Lb atly Sie 
<a a 
ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 87 
of the teeth ¢ = 2.2 inches; v = 10 inches; and k = 8 
inches; r = 1.4 inches. 
The magnetic saturation corresponding to those of the field 
system are, wa, = 640 and m = 230. 
From this data is obtained an armature system reluctance 
value as follows, by substituting the values in Formula 
(22): 
A _( 2.2X% 2.4 4 10 ) 
2 \8X 1.4 20K 230.9  2X8xX20x*640X.9 
0.313=0.54x10™. Ans. 
which is about 30% of the reluctance value of the field 
system, or 6% of that of the air gap. 
148. Reluctance of the Field Leakage Path.—In Fig. 
| 43, seven distinct directions are indicated in which the 
magnetic lines may leak outside of the useful cireuit. The 
magnetic lines passing in the direction of 6 and 7 are not 
actually lost to the useful armature magnetic circuit, pro- 
x 
—- 
—_— 
Fie, 43.—LEAKAGE PATHS OF THE FIELD MAGNET SysTEM 
OF A GENERATOR. 
viding that the precaution is taken of making the length of 
the armature core somewhat longer than that of the pole 
face. In this case the items 6 and 7 need not be calculated. 
In most cases the lines lost in the direction 4, are too small 
