Passenger Trains > Fuel & Power Question

I searched the site and didn't find anything, so I wonder if anyone could give some basic numbers for fuel consumption of a Genesis locomotive (a P42) in a typical operation -- say in a consist of two or three locos pulling the Empire Builder. I know there will be variances due to grade, speed, how much HEP is being drawn, etc. but I'm just looking for a ballpark.

Speaking of HEP, what's a typical HEP load on a train like the Empire Builder? Again, I know there will be variances based on if the heat is on, if the air conditioning is one, etc but I'm just curious how much electricity a typical consist needs. On multi-locomotive consists, do all the locomotives generate electricity for the train (spreading the load between them) or just the last one? I'd imagine just the last one due to trouble matching the phases between the locos.

Finally, what's the purpose of apparently "looping" the power through the train? I've noticed that every car is connected to every other car by two sets of 480V three-phase cables and that the last car has the cables "looped" back. Why not just a single cable from the locomotive to the back of the train? Is it to equalize the voltage through the consist or...?

Thanks!

ok here are some figures that I hope you can use, a GE P-42 fuel usage
Notch RPM Fuel usage RPM Fuel usage

8 1050 198 900 172
7 978 160 900 172
6 978 130 900 159
5 978 102 900 130
4 900 72 900 102
3 900 51 900 82
2 604 23 900 58
1 468 12 900 47
Idle 468 4 900 37
The second set of figures is for HEP at 400KW

Now this is for one P-42, in a multiple consist, which is usally 2 P-42's one engine will run the HEP (typically the second unit in the consist).

As far as looping there is a feed back circuit in the HEP cables running on 74 volts that has to make the circuit in order for the HEP to send power back to the consist. This is known as "Trian line complete" I.E. the 74 volt is sent to the back of the train on one set of the cables and then back forward on the other set thus completing the circuit. The HEP cables actully has 6 pins in it 3 big ones for 480 volt current and 3 smaller ones for the 74 volts.

Hope this answers your question

gregtravis Wrote:
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> basic numbers for
> fuel consumption of a Genesis locomotive (a P42)
> in a typical operation -- say in a consist of two
> or three locos pulling the Empire Builder.

Assuming 3 locos on-line, with one generating 400 kW of HEP and units loading at run-5, ballpark would be 345 gallons per hour. The HEP loco consumes about 133 gal/hr at the stated load; the other two units will drink about 106 gal/hr each.


> On multi-locomotive consists, do
> all the locomotives generate electricity for the
> train (spreading the load between them) or just
> the last one?

Only one unit at a time generates HEP, but it can be any unit in the consist, as HEP will run through locomotives as well. On trains that run several days (like the Empire) they may move the HEP from one loco to another at intermediate points enroute in order to balance the fuel consumption.


I'll let someone who knows the answers to tackle your other questions.

Thanks very much for that information! Ok, it sounds like the requirement for the "loop" of power is that there is a design consideration that stipulated that HEP not be supplied to the train if there were a break in the train -- i.e. if the train separates in half (uncouple), the HEP lines will automatically go dead. I'm assuming this is a safety issue?

Is 400KW a typical trainset load? I know the P42s are rated for 800KW. Assume 400KW would take about 600HP off the prime mover to generate.

In your table, the fuel consumption figures are gallons per hour?

thanks again

Some back-of-the-envelope WAG for a full Empire Builder (354 revenue passengers on board divided among 3 sleepers (132 passengers) and 3 coaches (222 passengers)):

~16,000 gallons of fuel consumed CHI-SEA (For convenience, I'm ignoring the leg to Portland and assuming the whole train goes to Seattle). Based on a 46 hour trip and 345 gallons/hour (three locomotives). $32K in fuel costs (assuming wholesale diesel @ $2/gallon (which may be a bit high))

49 passenger miles per gallon.

$53K in rail revenue ($150 per passenger (ignoring prices paid for accommodations (sleepers)).

The reason for the looping of the HEP is indeed as described. There are three large pins in each of the HEP cables, each of which carries one of the three phases. One of the three is a larger diameter pin so that it is impossible to plug things in wrong. In addition to the three large pins carrying the 480 V HEP, there are three shorter pins carrying 72 volts DC. The idea is that, were a plug to come loose or be pulled out while still energized, the circuit for the trainline complete would be broken (shutting off the HEP) before any of the 480 V pins would lose contact.

On the Pennsylvanians (42 or 44 and 43) the engineer usually gives fuel readings to the conductor leaving and arriving at Harrisburg. The consist runs to Pittsburgh, a timetable distance of 249 miles and lays over overnight before returning the next day. The train usually consists of one P42DC and 5 Amfleet cars. Comparing leaving fuel readings with the next day's returning figure they usually consumed about 750 gallons, more or less.

