From: cfmpublic@ns.sympatico.ca   
      
   On Tue, 19 Jan 2016 01:35:20 -0800 (PST), rcp27g@gmail.com wrote:   
      
   >On Friday, 15 January 2016 20:26:59 UTC+1, 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.   
   >   
   >I doubt that 11 kV is going to impose significant limits on power due to   
   current draw: in Germany ICEs run at 200 mph (320 km/h) under 15 kV, and on   
   classic lines in France and the Netherlands trains run at 100 mph (160 km/h)   
   under 1500 V DC.  There are    
   even trains in the UK running at 100 mph on 750 V DC 3rd rail (although a 3rd   
   rail has a larger cross section so can almost certainly cope with more current   
   than OHL).   
      
   Germany is 15 KV at 16 and 2/3 or 17 cycles.  DC is a different kettle   
   of fish where the amount of power is just volts times amperes.  In   
   doing the lookup to verify my hazy recollection I also found the   
   discussion of AC calculation which included the Power Factor and brief   
   discussions of impedance and reactive power which I almost understood.   
   Since the value of Power Factor is between 0 and 1 and varies with the   
   frequency, pursuit of the issue by someone who understands this far   
   better than I do would be helpful.   
   >   
   >Robin   
      
   --- SoupGate/W32 v1.03   
    * Origin: LiveWire BBS -=*=- UseNet FTN Gateway (1:2320/1)