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Question about horsepower in relation to head end power

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Posted by Big Bill on Monday, March 16, 2015 8:41 PM

Phelps

Ah...no. 1 HP = 0.746 kW period, end of discussion. That's the conversion between the two. I suspect you had in mind how the locomotive, prime mover, whatever, is rated - gross engine output (in the case of a diesel or tubine-powered locomotive), input to the generator for traction, output at the rail, drawbar power, whatever.

Phelps

Ah...no. 1 HP = 0.746 kW period, end of discussion. That's the conversion between the two. I suspect you had in mind how the locomotive, prime mover, whatever, is rated - gross engine output (in the case of a diesel or tubine-powered locomotive), input to the generator for traction, output at the rail, drawbar power, whatever.

 

True. While a 1000hp prime mover may actually put out 1000hp (or 746kW) to the generator, you will not get 746 kW to the wheels. All along the path, there are losses. How much depends on how well the design engineers did their job, but there will be losses.

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Posted by Phelps on Monday, March 16, 2015 8:06 PM

Ah...no. 1 HP = 0.746 kW period, end of discussion. That's the conversion between the two. I suspect you had in mind how the locomotive, prime mover, whatever, is rated - gross engine output (in the case of a diesel or tubine-powered locomotive), input to the generator for traction, output at the rail, drawbar power, whatever.

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Posted by D.Carleton on Monday, March 9, 2015 5:50 PM

zkr123

I would rather hear from those who know what they're talking about on here than go to  Google where the answers may not be accurate. 

So, in other words, you're lazy.

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Posted by erikem on Monday, March 9, 2015 2:23 PM

CSSHEGEWISCH

1 HP=746 watts is a translation from the British to the metric system as a measure of energy.  Efficiency has nothing to do with it.

 

Depends on whether the rating in KW is for electrical input or mechanical output. Efficiency doesn't have anything to do for the latter but does for the former.

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Posted by zkr123 on Monday, March 9, 2015 11:20 AM

I would rather hear from those who know what they're talking about on here than go to  Google where the answers may not be accurate. 

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Posted by CSSHEGEWISCH on Monday, March 9, 2015 7:01 AM

ACS-64 is rated at 8600 HP but this is a short-time rating.  I've read that the continuous rating is around 6700 HP.

1 HP=746 watts is a translation from the British to the metric system as a measure of energy.  Efficiency has nothing to do with it.

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Posted by erikem on Sunday, March 8, 2015 10:28 PM

blue streak 1

Is 5 HP ~= 4 KW ?   Is that why an ACS-64 is 6400 KW and 8579 HP ?

 

1 HP = 746W, so 4 HP ~= 3 KW assuming 100% efficiency. Given some losses between the catenary and wheel rims, 5 HP ~= 4 KW wouldn't be far off the mark.

 - Erik

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Posted by D.Carleton on Saturday, March 7, 2015 7:39 PM

blue streak 1

Is 5 HP ~= 4 KW ?   Is that why an ACS-64 is 6400 KW and 8000 HP ?

1 kW = 1.3405 HP, ergo, 6400 kW = 8579 HP.

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Posted by blue streak 1 on Saturday, March 7, 2015 5:46 PM

Is 5 HP ~= 4 KW ?   Is that why an ACS-64 is 6400 KW and 8579 HP ?

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Posted by Dutchrailnut on Saturday, March 7, 2015 3:58 PM

no, engines do not have capability to syncronize HEP sets, yes P30ch did, yes on LIRR equipment as it has a split HEP bus under cars.

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Posted by D.Carleton on Saturday, March 7, 2015 1:00 PM

No. I could write a dissertation on how HEP really works but it would be far more advantageous if the OP did some research on this wonderful thing we call the world wide web and learned the answer for himself.

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Posted by zkr123 on Saturday, March 7, 2015 11:51 AM

So if they used 2 engines, could they power 6 cars with  Head End Power? 

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Posted by Dutchrailnut on Saturday, February 28, 2015 6:49 PM

they already have a turbo , the BL20gh HEP is a Caterpliilar C-15 

the P40 and P42 and P32acdm are rated at max 1000 Kw HEP.

 

 

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Posted by zkr123 on Saturday, February 28, 2015 3:54 PM

So could they put a turbo in (like they do with cars) without disrupting the fuel efficiency? 

