GATE 2015 EE – SET 1 Question 34

Solution :

N_{s} = Synchronous speed

$$\phi $$ = 3 , f = 50 Hz , P = 4 ,

5^{th} harmonic = $$\frac{N_{s}}{5}$$

N_{s} = $$\frac{120f}{p}$$ = $$\frac{120*50}{4}$$= 1500 rpm

5^_{th} harmonic  = $$ \frac{N_{s}}{5} $$= $$\frac{1500}{5}$$ = 300 rpm

slip \Rightarrow  $$\frac{N_{s}+\frac{N_{s}}{5}}{N_{s}}$$

$$ \frac{1500+300}{1500}$$ =1.2

$$\frac{1+\frac{1}{5}}{1}$$=$$\frac{6}{5}$$=1.2