Locomotive electrical output

[dekemd]

Our comm center has a backup generator in case of power outages. It's basically the same as a locomotive, diesel engine driving a generator. It's rated at around 150 kilowatts. What is an average locomotive capable of putting out as far as electrical power? Say a sd40-2 or a AC4400?

[dekemd]

Our comm center has a backup generator in case of power outages. It's basically the same as a locomotive, diesel engine driving a generator. It's rated at around 150 kilowatts. What is an average locomotive capable of putting out as far as electrical power? Say a sd40-2 or a AC4400?

[zardoz]

If memory serves...

The SD40-2 works on a 400 volt system. Each traction motor is rated for up to 1500 amps (short-time rating), and there are 6 traction motors on an SD.

As watts=volts x amps, you get 400x1500x6 = 3,600,000 or 3600kw.

FYI - at full power an sd40-2 uses up to 800 gallons of fuel per hour.

I do not know any specs for other locomotives.

[zardoz]

If memory serves...

The SD40-2 works on a 400 volt system. Each traction motor is rated for up to 1500 amps (short-time rating), and there are 6 traction motors on an SD.

As watts=volts x amps, you get 400x1500x6 = 3,600,000 or 3600kw.

FYI - at full power an sd40-2 uses up to 800 gallons of fuel per hour.

I do not know any specs for other locomotives.

[Anonymous]

I think your figures are a little high. First of all if you are putting 1500 amps per traction motor in series you would need (6X1500) 9000 amps. I have never seen an amp meter go to 9000 amps. The voltage is determined by the speed the motor is turning. The voltage at low speeds and high amps might be as low as 75 volts. At sixty mph the amps drop and the voltage then rises to your quoted 400 volts. On a newer SD or Dash 9 you can go into diagnostics and check the voltage and current at various speeds.

[Anonymous]

I think your figures are a little high. First of all if you are putting 1500 amps per traction motor in series you would need (6X1500) 9000 amps. I have never seen an amp meter go to 9000 amps. The voltage is determined by the speed the motor is turning. The voltage at low speeds and high amps might be as low as 75 volts. At sixty mph the amps drop and the voltage then rises to your quoted 400 volts. On a newer SD or Dash 9 you can go into diagnostics and check the voltage and current at various speeds.

[zardoz]

pfrench-
you may be right regarding the voltage change in relation to traction motor speed (counter-electro-motive-force). However, the ratings at full power starting a train moving or pulling uphill at maximum throttle at 3mph I believe are correct.

The traction motors on an SD40-2 are permanently in parallel, and the ammeter shows the electrical output only to traction motor #2, not the entire set.

[zardoz]

pfrench-
you may be right regarding the voltage change in relation to traction motor speed (counter-electro-motive-force). However, the ratings at full power starting a train moving or pulling uphill at maximum throttle at 3mph I believe are correct.

The traction motors on an SD40-2 are permanently in parallel, and the ammeter shows the electrical output only to traction motor #2, not the entire set.

[Anonymous]

I have never seen a locomotive that was permanently in parallel by design. I do remember having one that would not go back into series by because of a fault, at slow speeds it would not pull itself. I have seen some SD39s that were designed for the yard that did not have parallel contactors. I also remember having an SD40-2 that blew it's series contactor when it dropped down under heavy load.

If what you say were true when the amp meter read 4000 amps the traction motor you say is rated for 1500 amps would surely fry.

[Anonymous]

I have never seen a locomotive that was permanently in parallel by design. I do remember having one that would not go back into series by because of a fault, at slow speeds it would not pull itself. I have seen some SD39s that were designed for the yard that did not have parallel contactors. I also remember having an SD40-2 that blew it's series contactor when it dropped down under heavy load.

If what you say were true when the amp meter read 4000 amps the traction motor you say is rated for 1500 amps would surely fry.

[oltmannd]

You are all making this too complicated. The straight conversion from HP to KW is there is .746 KW per HP. Both are units of power.

