90 ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
be more important the higher the voltage of the machine, 
because in high tension windings the inactive wire must 
be increased to guard against, breakdowns. 
Fig. 45, indicates an assumption of the direction of the stray 
lines around the inactive wire of an armature winding. 
152. Calculation of Armature Leakage Path Reluc- 
- tanece.—tThe expression of the armature leakage path 
reluctance, referring again to Fig. 42, is as. follows: 
5k 0.313 . 
2 4¢xlxo , 4¢xr[(a+n)+o] 
s(nta)' (a+n)xo 
r 
+(a-+n)+2l, . (24) 
The leakage lines of the inactive wires are assumed for an 
example, such as an armature with long coils as shown in 
Fig. 45. 
153. Example 18.—In order to obtain the reluctance of the 
| armature leakage path, the data required for the machine 
in question, Pars. 143 to 149, is known with the excep- 
tion of 1,, Fig. 45, which is equal to the length of the coil 
projection. 
In the present case, the armature has coils of different 
lengths, consequently, a mean value has to be found which 
in this ease is 1, = 6 inches. The value of the slot opening 
s=linch. From Formula (24), the following armature 
leakage path reluctance is obtained : 
Hr 0 313 
2 4X 2.2X20X2.4 ,4%2.2X1.4X16.4 
1x14 cS 14 X 2.4 
r 
414412 
= bl K LO lee 
This value is over 6 times larger than that of the air gap. 
The proportion between these two values has an important 
influence on the short circuit current, see Pars. 157 and 
158. 