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Posted by blue streak 1 on Saturday, February 28, 2015 2:21 PM

Dutchrailnut

again yes the HEP on BL20gh is restricted to 320 Kw it could have supplied the private cars as long as power was managed,

 
Kw HEP available is different for each loco and even some locos in the same line.
The specifications for the ACS-64s is 2 independent inverters of 1000 Kw each for reduntantancy. So one should be able to supply a train of 17 - 18  NEC Amfleets.
The P-40s for Auto train may be somewhat higher ( 900 Kw ? ) than other P-40s.
Other locos are anywhere from 500 - 800 Kw but have no idea if those numbers are correct. 
As  Amtrak built locos and motors each order kept the same or more Kw capacity. 
Added to the complications of load available is the max demand for each type of passenger car ( sleeper, diner, lounge, coach, led  lighting or not, single or bi-level, etc ) is different.
For diesel locos remember  for every Kw used for HEP that is one less Kw for traction.
If anyone has the max HEP output for each locomotive and motor both Amtrak and commuter it would be helpful.
 
 
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Posted by Dutchrailnut on Saturday, February 28, 2015 1:49 PM

again yes the HEP on BL20gh is restricted to 320 Kw it could have supplied the private cars as long as power was managed, kill HVAC no cooking no big power use. Most rail cars only use about 60 Kw so it should have been sufficient for 5 cars plus , commuter cars have a very HEP demand vs Amtrak or private cars, at station stops all doors open at once letting either heat or AC fly out the doors. but then what do I know only operated these things since they were deliverd.

 

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Posted by D.Carleton on Saturday, February 28, 2015 12:57 PM

The BL20GH does not have a full size HEP plant for mainline trains. Two years ago we were moving the private cars for display into Grand Central Terminal. Amtrak power got us as far as Harmon and a single BL20 (slowly) dragged us in to the terminal and switched the cars for the weekend festivities. We were dark for the trip from Harmon south because the BL20's HEP plant was not large enough to power the train.

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Posted by BaltACD on Saturday, February 28, 2015 7:43 AM

zkr123

If a passenger locomotive pulls more than the HEP allows, what would happen?

For example, Metro North has  a  locomotive called BL20GH even though it has 2200hp engine it can only pull three passenger cars. What would happen if it pulled four cars?

Are we talking pulling, or powering a train.

Depending on grades, the locomotive can PULL many more than 3 cars, however, for each additional car (load weight) the train will accelerate to it's cruise speed in a longer amount of time.  I suspect for scheduling purposes the trains are limited to 3 cars as that size train will accomodate the proper number of passengers and will accelerate acceptably and maintain the operating schedule.

I fully expect that the HEP function on these engines will adequately supply more than 3 commuter cars.  Amtrak engines routinely supply HEP for 9 cars.

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Posted by Dutchrailnut on Saturday, February 28, 2015 7:37 AM

only thing restricted to 4 cars on a BL20gh is the HEP unit, since engine is for branch line service only when in passenger service. The main engine has no restrictions and they are General Purpose locomotives. they have been succesfully used to tow Acela's and even a dead train 49 from yonkers to Pougkeepsie. Can it feed HEP to more cars ?? sure as long as load is reduced , kill HVAC but leave ventilation and lights on, it can supply 10 or more cars before HEP shuts down on overload.

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Posted by D.Carleton on Saturday, February 28, 2015 12:57 AM

zkr123

If a passenger locomotive pulls more than the HEP allows, what would happen?

For example, Metro North has  a  locomotive called BL20GH even though it has 2200hp engine it can only pull three passenger cars. What would happen if it pulled four cars?

First off, the BL20GH has two engines: one for traction and the smaller one for HEP loads. If there were four coaches or if the HEP load were too great for the generator then the generator would trip on whatever safety function is installed to protect it from damage: high engine temperature, high generator load, et. al.

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Posted by erikem on Friday, February 27, 2015 11:12 PM

Most likely it would have noticeably slower acceleration and possibly lower top speed. That's assuming that four cars worth of HEP laod don't trip the HEP breaker.

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Question about horsepower in relation to head end power
Posted by zkr123 on Friday, February 27, 2015 9:11 PM

If a passenger locomotive pulls more than the HEP allows, what would happen?

For example, Metro North has  a  locomotive called BL20GH even though it has 2200hp engine it can only pull three passenger cars. What would happen if it pulled four cars?

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