JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ELECTRICAL ENGINEERING Previous Question Paper (April - 2018 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
PART A
State laws of resistance.
Answer
The laws of resistance state that the resistance of a conductor is directly proportional to its length (R ∝ l), inversely proportional to its cross-sectional area (R ∝ 1/A), and depends on the nature of the material (resistivity) and its temperature.
Define self and mutual inductance. Give formula for coefficient of coupling.
Answer
Self-inductance is the property of a coil to oppose any change in current flowing through it by inducing an emf. Mutual inductance is the property where a change in current in one coil induces an emf in a nearby second coil. The coefficient of coupling (k) is given by:
Two impedances 5+6j and 3+4j are connected in parallel. Find equivalent conductance and susceptance.
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Two phasors 6+7j and 3+4j are to be multiplied. Find the real and imaginary values and represent in polar form.
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What is OCC? Why it is so called.
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What is back emf? What is its significance?
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What is condition for maximum efficiency in a transformer?
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Differentiate between squirrel cage and slip ring induction motors.
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What is synchronous impedance and synchronous reactance?
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What is the principle of alternator?
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PART B
Three resistances 5ohms, 6 ohms and 10 ohms respectively are connected in star. Find equivalent resistances when connected in delta.
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What are the various torques present in an electrical instrument?
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What are the characteristics of series circuits? Derive them.
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What are the characteristics of parallel circuits? Derive them.
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What are the various methods of measuring three phase power?
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What is the method suitable for both balanced and unbalanced loads?
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In an electrical circuit voltage applied is 400 +60 j and impedance is 5+4j ohms respectively. Find the current flowing and power and power factor.
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Differentiate between RMS and average values of an ac quantity.
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With a suitable experiment draw the OCC of a D.C. Shunt generator.
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Derive EMF equation of D.C. Generator.
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With a neat circuit explain the working of a three point starter.
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Give the significance of over load and no volt coils.
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Explain the method of conducting O.C and S.C test on single phase transformer.
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Explain how to find efficiency and regulation from above test.
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What is rotating magnetic field? Why it is so called.
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Give merits and demerits of squirrel cage motors over slip ring motors.
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Explain the operation of alternator with necessary diagram.
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Give the method of finding regulation of an alternator.
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Draw the OCC and SCC of an alternator by suitable experiment.
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What are the advantages of stationary magnetic field over rotating magnetic field?
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