‘140 ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
by. & == 4 +o ~ where 1, , in the present case, gives a 
value of 
5 a 0.313 
2 4X 2.05 X 9.5 X 2.4 , 42.05 1.5(14.44+2.40) | 9. . 
0.9X%14,4 1° 14.4 2.4 : 
0 313 _ 64 
oe 5+6-+ 28.5 ~I08 
“for the reluctance of the field leakage path. 
The air gap reluctance has been found in eis 238 to be 
0 
ta 7 so that the factor k, =1+5 T= 116, which 
feet that if the effective armature men ampere turns 
on short circuit are equal to say 1,000, the corresponding 
pare ampere turns will be k, X 1,000 = 1,160. 
| 
244. The Short Circuit Characteristic.— Suppose for ex- 
ample, the field excitation A, is equal to 2,000 ampere 
| turns, the resulting short cireuit current will have a 
value of 
2p X A,=k, X 2.12 
ZxC en 72xK18 
2 =12 x 2,000=1.16 2.12 32 CS 
Z. 
where 238 the number of armature turns per phase and 
C the short cireuit current per phase, which in this par- 
ticular case is equal to 45.5 amperes. 
This current value erected as ordinate above the excitation 
as abscissa, is one point, B, on the characteristic curve, 
which is a straight line, another point O being the zero 
point of the co-ordinate system. 
It is interesting to note, that the short circuit current corre- 
sponding to the excitation of the normal open cireuit 
voltage is about 1.9 times larger than the normal armature 
current, which is 66 amperes. 
