Diverdan,
Good stuff!
My xmr application notes that I got from an old-timer DTDT design engineer indicated that one can expect a 30year life based upon a 35% avg. loading per accepted "industry standards" on loading.
My notes also indicate that there is a sever penalty that is paid for 100% loading, expect 3-5 years based upon 30degC avg. ambient w/40degC max. (My notes don't specify but I would assume that it's for a 150degC transformer.)
Also, for each 10degC above 30degC reduces the life of the transformer by 50%.
Dave
