480 Pu/pin — Resonance Analysis of Alternating Currents. 



auxiliary resistance of 50 ohms the resonant rise was 122 volts 

 we have with a rough approximation, 



122X66 



a;= = 503 volts. 



16 



In this manner the figures of the fourth column were 

 obtained. They are only very rough approximations, but still 

 they give a fair idea of the ratio of the fundamental to the 

 upper harmonic at various loads. Curves I and II, fig. 6, were 

 plotted from these data. The secondary amperes were taken 

 for the abscissae and the corresponding resonant rises in volts 

 for the ordinates. Curve III represents Curve II plotted on a 

 different scale for the volts of the resonant rise of potential. 

 These are given in the right hand vertical column of the dia- 

 gram. This curve gives a better picture of the gradual apparent 

 increase of the harmonic. An inspection of I and II shows 

 clearly how much more rapidly the fundamental increases than 

 the harmonic. In reality the increase is even more rapid y 

 for according to Table V it appears as if the strength of the 

 harmonic increased with the secondary current, only much 

 less rapidly than the fundamental. For instance, at open sec- 

 ondary the voltmeter indicated 65 volts for the resonant rise 

 of the fundamental ; and at 56 amperes in the secondary this 

 rise was indicated by 202 volts. But it must be noted that in 

 the first case the voltmeter needle went from practically zero at 

 no resonance, to 62 when resonance was reached / whereas in 

 the second case it went from 135 volts at no resonance to WB 

 volts when resonance was reached, so that the real resonant rise 

 was practically the same in both cases. Similarly for all other 

 loads in the secondary. Ic follows, therefore, that if the har- 

 monic increased at all with the increase of the load, this 

 increase was much smaller than appears at first sight from the 

 data of Table V. The more important conclusion, however, 

 which follows from this experiment and which I wish to point 

 out more particularly is that the harmonic which manifests 

 itself in the distortion of the primary current when there is 

 no load in the secondary is present at all loads, if not stronger, 

 then certainly with about the same strength. At full load this 

 harmonic could not possibly be detected by Joubertfs method of 

 sliding contact ; it is so exceedingly small in comparison to 

 the fundamental. 



This persistence of harmonics at all loads even when com- 

 pletely hidden by the fundamental wave holds true also when 

 their origin can be traced to the action of the armature of the 

 generator as in the case of the machine with slotted iron core 

 armature. In all cases their strength depends upon the mean 

 intensity of magnetization of the magnetic circuits to which 

 they ovje their oriyin and upon nothing else. 



