GATE 2018 EE – Question 59
A phase controlled single phase rectifier, supplied by an AC source, feeds power to an R-L-E load as shown in the figure. The rectifier output voltage has an average value given by $V_o=\frac{V_m}{2\pi}(3+\cos\alpha)$, where $V_m=80\pi$ volts and $\alpha$ is the firing angle. If the power delivered to the lossless battery is 1600 W, $\alpha$ in degree is ________ (up to 2 decimal places).
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 90
Explanation
The battery power is $80I_o=1600$, so $I_o=20$ A. Then $V_o=80+2\times20=120$ V. With $\frac{V_m}{2\pi}=40$, $40(3+\cos\alpha)=120$ gives $\cos\alpha=0$ and $\alpha=90^\circ$.