JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ELECTRICAL ENGINEERING Previous Question Paper (November/December - 2017 - R13)
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
Define self and mutual inductances.
Answer
Self-inductance is the property of a coil by which it opposes any change in the current flowing through it by inducing an electromotive force (EMF) within itself. It is defined as the ratio of the flux linkage of the coil to the current producing it, given by
Mutual inductance is the property by which a change in current in one coil induces an EMF in a neighboring coil due to the magnetic coupling between them. It is defined as the ratio of the flux linkage in the second coil to the current in the first coil, expressed as
If two resistances having 3 ohm and 6 ohm, what is the equivalent resistance value if they are connected in i) series ii) parallel.
Answer
Given resistances are R1 = 3 Ω and R2 = 6 Ω.
i) For a series connection, the equivalent resistance Req is the sum of individual resistances:
ii) For a parallel connection, the equivalent resistance Req is calculated using the formula:
If v(t)= Vm sinωt then write the equations for average and rms values.
Answer
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Write the resonant frequency formula for series and parallel R,L and C circuit.
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Write the EMF equation for DC generator, explain the terms in brief?
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What are the different types of dc motors?
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What is the principle of operation of single phase transformers?
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Write the applications of Induction Motors.
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What is the principle of operation of alternators?
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What is meant by voltage regulation and conclude weather voltage regulation should be high or low?
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Part B
If three resistance of each 3Ω, 6Ω, 9Ω are connected in star then convert the star to delta circuit.
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Explain the faraday's laws of electromagnetic induction and lenzs law.
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Explain the constructional features of moving iron instrument with relavent diagram in detail.
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If R, L, C are connected in series and parallel then obtain the resonant frequency for the series and parallel circuits.
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A circuit having the resistance 10 ohm, inductance 20 mH, capacitance 50µF are connected in series and having frequency of 50Hz, then what is the impedance value of the circuit?
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A circuit having resistance 20Ω, inductance 50 mH, and capacitance 20 µF, if they are connected in series then find resonance frequency.
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Explain principle of operation of dc machine with neat diagram and derive emf equation.
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What is a starter, explain 3-point starter in detail with neat sketch?
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Define efficiency and regulation of a single phase transformer.
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Explain the constructional features of a single phase transformer with neat diagram.
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What are the different types of induction motor, explain any one of them in detail?
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Explain slip-toque characteristics of induction motor.
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Explain the working principle of alternator and derive its EMF equations.
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Explain the O.C test of alternator with neat diagram.
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A 3-phase star connected alternator is rated at 1600 KVA 13.5kV. The effective armature resistance and synchronous reactance are 1.5 ohms and 30 ohm per phase, respectively. Find regulation, for a load of 1280 kW, rated voltage and power factor of (a) 0.78 leading, (b)unity, (c) 0.8 lagging.
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