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In article <731@hutto.UUCP> henry@hutto.UUCP (Henry Melton) writes:
>Does anyone have any definitive numbers on the efficiency of
>transformers?  in particular, the ones on the poles outside the house.

When I worked in the utility power industry (as a health-physicist), a
typical efficiency quoted by those who are supposed to know, for 
generator-to-outlet is about 98%.  Transformer efficiency varies roughly 
as the inverse of capacity.  The 2000 megawatt main station transformers
are 99.99+% efficient - even 0.1% loss of 2000 megawatts would be 2 megawatts
of heat dissipation!  Most of these transformers are convection-cooled 
except in the hottest weather.  The least efficient transformers are the
pole-pigs hanging outside your house.  These 20 to 40 kva transformers
are typically 99+% efficient and represent the single largest loss center
in the distribution center (opinion/guestimate).

Improvements in transformer design would generally affect efficiency in
the 0.1% or so range.  Even in this range, the effect on the bottom line
of a utility would be remarkable.  Tenths of a percent improvements are
well worth the effort.  Most research work that I read about involve 
experiments with amorphous Iron for core construction and better magnetic
coupling.

73, john

-- 
John De Armond, WD4OQC                     | Manual? ... What manual ?!? 
Sales Technologies, Inc.    Atlanta, GA    | This is Unix, My son, You 
...!gatech!stiatl!john                     | just GOTTA Know!!!