However, a locomotive's HP is rated at the shaft going INTO the main generator/altenator. e.g. an SD60 is rated at 3838 HP under AAR std conditions, but only 3604HP (2689KW) comes out of the main generator as electrical energy headed for the traction motors.

In notch 8 - 904 RPM, a 10 pole AR10 alternator (EMD 40 series) makes 75Hz AC power. To use as an emergency generator, you'd have to operate it at 720 RPM, roughly notch 6, so output would be 60 Hz.

[oltmannd]

You are all making this too complicated. The straight conversion from HP to KW is there is .746 KW per HP. Both are units of power.

However, a locomotive's HP is rated at the shaft going INTO the main generator/altenator. e.g. an SD60 is rated at 3838 HP under AAR std conditions, but only 3604HP (2689KW) comes out of the main generator as electrical energy headed for the traction motors.

In notch 8 - 904 RPM, a 10 pole AR10 alternator (EMD 40 series) makes 75Hz AC power. To use as an emergency generator, you'd have to operate it at 720 RPM, roughly notch 6, so output would be 60 Hz.

[zardoz]

I wi***o continue with this only for my own information; I am not questioning anything either pfrench or oltmannd have said.

I remeber back when operating old EMD equipment (gp7, gp30; gp35 etc) that when accelerating a train, the engineer had to be aware of the speed at which each locomotive made 'transition' from series to parallel. If more than one locomotive made transition at the same time, a break-in-two was a real possibility due to two (or more) locomotives temporarily losing power (during the actual change from series to parallel) and then both coming back on line. During the power drop, it was a possibility that (depending on grade and other factors) that a small portion of the train could run-in a bit, then when power came back, the locomotives and the few cars that ran in would accelerate quickly. When the slack would finally get to the point of being fully stretched agian, the train would break at that point.

When we got the (then) new SD40-2, the transition speed was no longer an issue due to the fact there was no 'transition point' Perhaps the transition was done electronically and modified so as to not cause the above-mentioned problem. But I never noticed and change in locomotive operating conditions as the train accelerated.

I would appreciate any info from other engineers regarding this. In the meanwhile, I'm going to dig thru my old RR stuff and see if I can find my operating manual for the SD's.

[zardoz]

I wi***o continue with this only for my own information; I am not questioning anything either pfrench or oltmannd have said.

I remeber back when operating old EMD equipment (gp7, gp30; gp35 etc) that when accelerating a train, the engineer had to be aware of the speed at which each locomotive made 'transition' from series to parallel. If more than one locomotive made transition at the same time, a break-in-two was a real possibility due to two (or more) locomotives temporarily losing power (during the actual change from series to parallel) and then both coming back on line. During the power drop, it was a possibility that (depending on grade and other factors) that a small portion of the train could run-in a bit, then when power came back, the locomotives and the few cars that ran in would accelerate quickly. When the slack would finally get to the point of being fully stretched agian, the train would break at that point.

When we got the (then) new SD40-2, the transition speed was no longer an issue due to the fact there was no 'transition point' Perhaps the transition was done electronically and modified so as to not cause the above-mentioned problem. But I never noticed and change in locomotive operating conditions as the train accelerated.

I would appreciate any info from other engineers regarding this. In the meanwhile, I'm going to dig thru my old RR stuff and see if I can find my operating manual for the SD's.

[Anonymous]

An SD40-2 does transition much smoother, you will still see the fluctuation in the amp meter when the transition occurs. It is not done electronically there are still serial and parallel contactors in the lower electrical cabinet.

[Anonymous]

An SD40-2 does transition much smoother, you will still see the fluctuation in the amp meter when the transition occurs. It is not done electronically there are still serial and parallel contactors in the lower electrical cabinet.

[dekemd]

Thanks guys. So we're talking in the 2.5 to 3 Megawatt range. That's what I wanted to know. But you did bring up another question. Tell me about the series to parallel transition. I understand series and parallel circuits. What I want to know is what advantages you gain by running the motors is series and then parallel.

