P42DC HEP

[CSXfoamer1997]

About how many Viewliners, or Superliners for that matter, can one P42DC supply Head-End Power to?

 

[CCC1007]

Amtrak uses a limit of 8 for one locomotive.

Not sure if baggage cars are counted against that number

 

[printman2000]

Not that y'all are saying this, but I do not think more than one loco at a time can provide HEP.

 

[CCC1007]

True, they lack the synchronized generating equipment to do so.

 

[Fred Wis.]

Parden my ignorance, but does this mean Amtrak LD trains are limited to 8 passenger cars? If this is as stated, then capacity would be limited per train, to whatever 8 cars can carry, and any further capacity would require additional trains on routes. Am I understanding this correctly? So additional cars for the rolling stock inventory would only give limited extra capacity without more engines, and slots for the additional trains?

 

[printman2000]

Amtrak uses a limit of 8 for one locomotive.

Not sure if baggage cars are counted against that number

Not so sure about the 8 limit. I have been on several train with more cars than that (even when not including baggage).

 

[fixj]

The Auto Tran runs with 15 or 16 cars. these consists have had a lot of conversion to LED lighting which must cut down on the power load.

 

[CCC1007]

The original question was for one locomotive, and I think the reduction in traction power for hep is their reasoning in most cases.

 

[A Voice]

The issue with a single locomotive is having enough power for both the HEP and the traction motors. One engine can supply more than eight cars, but when you have a second locomotive on the train all its power can then be used to get the train over the road. Amtrak actually has regularly run trains with ten (or more?) cars and a single engine, such as on the Star and Meteor, but grades on those lines aren't so severe.

 

[Fred Wis.]

OK I get it now. That makes sense. So as long as there are 2 engines, the 2nd one can handle more than 8 cars.A number of years back, I was riding the Southwest chief east bound , when we left Lamy NM ,up a long grade, on a hot summer day, the train was unable to make it to the top. We backed down the grade, and after a short time the conductor came on the P.A. to explain that we could either wait for a helper engine to come to our rescue for a push, or they could try shutting down the HEP, and take another run. The passengers cheered for the 2nd try, and that is what they tried. We made it to the top, ( louder cheers) where they turned the lights and air conditioning back on.

 

[west point]

Yes been on that HEP off situation climbing to Moffett tunnel and up Helper grade.

 

[neroden]

The LSL routinely has 12 cars requiring HEP. It normally runs with two locomotives but I've seen it run with one. Of course the route is *very* flat (it's the so-called "Water Level Route"); you do climb up the Mohawk Valley but it sure doesn't feel steep.

 

[PVD]

Actually, the Water Level part up the Hudson to Albany from NYP usually runs with a single P32-DM. They don't get the P-42 until Albany.

 

[PerRock]

Actually, the Water Level part up the Hudson to Albany from NYP usually runs with a single P32-DM. They don't get the P-42 until Albany.

It is also (normally) a shorter train thru that section. As part of the train is split for Boston.

peter

 

[jis]

Actually, the Water Level part up the Hudson to Albany from NYP usually runs with a single P32-DM. They don't get the P-42 until Albany.

It is also (normally) a shorter train thru that section. As part of the train is split for Boston.

peter

However these days the entire train is running to/from NYP, and it is still doing so with a single P32-ACDM AFAICT.

 

[PVD]

But for quite a while it has been coming up from NYP complete, the work at Albany precludes the split/join so they have been running a stub to Boston. It is a pretty long consist (10 cars) for a single P32. It shouldn't be much longer (hopefully) before it returns to the old way.

 

[Crescent ATN & TCL]

The # of cars isn't the limit, it is all to do with the amperage in the electrical system of the train. Amps=Volts/Load. If the amps get too high because the load on the system is too great the system starts overheating, this is prevented by circuit breakers or fuses. For example 5 diner/cafe cars will put much more of a load on the system than 5 coach cars would. Amtrak has calculated the number of amps pulled by car type and compares that to the max allowed by the HEP system, this is how they determine the limit for each consist.

Amtrak could increase the # of cars allowed on the HEP system by converting to a higher voltage but this will require new HEP cables to be run through the cars and new step down transformers to convert the new voltage to the 120/240 volts used by the car, the next standard voltage is 600 volts in the US.

