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Date: 01/09/20 14:10
Silver Star motive power
Author: SpeederDriver

Interesting that 91 has been running with two units ever since the breakdown a couple of weeks ago tied up the A Line.  I wonder if this is an Amtrak initiated thing or if CSX now requires it.



Edited 1 time(s). Last edit at 01/09/20 14:11 by SpeederDriver.



Date: 01/09/20 14:39
Re: Silver Star motive power
Author: MEKoch

Since Amtrak is not smart enough to do it, I hope that CSX requires it.  



Date: 01/09/20 15:37
Re: Silver Star motive power
Author: joemvcnj

When they add the diner on May 1, the train will get a little heavier. 



Date: 01/09/20 16:43
Re: Silver Star motive power
Author: ctillnc

.. and HEP consumption will increase.



Date: 01/09/20 19:47
Re: Silver Star motive power
Author: ShortlinesUSA

What do you mean there? Two locomotive consists I've seen all my life (dating back to New F40PHs) always have had the rear unit running HEP and the lead just under regular load.

Posted from Android



Date: 01/09/20 20:51
Re: Silver Star motive power
Author: GenePoon

Due to phasing of the AC current, two engines cannot in tandem both supply HEP to the same consist. 

A lead unit can supply HEP to the train but any following units must be in passthrough mode.



Date: 01/10/20 06:36
Re: Silver Star motive power
Author: ctillnc

I never said to put two electrical sources in parallel (give me a break, I'm an electrical engineer.) HEP is parasitic on the prime mover. With one locomotive, the HP available for traction is a lot less than the nominal 4200. The train gets longer, and worse the diner draws a disproportionate number of amps. So the result is a sluggish train on a track-and-a-half route whose schedule depends on a lot of 79 mph running. Big difference between one locomotive and two in that scenario.



Edited 3 time(s). Last edit at 01/10/20 06:39 by ctillnc.



Date: 01/10/20 06:48
Re: Silver Star motive power
Author: mbrotzman

ctillnc Wrote:
-------------------------------------------------------
> I never said to put two electrical sources in
> parallel (give me a break, I'm an electrical
> engineer.) HEP is parasitic on the prime mover.
> With one locomotive, the HP available for traction
> is a lot less than the nominal 4200. The train
> gets longer, and worse the diner draws a
> disproportionate number of amps. So the result is
> a sluggish train on a track-and-a-half route whose
> schedule depends on a lot of 79 mph running. Big
> difference between one locomotive and two in that
> scenario.

I've been told the rule of thumb is that the HEP load drops 4200hp down to 3200-3600 available for traction.

Keep this in mind when people extole the SC44 or HSP46 as being more powerful when a lowly MP36PH-3C will likely match them on power available for traction due to the presence of a HEP pony engine.



Date: 01/10/20 07:12
Re: Silver Star motive power
Author: Lackawanna484

BrightLine uses an SC44 on each end of a four car (IIRC) train. The train accelerates like a rocket, comparable in my experience to an NJ Transit  ALP46 motor with a ten car train



Date: 01/10/20 09:03
Re: Silver Star motive power
Author: joemvcnj

Converting all coach lighting from quartz-halogen to LED had to reduce amperage demand just a little.

Posted from Android



Date: 01/10/20 15:56
Re: Silver Star motive power
Author: ctillnc

> I've been told the rule of thumb is that the HEP
> load drops 4200hp down to 3200-3600 available for
> traction.

With max HEP amperage into the consist, I believe traction HP is in the 2600-2800 range. But that's mostly a factor in the Auto Train. 



Date: 01/10/20 16:46
Re: Silver Star motive power
Author: DWitte

Lackawanna484 Wrote:
-------------------------------------------------------
> BrightLine uses an SC44 on each end of a four car
> (IIRC) train. The train accelerates like a rocket,
> comparable in my experience to an NJ Transit 
> ALP46 motor with a ten car train

Brightline locomotives are SCB40s. 4000hp

Duane Witte
Holt, MO



Date: 01/11/20 04:57
Re: Silver Star motive power
Author: KV1guy

Traction hp for a p42 in HEP mode is limited to no.7 throttle at 3750hp.

There is no mandate for Amtrak using 2 locos on the Star other than CSX's when running over the Hamlet and Columbia subs and the train reaches more than 12 cars. Yes, you get better acceleration with 2 units, but the train handles better with just one once you're up to speed, minus wheel slip. Plus 2 units on a short consist will work you to death in this type of undulating territory.

Posted from Android



Date: 01/11/20 16:05
Re: Silver Star motive power
Author: ctillnc

> 2 units on a short consist will work you to death
> in this type of undulating territory.

Think of the engineers on the Southern Crescent who had four E8 units and sometimes fewer than 10 cars south of Atlanta. 



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