1. A half-wave rectifier circuit using ideal diode has an input voltage of 20sinωt volt. Then average and RMS value of output voltage respectively are
- 10/π V and 10 V
- 20/π V and 5 V
- 20/π V and 10 V
- 10/π V and 5 V
2. The input power factor of the converter circuit may be defined as the ratio of
- total mean input power to the total rms input volt amperes.
- total rms input volt amperes to the total mean input power.
- total peak input volt amperes to the total rms input volt amperes.
- total input rms volt amperes to the total input peak volt amperes.
3. Compute the ripple factor of a single-phase full-wave rectifier with load resistance R = 10 kΩ. Forward bias dynamic resistance of diodes used is 100 Ω. The rms voltage across secondary winding is 330 V.
4. A single-phase two pulse converter feeds an R-L load with insufficient smoothing but the conduction is continuous. If the resistance of the load circuit is increased, then
- the ripple content of the load current will remain the same.
- the ripple content of the load current will decrease.
- the ripple content of the load current will increase.
- there is possibility of discontinuous conduction due to an increase in the ripple content.
5. The use of multiphase rectifier in place of single-phase rectifier results in
- Increased output voltage and reduced harmonics
- Increased output voltage and increased harmonics
- Decreased output voltage and reduced harmonics
- Increased output voltage and no effect on harmonics
6. The average output voltage of a fly-back converter is Vo = 24 V at a resistive load of R = 0.8 Ω. The duty cycle ratio is α = 50% and the switching frequency is f=1 kHz. The on-state voltage drop of transistors and diodes are V, = 1.2 V and Vd = 0.7 V respectively. The turn ratio of the transformer is ‘a’ = Ns/Np = 0.25. What is the efficiency of the converter?
7. Which one of the following statements is correct?
The function of the bleeder resistor in a power supply is
- to ensure a minimum current drain in the circuit
- to increase the output d.c. voltage
- to increase the output current
- same as that of a load resistor
8. The characteristic features of discontinuous conduction compared to continuous conduction in a two-pulse, single-phase bridge converter are
- larger average value of load voltage and larger ripple-content
- larger average value of load voltage and smaller ripple-content
- smaller average value of load voltage and smaller ripple-content
- smaller average value of load voltage and larger ripple-content
9. In a three-phase full-wave a.c. to d.c. converter, the ratio of output ripple-frequency to the supply voltage frequency is
10. The total harmonic distortion (THD) of ac supply input current of rectifiers is maximum for
- single-phase diode rectifier with dc inductive filter
- 3-phase diode rectifier with dc inductive filter
- 3-phase thyristor rectifier with inductive filter
- single-phase diode rectifier with capacitive filter