92 ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
value corresponding to machines with a large number of 
poles. 
For the approximate calculation of leakage factor the fol- 
lowing simple Formula (27), will be found useful: 
157. Effect of Leakage on Short Cireuit Current.— 
The effect of leakage on the short circuit current reveals 
itself in the factor k,, which in Par. 121 has been defined 
as the ratio between the ampere turns of the field system 
and the corresponding ampere turns of the short circuited 
armature. 
The symbolical expression of this factor is: 
| + <3 os aes Silinag acs (28) 
In the case of the alternator under discussion, Equation 
(28), gives: 
k=1l+te Sf Ae EP = 1.26, 
458. Normal Value of Factor k,—In modern alternators | 
this factor has values which lie between 1.05 and 17.5. 
A generator with a higher factor than that mentioned 
possesses excessive leakage, but it must be remembered, 
that the larger the number of poles the greater will k, be 
for the same type of machine. 
159. Demagnetizing Effect of Armature Ampere 
Turns.—The demagnetizing effect of the armature 
ampere turns is the third factor which influences the 
