XPost: rec.crafts.metalworking   
   From: dhky@shaw.ca   
      
   On 20/11/2013 2:10 PM, krw@attt.bizz wrote:   
   > On Tue, 19 Nov 2013 15:38:58 -0800, Don Kelly  wrote:   
   >   
   >> On 17/11/2013 2:18 AM, depucca wrote:   
   > <...>   
   >   
   >> An extreme case that I know of was where a farmer with a single phase   
   >> supply had a large induction motor which he connected mechanically to a   
   >> smaller single phase motor and excited one phase with the result  that   
   >> he could generate 3 phase which he used to drive another 3 phase motor.   
   >> It worked well and was cheap because the polyphase motors were surplus   
   >> units. Sure the energy all came from the single phase supply but it was   
   >> a lot less expensive than getting 3 phase in a remote area or buying a   
   >> large single phase machine (and not a great deal less efficient).   
   >> Nowadays there are electronic drives that do the job better  for less   
   >> money but then, many weird and wonderful arrangements and machines were   
   >> used.   
   >   
   > Why didn't he just use a rotating phase converter?  A three-phase   
   > motor is often the cheap solution.  These are often used by hobbyists   
   > to make use of surplus three-phase power tools.   
   >   
   > http://www.kayind.com/basics/what.htm   
   >   
   > <...>   
   >   
   Essentially a 3 phase induction  motor at no load and excited on only   
   one phase is a single to 3 phase converter.   
   This is what I was referring to in the farmers case- I got off topic.   
      
   --   
   Don Kelly   
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