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T.E. (Electrical) (Semester – I) Examination, 2013MICRO-CONTROLLER APPLICATIONS

(2008 Course)

Time : 3 Hours Max. Marks : 100

Instructions : 1) Attempt any three questions from Section I and Section IIon separate answer sheet.

2) Figures to the right indicate full marks.3) Neat diagram must be drawn wherever necessary.4) Use of non programmable calculator is permitted.

SECTION – I

1. a) Explain the concept of memory banks. How and in what sense is the SFRaddress different than the upper 128 bytes of on chip RAM ? 6

b) Explain how the status of EA pin affect to access the internal and external

program memory with neat diagram. 6

c) What do you mean by the term quasi-bi-directional port ? Why is port 0 of8051 true bi-directional ? Explain with figure. 6

OR

2. a) What are the function of the following pins 10

i) RXD ii) 0INT iii) T0

iv) WR v) XTAL2

b) What are the salient features of 8051 family of microcontroller ? 4

c) Explain the utility of internal RAM with an example. 4

3. a) Explain all bit manipulation instruction with an example. 8

b) Write an assembly language program to find smallest number in an array. 8OR

4. a) Explain all types of JUMP and CALL instructions of 8051 microcontroller. 8

b) Explain ROTATE and SWAP instruction. 4

c) Calculate the largest possible time delay for timer in 8051 operating in mode 1with crystal frequency of 6 MHz. 4

P.T.O.

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5. a) With XTAL = 11.0592 MHz, find the TH1 value needed to have the followingbaud rate : 8

a) 9600 b) 2400 c) 1200

b) Explain the role of SMOD in serial communication. 8

OR

6. a) How the data is transferred using I2C Bus ? 8

b) Explain the SPI Bus communication protocol with Master and threeindependent Slave. 8

SECTION – II

7. a) Write short notes on assembler, programmer, simulator and emulator. 8

b) Explain the interfacing of 8051 with computer through RS232 with neat sketch. 8

OR

8. a) Describe tools helpful in various stage of microcontroller development system.Give the flow chart for development of microcontroller based product. 6

b) Explain with neat diagram the interfacing of 8051 with external memory. 10

9. a) Draw a schematic diagram and write assembly language program to rotateStepper motor in 100 rotation. [1.8° full step, 200 steps/revolution]. 12

b) Draw and explain the block diagram to implement the measurement oftemperature of an electric oven using 8051 microcontroller. 6

OR

10. a) Explain the procedure of interfacing of ADC 0809 to 8051 microcontroller.Draw relevant schematic diagram. 10

b) Write a program to generate following waveform using DAC interfaced with8051 microcontroller. Draw the relevant block diagram. 8

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11. a) With the help of neat diagram explain the interfacing of LCD with 8051microcontroller. 8

b) With the help of neat diagram and flowchart explain the concept ofmeasurement of reactive power using 8051 microcontroller. 8

OR

12. Write short notes on any two of the following : 16

i) 8051 microcontroller based speed control the DC motor.

ii) 8051 microcontroller based frequency measurement.

iii) 8051 microcontroller based current measurement.

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B/II/13/

Total No of Questions: [12] SEAT NO. :

[Total No. of Pages : 2 ]

T.E. 2008 (Electrical ) 303142: ELCTRICAL MACHINES - II

(Semester - II)Time: 3 Hours Max. Marks : 100Instructions to the candidates:

1) Answers to the two sections should be written in separate answer books.2) Answer three questions from each section.3) Neat diagrams must be drawn wherever necessary.4) Figures to the right side indicate full marks.5) Use of Calculator is allowed.6) Assume Suitable data if necessary

SECTION I

Q1) a) Define voltage regulation of alternator at full load. Can voltage regulation be positive or negative? When?

[4]

b) From the following test result determine the voltage regulation of a 2000 V 1 phase alternator delivering a current of 100 A at i) 0.71 lag pf ii) 0.8 lead pf

Test result- full load current of 100 A is produced on short circuit by a field excitation of 2.5 A . An emf of 500 V is produced on open circuit by the same excitation. Given armature resistance = 0.8 ohms

[8]

c) What is meant by short circuit ratio in case of alternator? Elaborate its significance.

