32 Proceedings of the Royal Society of Victoria. 



and 



^i^!^=.l+ ^^"(^ + ^) (see §13) 

 q^s^ fi^C.2 6,Cos<f> 



Sin(8 + ^) 



where C^, Co, and 6^ are full load values. 



In addition let us arrange that the copper and iron losses shall 

 be equal at full load. Then (see § 17), as 2=1, 



SO that 



K=Sin(8 + 0)^ 2 



For the determination of k and other small correcting terms, 

 an approximate value of t must be known. We can easily 

 obtain one by a rough preliminary calculation in which these 

 correcting terms are neglected, or from the formula given in 

 § 55, when r for some other transformer of the same type is 

 known. 



The first method gives us t=6000 ; 

 hence as 



S-=50°, Sin8-=.766, 



Cos(^ = .8, (/)=37', 

 we find that, 



^,Cos0=48, ^,=60, 



K-.02, T,/T,= l.02, 



^^=.01 



T 



and taking ^3= -.00024 (see § 28), 



Cos(p'=.808 at full load (see §§ 10, 27). 

 Substituting the value of k thus determined in the expressions 

 for q^Si, and q.^s., we get 



^15-1^1.176^^ q.2h=^-^^^^^- 

 Hence, the total volume of copper being 



=/(^i^i + q,s,)=8{A + (3){q,s, + q,s.,), 

 it is 



= 18.63//^(/' + /3), 

 and as the copper losses at full load are 



= 15.10"' X volume, 



