462 



ELECTRICAL EQUIPMENT 



current for which it is to be used to the current for which it is 

 designed. 



Far Example: A 3^-per cent 350-amp. reactor may be used in a 



> Qfjn 



300-amp. circuit where it will insert 3J X =3 per cent reactance. 



ooU 



From the foregoing it is seen that a 3J per cent, 25-cycle, 

 13,200-volt, 350-amp. reactor will introduce in a 40-cycle, 11,000- 



40 



volt, 300-amp. circuit a reactance of approximately 3|X 



Zo 



13.200 300 __ 



Effect of Reactance on Power-factor. Increasing the reac- 

 tance in the system results but in a slightly lower power-factor, 

 the curve in Fig. 286 showing the variation of power-factor with 

 per cent reactance. It is to be noted that if the power-factor of 

 the circuit were 90 per cent, corresponding to a reactance of 44 per 

 cent, then the introduction of a 3J per cent reactor would increase 



ID 20 30 40 50 60 70 80 90 100 

 Per Cent Reactance of Circuit 



FlG. 286. 



the reactance of 47J per cent and the power-factor would be low- 

 ered to 88 per cent. The introduction of a slightly larger reactor, 

 say 4.2 per cent, would decrease the power-factor to practically 

 the same amount. On the other hand, if the power-factor of the 

 circuit were 70 per cent, the introduction of a 3J per cent reactor 



