CHAPTEE XII. 



Design of Transformers Effects of Magnetic Leakage Core Laminations- 

 Methods of testing Transformers Calculation of Hysteresis Loss Regula- 

 tion of Transformers Insulation and Temperature Tests. 



DESIGN OF TRANSFORMERS. 



65. We do not propose to enter into an exhaustive treatment of 

 the design of transformers, as we should be compelled to study 

 closely several types, the general principles of all of which are 

 the same, and the differences only in details of construction. 



We shall, therefore, only indicate the nature of the calculations 

 involved, referring at the same time to such practical points as 

 depend upon previous experience. 



66. Before commencing a design, we must have the following 

 data : 



(1) The full-load output ( W watts) of the transformer. 



(2) The primary impressed P.D., EI volts. 



(3) The secondary terminal P.D., E% volts. 



(4) The copper and iron losses in percentages of the full-load 

 output. 



(5) The maximum induction density, B, at which the iron of 

 the transformer is to be worked. 



(6) The frequency, n, of the primary supply current. 



(7) The thickness and permeability of the core stampings. 



(8) The type of transformer to be made. 



(9) The maximum permissible rise of temperature. 



We propose to give approximate calculations in the following 

 particular case. 



Let W= 10,000 watts. 

 Ei = 1,000 volts. 

 E% = 100 volts. 



B = 2,500 lines per square centimetre. 

 50 complete cycles per second. 



