Electrical Machines - Dec 2012

Electronics Engineering (Semester 4)

TOTAL MARKS: 60
TOTAL TIME: 2 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Use suitable data wherever required.
(4) Figures to the right indicate full marks.

Answer any four:-

1 (a) Define sensitivity of an analog instrument. For PMMC instrument with FSD=100 mA find sensitivity.(5 marks) 1 (b) What is Meggar? Explain its working.(5 marks) 1 (c) For ADC, define resolution. Give suitable example.(5 marks) 1 (d) Explain the working principle of DC motor.(5 marks) 1 (e) Explain the function of delay line in oscilloscope. What are the types of delay lines?(5 marks) 2 (a) What is intensity modulation? For what purpose it is used? Can phase and frequency be measured using intensity modulation?(10 marks) 2 (b) What is Q meter? Explain any one of the types of Q meter with the help of circuit diagram.(10 marks) 3 (a) Draw and explain Kelvin's Bridge.(10 marks) 3 (b) Explain the operating principle of 3-phase induction motor.(10 marks) 4 (a) Draw and explain the block diagram of digital storage oscilloscope.(10 marks) 4 (b) Explain R-2 R ladder technique of digital to analog converter.(10 marks) 5 (a) Draw and explain any one of the types of electronic voltmeter. State its two advantages over analog voltmeter.(10 marks) 5 (b) Explain digital phase meter using flip flop. Draw relevant waveforms at each point in a block diagram to illustrate.(10 marks) 6 (a) Explain Schering bridge for measurement of capacitance. Derive the equation of unknown capacitance at balanced condition.(10 marks) 6 (b) What is energy meter? Draw its constructional view and explain.(10 marks)

Write short notes on (any one):-

7 (a) Variable reluctance stepper motor.(10 marks) 7 (b) A.F. signal generator(10 marks) 7 (c) Digital frequency meter.(10 marks)