From: cfmpublic@ns.sympatico.ca   
      
   On Tue, 9 Feb 2016 11:49:35 -0500, Jishnu Mukerji   
    wrote:   
      
   >On 1/15/2016 2:26 PM, Stephen Sprunk wrote:   
   >> On 14-Jan-16 17:10, Clark F Morris wrote:   
   >>> Stephen Sprunk  wrote:   
   >>>> On 11-Jan-16 00:50, Michael Moroney wrote:   
   >>>>> They really aren't completely independent.  Converting to 2x25kV   
   >>>>> as the first step would require 25kV 25Hz transformers and   
   >>>>> equipment, only to be replaced by 60Hz on the next step.  If   
   >>>>> combined, one entire set of equipment could be skipped.   
   >>>>   
   >>>> 25Hz transformers can handle 60Hz.  It'd be simplest to go to   
   >>>> 12.5kV 60Hz first, which wouldn't require _any_ new equipment, a   
   >>>> few phase breaks at most.  (That assumes all 25Hz-oly wayside   
   >>>> equipment has been replaced with 25/60Hz equipment, which Amtrak   
   >>>> has been doing as the former fails since at least the 1980s.)   
   >>>   
   >>> Except as I understand it, 12.5 KV won't give enough power to   
   >>> support 100+ mile an hour operation.  Note the relatively slow speeds   
   >>> on the Metro-North New Haven line.   
   >>   
   >> Amtrak (and its predecessors) have been doing up to 135mph on 11kV 25Hz   
   >> lines for around a century; the main reason they couldn't go faster was   
   >> the variable-tension catenary.  That's roughly twice as much current as   
   >> 200mph on 2x25kV lines in France and China, so I'm not sure current is   
   >> really a limiting factor.   
   >>   
   >> S   
   >   
   >125mph operations began in the late 60's as part of the NECIP. Before   
   >that the highest anyone might have gone is 100mph or so. So no, no one   
   >has been operating at upto 135mph for a century. Just 50 something years   
   >at 125mph.   
   >   
   >MNRR is yet to complete their conversion to Constant Tension catenary.   
   >About 80% of the project is done with 20% remaining. They did convert to   
   >60Hz quite a while back.   
   >   
   >Amtrak is neither changing the voltage nor the frequency on NEC south.   
   >They are adding 25Hz capacity. They don't foresee any problem with   
   >operating at 160mph using 12.5kV 25Hz.   
      
   From what I gathered from Harry Rappaport's (I hope I remembered the   
   name correctly), the problem would come if they went to 60 cycles and   
   stayed at 12.5 KV.  From postings here the problem with 25 cycles is   
   the weight of the transformers and possibly other electrical   
   equipment.  Since my expertise is computer programming, not electrical   
   engineering I may have things mixed up.   
      
   Clark Morris   
   >   
   >Also BTW, Amtrak's conversion to position light does not remove the   
   >middle lamp. Effectively just replaces the lamps with color LED. In   
   >addition additional logic is added for additional flashing aspects. The   
   >old signal heads do not have the logic to display flashing aspects.   
   >   
   >TAFN   
      
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