Power Electronics (3140915) MCQs

MCQs of AC-DC Converters

Showing 21 to 30 out of 107 Questions
21.
A 230V, 50Hz, single-pulse SCR is feeding a RL load with α = 40° and β = 210°. Find the value of average output voltage
(a) 54 V
(b) 106 V
(c) 84 V
(d) 32 V
Answer:

Option (c)

22.
A single-pulse transformer with secondary voltage of 230 V, 50 Hz, delivers power to bulb of R = 10 Ω through a half-wave controlled rectifier circuit. For α = 60°, find the average current in the bulb
(a) 2.5 A
(b) 7.7 A
(c) 9.6 A
(d) 3 A
Answer:

Option (b)

23.
A single-pulse transformer with secondary voltage of 230 V, 50 Hz, delivers power to bulb of R = 10 Ω through a half-wave controlled rectifier circuit. For α = 60° and output AC power of 2127 Watts, find the rectification efficiency
(a) 98.6 %
(b) 42 %
(c) 28 %
(d) 19 %
Answer:

Option (c)

24.
An SCR rectifier circuit is designed such that the average output voltage is 77.64 V & RMS value of output voltage is 145.873 V. Find the voltage ripple factor.
(a) 1.879
(b) 0.532
(c) 1.590
(d) 0.629
Answer:

Option (c)

25.
Find the expression for the average value of the output voltage for the below given circuit. Consider the load current to be continuous, firing angle = α, transformer ration 1:1 and Vs = Vm sinωt.
(a) (Vm/π)cosα
(b) (Vm/π)(1+cosα)
(c) (2Vm/π)cosα
(d) (2Vm/π)(1+cosα)
Answer:

Option (c)

26.
A fully controlled converter uses
(a) diodes only
(b) thyristors only
(c) both diodes and thyristors
(d) none of the mentioned
Answer:

Option (b)

27.
A single phase full-converter using R load is a _________ quadrant converter and that using an RL load without FD is a __________ quadrant converter
(a) 1,1
(b) 2,1
(c) 1,2
(d) 2,2
Answer:

Option (c)

28.
The PIV for each diode in a single-phase, full converter with B-2 type (bridge) of controlled rectifier is_______________. Consider supply voltage as Vs = Vm sinωt.
(a) 2Vm
(b) Vm
(c) Vm/2
(d) Vm/√2
Answer:

Option (b)

29.
A single-phase full converter B-2 type (bridge) connection has a RLE type of motor load connected. The minimum requirement to turn-on the device is
(a) α > 30°
(b) Vm sinα > E
(c) Vm sinα < E
(d) α < 30°
Answer:

Option (b)

30.
A motor load is connected to a single-phase full converter B-2 type controlled rectifier. The net energy is transferred from ac source to the motor (dc load) when
(a) π+α > 90
(b) π-α > α
(c) π+α > α
(d) π-α > 90
Answer:

Option (b)

Showing 21 to 30 out of 107 Questions