From: stephen@sprunk.org   
      
   On 09-Feb-16 10:49, Jishnu Mukerji wrote:   
   > On 1/15/2016 2:26 PM, Stephen Sprunk wrote:   
   >> 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.   
   >   
   > 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.   
      
   NECIP wasn't until 1976.  Are you thinking of the HSGTA of 1965?   
      
   Still, point taken; a century at 100mph, half a century at 125mph, and   
   less than that at 135mph.  That detail doesn't affect my point at all.   
      
   > 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.   
      
   12.5kV means four times as much current as 2x25kV, but if they think   
   their decrepit infrastructure can handle the load, c'est la vie.   
      
   Variable-tension and 25Hz are far more pressing problems that can be   
   corrected independently, though it'd be wise to do both in a way that   
   makes moving to 2x25kV later much easier.   
      
   > Also BTW, Amtrak's conversion to position light does not remove the   
   > middle lamp. Effectively just replaces the lamps with color LED.   
      
   Unless it can change colors, the middle lamp can only be used with one   
   CPL aspect, so you might as well remove it and save the cost.   
      
   None of the NORAC diagrams I can find show a middle lamp for any CPL   
   aspect, so it appears Amtrak et al reached the same conclusion.   
      
   S   
      
   --   
   Stephen Sprunk         "God does not play dice."  --Albert Einstein   
   CCIE #3723         "God is an inveterate gambler, and He throws the   
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