226 



ALTERNATORS. 



the characteristic curve with even greater force. It would 

 thus be extremely difficult in practice to take a series of 

 readings of current with the power-factor adjusted in each 

 case to a constant value. 



If complete curves at different power-factors are required, 

 and not an isolated point only on each curve (which is often 

 enough for practical purposes), the same process of plotting 



1-0 



40 50 60 70 80 90 100 



Volts. 

 FIG. 105. VARIATION or VOI/TAGK WITH POWER FACTOR. LAGGING CURRENT. 



auxiliary curves comparing power-factor and voltage must 

 be resorted to in this case also. 



The following description of an actual test will indicate 

 the method to be adopted-in obtaining complete curves. 



The machine experimented upon was a 1 kw. 4-pole 

 Crompton alternator, with rotating armature. 



