ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 91 
— 
154. Effect of Leakage on Various Characteristics.— 
The leakage of the exciting field and that of the armature 
system are mentioned in Par. 136 as one of the elements 
which affect the inherent regulation. 
The former shows its direct influence in the calculation of 
the open cireuit characteristic, but the effect of the latter 
is more prominent on the short cireuit current char- 
acteristic. 
155. Leakage Factor.—tThe leakage factor, which is intro- 
duced in predetermining the ecaleulation of the no-load 
characteristic, is defined as the ratio between the flux 
generated in the pole core inside the field coils and the 
flux which actually cuts the armature coils, which is 
useful for the generation of the E. M. F. in the armature 
winding. 
The symbolical expression of. this factor is: 
3 F, ea ae 
1 Sk ee aha se eral avandia. x (25) 
The definition of the various symbols is given in Par. 138. 
The third and fourth items in the above equation are in most 
eases negligible, especially if the armature core is not 
highly saturated and for practical caleulations the follow- 
ing simplified Equation (26), gives satisfactory results: 
‘oli aememaieete res 
and for the particular alternator which has 30 poles, a 
leakage factor of o = 1+ ki = 1.33 is obtained. That 
‘is to say: Out of every 133 lines generated in the field . 
system only 100 will cut the armature coils. 
156. Leakage Factor of Revolving Field Type Alter- 
é nators.—In modern revolving field alternators the leak- 
age factor lies within the limits of 7.15 to 1.5, .the latter 