[6]

ORQ2) a) Compare salient pole type rotor construction with non salient pole type

construction in case of 3 phase alternator.[4]

b) Explain the ZPF method for determining voltage regulation of alternator. [8]

c) A 3 phase 16 pole alternator has star connected full pitch winding with 144 slots & 10 conductors per slots. The flux per pole is 0.03 Wb sinusoidally distributed & the speed is 375 rpm. Calculate the phase value of induced emf.

[6]

Q3) a) Explain any two methods of starting 3 phase synchronous motor. State applications of 3 phase synchronous motor.

[8]

b) A 2 MVA 3 phase 8 pole alternator is connected to 6000 V, 50 Hz busbars & has synchronous reactance of 4 ohms per phase. Calculate the synchronizing power and synchronizing torque per mechanical degree of rotor displacement at no load. Assume

[8]

ORQ4) a) What is synchronizing of alternator? what are different methods of

synchronizing? Explain dark lamp method of synchronizing[8]

b) Explain the operation of synchronous motor at

1) Constant load & variable excitation2) Constant excitation & variable load

[8]

Q5) a) With neat diagram explain construction & working of 3 phase synchronous induction motor.

[8]

b) Write a short note on 3 phase induction generator [8]

OR

Q6) a) Explain testing of 3 phase induction motor as per IS 325 & IS 4029 [8]b) Explain V/f method of speed control of 3 phase induction motor. Why the ratio

V/f is to be kept constant?[8]

SECTION II

Q7) a) With the help of suitable waveforms, explain the nature of torque developed for DC series motor if it is connected to ac supply.

[8]

b)A 2 pole, 50 Hz, 230 volt universal motor has 1200 armature turns and 400 series field turns. When operated on ac supply, the full load current is 1 Amp, field flux is 0.8 m Wb and speed is 7000 rpm. The total resistance and leakage reactance are 20 and 30 . Neglect iron loss of motor. Find –

(i) Transformer emf induced in armature by quadrature flux. (ii) Quadrature flux Full load output

[8]

ORQ8) a) With suitable diagram explain inductively compensated AC series motor [8]

b) Explain the procedure to plot circle diagram of AC series motor. How to get following parameters from circle diagram- 1)Net mechanical output 2)Motor efficiency

[8]

Q9) a) What are slot harmonics? What are their effects on performance of machine? How these can be mitigated?

[8]

b) Explain construction and working of permanent magnet DC motor. State its applications.

[8]

ORQ10) a) Explain construction and working of linear induction motor. State its

applications.[8]

b) Explain construction and working of brushless DC motor. State its applications. [8]Q11) a) Explain cross field theory with suitable diagrams. [9]

b) Explain construction, working and speed torque characteristics of capacitor start-capacitor run motor.

[9]

ORQ12) a) With suitable circuit diagram explain –No load test and blocked rotor test on

single phase induction motor. How equivalent circuit parameters are obtained from these tests?

[9]

b) Explain double field revolving theory with suitable diagrams. [9]XXXXXXX

��������� [4459] – 162

T.E. (Electrical) (Semester – l) Examination, 2013ELECTRICAL MACHINES – II

(2008 Course)

Time : 3 Hours Max. Marks : 100

Instructions : 1) Answer 3 questions from Section I and 3 questions fromSection II.

2) Answers to the two Sections should be written in separatebooks.

3) Neat diagrams must be drawn wherever necessary.4) Black figures to the right indicate full marks.5) Use of logarithmic tables, slide rule, Mollier charts, electronic

pocket calculator and steam tables is allowed.6) Assume suitable data, if necessary.

SECTION – I

1. a) Define voltage regulation for an alternator at full load. What are the methodsof finding out voltage regulation of alternator ? Which method is most correct ? Why ? 6

b) With usual notations derive the emf equation of 3 phase synchronous machine. 4

c) A 3 phase star connected alternator is operated for O.C and S.C. test. Thealternator is rated as 1000 KVA, 2000 V, 50 Hz with armature resistance of 0.3 Ωper phase. Determine the voltage regulation of alternator at 0.8 p.f. lag. Usemmf method. 8

If (Amp) 10 20 25 30 40 50

O.C. voltage (v) 800 1500 1750 2000 2350 2600

S.C. arm current (A) − 200 250 300 − −

OR

P.T.O.

