thanks for the comments

my question is,
if small transformers are less efficient, how do inverters that use them
in the final stage (60 hz) reach overall efficiencies of ~90%?

it would seem to me that perhaps the transformers used in inverters must be
more efficient than their off the shelf counterparts.

if they were 80% efficient, then the rest of the circuit, controls, cooling fans, etc would have to be at the very least 100% efficient for an average of 90% overall.
(and we all know nothing in the real world is 100% efficient)

the reality would seem that the electronics would be closer to maybe 95% efficient
and the transformer to be 85% for it to average out at 90%?
that is if the losses are about evenly shared between the electronics and the final stage transformer?
it would seem to me that the losses would be weighted toward the transformer instead of the electronics in reality, so would it not follow that the transformer would have to be much closer to 90% for the total of the inverter to achieve 90% efficiency?

i have two sets of transformers out of inverters, they are both EI cores
but are built up that way, out of seperate pieces interweved to form the E section
and the I section rather than the more common stamped complete E section with its complimentary I stampings.

perhaps the inverter transformer cores are made to a higher standard and therefore achieve higher efficiency?

just trying to get an understanding of these efficiencies,, there is not much written about transformers in this kva rating that i have found.

if it is true that inverter transformers are built to a higher standard and achieve higher efficiencies it would appear to me that old inverters/ups transformers might be useful for power conversion/transmission of diy'er windgenerators.

thoughts?