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Electrical Machines : Question Paper May 2012 - Electronics Engineering (Semester 4) | Mumbai University (MU)
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Electrical Machines - May 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.
Any four:-
1 (a) A PMMC instrument has FSD to 100 ?A coil resistance is 1 kΩ. Calculate the required shunt resistance value to convert the instrument in to an ammeter with (i) FSD=100 mA (ii) FSD=1A.(5 marks)
1 (b) What is the difference between electrical instruments and electronic instruments?(5 marks)
1 (c) Explain basic principle of frequency meter.(5 marks)
1 (d) When oscilloscope time base is disconnected and various types of signals are connected to vertical and horizontal inputs then draw displays
Vertical I/P | Horizontal I/P | |
i) | Sine Wave | OV |
ii) | Sine Wave | Sine Wave..... same 'f' 0° phase |
iii) | Sine Wave | antiphase sine wave |
iv) | Sine Wave | Sine wave with 90° phase, same frequency |
If voltmeter is connected across supply type connection the measured current is 0.5 A and voltmeter indication is 500 V. Ammeter has a resistance Ra=10 Ω. Calculate the value of 'R'.(10 marks) 6 (a) With reference to the characteristics and applications, differentiate between D.C. shunt and series motors.(10 marks) 6 (b) Explain the principle of operation of PMMC and moving Iron type of instruments. Compare the two basic types.(10 marks) 7 (a) What are the various torques required in PMMC? How they are generated? What is the requirement of each of the torque?(10 marks) 7 (b) Draw only the Kelvin's double bridge.(6 marks) 7 (c) Explain in short basic principle of working of stepper motor?(4 marks)
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