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GITAM INSTITUTE OF TECHNOLOGY GITAM UNIVERSITY (Declared as deemed-to-be-University u/s 3 of UGC Act, 1956) Rushikonda, Visakhapatnam-530 045(AP) Accredited by NAAC with ‘A’Grade DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING Model Question Paper for Ph.D. Entrance Examination (2012-13) Note: marks. 1. 1. Answer all questions 2. All questions carry equal Maximum Marks: 60 Time: 2hrs. What is the significance of Bibliography 2. The figure above shows imports for three types of steel over a six month period. Use this information to answer the following questions. a) Which month showed the largest decrease in total imports over the previous month? b) What was the percentage of scrap steel imported in the 6 month & period? 3. The pie charts above show the percentage of students in each faculty at North West University and the number of non-US students in the Arts faculty. These percentages have been rounded to the nearest whole number. There are a total of 1049 students in the Arts faculty. Use this information to answer the following questions. a) How many students are there in the Engineering faculty? b) If six percent of Science students are Asian. How many Asian students are there studying Science? 2 0 1 2 4. If A = 0 2 0 . Find eigen values of A and A . 1 0 2 5. Solve (1 x) 2 d2y dy (1 x) y sin (2 log(1 x)) . 2 dx dx 6. What value of shunt resistance is required for using a 50 μA meter movement, with an internal resistance of 250Ω, for measuring 0-500mA? 7. Sketch the magnitude and phase angle of the impedance of a series resonant RLC circuit as a function of frequency. 8. Why a 3-phase induction motor can not develop torque when running at synchronous speed. 9. List the various techniques used to measure high DC voltages. 10. Why a circulating current dual converter is faster than its counter part? 11. What are the conditions for successful switching of an SCR? 12. List the methods used to protect over head lines from lightning over voltages and switching surges of short duration. 13. Explain the power reversal in HVDC transmission systems. 14. List the methods of reducing inductive reactance of a transmission line? 15. Differentiate between base load power plant and peak load power plant. 16. What is a state model? 17. Describe the limitations of Kelvin’s Law. 18. Explain why salient type rotors are not used in alternators driven by steam turbines. 19. Define active recovery voltage. 20. Draw the characteristic of a mho relay on R- X diagram. 21. How will the inclusion of a series capacitance affect the regulation of a transmission line? 22. Mention the objectives of automatic generation control in a power system. 23. What is meant by crawling of an induction motor? 24. Name the different methods of improving string efficiency of a string of suspension type insulators. 25. Give the pole-zero placement in s-plane for a lead compensator. 26. Why is the insulation grading done in the under ground cables? 27. What is the difference between Biomass and Biogas? 28. List the factors to be taken into account for the choice of voltage of a transmission line. 29. State the merits of ring distributor. 30. How is time delay produced in static over current relay SYLLABUS FOR Ph.D. ENTRANCE EXAMINATION IN ELECTRICAL AND ELECTRONICS ENGINEERING (2012-13) General : Basic elements of Research Paper and Thesis Computer knowledge on development of graphs bar charts and pi charts Linear differential equations of higher order with constant coefficients – Cauchy, Legender’s homogeneous equations – simultaneous linear differential equations. Rank of a matrix – eigen values and eigen vectors – Caylgey Hamilton theorem – quadratic forms. Correlation – coefficient of correlation – lines of regression – rank correlation. Networks: D.C. and A.C. circuits - loop and nodal analysis, source transformation, star-delta transformation, Superposition, Reciprocity, Thevenin’s, Norton’s, Maximum power transfer theorems, time response of circuits, complex power, resonance, two port networks, solution of balanced and unbalanced 3- circuits. Electrical Measurements: Bridges and potentiometers; indicating instruments - PMMC, moving iron, dynamometer, electrostatic and induction type meters, ammeters and voltmeters, errors in indicating instruments; wattmeter, energy meter and other measuring instruments - measurement of power, energy and power factor and frequency, errors and compensation. Control Systems: Transfer function, block diagrams, servo and stepper motors, error constants, stability, Routh and Niquist criterion, Bode plots, root loci, lag, lead and lead-lag compensation, PD, PI & PID controllers, state space model, state transition matrix, controllability and observability. Electrical Machines: Energy conversion principles; DC machines - types, generator characteristics, armature reaction and commutation, testing and speed control of dc motors; three phase induction motors - principles, types, performance characteristics, starting testing and speed control, single phase induction motors; synchronous machines - performance, regulation and parallel operation of generators, synchronous motor starting, characteristics and applications; single phase transformer - equivalent circuit, phasor diagram, testing, regulation and efficiency; three phase transformers. Power Systems: Generation of electrical Power; transmission line parameters; sag calculations; insulators and cables; economic operation; symmetrical components and fault analysis; load flow analysis; steadystate and transient stability analysis; load frequency control; circuit breakers and protective relays; basics of HVDC transmission and FACTS; power quality. Power Electronics and Drives: Semiconductor power diodes and power transistors; thyristors family – SCR, Triac, GTO, MOSFET and IGBTs; SCRs - gatecharacteristics, static and dynamic characteristics, triggering circuits, phase control rectifiers, choppers, inverters, ac to ac converters; basis concepts and control of dc and ac drives; electrical traction.