Each HEP jumper, which consists of 3 4-0 cables and 1 10-3 SO cord, is capable of handling at most 400 amps. The system is designed to handle 1600 amps, thus the 4 parallel runs. While a single run could be made, the cable size would be unwieldy. Also, a connection would have to be devised that connected in the middle of the car, or crossed the coupler and center sill in some way. An 800 kW alternator as is now found in long distance locomotives generates up to 1200 amps. The old P30ch locos had multiple HEP generators that could be paralleled, generating up to 1,600 amps.

1200 amps will handle a maximum length train in winter...

I thought the GEs had a rectifier/inverter to supply HEP from the main alternator so that it didn't have to run at a high rpm continuously, but the above figures indicate that it runs at 900rpm when generating HEP. Am I incorrect with the inverter thing?

Andy Brown

> Based on a 46 hour trip [Chicago-Seattle]
> and 345 gallons/hour (three locomotives).

Apparently Amtrak can do better than that--
i.e. the train doesn't actually require
three units in Run 5, on average.

In April 1977 somebody tested Amtrak #4:

LA-La Junta 1235 miles 4930 gallons
(three SDP40F, 14 cars)

La Junta-KC 539 miles 1260 gallons
(two SDP, 14 cars)

KC-Chicago 451 miles 1120 gallons
(two SDP, 12 cars)

gregtravis Wrote:
-------------------------------------------------------
> Some back-of-the-envelope WAG for a full Empire
> Builder (354 revenue passengers on board divided
> among 3 sleepers (132 passengers) and 3 coaches
> (222 passengers)):
>
> ~16,000 gallons of fuel consumed CHI-SEA (For
> convenience, I'm ignoring the leg to Portland and
> assuming the whole train goes to Seattle). Based
> on a 46 hour trip and 345 gallons/hour (three
> locomotives). $32K in fuel costs (assuming
> wholesale diesel @ $2/gallon (which may be a bit
> high))
>
> 49 passenger miles per gallon.
>
> $53K in rail revenue ($150 per passenger (ignoring
> prices paid for accommodations (sleepers)).


Mild correction, the EB runs with two locos (I don't know why I was thinking three but I just looked at a bunch of old trip pictures I've taken on the EB and they all have two locos).

So fuel consumed is closer to 11,000 gallons each way and ~71 MPG (per passenger, full train). $22K in fuel costs on $53K in rail revenue.

NB the above note about the Southwest Chief's actual consumption of ~7,000 gallons over roughly the same route length as the EB. If we consider the Genesis locomotives as 20% more efficient than the SDP40F, or about 6,000 gallons (instead of 11,000) then we get all the way down to $12K for fuel costs and 130 MPG (per passenger, full train). Which is really getting into the ballpark.

AndyBrown Wrote:
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> I thought the GEs had a rectifier/inverter to
> supply HEP from the main alternator so that it
> didn't have to run at a high rpm continuously, but
> the above figures indicate that it runs at 900rpm
> when generating HEP. Am I incorrect with the
> inverter thing?
>
> Andy Brown


No, the P40DC and P42DC have to run at 900RPM exactly when generating HEP.

it has to do with the phase of the electricity.... it is 60 hz and for that to happen the engine needs to be turning 900 rpm (actually it is 894 rpm but what is a few rpm)

What's with the 894 RPM? I think the F40PH manual says 893 RPM. If the HEP alternator is a 4 pole machine it needs to turn at 1800 RPM to make 60 Hz. Is the gear box something other than exactly 2:1 speedup or are they choosing for some reason to generate something slightly less than 60 Hz? I asked this several years ago and someone said this was just a nominal number. That may be but why not make 900 RPM / 60 Hz the nominal figures? Maybe the gear ratio isn't 2:1 after all?

gregtravis Wrote:
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>
> No, the P40DC and P42DC have to run at 900RPM
> exactly when generating HEP.

So is there a separate HEP alternator or does the power come off the main? I'm trying to figure out why I was thinking the GEs' HEP was set up differently than the F40s'; maybe it was just something I dreamed up.


>filmteknik Wrote:
-------------------------------------------------------
> What's with the 894 RPM? I think the F40PH manual
> says 893 RPM. If the HEP alternator is a 4 pole
> machine it needs to turn at 1800 RPM to make 60
> Hz. Is the gear box something other than exactly
> 2:1 speedup

I was thinking the F40s' HEP alternator was not gear driven, but directly coupled to the main shaft (making it an 8 pole?). Am I incorrect?

