ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 185 
design, which proves to be in accordance with the speci- 
fication. | 
355. Summary of Design.—The economy in the principal 
dimensions may be indicated by the value of the output 
47.5" X 11 X 3.75 
constant, which is 300 = 31x 10°. 
The amount of copper used in the field is........ 835 Ibs. 
the amount of copper used in armature is...... TT ae 
the weight of the armature stampings is....... 4400 “‘ 
which, compared with the data of Fig. 14, shows the | 
proper specific utilization of the respective materials. 
DESIGN OF A REVOLVING FIELD TYPE SINGLE- 
PHASE ALTERNATOR. 
396. General Specification of Alternator.—This high 
tension single phase alternator must be capable of supply- 
ing a lighting circuit at a frequency of 60. 
The capacity of the machine must be 520 KVA., the power 
factor of the line and transformers ‘being assumed as 
0.95. | 
The working voltage required is 2,800 volts; the voltage drop 
on a non-inductive full load should not exceed 6 per cent. ; 
the full load efficiency should not be less than 93 per 
cent., and the maximum temperature rise in any part of 
the machine should not exceed 80° F. 
357. Arrangement of Winding.—The prime mover being 
a steam engine direct coupled to the alternator, the speed 
is fixed at 300 revolutions per minute, therefore, the alter- 
c 60 x 60 : , : 
nator will have ROW = 12 pairs of poles, which is 
equal to 24 poles. 
With regard to the proper distribution of the winding to 
