power electronics Mcqs
201. In EMC signal, the source delivers maximum power to the input of transmission line when the transmission line input impedance
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A. None of these

B. Is equal to the source resistance

C. Smaller than the source resistance

D. Greater than the source resistance

202. DIAC are specifically designed to trigger______________?
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A. SCR

B. TRIAC

C. GTO

D. Only (a) and (b)
203. The curve between V and I of SCR when anode is positive w.r.t cathode and when anode is negative w.r.t cathode are known as_____________________?
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A. both as forward characteristics

B. both as reverse characteristics

C. former as forward characteristics and later as reverse characteristics

D. former as reverse characteristics and later as forward characteristics

204. The on state voltage drop of IGBT consists of__________?
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A. Drop across the drift region

B. Drop across MOSFET portion

C. All of these

D. Drop across the collector junction

205. The output power of the cascaded amplifier / attenuator system can be determined using___________?
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A. Actual gain of amplifier

B. Actual gain of attenuator

C. Gain in dB of amplifier and attenuator

D. Actual gain of amplifier and attenuator
206. Power transistor are type of___________?
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A. B.JTs

B. All of above

C. IGBTs

D. MOSFETs

207. A single phase full bridge inverter can operate in load commutation mode in case load consists of____________?
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A. RLC overdamped.

B. RLC critically damped.

C. RL.

D. RLC underdamped.
208. Which of following devices has highest di/dt and dv/dt capability?
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A. SITH

B. SCR

C. SIT

D. GTO
209. The effects of EMI can be reduced by____________?
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A. All of these

B. Reducing the susceptibility of the receptor

C. Reducing the efficiency of the coupling path

D. Suppressing emissions

210. The phase angle of gate signal in TRIAC can be shifted by using_____________?
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A. A variable resistor

B. An inductor

C. Only (a) and (b)

D. A capacitor

211. To detect an over current fault condition, the most reliable method is to connect a_____________?
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A. Voltage sensor across IGBT

B. Current sensor in series with IGBT

C. Current sensor across IGBT

D. Voltage sensor in series with IGBT

212. In square wave operation mode of 3 phase VSI, the VSI
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A. Can control the load voltage

B. Cannot control the load voltage except by means of dc link voltage

C. Cannot control the load voltage except by means of dc link current

D. Cannot control the load voltage

213. If the anode current is 800 A, then the amount of current required to turn off the GTO is about____________?
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A. 200 A

B. 400 A

C. 600 A

D. 20 A

214. During reverse recovery time__________________?
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A. charge carrier of junction J2 recombined

B. charge carrier of junction J1 is swept out

C. charge carrier of junction J3 is swept out

D. both B and C
215. Maximum di / dt in a SCR is________?
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A. Directly proportional to Vm of supply voltage

B. Inversely proportional to Vm of supply voltage

C. Inversely proportional to L in the circuit

D. Both A and C

216. A step down choppers can be used in___________?
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A. All of these

B. Electric traction

C. Electric vehicles

D. Machine tools

217. Which following is a two terminal three layer device?
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A. BJT

B. MOSFET

C. None of above

D. Power dioed

218. The main objective of static power converters is to____________?
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A. Obtain an ac output waveform from a dc power supply

B. Obtain an ac output waveform from a ac power suppl

C. Obtain an dc output waveform from a dc power supply

D. Obtain an dc output waveform from a dc power supply

219. A full wave rectifier with resistive load produces___________?
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A. Do not produce harmonics

B. Fifth harmonic

C. Second harmonic

D. Third harmonic

220. Electrical power output in a d.c. generator is equal to____________?
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A. Electrical power developed in armature iron and copper losses

B. Mechanical power input iron and friction losses

C. Mechanical power input iron and friction losses copper losses

D. Electrical power developed in armature copper losses

221. What happen due to high di / dt____________?
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A. None of these

B. Insulation failure

C. Breakdown of junction

D. Local hot spot
222. A thyristor equivalent of a thyratron tube is a _________?
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A. None of above

B. Diac

C. Silicon controlled-rectifier SCR

D. Triac

223. In a three phase voltage source inverters____________?
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A. Only amplitude of voltage is controllable

B. Only phase is controllable

C. Both amplitude and phase is controllable

D. Amplitude, phase and frequency of voltages should always be controllable
224. Which of the following is used in SCR to protect from high dV / dt__________________?
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A. Snubber circuit

B. Circuit breaker

C. Equalizing circuit

D. Fuse

225. In rectifiers, load current flow is_________?
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A. Either (a) or (b)

B. Bidirectional

C. Non directional

D. Unidirectional
226. Anode of an operational SCR is _______________?
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A. Always negative w.r.t cathode

B. Always negative w.r.t anode

C. Always positive w.r.t cathode

D. Always positive w.r.t anode

227. For series connected SCRaEURs dynamic equalising circuit consists of___________?
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A. R and C in series but with diode across C

B. R and C in series but with diode across R

C. Series R and diode with C across R

D. Series R and diode with C across R