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[4459] – 162 -2- ���������

2. a) Elaborate the effect of power factor on armature reaction in case of alternator. 6

b) Compare salient pole and nonsalient pole type synchronous machines. 4

c) Determine the voltage regulation of 2000 V, 1 phase alternator having currentof 100 A at (I) 0.8 pf lead (II) 0.71 pf lag. Given that a field current of 2.5 Ampproduces full load current of 100 Amp on short circuit and an emf of 500 V onopen circuit. 8

3. a) State the necessity of synchronization of 3 phase alternators. What are thenecessary conditions for synchronization ? Describe bright lamp method withneat diagram. 8

b) A 50 HP 410 V 50 Hz 3 phase star connected synchronous motor has full loadefficiency of 85%. The synchronous impedance of the motor is (0.2 + j 2.0) Ωper phase. If the excitation of the motor is adjusted to give leading p.f. of0.85. Calculate :I) Full load induced emf line value.II) Mechanical power developed. 8

OR

4. a) A 5 KVA 200 V star connected 3 phase salient pole alternator with direct andquadrature axis reactance of 12 Ω and 7 Ω respectively, delivers full loadcurrent at unity p.f. Calculate the excitation voltage and voltage regulation atfull load.

Neglect armature resistance. 8

b) Describe the phenomenon of hunting in synchronous motor. Explain how itcan be reduced. 8

5. a) State different methods of speed control of 3 phase induction motor. Explainv/f method of speed control of 3 phase I.M. Why v/f ratio is to be kept constantin this method ? 8

b) Explain operation of 3 phase induction motor as an induction generator. Stateadvantages and applications of 3 phase induction generator. 8

OR

6. a) Write a note on 3 phase induction voltage regulator. 8

b) With neat diagram explain construction and working of 3 phase synchronousinduction motor. 8

��������� -3- [4459] – 162

SECTION – II

7. a) Discuss the different modifications necessary in design and construction ofDC series motor so that it can work satisfactorily on AC supply as a universalmotor. 6

b) A 2 pole universal motor operates on AC supply drawing 4.6 Amp from supplyand runs at 5000 rpm. It draws input power of 320 watt at 100 volt supply.Armature winding resistance is 3.6 Ω . Calculate maximum value of flux perpole and effective armature reactance. Draw respective phasor diagram. 6

c) Draw performance characteristics curves of universal motor and state itsapplications. 6

OR

8. a) Why compensation is necessary in AC series motor ? Explain any one methodof providing compensation. 6

b) Draw and explain exact phasor diagram of AC series motor. 6

c) Explain procedure to plot circle diagram of AC series motor and draw circlediagram representing respective voltage drops in motor, different lossesoccurring in motor. 6

9. a) Explain crawling in three phase induction motor and draw respective speed-torque characteristics indicating the effect of crawling. 8

b) With suitable diagrams explain construction and working of permanent magnetstepper motor. Draw and explain briefly its performance characteristics. 8

OR

10. a) What are slot harmonics in case of alternator ? How the performance ofalternator is affected due to slot harmonics ? State and explain methods tomitigate slot harmonics. 8

b) With suitable diagram explain construction and working of linear inductionmotor. State its advantages and disadvantages, applications. 8

11. a) A single phase induction motor is rated 1 kW, 230 volt, 50 Hz. The statorresistance is 2.2 Ω and reactance is 3 Ω . The rotor-resistance referred tostator or primary is 3.8 Ω and reactance referred to stator or primary is2.1Ω . The magnetising reactance is 86Ω . Find the input power drawn bymotor, power factor and efficiency if motor operates at a slip of 0.06. Drawequivalent circuit of motor representing all the values. 10

b) Explain working principle of shaded pole motor with suitable diagrams. 6OR

12. a) Following rest results are obtained for no load test and blocked rotor test onsingle phase induction motor.

No load test 220 V 4 A 100 W

Blocked rotor test 110 V 10 A 400 W

The stator winding resistance is 2 Ω . Calculate the parameters of equivalentcircuit and draw equivalent circuit. 10

b) Explain double field revolving theory for single phase induction motor. 6

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B/II/13/

[4459] – 162 -4- ���������

PUNE UNIVERSITY QUESTION PAPERS3rd Year Electrical Engineering (2009-

2014)

Publisher : Faculty Notes Author : Panel Of Experts

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