36 Proceedings of the Royal Society of Victoria. 



transfotmer we have designed. Those in Fig. 3 refer to it when 

 operating the kind of load for which it was designed, namely, one 

 with a constant power factor of .8, while those in Fig. 4 refer to 

 the same transformer when operating a non-inductive load. A 

 comparison of tliese theoretical curves with similar ones obtained 

 practically from actual transformers will afford a further illustra- 

 tion of the agreement between the theory I have given and 

 practice. 



40. In the preceding design it was arranged that the current 

 densities in the two coils should be equal at full load. Any other 

 desired distribution of current density, however, can be equally 

 well dealt with. 



Thus if Kj and K.^, the copper losses per c/n'^ at full load, be 

 each given, we know d and C2 as K=^pf^, and 



K is determined as in ^ 30, by aid of an approximate value of t, so 

 that the ratio 



?-^ can be found ; 



and as i'i + i'.2=4(6'" we can determine Si and s., and proceed as 

 before. 



Again if K^ be given, and we wish to arrange so that at full 

 load the primary and secondary copper losses shall be equal, we 

 have 



^UlI^I+k (as above), 



and ^i5'i/iKi=^2-S"24K2 

 or (/iSiCi^=^2W 

 as /i=4 *i^cl Is^^^pr^ 



hence ^^={1+k)% 



which with s-^ + s^^Aib' 



determine j'j and So, and we proceed as before. 



In transformers of the core or H type, in which the primary 

 coil almost completely surrounds the secondary, /^ is greater than 

 4, and the preceding method would have to be modified. 



