Electronics and Electrical Engineering - Jun 2015

Mechanical Engineering (Semester 4)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.

Answer any one question from Q1 and Q2

1 (a) Explain TMOD register and specify its operating modes.(6 marks) 1 (b) Explain different addressing modes supported by 8051 microcontroller.(6 marks) 2 (a) What is Program Status Word (PSW) ? State the function of each flag in it.(6 marks) 2 (b) Discuss asynchronous and synchronous data transfer formats.(6 marks)

Answer any one question from Q3 and Q4

3 (a) Derive the expression for the torque developed in a three- phase induction motor under running conditions. Hence state the equation for maximum torque developed.(6 marks) 3 (b) A 200 V, 4 Pole, Lap wound DC shunt motor has 800 conductors on its armature. The resistance of armature winding is 0.5 Ω and that of shunt field winding is 200 Ω. The motor takes current of 21 A and flux per pole is 30 MWb. Find the speed and gross torque developed in armature.(7 marks) 4 (a) Explain V/f control method for controlling speed of three-phase induction motor.(6 marks) 4 (b) Draw and explain characteristics of DC shunt and series motors.(7 marks)

Answer any one question from Q5 and Q6

5 (a) Discuss advantages of digital voltmeters over analog voltmeters. Also mention its limitations.(6 marks) 5 (b) Explain working of conventional standard signal generator with the help of neat diagram.(6 marks) 6 (a) Explain working of digital multimeter with the help of block diagram.(6 marks) 6 (b) Enlist applications of Cathode Ray Oscilloscope (CRO) for measurement of various electrical quantities.(6 marks)

Answer any one question from Q7 and Q8

7 (a) Explain two wattmeter method used for measuring three-phase power in a star connected balanced load supplied by symmetrical a.c. with the help of neat connection diagram and phasor diagram.(6 marks) 7 (b) What is an AC bridge ? Enlist AC bridges. Derive the general equations for balance of an AC bridge.(7 marks) 8 (a) Two wattmeters are connected to measure total power in a three-phase circuit. One reads 4800 W while the other reads backwards. Over reversing the connections of the later, it reads 400 W. Find total power absorbed and power factor of circuit.(6 marks) 8 (b) What is Wien's bridge? Derive the expression for unknown frequency in terms of bridge parameters.(7 marks)