Question
The voltage at the input of an AC-DC rectifier is given by v (t) = 230 √2 sinωt where ω = 2π × 50 rad/sec. The input current drawn by the rectifier is given by
i(t)= 10 sin (ωt- π/3) + 4 sin (3ωt- π/6) + 3 sin (5 ωt- π/3)
The input power factor, (rounded off to two decimal places), is, ________ lag.
Answer :
0.4473 (Range : 0.43 to 0.47)
Given :
I. v (t) = 230 √2 sinωt
II. i(t)= 10 sin (ωt- π/3) + 4 sin (3ωt- π/6) + 3 sin (5 ωt- π/3)
III. f = 50 Hz
IV. ω = 2π × 50 rad/sec.
Input power factor (IPF),
V ( t) |RMS = 230 V, i1( t) |RMS= 10/√2 A
Fundamental displacement factor (FDF) = cos ∅1 = cos π/3= 1/2
Where, ∅1 is the angle between voltage and fundamental component of current
i( t) |RMS = √( 10/√2)2 + ( 4/√2)2 + ( 3/√2)2 = 7.905 A
We know, IPF = Distortion factor Fundamental displacement factor
IPF = g × FDF
Also, g= i1( t) |RMS/ i( t) |RMS = (10/√2)/ 7.905 = 0.8946
Therefore, IPF = 0.8946 × 0.5 = 0.4473
Hence, the correct answer is 0.4473
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