ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 11 
*the short circuit current EF corresponding to'OE, will 
be the ordinate of the V curve when BG, erected perpen- 
dicular to OO', through the point B, is made equal to EF. 
This method is applied in Fig. 94 for the under and over 
excited states of the synchronous motor. 
446. Resultant Shape of Curve.—The same method may 
be applied for any other load of the motor and it should be 
noted that the smaller the load, the steeper will be the 
branches of the V curve. 
LFUCHNTY BW %. 
xe s 3 & S % 
NX 
LOSSLE LN SP 
10 
4. 
ia ey 
5. ” "2 ff . 
* 700 200 300 400 Soo 
LNPUT LV kh. 
Fig. 95.—EFFIciIeENcyY Curvres or 450 H. P., 500 Revs., 50-CyrcLe 
SYNCHRONOUS 3-PHASE Moror. 
447. Power Factor Curve.—The corresponding power fac- 
tor curve is obtained simply by plotting the values of 
cos ~ in terms of the respective ampere turns, The re- 
spective angles @ are indicated in Fig. 94. 
For the particular case of the 450 H.P. motor, the V and 
power factor curves indicate that the field excitation is to 
be increased from 6,300 ampere turns to 7,600 per pole, if 
the armature has to carry a leading current of cos p= 0.9 
phase displacement. 
448. Other Characteristices.—A second group of char- 
acteristics is given in Fig. 95. 
