INDUSTRIAL AND POWER ELECTRONICS

1. The major advantage of a bridge rectifier is that
a) no centre-tap transformer is required
b) the required peak inverse voltage of each diode is double of that for a fullwave rectifier
c) peak inverse voltage of each diode is half of that for a full-wave rectifier
d) the output is more smooth
ans. c

2. A bridge rectifier provides 50 mA current at 150V : The transformer voltage specification is
a) 220 V:167 V
b) 120 V:150 V
c) 220 V:236 V
d) 120 V:110 V
ans. a

3. A bridge rectifier provides 50 mA current at 150V. The average current and PIV of each diode, respectively are
a) 79 mA, 167 V
b) 25 mA, 236 V
c) 79 mA, 236 V
d) 25 mA, 120 V
ans. b

4. Which of the following circuits cannot be operated directly from the mains?
a) Half-wave rectifier
b) Centre-tap full wave-rectifier
c) Bridge rectifier
d) voltage doubler
ans. b

5. For a filter , no load output voltage is 300 V and full-load output voltage is 280 V . The voltage regulation of the circuit is
a)  9.6%
b) 7.1%
c)  6.7%
d) 4.2%
ans. a

6. A typical value of filter capacitor for 50 Hz input is
a) 1000 microF
b) 50 microF
c) 10 microF
d) 100 pF
ans. b

7. A typical value of induction filter for 50Hz input is
a) 10 H
b) 100 mH
c) 10 mH
d) 100 microH
ans. a

8. If the ripple factor of the output wave of a rectifier is low, it means that
a) output voltage will have less ripple
b) output voltage will be low
c) filter circuits may not be required
d) none of these
ans. a

9. In a rectifier circuit, the load connected is of low value. For proper filter operation, it is required that
a) a capacitor is to be included in the circuit
b) a bleeder resistance is to be placed in the circuit
c) an inductor filter is to be included in the circuit
d) all of the above
ans. c

10. The limitation of the voltage multiplying circuit is that
a) the output has high ripple content
b) high output voltage is difficult to obtain
c) high output current is difficult to obtain
d) the size of the capacitors become very large
ans. c