• How much energy is used for Head End Power?

  • General discussion about railroad operations, related facilities, maps, and other resources.
General discussion about railroad operations, related facilities, maps, and other resources.

Moderator: Robert Paniagua

  by gearhead
Even if the train is standing still it must be using large amounts of power with lap tops, lights air condistioning ect.
  by Ken W2KB
David Benton wrote:i think around 800kw . I think its an area that could be improved greatly .
Curious as to your ideas on ways to improve. ??
  by David Benton
well . i must admit , i was thinking about amtrak and similiar hep systems . but this is in the hsr forum .Which i presume would have Hep pretty efficent , to save weight if nothing else .
Anyway , as far as amtrak style HEP systems go , i would think the peak load could be reduced significantly . This would be especially benefical to a diesel locomotive under accleration , presuming the saved power would go to traction .
The area that most savingss could be made would be water heating , hvac , and space heating . Which would also be the biggest users . These could be pretty well cut out altogether when the loco is accerlerating , and increased when under regenrative braking , again presuming some of the regen power could be used for hep . with modern control systems i dont think it would be too hard to do .
Led lights and lithuim batteries would also represent savings in power required and weight , but i would think this is a fairly small portion of the power consumed . lithuim or other advanced batteries( or storage , super caps seem to have taken a back seat ) may make larger capacity battery banks feasible for the same wieght , allowing inverter /charger systems to store power under regenbraking for use later .
but as i say , for a hsr or any train under cantenary , most of this is not needed . i guess there is diesel hsr under the criteria listed for this forum .
  by gprimr1
Moved to railroad operations since it's a general question.
  by DutchRailnut
How much HEP is determined on how much is on in the cars and how many cars.
the locomotive can deliver a max of 800Kw on Amtrak P40/42/32 (on a 3 car train the max would be around 120Kw)
  by BobLI
Dutch, How much HP is lost when using 800KW? is there a formula for HP vs KW usage?
  by RhoXS
Assuming 100% efficiency, 746 watts = 1 HP.

800 KW = 1,072 HP

Both watts and horsepower are in units that define the rate energy is being transferred. Since they both define the same thing only a conversion factor is needed to convert from one to another. They are both in units of energy/time.

In practice, it will require more than 1 shaft horsepower to generate 746 watts because real world equipment is not 100% efficient. Energy is lost in bearing friction, windage, generator winding resistance, etc. Therefore the amount of mechanical energy necessary to drive the generator loaded to 800 KW will be somewhat greater than 1,072 HP.

Assuming a large electrical load (lots of watts and near nameplate rating), efficiency is probably around 90% although I have no experience with railroad locomotives to know what some electrical parameters are likely to be that will effect this.

  by DutchRailnut
since 60 Hz is a requirement on DC units like P40/P42 the HEP mode knocks down locomotive to 900 RPM and a max of 3644 hp or so vs 4200 Hp for non HEP mode.
  by David Benton
rule of the thumb for small standby generators is 2 h.p engine power for every 1 k.w of electrical power required . i would think the deisel locomotive is of similar efficency .
  by kaitoku
For reference:
On a JR Tokai 700 series HSR trainset:
airconditioning 33.7kw/car x 16 car train= 539.2kw
heating 39.6kw/car x 16 car train= 633.6kw
figures do not include requirements for lights/power outlets, etc.
  by slchub
I don't notice too much of a gain with HP when I have three P42's, with one P42 providing HEP only, and the other two providing full pulling power on the CZ. Even when we have two lashed up and we head of the grades either direction, they pull just as well, so the loss of HP with 9 or 10 cars is minimal. My concern is the amount of time it takes for the traction motors to come to life when you notched out to run 4 and above.