30 Proceedings of the Royal Society of Victoria. 



that 



y = 4847, 8=50° yii=2250, 

 which satisfy the sine wave equation 



Zf;y-Sin8 _^^^ 



OTTfX 



which states that the iron loss per cm.''' per second is 10" ergs. 

 The core loss will therefore be 144.10^/3-(2<^ + /3) at full load. 



29. The kind of winding to be adopted will depend on the 

 excellence of regulation for inductive loads that is required. 

 In Section III. will be shown how to calculate the leakage 

 coefficients for different kinds of windings, and how the regu- 

 lation for inductive loads that these windings will give, may 

 with considerable accuracy be predetermined. 



A very important consideration with regard to the arrange- 

 ment of the windings is clearly shown by the general expression 

 for the efficiency given in § 15. It will be seen that in the 

 denominator, positive terms depending on x,, the leakage co- 

 efficient of the secondary, occur, of the first order in small 

 quantities for inductive loads, and of the second order for non- 

 inductive loads. Hence it is obvious that if we have a choice, 

 we should so place the secondary windings or sections that x^ is 

 the least possible. Now it will be shown in Section III. that, 

 with interleaved windings symmetrically arranged with regard 

 to the middle line across the window, which line must there- 

 fore bisect the central section of one of the coils, the leakage 

 coefficient of that coil to which the two outer sections belong is 

 negative. Hence the most efficient arrangement is that in which 

 the two outer sections belong to the secondary or output coil. 

 The regulation will be the same whether one or other of the coils 

 has the outer positions, as it depends on .Tj + Xj, which is little or 

 not at all affected by the interchange. 



Assuming that for the present design a winding in three 

 sections will give satisfactory regulation, we will place the whole 

 primary coil as a single section in the central position between 

 the two halves of the secondary coil. 



For such a winding, when the iron and copper losses per cm^, 

 and the space factors are as we assume in this design, and 

 when /x = 2250 (see § 51), 



