From: cfmpublic@ns.sympatico.ca   
      
   On Sun, 14 Feb 2016 11:28:14 -0000 (UTC), bob    
   wrote:   
      
   >Clark F Morris  wrote:   
   >> On Thu, 11 Feb 2016 07:21:49 -0800 (PST), rcp27g@gmail.com wrote:   
   >>   
   >>> On Thursday, 11 February 2016 03:24:33 UTC+1, Stephen Sprunk  wrote:   
   >>>> On 09-Feb-16 10:49, Jishnu Mukerji wrote:   
   >>>   
   >>>>> 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.   
   >>>   
   >>> As I pointed out elsewhere in the thread, DB (German railways) operate   
   >>> significantly higher power trains (200 mph ICE3 units) under 15 kV 16.7 Hz   
   catenery.   
   >>>   
   >>>> 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.   
   >>>   
   >>> The constant tension catenery is the biggest impediment to improved   
   >>> performance on the NEC.   
   >>   
   >> My point was about 12.5 KV at 25 Hz vs. 12.5 Kv at 60 Hz.  If I   
   >> understand Stephen correctly, with modern equipment the difference in   
   >> power factor  becomes neglible unlike say 25 - 30 years ago when I   
   >> first heard about this.   Thus it was about how much power could be   
   >> transmitted to the train at a given voltage and frequency.   
   >   
   >Right, but there are plenty of examples of high power locomotives on the   
   >Swiss/German/Austrian 15 kV 16.7 Hz networks that cope with low frequency   
   >and not much higher voltage. Going back to the days before power   
   >electronics, for example the Swiss Ae 6/6 were built starting in 1955 and   
   >are rated at 4.3 MW which is within the range of modern high speed train   
   >power cars. Modern European locomotives are all designed to run on the main   
   >four systems of 25 kV 50 Hz, 15 kV 16.7 Hz, 3 kV DC and 1500 V DC. While   
   >they sometimes have a lower power output on DC, there is no problem with   
   >the low frequency system.   
      
   As I understand it, the amount of AC power that can be transmitted at   
   a given voltage is inversely proportional to the voltage.  Thus a   
   train that could get the required power at 15 KV 16.7 Hz could not get   
   it at 15 KV 50 Hz.  Also I note that at least some of the   
   multi-voltage ICE trains and TGVs have different power ratings   
   depending on the power source.   
      
   Clark Morris   
   >   
   >Robin   
      
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