Roll No. EEEEEEEE | Total No. of Pages : 02
Total No. of Questions : 09
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B.Tech.(EE)/(Electrical & Electronics)/(Electronics & Electrical)(2011 Onwards)
(Electrical Engineering & Industrial Control) (2012 Onwards)
(Sem.-5)
POWER ELECTRONICS
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Subject Code : BTEE-504M.Code : 70557
Time : 3 Hrs. Max. Marks : 60
INSTRUCTION TO CANDIDATES :
- SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
- SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
- SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.
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SECTION-A
- Answer briefly :
- Differentiate between holding and latching current in a Thyristor.
- What is the role of dv/dt in the operation of a Thyristor?
- Differentiate between Diac and Triac.
- What is the function of free wheeling diode?
- What is a LASCR?
- Write applications of a Thyristors.
- What is the importance of Surge current rating of a Thyristor?
- Draw turn on characteristics of a Thyristor.
- Draw snubber circuit.
- What is duty cycle of a chopper?
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SECTION-B
- Explain two transistor model of a Thyristor.
- Compare power MOSFETs with BJTs.
- Discuss operation of single phase mid-point cycloconverter with R-L load for continuous conduction with relevant circuit diagram and necessary output waveforms.
- Describe the working of step down chopper and derive expression for output voltage.
- Draw and explain the simple SCR series inverter circuit employing class A type commutation with the help of important waveforms. State the limitations of this inverter.
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SECTION-C
- What are the methods for voltage control within the inverters? Explain in detail with waveforms.
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- Define string efficiency for series /parallel connected SCRs .Show the string efficiency of two series connected SCRs is less than one.
- Explain the difference between class A and class B commutation.
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- A 230V, 50 Hz, one pulse SCR controlled converter is triggered at a firing angle of 40° and the load current extinguishes. at an angle of 210°. Find the current turn off time, average output voltage and average load current for
- R=5O and L =2 mH.
- R=5O, L=2mH and E=110 V.
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.
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This download link is referred from the post: PTU B.Tech Dec 2018 5th Semester Question Papers || Punjab Technical University
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