Reg 210.2 न 00000EC30712 19017:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
Fifth semester B.Tech degree examinations (S) September 2020

Course Code: EC307
Course Name: POWER ELECTRONICS & INSTRUMENTATION
Max. Marks: 100 Duration: 3 Hours
PART A
Answer any two full questions, each carries 15 marks. Marks
1 a) Explain the structure of power BJT with neat schematic. (6)
b) Explain switching characteristics of power diode with the help of waveform. (6)
c) What is the importance of free-wheeling diodes in converters? (3)
2 a) Draw and explain the circuit diagram of Boost converter with inductor current (8)
and switching waveform.
b) Describe the working of IGBT and draw input and output characteristics. How (7)
does latch up occurs in IGBT?
3 ஐ Define the working of fly back converter with neat diagram. (5)
b) Draw the VI characteristics of GTO and list its various modes. (3)
c) Explain the working of full bridge isolated converters with help of circuit (7)
diagram and relevant waveform.
PART ‏تا‎
‎Answer any two full questions, each carries 15 marks.
4 a) List any five differences between offline UPS and online UPS. (5)

b) With neat circuit diagram and switching waveform explain the working of push (10)
pull inverters.
5 a) Explain how to measure an unknown resistance using Wheatstone’s bridge with (5)
the help of schematic.
b) Describe phase vector modulation of three phase inverter. (5)
c) Define the following Static Characteristics: (5)
i) Accuracy ii) Precision iii) Repeatability iv) Reproducibility v) Resolution
6 8) List any two differences between half bridge and full bridge inverter. (3)
b) Explain different classification of instruments. (8)

c) Define Q-factor. (4)