KKWAGH POLYTECHNIC COLLEGE, NASHIK
ELECTRICAL DEPARTMENT
Class:- TYEE
Subject:- Power Electronics(PEL)
Chapter No.1
Q.1 Describe different modes of operation of a thyrister with the help of its static V-I characteristics.
(6 marks )
Q.2 Define the terms : Holding current ,latching current and break-over voltage. (6 marks )
Q.3 With the help of neat diagram ,explain the transistor analogy of SCR.
(4 marks )
Q.4 Give the constructional details of SCR. Sketch its schematic diagram and its circuit symbol .
(4marks)
Q.5 What is commutation? List out type of commutation methods. (4 marks )
Q.6 With neat circuit Explain:
( each 4 marks )
1. Resonant commutation
2. Self commutation
3. Complementary commutation
4. Auxiliary commutation
5. External pulse commutation
6. Natural commutation
Q.7 Compare forced commutation with natural commutation on the basis of input supply ,circuit component required
,application .
( 4 marks)
Q.8 Explain in brief various types of triggering methods of SCR .Which is the universal method? (4marks )
Q.9 Sketch circuit diagram and explain synchronized UJT trigger circuit. (4 marks )
Q.10 Draw the symbols of DIAC ,SUS ,PUT and IGBT. State one application of each . (4 marks )
Q.11 Describe A.C. and D.C. gate control circuit of SCR .
(4 marks )
Q.12 List the factors required for selection of heat sink used for SCRs . (4 marks )
Q.13 List any eight specification of SCR (4 marks )
Q.14 Describe principle of forward voltage and light triggering methods of SCR. (4 marks )
Q.15 Draw symbol and V-I characteristics of SCR and TRIAC .
(6 marks )
Q.16 Describe dv/dt and di/dt rating of SCR.
(4 marks )
Q.17 Describe the effect of gate current on forward break-over voltage of SCR. (4 marks )
Q.18 List out various voltage and current rating of SCR. State the meaning of working repetitive and surge rating .
(4 marks )
Q.19 How to test SCR?(4 marks )
Q.20 Compare power transistor with thyrister . (4 marks )
Chapter no : 2
Q. 1 What is converter ? state basic features of converter.
(4 marks)
Q.2 List out application of converter .
(4 marks)
Q.3 With neat waveform explain principle of phase control .
(6 marks)
Q.4 Compare uncontrolled and controlled rectifier .
(4 marks)
Q.5 State the effect of inductive reactance lode on the performance of controlled rectifier . How to eliminate this
effect ?
(4 marks )
Q.6 State the detail classification of controlled converters.
(6 maks )
Q.7 Define following terms :
(2 marks each )
(a) Firing angle
(b) Conduction angle
(c) Extension angle
(d) One quadrant converter
Q.8 What is semiconductor , full converter and dual converter ?
(4 marks)
Q.9 With neat circuit diagram and waveform explain the operation of single –phase half –wave controlled rectifier
with RL load. Why free –wheel diode is connected across the load .
(6 marks)
Q.10 What is a flywheel diode ? State its advantages .
(4 marks )
Q.11 Sketch circuit diagram of M-2 connection with resistive lode ,indicate current direction . (4 marks)
Q.12 Compare mid-point converter with bridge converter .
(4 marks)
Q.13 With neat circuit diagram and waveform explain bridge converter.
(8 marks)
Q.14 State advantage and limitation of bridge convert .
(4 marks )
Q.15 List out types of three-phase converter. State application of three –phase converter. (4 marks)
Q.16 Explain with circuit diagram three-phase fully controlled bridge converter with RL load. State firing sequence
.sketch waveform for =60
(8 marks)
Q.17 Compare single –phase and three – phase convert .
(4 marks)
Q.18 Illustrate the effect of source impedance on converter operation .
(4 marks)
Q.19 what is a cyclo-converter ? State its types .List out application .
