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Alternator , generator efficiency

  1. Mar 8, 2014 #1
    Hi I've been looking in google although I can't find a definitive answer, what are the usual efficiency range for alternators, some talk about brushed ones in the range of 50 to 60 % , brushelss some say go as highas 75%, maybe some of you folks know from your experience what are the typical efficiency of a power station generator for example, does the efficiency increase with size?
  2. jcsd
  3. Mar 8, 2014 #2


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    Staff: Mentor

    It does increase with size and power stations run on the order of 95%.
  4. Mar 9, 2014 #3
    You may want to read this thread https://www.physicsforums.com/showthread.php?t=738434&page=4
    It doesn't give the complete answer, but discuss about generator efficiency. Generators are never high efficient machines.
  5. Mar 9, 2014 #4

    jim hardy

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    I believe you'll find power plant alternators can beat 98%.
    They do tricks like use compressed hydrogen for cooling because hydrogen being less dense than air takes less power to pump .
    Utility would prefer to sell that energy as electricity than dump it as heat.
    Here's a Toshiba link offering 99%.

    In a car alternator the only incentive for efficiency is there's less heat to get rid of, so efficiency lets you reduce heat transfer area which means a more compact unit.
    With today's smaller engines and fuel economy mandates there's probably increased attention to efficiency - but in my day everybody had 400 cubic inches and a half acre engine compartment..

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