20 Proceedings of the Royal Society of Victoria. 



we have at full load 

 10000^^, 



but .r=ji'X = .0218 and t=^yT = .OU 

 ^X_ .0218 i^^T _ -016 



•'• ^^ Po~ 10000 """"^ ^^ Po~ 10000 (^-^ 



where Pq has its usual signification (see § 18). 



The iron loss is given as 1-38 watts, and we may consider it as 

 constant without introducing any appreciable error, so that 



PoSin8= 138.10' 

 hence from (I.) 



TSin8 = --^l^-^^^ = .000221 



(11.) 



The maximum efficiency of the transformer when Cos(^=l 

 being very approximately 



= ==- (see § 15) 



l + 2\/TSin8 



is =.971 



which is the same as the observed value at full load. 



The copper losses Hj + Ha when ^ = being 



H,+H,= Ip./(D,;^+?^^) 



•016 T>,/ri-2 138. 10^ 



ioxh,+h,)=joqo/4Do + -^^) 



where, when Cos0=l. 



D„^=l + 2l^P, + i(6li, + f;V./ (see§ 18) 



and substituting from (I.) 



32^ P., _L/Z?V 



^»'~-^^T0' 10'^lO"VlOV 



Let the load be 10000 z watts so that z is the fraction of full 

 load then 



P, = 100002 10' 

 and the copper losses in watts for any fraction z of the full load 

 are 