Andy

AndyBrown Wrote:
-------------------------------------------------------
> gregtravis Wrote:
> --------------------------------------------------
> -----
> >
> > No, the P40DC and P42DC have to run at 900RPM
> > exactly when generating HEP.
>
> So is there a separate HEP alternator or does the
> power come off the main? I'm trying to figure out
> why I was thinking the GEs' HEP was set up
> differently than the F40s'; maybe it was just
> something I dreamed up.

On the "Genesis" locomotives, HEP is generated from an alternator connected directly to the prime mover (i.e. the same diesel that generates power for the traction motors). Some of the F40s have a totally separate diesel which drives the HEP alternator, meaning the prime mover can run at any RPM even if the loco is providing HEP. Not so with the Genesis locos.

By the way, the HEP alternator takes about 1,000 HP off the loco at full electrical (800KW) demand.

>
>
> >filmteknik Wrote:
> --------------------------------------------------
> -----
> > What's with the 894 RPM? I think the F40PH
> manual
> > says 893 RPM. If the HEP alternator is a 4
> pole
> > machine it needs to turn at 1800 RPM to make 60
> > Hz. Is the gear box something other than
> exactly
> > 2:1 speedup
>
> I was thinking the F40s' HEP alternator was not
> gear driven, but directly coupled to the main
> shaft (making it an 8 pole?). Am I incorrect?

Again, some of the F40s have a totally separate diesel to make HEP

>
> Andy

I think that the info about F40 having a separate HEP generator power plant is wrong information. Every AMTK F40 I ever saw ran at Run 8 when stopped in the station. I might be wrong on the exact notch number, could have been 6,7 or 8, but they were loud. The engine power did not alter (increase) as the train departed.

gregtravis Wrote:
-------------------------------------------------------
> So fuel consumed is closer to 11,000 gallons each
> way and ~71 MPG (per passenger, full train).

I think you did pretty good with your Wild Ass Guess. If you take your 71 passenger-miles/gallon and convert to BTU/passenger-mile (using 139,000 BTU/gallon for diesel), you get 1958 BTU/passenger-mile. That compares with the 2650 BTU/passenger-mile for intercity Amtrak, year 2006 (USDOE Transportation Energy Data Book 27th Edition P. 2-16). However you use a full train, while the DOE figures use actual passengers. Even though many segments of the Empire Builder may run full on many days, envisioning an average load factor of over 50 percent is difficult. Let's go with 50 percent to bring your estimate to 3916 BTU/passenger-mile. Now we are about 50 percent higher than the DOE figures.

Can this discrepancy be explained? I think so. In previous analysis, I have found that tare weight per seat-mile is about double for Superliner LDT's versus Amfleet corridor trains. That could easily increase the average figure from DOE by about 50 percent for LDT's. These results lead to some important policy implications in regards to energy usage. For instance, air travel is more energy efficient than LDT's. If you have two or more people in an automobile, the energy efficiency is better than LDT's. Intercity buses beat the heck out of LDT's in regards to energy. Justify a LDT as a pleasurable experience, but calling on energy efficiency is highly disingenuous.

> I think that the info about F40 having a separate
> HEP generator power plant is wrong information.
> Every AMTK F40 I ever saw ran at Run 8 when
> stopped in the station.

Depends what you mean by "a separate HEP
generator power plant". They did have a
separate HEP alternator that was powered
by the main 16-645 engine; AFAIK no Amtrak
F40s ever got the separate CAT HEP diesels
that commuter F40s often have now.

So when the train is under way, or ready
to get under way at a station stop, the
main engine did turn at full speed even
with the throttle at Idle. But if they
were making a long stop the engineer
could switch to Standby (or whatever it
was called), where HEP came from the
traction alternator, allowing the 16-645
to run slower and quieter. No traction
power at that setting.

The Amtrak F40 HEP alternator was geared;
don't recall the ratio offhand, but I think
it did turn 1800 RPM.

(Do gears maybe wear more evenly if their
ratio isn't exactly 2:1?)

Cameraman Wrote:
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> I think that the info about F40 having a separate
> HEP generator power plant is wrong information.
> Every AMTK F40 I ever saw ran at Run 8 when
> stopped in the station.

You are correct. All Amtrak F40 HEP generators were direct-drive units. The shaft came off the front of the prime mover, went through a 1:2 gearbox, and then to the HEP alternator. Prime movers ran at 900 RPM all the time; HEP generator ran at 1800 RPM. I've heard co-workers refer to them as 'growlers'.

Some F40's acquired by commuter services after Amtrak retired their units have been refitted with a second diesel engine, usually a Caterpillar, to drive the HEP system. Shaft from the PM to HEP has been eliminated on these units. Saves fuel and reduces emissions.