with AC and not have to be retired prematurely.
With the new inverters it doesn't really matter what the input DC voltage is as it can provide the proper AC power to the traction motors and also all the other auxillarys needing different types of AC.
blue streak 1 The rapidly changing world of electrical equipment is staggering. When I went to college no one thought that electrical work would change much (a mature technology - ha). Now it is changing so fast that it makes a person's head swim. The new 4 wave rectifiers and the new inverters will make - in a few years AC the same price as DC. The applications that are mentioned in light rail rapid transit also leads to this. I forecast that in a few years a standard car (al-la-PCC) will be manufactured and be able to operate on any DC system electrical power standards. DC to AC may also not be far away This ability will allow systems such as METRA electric and South shore to operate on the present 3000V DC and on an AC system (lower construction costs) on any expansions done on these systems. That way when any section of the DC CAT and power supplys get to the end of its useful life in various sections it can be replaced with AC and not have to be retired prematurely. With the new inverters it doesn't really matter what the input DC voltage is as it can provide the proper AC power to the traction motors and also all the other auxillarys needing different types of AC.
I'd like to see a standardized car, too. It seems that the LRV needs of many domestic transit systems are close to the same.
Do you think a new standardized (streetcar/LRV) will come out of N. America, Asia or Europe?
al-in-chgo I'd like to see a standardized car, too. It seems that the LRV needs of many domestic transit systems are close to the same. Do you think a new standardized (streetcar/LRV) will come out of N. America, Asia or Europe?
Well --- Knowing how politics are the idea of an ofshore standard is unlikely. Same in the States unless congress steps in and requires a standard car for receiving federal dollars to help buy them. Then the biggest problem would be those system that have installed incompatible signal systems. A positive item for all units would be --- off the shelf 60Hz systems --- that are much cheaper than unique systems.
bubbajustinWhen the electricity leaves the alternator, is it converted to DC power? Or vise-versa?
The output of the alternator windings is AC - as a matter of fact, virtually all "generators" at electric power generating stations are alternators. As in an automobile alternator, the alternating current from the windings is rectified by diodes to produce DC.
In an "AC" locomotive, the DC from the rectified alternator output is run into an inverter to produce a variable voltage variable frequency AC for use in the traction motors. The variable frequency is needed to accommodate the varying locomotive speeds (AC motors fed by a fixed frequency are pretty much single speed) and the variable voltage is needed to supply the proper current to the motors.
Just how exactly are you giving a train a roll by?
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well youll' laugh butt I step out of the car and look at the wheels and couplers to see if anythings wrong. I like to think of myself a a special person.
I think all of us train fanatics do a little closer inspection of things than the average person waiting for a train, after all counting cars gets redundant after awhile.
I agree with train fan. Us railfans do look at things more closely. It makes me dizzy to count cars sometimes! I Just like to think of myself as making sure the world is safer one railcar at a time! te he!
I asked te same question several years ago.
"AC" is far superior then the manufactures should change over and be making them exclusivity. Then the price would drop. I think it is the old way of thinking, "That is the way my grandfather done it and that is the way it has to be done".
I know as an electrician only AC motors had speed controls and worked like the Devil.
spikejones52002 I asked te same question several years ago. "AC" is far superior then the manufactures should change over and be making them exclusivity. Then the price would drop. I think it is the old way of thinking, "That is the way my grandfather done it and that is the way it has to be done". I know as an electrician only AC motors had speed controls and worked like the Devil.
I think the manufactures will work out the bugs and then the motors price will drop. Everything starts out expensive, then over-time it gets cheaper... (thearetically)
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