Electronics and Electrical Engineering - May 2014

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 following instructions of 8051 microcontroller quoting suitable examples.
(i) ORL A, #data (ii) RRC A (iii) RET(6 marks) 1 (b) Differentiate between asynchronous and synchronous data transfer.(6 marks) 2 (a) Explain the use of following registers associated with 8051 microcontroller. i) DPTR
ii) Program Counter <br? iii)="" accumulator<="" a="">

</br?>(6 marks) 2 (b) What are Timer0 (T0) and Timer1 (T1) registers supported by 8051 microcontroller? How are these started and stopped?(6 marks)

Answer any one question from Q3 and Q4

3 (a) Draw and explain characteristics of DC shunt and series motors.(6 marks) 3 (b) A 50 Hz, 8 pole, 3 phase induction motor has full load slip of 4%. The rotor resistance is 0.001 ohm/phase and standstill reactance is 0.005 ohm/phase. Find i) the ratio of maximum torque to full load torque ii) the speed at which maximum torque occurs.(6 marks) 4 (a) A 230V DC shunt motor has armature resistance of 0.2 Ohm and field resistance of 115 Ohm. It runs at 1500 RPM and draws a current of 50 A on full load. Calculate its speed at half load condition.(7 marks) 4 (b) Distinguish between squirrel cage and slip ring induction motors.(6 marks)

Answer any one question from Q5 and Q6

5 (a) Compare analog voltmeter and digital voltmeter.(6 marks) 5 (b) Explain working of CRO with the help of schematic showing its various parts.(6 marks) 6 (a) Explain working of digital frequency counter with the help of block diagram.(6 marks) 6 (b) State advantages of digital multimeter. Mention typical specifications of digital multimeter.(6 marks)

Answer any one question from Q7 and Q8

7 (a) Explain the sphere gap method used for measurement of peak value of voltage.(7 marks) 7 (b) Two-wattmeter method is used for measurement of input power of a three phase induction motor. If two wattmeter readings are 1700 watts and 1100 watts; determine i) input power to motor ii) power factor of the motor iii) input current drawn from 440 V, 3 phase AC supply.(6 marks) 8 (a) What is Wien's Bridge? Derive expression for frequency of Wien's Bridge.(7 marks) 8 (b) Explain one wattmeter method used for measuring reactive power of a three phase balanced load with the help of connection diagram and phasor diagram.(6 marks)