CORE LOSS AND ANN! AL EFFIC1KNYY 61 

 Th. output from the transformer per annum amounts to 

 X 20 000 = 35 000 kw la- 



ami tin- input amount > to the sum of the output, tlie core loss 

 ami the r 2 It losses per annum. Thus the input per annum 

 is made up i't' 



Core loss . ... Hr,0 kw. hr. 



Copper loss ..... 680 



Output 000 



rotd input 



"annual" efticit i:e\ (or. pret'eraldy. the " energy " 

 juently equal to 



85 000 X 100 



87290 =93,9 per ont. 



Now although, as already stated on p. 58, in practice certain 

 advantages usual mi transformers 



for the same regulation, ami eon> t -,ju,-ntly \\ith approximately 

 the same copper loss, let us, m 



on with the transformer we have just designed and which 

 we may designate as Transform, r A, an alternative \\hieh we 

 shall designate as Trans! -a- in 1 : 



; er loss at rated load tfl to 1*8 per cent. . 



rated output (i.e., to 860 watts) and tin 



rated output a.> ., to 190 watts), let us in Trans- 



thett value.s and 



a copper loss at rated load of only 190 watts and for a core loss 



of 860 watts, \\hih this h ads to u design as regards 



Aggregate cost for copper and iron, it must be provided 



\\itli ju-t as large a case as ti the total 



int. -rniil losses at rated load are the same, and it \\ill < onse- 



be necessary t< same extnual radiating 



surface . have the tame temperature rise when 