 

[PVD]

Aren't they running 480V AC for HEP? Would not be surprised if A/C + heating systems are 277/480V, commercial industrial motors often are. 3 phase 480 is pretty common in the US because 277/480 panels for office building lighting or industrial process is prety standard. Step down transformers feed the other panels. 600V would not be a common AC voltage. If I recall, present FRA regs preclude high voltage trainlines for HEP, but I might be mistaken. Load in the above calculation (usually taught as part of classic ohms law E=IxR) has to include the resistance of the circuit and its connections which is proportional to length. Conductors have to be large enough to deliver a given voltage to the endpoint with (usually) less than 3% drop. 10 cars would be around 850 feet. That is not insignificant in calculation.

 

[TinCan782]

arent they running 480V for HEP? Would not be surprised if A/C systems are 480V, commercial industrial motors often are. 3 phase 480 is pretty common in the US because 277/480 panels for office building lighting or industrial process is prety standard. 600V would not be a common AC voltage. If I recall, present FRA regs preclude high voltage trainlines for HEP, but I might be mistaken.

Yes, if you look at the connector labeling at the car ends, you'll 480V (with warning!).

 

[jis]

The # of cars isn't the limit, it is all to do with the amperage in the electrical system of the train. Amps=Volts/Load. If the amps get too high because the load on the system is too great the system starts overheating, this is prevented by circuit breakers or fuses. For example 5 diner/cafe cars will put much more of a load on the system than 5 coach cars would. Amtrak has calculated the number of amps pulled by car type and compares that to the max allowed by the HEP system, this is how they determine the limit for each consist.

Amtrak could increase the # of cars allowed on the HEP system by converting to a higher voltage but this will require new HEP cables to be run through the cars and new step down transformers to convert the new voltage to the 120/240 volts used by the car, the next standard voltage is 600 volts in the US.

These days it appears that the number of cars is limited more by the capacity of the source than by the capacity of the cable. That could change with higher capacity HEP sources coming on line.

In India, which uses a different HEP/EOG system, 20 Air Conditioned cars powered from single HEP/EOG source is not uncommon.

 

[willem]

The # of cars isn't the limit, it is all to do with the amperage in the electrical system of the train. Amps=Volts/Load.

Doesn't that equation say that a higher load results in lower amps, at constant voltage?

 

[PVD]

Well, the new Siemens (both electric and diesel) are rated for 1000kva HEP, but in the diesels, that is still subtracting from the total provided by the prime mover, which isn't producing more (to any degree) than the present generation. Very often people underestimate locos like the F59 series because they don't realize that HEP comes from a separate gen-set, and 3000+ HP is not much different than a P42 supplying full HEP loads.

 

[jis]

The # of cars isn't the limit, it is all to do with the amperage in the electrical system of the train. Amps=Volts/Load.

Doesn't that equation say that a higher load results in lower amps, at constant voltage?

The correct equation is I (Amps) = V (Volts)/R (Ohms) where R is resistance. R actually goes down when you add a bunch of resistors in parallel, hence the current goes up. The relevant equation for adding resistances in parallel is 1/RT = 1/R1 + 1/R2 + 1/R3 + .... if two resistance are added in parallel the resulting resistance RT = ( R1 x R2 ) / ( R1 + R2)

For more detail see: http://www.electronics-tutorials.ws/resistor/res_4.htmlfor example.

Power consumed (load) is V square / R. At constant voltage, as resistance goes down power (and hence load) goes up.

 

[west point]

Some one who can provide a cite needs to list the HEP generating capacity of each loco. Siemens we know is using the same 1000Kw inverter for both ACS-64s and Chargers. Other locos are not so certain. It has been posted that the P-40s assigned to Auto Train have a bigger capacity ? Is that true and what are the power capacities of each loco and are there any subsets ? The third rail locos may have 2 different capacities depending if on 3rd rail or loco ?

 

[CSXfoamer1997]

The # of cars isn't the limit, it is all to do with the amperage in the electrical system of the train. Amps=Volts/Load. If the amps get too high because the load on the system is too great the system starts overheating, this is prevented by circuit breakers or fuses. For example 5 diner/cafe cars will put much more of a load on the system than 5 coach cars would. Amtrak has calculated the number of amps pulled by car type and compares that to the max allowed by the HEP system, this is how they determine the limit for each consist.

Amtrak could increase the # of cars allowed on the HEP system by converting to a higher voltage but this will require new HEP cables to be run through the cars and new step down transformers to convert the new voltage to the 120/240 volts used by the car, the next standard voltage is 600 volts in the US.

These days it appears that the number of cars is limited more by the capacity of the source than by the capacity of the cable. That could change with higher capacity HEP sources coming on line.

In India, which uses a different HEP/EOG system, 20 Air Conditioned cars powered from single HEP/EOG source is not uncommon.

Wow! Lucky them!