130 



ELECTRICAL ENGINEERING 



amperes and a fifth harmonic of -V 1 = 5 amperes in quadrature 

 ahead of the e.m.f. 's producing them. The fifth harmonic is 

 much more prominent in the capacity circuit than in either of 

 the others and thus the capacity tends to exaggerate the harmonics 

 in a peaked wave. 



The main current 7 consists of a fundamental and a fifth har- 

 monic. The fundamental is the resultant of the fundamental 

 currents in the three branches and from Fig. 99 (d) is found to be 

 10 amperes in phase with fundamental e.m.f. 



The fifth harmonic is the resultant of the fifth harmonic cur- 

 rents in the three branches and from Fig. 99 (e) it is found to be 

 4.8 amperes, leading the fifth harmonic e.m.f. by nearly a quarter 

 of a cycle. The main current is shown in Fig. 99 (c). 



(4) If the same e.m.f. is impressed on the terminals of the cir- 

 cuit CD in Fig. 100 (a) determine the current flowing. The re- 



R=10bm 



X = 2 Ohms at 60 Cyelw 

 X=100hm. at260 Cycles 



Xc=600hmi 

 at 60 Cjoltfl 



FIG. 100. 



sistance of the circuit is 1 ohm, the reactance is 2 ohms at 50 

 cycles and 10 ohms at 250 cycles and the condensive reactance is 

 50 ohms at 50 cycles and 10 ohms at 250 cycles. 



100 

 The main current consists of a fundamental of , 



Vl + (50 - 2) 2 



100 

 = -TQ- = 2.05 amperes leading the fundamental e.m.f. by nearly 



90 degrees and a fifth harmonic of 



10 



=10 amperes. 



Vl 2 + (10 - 10) 2 



The circuit is resonant for the fifth harmonic e.m.f. at 250 

 cycles and so the fifth harmonic current is very much exagger- 

 ated. The current is plotted in Fig. 100 (6). 