Derrick

[dekemd]

Thanks guys. So we're talking in the 2.5 to 3 Megawatt range. That's what I wanted to know. But you did bring up another question. Tell me about the series to parallel transition. I understand series and parallel circuits. What I want to know is what advantages you gain by running the motors is series and then parallel.

Derrick

[zardoz]

I do not know too much about electrical matters other than what I learned when in locomotive class. I do know that locomotives use series to start moving, and around 20-25mph transitioned to parallel. On the GP30 and GP35 locomotives there were (if memory serves) about 20 transition steps, with the main one around 23mph. There was a series, series shunt, parallel, and parallel shunt on the E8 & E9 locomotives we used for suburban service. I do know that the F40PH locomotives do NOT have any transition steps, the result being that they are very slow off the line. They would be terrible units for suburban service except for the fact that they made up for the slow starting by virtue of good acceleration above 20mph. When starting a heavy train a locomotive can develop over 1500 amps per traction motor, even if the throttle might only be in 3rd or 4th notch. But at 50mph in the 8th notch a locomotive might only be pulling 300 amps. And in full dynamic braking each motor (SD40-2) can generate up to 900 amps of braking power.

[zardoz]

I do not know too much about electrical matters other than what I learned when in locomotive class. I do know that locomotives use series to start moving, and around 20-25mph transitioned to parallel. On the GP30 and GP35 locomotives there were (if memory serves) about 20 transition steps, with the main one around 23mph. There was a series, series shunt, parallel, and parallel shunt on the E8 & E9 locomotives we used for suburban service. I do know that the F40PH locomotives do NOT have any transition steps, the result being that they are very slow off the line. They would be terrible units for suburban service except for the fact that they made up for the slow starting by virtue of good acceleration above 20mph. When starting a heavy train a locomotive can develop over 1500 amps per traction motor, even if the throttle might only be in 3rd or 4th notch. But at 50mph in the 8th notch a locomotive might only be pulling 300 amps. And in full dynamic braking each motor (SD40-2) can generate up to 900 amps of braking power.

[oltmannd]

Transition is a way of matching the locomotive's performance needs to the abilities of the main generator. The main generator has a current limit and a voltage limit inherent in it's design. If required to produce too much current, the windings will get too hot (from their own internal resistance) and the insulation will melt and the generator will have shorted windings. If the voltage gets too high, either the commutator will flash over (DC generator) or the rectifying diodes with fail (AC "generator" a.k.a. alternator).

When starting a train, you want lots of pulling force. Pulling force is proportional to the current flowing thru the traction motors. If each motor can take 900 Amps and I put them all in parallel, I'd need a main gen that can do 5400 Amps! Meltdown city! If I put them all in series, I only need 900 Amps, but I'd need to do it a6 times the voltage of having them all in parallel

As a traction motor turns, it create "back EMF" or a voltage that opposes the voltage imposed on it. The faster it turns, the higher this back voltage gets. In order to keep the motors taking the same HP, I need to raise the voltage on them higher than the back EMF. Lets say, at 60 mph I need 900 VDC at full throttle. If I arrange my 6 traction motors in parallel, I'd need a generator that can do 6000 Volts. Flashover City! If I arrange them in parallel, I only need 900 volts (but 6 times the current).

Transition requires reconfiguration of how the motors are connected to the generator. This is usually done with some really big contactors and switches. Typically, a six axle will require two arrangements. All six in parallel or three pairs of two. Lately, (SD50/Dash8 and newer) transition takes place on the main generator. The generator has two sets of winding that are arranged in series or parallel by means of a single contactor (switch). This has made for much smoother transition.

Four axles since the GP40 are full parallel all the time. The reason an Amtrak F40 accelerates more slowly than a GP40-2 is most likely gear ratio. The Dash 2 control system is identical.

