ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 
431. 
432. 
4353. 
ASA. 
SoLution: The normal mechanical output being equal to 
450 H. P. its equivalent in K.W. will be A.W.= H.P. x 
.746 = 335 K.W.; and under the specified conditions 
KW. 335 
the input amounts to 008 Boe i 400 
KVA. | 
Therefore for a star connected armature, the phase current 
400,000 ; 
i =, = . See E 
will be 73 3500 66 amps. See Equation (5) 
Data for Design.—In comparing the present data with 
that of Par. 210, it is obvious that the alternator design 
developed in Pars. 211 to 268 may be used for this 
particular synchronous motor. 
Interpretation of Characteristics.—Fig. 94, 
contains five different characteristics: The curves 1, 2 
and 3 are the no-load, short circuit, and load characteristics, _ 
respectively, the latter referring to an armature phase 
current of 66 amps. with a phase displacement of cos g = 
0.9. 
Curve No. 4, is the so called V-characteristic of a synchronous 
motor and gives the armature current in terms of the 
excitation when the mechanical output 450 H.P., the 
terminal pressure 3,500 volts, and the speed 500 revs. ie 
minute, are constant. See Par. 440. 
Curve No. 5, represents the corresponding power factors in 
terms of the excitation. 
Important Characteristices.—All the working con- 
ditions of the machine as a generator or motor, are entirely 
fixed by the no-load and the short circuit characteristics 
and the three other curves are simply deduced from these, 
to illustrate the various electrical features. 
The no-load and short circuit characteristics permit further 
conclusions with regard to the mechanical property of 
overload capacity. : 
Overload Capacity.—In the following paragraphs the 
overload capacity is understood to be the ratio between 
