84 



PROCEEDINGS OF SECTION A. 



22. In order to illustrate the practical application of tlie foregoing 

 theory, I will determine the performance of a small two-pole alternator 

 when carrying a rather heavy non-inductive load. 



The details of the alternator are as follows : — 



diameter 12 cm. 

 len fifth 8 cm. 



Armature - 



turns n = 100 



V, resistance ^25 ohms. 

 Air gap = 1 m.m. 



! turns V = 400. 

 resistance p :^ 3 ohms, 

 exciter three storage cells ; q 



G"6 volts. 



Frequency 



^tt; i.e. 



200. 



Magnetic leakage = 5 per cent. 



Plux operator G- := gi~ where g = 5000, 8 = 3°. 



Let the external resistance in the armature circuit in. the case in hand 

 be ^15 ohms so that r = 5 ohms. 



Hence {see section 21) — 

 I = 5.10', P = -05? = ^25.10' 

 A = S.10^ X'=^05A=4.10' 

 m=2.10\ r=5.10\ p^S.lO", oj=200, 8=3°, and a^=2'ql =U (abs.) 



Using these values for the constants and the formulae in section 21, 

 we obtain the t, t, operators which are given in the following 

 table: — 



[Note that the t operators are all practically equal and .simple numerical multi 

 pliers. (See section 8.)] 



