Power Electronics MCQs 1

Power Electronics MCQs 1:- In This Article, we have provided some MCQs For Power Electronics Students. Power Electronics MCQs 1 could be quite helpful for those who are preparing for GATE, ESE, or for any interviews you can take a look at it.

1.The peak inverse voltage required for the diode shown in the figure below is

• a) 300 V
• b) 100 V
• c) 200 V
• d) 400 V

Ans:- d) 400 V

2. For high frequency applications of over10 kW power rating, …………….. type of diodes are used:

• a) Power frequency
• b) Schottky
• c) fast recovery
• d) medium recovery

Ans :- c) fast recovery

3. An SCR with a latching current of 10 mA is connected to 10V, 50 Hz sinusoidal source feeding an R-L load of 100Ω, 10mH connected in series. If the SCR is fired at ωt= 45°, with a single firing pulse width duration of 7.5 μs, the current in the circuit after the firing instant will be

• a) 100 mA
• b) 70 mA
• c) 0 A
• d) None of the above

Ans:- c) 0 A

4. A conducting thyristor can be turned-off by …………(decreasing/increasing) the anode current ……….. (below/above) the ………….(latching/holding) current and applying a ………….(zero/forward/reverse) voltage across the SCR for a short interval.

• a) decreasing, below, holding, reverse
• b) decreasing, below, latching,
• c) reverse increasing, above, latching, zero
• d) increasing, above, holding, reverse

Ans:- a) decreasing, below, holding, reverse

5. A single phase ac voltage source of peak magnitude Vm volts and source frequency of ω rad/s, feeds a resistive load through a full-wave rectifier circuit. The average output voltage, V0 (in volts) of the rectifier circuit with diodes having reverse recovery time of trr seconds is given by,

• a) V0 =2Vm/π
• b) zero
• c) V0 =(2Vm/π) (1+cosωtrr
• d) V0 =(Vm/π) (1+cosωtrr)

Ans :- d) V0 =(Vm/π) (1+cosωtrr)

6. The ON state resistances of two power diodes connected in parallel to share a load of 1 kA are 0.55 and 0.65 mΩ respectively. The value of series resistance (in mΩ) to be connected with each of them to ensure equal current sharing with a tolerance of 10% is

• a) 0.1
• b) 0.4
• c) 0.675
• d) 0.735

Ans:- b) 0.4

7. An SCR circuit has the following rating: VLine=220V rms., f=50Hz load resistance, Rl=60 Ω, dv/dt=70 V/μs and di/dt = 60A/μs. The value of snubbing capacitor (in pF) and snubbing inductance (in μH) needed are ……………, and …………….. respectively.

• a) 86.42, and 4.44
• b) 74.08, and 5.18
• c) 52.38, and 3.66
• d) 0.074, and 5.18

Ans:- b) 74.08, and 5.18