Electrical Engineering: Power Electronics MCQ

6. Question

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 Vo = Vm(3 + cosα) / 2π ,where Vm = 80π volts and α is the firing angle. If the power
delivered to the lossless battery is 1600 W, α in degree is________ (up to 2 decimal places).

7. Question

In the circuit shown in the figure, the bipolar junction transistor (BJT) has a current gain β = 100. The base-emitter voltage drop is a constant, VBE = 0.7⁡V. The value of the Thevenin equivalent resistance RTh (in Ω) as shown in the figure is ______ (up to 2 decimal places).

8. Question

For the circuit shown below, assume that the OPAMP is ideal.

Which one of the following is TRUE?

9. Question

In the circuit shown all elements are ideal and the switch S is operated at 10 kHz and 60% duty ratio. The capacitor is large enough so that the ripple across it is negligible and at steady state acquires a voltage as shown. The peak current in amperes drawn from the 50 V DC source is ________ . (Give the answer up to one decimal place.)

10. Question

The figure below shows the circuit diagram of a controlled rectifier supplied from a 230 V, 50 Hz, 1-phase voltage source and a 10:1 ideal transformer. Assume that all devices are ideal. The firing angles of the thyristors T 1 and T 2 are 90º and 270º, respectively.