On 02.09.15 16:19, hancock4@bbs.cpcn.com wrote:   
   > On Monday, August 31, 2015 at 3:16:32 PM UTC-4, Stephen Sprunk wrote:   
   >> I can't think of how that'd relate to trains with electric traction.   
   >   
   > Very broadly, but the overall principal is the same--slower acceleration   
   saves power.  In old style DC power control systems, there was a control   
   'logic' that regulated how much power was fed to the motors to accelerate the   
   train.  They used a    
   combination of resistance and series/parallel connection of the motors.  The   
   economy mode optimized that combination to save on power.   
   >   
   > In the earliest traction systems (100+ years ago), there was no logic, and   
   the motorman notched up by hand.  A good motorman was easy on equipment, but a   
   bad one wasted power and was rough on equipment.  Automatic control was   
   developed very early on.   
   >   
      
   Older London Underground trains also have Encon control, though it is in   
   the reverser, rather than in separate switch.   
      
   Those trains have or had two forward positions in their reversers,   
   rather than the separate toggle switch that they have in New York.   
      
   What they in New York call "local setting," they call "weak field" here.   
      
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