From: stephen@sprunk.org   
      
   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   
      
   --   
   Stephen Sprunk         "God does not play dice."  --Albert Einstein   
   CCIE #3723         "God is an inveterate gambler, and He throws the   
   K5SSS        dice at every possible opportunity." --Stephen Hawking   
      
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