156 ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
to obtain a satisfactory knee or bend in the open char- 
acteristic curve. 
The wheel rim contributes very few ampere turns to the 
required amount, as the sectional area has been fixed ex- 
elusively to obtain the specified flywheel effect. 
LACITATION IN AMPERETURNS:. 
2000 4000 
‘ 
‘ 
TERMIWAL “PRESSURE IW VUTS: 
: 
o 
ooee 
----" 
mor 
Fig. 73.—CHARACTERISTICS OF THE 375 KVA., 938 REvs., 
50-CYCLE 2-PHASE ALTERNATOR. 
289. Field Ampere Turns. 
The maximum number of field 
ampere turns can be fixed, by determining the regulation 
of the alternator for cos g=0.8 inductive full load, as 
the generator has to supply current to a power circuit. 