(4 marks)
Q.20 State features of cyclo-converter.
(4 marks)
Q.21 Sketch circuit diagram and waveform for mid –point type single – phase cyclo-converter.
(4 marks)
Q.22 Explain three- phase to single – phase cyclo-converter .
(8 marks)
Q.23 Sketch circuit diagram of mid –point type and bridge type three-phase to three – phase cyclo-converter.
(8 marks )
Q.24 What is cyclo-inverter ? State its working principle .
(4 marks )
Q.25 What is IGR ? State its effect.
(4 marks)
Q.26 Sketch fully controlled bridge rectifier with source inductance and sketch its equivalent circuit .
(4 marks)
Chapter no 3:
Q.1 What is an inverter ? which device are used for inverter ? Compare transistorized inverter with SCR inverter.
(6 marks)
Q.2 List out features and applications of inverter .
(4 marks )
Q.3 How inverters are classified ?
(4 marks)
Q.4 Compare voltage fed invert with current fed inverter .
(4 marks)
Q.5 What is a series inverter ? Sketch circuit diagram and associated waveform of a basic series inverter. State its
operation and limitations.
(8 marks )
Q.6 Sketch circuit diagram of modified series inverter with coupled inductors and modified series inverter half bridge
type.
(4 marks)
Q.7 Explain with circuit diagram three-phase series inverter .
(4 marks )
Q.8 With neat circuit diagram and wave form explain the operation of parallel inverter . (8 marks)
Q.9 State the limitations of parallel inverter .How these limitation are overcome in modified parallel inverter ? Sketch
its circuit diagram .
(6 marks)
Q.10 Sketch circuit diagram of McMurry Bedford half bridge inverter. What is the drawback of half bridge inverter ?
(4 marks)
Q.11 Along with waveforms explain full bridge inverter circuit operation .Sketch its circuit diagram .
(6 marks)
Q.12 Sketch circuit diagram of modified McMurry inverter and McMurry Bedford inverter . (6 marks)
Q.13 Why output voltage control is necessary ? State methods for this opration .
(4 marks )
Q.14 Explain the methods of output voltage control using external A.C. voltage control. (4 marks )
Q.15 List out and sketch block diagram of four methods of input D.C. voltage .
(8 marks )
Q.16 With waveform explain single pulse PWN inverter .
(4 marks)
Q.17 How multiple pulse PWN operate ? Sketch its waveform.
(4 marks)
Q.18 Compare sinusoidal PWM and Multiple pulse PWN inverter .
( 4 marks)
Q.19 What is harmonic ? State drawbacks of presence of harmonic .
(4 marks)
Q.20 List out methods for harmonic reduction . Explain LC filter method.
(4 marks)
Q.21 How resonant filter is used to eliminate harmonics ?
(4 marks)
Q.22 What is OTT filter ? Sketch its circuit diagram.
(4 marks)
Chapter no:4
Q.1 Draw basic diagram of chopper and sketch input and output waveforms.
(4 marks)
Q.2 Describe the working of jones chopper with circuit diagram .
(4 marks)
Q.3 Classify choppers according to direction of output voltage and current . Draw their configuration .
(4 marks )
Q.4 Explain With Waveforms the constant frequency system and variable frequency system and variable frequency
system communication method in chopper.
(4 marks)
Q.5 Draw the voltage and current waveform and explain with circuit diagram load communication method in
chopper .
(8 marks )
Q.6 Compare step –up chopper and step –down chopper on the basis of output voltage ,effect of duty cycle
,chopping element position and circuit configuration .
(6 marks )
Q.7 State the working principle of chopper .
(4 marks)
Q.8 List out any four features of chopper and sate any four applications of chopper. (4 marks )
Q.9 Explain the role of inductor in step-down and step –up chopper .
(4 marks )
Q.10 What is PWM chopper? State its advantages.
(4 marks )
Q.11 What is frequency modulation chopper control ? State two methods for this control. List drawbacks of this
control method.
