GATE EE 2017 Electrical and Electronic Measurements Solution Q 5 - Grad Plus

# GATE EE 2017 Electrical and Electronic Measurements Solution Q 5

The following measurement are obtained on a single phase load: V = 220 V ±1%. I = 5.0 A ± 1% and W=555 W ± 2%. If the power factor is calculated using these measurements, the worst case error in the calculated power factor in percent is __ (Give answer up to one decimal place.)

Ans. 0.5 ± 4 %

Explanation:

We know that, W=V×I×cos (Φ)

p.f= cos (\phi )=\frac{W}{V.I} \therefore P.F.=\frac{555\pm2\%}{(220\pm1\%)(5\pm1\%)}=\frac{555}{220\times5}\pm4\%

Hence, p.f=cos(Φ)=0.5 ±4%

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