Answer Posted / vinayak

i) input = 240 vac*5 a a.c.* 0.98 pf = 1176 watts
dc side output = 54 vdc * 62.6 a d.c =3380.4 watts
since eff. = o/p / i/p = 3380.4/1176 = 287.45 %
so it will be, instead of power losses , power producing
pl. check i ac & p.f. & o/p i dc , also 240 is i
phase or 3 phase ckt?

ii) input v ac 415 , a ac 525 ,say p.f 0.8 i/p power =
1.732*415*525*0.8=301887.6 watts
output vdc 92 , adc 2700 = 92*2700 = 248400 watts
eff. = o / i put = 248400/301887.6 = 82.28 %

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