Alternator , generator efficiency

  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. russ_watters

    Staff: Mentor

    It does increase with size and power stations run on the order of 95%.
  4. You may want to read this thread
    It doesn't give the complete answer, but discuss about generator efficiency. Generators are never high efficient machines.
  5. jim hardy

    jim hardy 5,455
    Science Advisor
    Gold Member
    2014 Award

    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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