(8 marks)
Q.12 How chopper are classified according to output voltage level, output voltage control .List drawbacks of this
control method.
(8 marks)
Q.13 Explain with circuit diagram class – B chopper.
(4 marks)
Q.14 Compare class –c and class –D chopper .
(6 marks )
Q.15 How many SCRs are required in type –E chopper? Explain its operation with circuit digram .
(8 marks)
Q.16 What is commutation ? How commutation is done in chopper circuit ?
(4 marks)
Q.17 State advantages and drawbacks of voltage commutated chopper.
(4 marks)
Q.18 Sketch circuit diagram of current commutated chopper .Explain its operation using related waveforms.
(6 marks)
Q.19 Compare inverter circuit with chopper circuit .
(4 marks)
Q.20 What is TRC ? Explain its operation .
(4 marks )
Chapter no:5
Q.1 Describe with neat diagram speed control of D.C. series motor using single –phase half controlled convertor .
(4 marks )
Q.2 Describe with neat diagram battery charging using SCR.
(4 marks)
Q.3 Describe with circuit diagram speed control of induction motor using voltage source inverter.
(8 marks )
Q. 4 Draw the circuit diagram of D.C. and A.C. circuit breaker .
(8 marks )
Q.5 Draw the circuit diagram of single –phase full converter method for speed control of D.C series motor .Draw the
waveform for discontinuous motor current .
(4 marks )
Q.6 How variable voltage variable frequency method can be used for speed of three phase induction motor ?Describe
with circuit diagram.
(6 marks)
Q.7Explain the operation of D.C. series motor speed control using single phase fully controlled converter Draw the
waveform with and without freewheeling diode .
(8 marks )
Q.8Draw a neat diagram of three –phase cyclo-converter for speed control of induction motor .(6 marks0
Q.9 state any eight application based on power electronics is electronics in electrical field.
Q.10 Draw a neat circuit diagram of current source invert for A.C. motor drive and describe its working.
(6 marks )
Q.11 Explain with circuit diagram the application of SCR for VAR compensation in power system . (6 marks )
Q.12 Discuss briefly the role of inverters in the speed control of induction motor .
(4 marks)
Q.13 Briefly state the PWM principle in the speed control of voltage controlled inverter fed induction motors.
(4 marks )
Q.14 State the Advantages thyrisorsied drive controlled method.
(4 marks)
Q.15 State the features of industrial drive
( 4 marks)
Q.16 Compare A.C. derive with D.C. drive .
(4 markes0
Q.17 List out merits and demerits of solid state D.C. derive
(4 marks)
Q.18 List out methods of speed control of series motor using SCRs.
(4 marks )
Q.19 What are the advantages of three –phase D.C. drive over single –phase D.C. drive ? (4 marks)
Q.20 Sketch armature voltage and armature current waveform for three –phase full convertor D.C. drive with firing
angle 60 and 90
(4 marks)
Q.21state merits of chopper based D.C. drive.
(4 marks )
Q.22 What is D.C. servo motor ?Explain block diagram of closed loop D.C. servo drive. (8 marks)
Q23.Sketch circuit diagram of PWN inverter A.C. drive using SCR.
(4 marks)
Q.24 State features of PWM inverts I.M.drive.
Q.25 Sketch circuit diagram of CSI feeding a three-phase induction motor and state its features
(8 marks)
Q.26 What is stepper motor ? Sketch block diagram of open –loop control system for stepper motors .List out
application of stepper motor .
(8 marks)
Q.27 What is A.C. servo motor ?
(4 marks)
Q.28 Sketch circuit diagram of series resonant inverter and parallel resonant inverter induction heating system.
(8 marks)
Q.29 State the role of thyristors in dielectric heating.
(4 marks )
Q.30 Explain electric weld control system.
(6 marks)
Q.31 Describe static excitation system of alternator .
(6 marks)