advertisement

Total No. of Printed Pages:2 SUBJECT CODE NO:- P-265 FACULTY OF ENGINEERING AND TECHNOLOGY T.E. (EC/ECT/IE/E&C) Examination MAY/JUNE-2016 Power Electronics (Revised) [Time:Three Hours] “Please check whether you have got the right question paper.” i) Q.No.1 and Q.No.6 are compulsory. ii) Solve any two questions from each section from remaining i.e. from Q.2 to Q.5 and Q.7 to Q.10. iii) Assume suitable data, if necessary. Section A N.B Q.1 [Max Marks:80] Solve any two. I. Step-up cycloconverter II. Gate characteristics of SCR III. What is commutation? Why it is necessary in SCR? IV. Integral cycle control 10 Q.2 a) With the help of near circuit diagram and waveforms, explain V-1 characteristics of power BJT. 08 b) For an SCR, the gate – cathode characteristic has a Vs=15V, a straight line slope of 130 and allowable 07 gate power dissipation of 0.5 watts, compute the gate – source resistance. Q.3 a) With the help of a neat circuit diagram and waveforms explain line – synchronized VJT triggering circuit. b) The trr= 5 and . If SF=0.5, Determine i. QRR ii. IRR 08 Q.4 a) Explain the effect of source inductance “Ls” on performance of 3- converter? b) Explain full converter with R – load with neat circuit diagram and waveforms. 08 07 Q.5 a) Explain class-B commutation technique with neat circuit diagram and waveforms. b) Explain A.C. voltage controller with RL load. 08 07 07 Section B Q.6 Solve any two. I. Series Inverter II. Four quadrant chopper III. HF heating IV. Ring counter circuit 10 a) With the help of neat circuit diagram and waveforms. Explain working of 1800 conduction mode of bridge inverter. b) Calculate o/p frequency of series inverter with L=10mH, c= , RL=500Ω , Toff = 250 , tq=25 Q.7 P-2016 fef42b729058a5c83fe99157e237f4f2 08 07 Q.8 a) Explain voltage commutated chopper with neat circuit diagram and waveforms? b) The dc chopper has a resistive load of R=10Ω, I/P dc voltage is 220V. When the chopper switch remains on, it’s ON state voltage drop is 2V. Chopper frequency is 1 KHz. If duty cycle is 50% Determine, 1) Average O/P load voltage 2) RMS O/P Load voltage 3) Effective I/P resistance 08 07 Q.9 a) Explain time delay circuit with neat waveforms and circuit diagram. b) Explain flasher circuit with neat waveforms. 08 07 Q.10 a) With the help of neat circuit diagram derive the expression for IL(MAX) and IL(MIN) of class – A chopper. 08 b) Explain various voltage control techniques of an Inverter. 07 P-2016 fef42b729058a5c83fe99157e237f4f2