[oltmannd]

Transition is a way of matching the locomotive's performance needs to the abilities of the main generator. The main generator has a current limit and a voltage limit inherent in it's design. If required to produce too much current, the windings will get too hot (from their own internal resistance) and the insulation will melt and the generator will have shorted windings. If the voltage gets too high, either the commutator will flash over (DC generator) or the rectifying diodes with fail (AC "generator" a.k.a. alternator).

When starting a train, you want lots of pulling force. Pulling force is proportional to the current flowing thru the traction motors. If each motor can take 900 Amps and I put them all in parallel, I'd need a main gen that can do 5400 Amps! Meltdown city! If I put them all in series, I only need 900 Amps, but I'd need to do it a6 times the voltage of having them all in parallel

As a traction motor turns, it create "back EMF" or a voltage that opposes the voltage imposed on it. The faster it turns, the higher this back voltage gets. In order to keep the motors taking the same HP, I need to raise the voltage on them higher than the back EMF. Lets say, at 60 mph I need 900 VDC at full throttle. If I arrange my 6 traction motors in parallel, I'd need a generator that can do 6000 Volts. Flashover City! If I arrange them in parallel, I only need 900 volts (but 6 times the current).

Transition requires reconfiguration of how the motors are connected to the generator. This is usually done with some really big contactors and switches. Typically, a six axle will require two arrangements. All six in parallel or three pairs of two. Lately, (SD50/Dash8 and newer) transition takes place on the main generator. The generator has two sets of winding that are arranged in series or parallel by means of a single contactor (switch). This has made for much smoother transition.

Four axles since the GP40 are full parallel all the time. The reason an Amtrak F40 accelerates more slowly than a GP40-2 is most likely gear ratio. The Dash 2 control system is identical.

[zardoz]

oltmannd-
very interesting. thanks

[zardoz]

oltmannd-
very interesting. thanks

[adrianspeeder]

oltmannd, thanks a lot
I am going to be an electrical engineer, so this topic is interesting to me. Every time I asked someone I would get an answer like “I don’t know.” What you said makes sense to me, and that’s one less question in my mind.
Do you know what type of wire is used between the main generator and the traction motors?
Thanks,
Adrian

[adrianspeeder]

oltmannd, thanks a lot
I am going to be an electrical engineer, so this topic is interesting to me. Every time I asked someone I would get an answer like “I don’t know.” What you said makes sense to me, and that’s one less question in my mind.
Do you know what type of wire is used between the main generator and the traction motors?
Thanks,
Adrian

[dekemd]

oltmannd,

After thinking about it last night, that was the reason I came up with. Thanks for the great explanation. I had the concept figured out, just didn't know how to explain it.

Derrick

[dekemd]

oltmannd,

After thinking about it last night, that was the reason I came up with. Thanks for the great explanation. I had the concept figured out, just didn't know how to explain it.

Derrick

[oltmannd]

QUOTE: Originally posted by adrianspeeder

oltmannd, thanks a lot
I am going to be an electrical engineer, so this topic is interesting to me. Every time I asked someone I would get an answer like “I don’t know.” What you said makes sense to me, and that’s one less question in my mind.
Do you know what type of wire is used between the main generator and the traction motors?
Thanks,
Adrian

Big. Copper. Lots of 0s in the gauge. With synthetic rubber insulation. The builders messed around using aluminum for a while in the late 60s - early 70s, but it caused lots of fires.

[oltmannd]

QUOTE: Originally posted by adrianspeeder

oltmannd, thanks a lot
I am going to be an electrical engineer, so this topic is interesting to me. Every time I asked someone I would get an answer like “I don’t know.” What you said makes sense to me, and that’s one less question in my mind.
Do you know what type of wire is used between the main generator and the traction motors?
Thanks,
Adrian

Big. Copper. Lots of 0s in the gauge. With synthetic rubber insulation. The builders messed around using aluminum for a while in the late 60s - early 70s, but it caused lots of fires.