GATE 2018 EE – Question 33
The waveform of the current drawn by a semi-converter from a sinusoidal AC voltage source is shown in the figure. If $I_0=20$ A, the rms value of fundamental component of the current is ________ A (up to 2 decimal places).
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Correct answer: 17.21 to 17.39
Explanation
The current is a quasi-square wave of height $I_0$ with a delay of $\alpha=30^\circ$ and width $180^\circ-\alpha$ per half cycle. Its fundamental rms is $\frac{2\sqrt2}{\pi}I_0\cos\frac\alpha2=0.9003\times20\times\cos15^\circ=17.39$ A.