JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY, HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY, HYDERABAD B.Tech I BASIC ELECTRICAL ENGINEERING Previous Question Paper (December - 2018 - R18)
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.
Part A
Define linear and non linear elements.
Answer
A linear element is one whose V-I characteristic is a straight line passing through the origin, meaning it obeys Ohm's Law (e.g., a resistor). A non-linear element is one whose V-I characteristic is not a straight line, meaning its parameters change with voltage or current (e.g., a diode or transistor).
What is complex power?
Answer
Complex power (S) is the vector sum of real power (P) and reactive power (Q) in an AC circuit. It is expressed in Volt-Amperes (VA) as
What is meant by equivalent resistance of a 1-Φ transformer when referred to primary?
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Write the merits and demerits of slip-ring induction motor.
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What is MCB?
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Five 2V cells, each having an internal resistance of 0.2Ω are connected in series to a load of resistance 14 Ω. Find the current flowing in the circuit.
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What is phase difference? Explain.
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Write different types of losses in transformers.
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What is the necessity of starter in starting of a 3-Φ Induction motor?
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What is the necessity of earthing in domestic buildings?
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Part B
Explain about different types of sources.
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Calculate the power absorbed by each component in the circuit shown in figure 1.
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State and explain Thevenin’s theorem.
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In the circuit shown in figure 2, determine ‘V’ using Thevenin’s theorem.
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Compute the average value of square wave form shown in below figure 3.
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A coil takes a current of 1 A at 0.6 lagging power factor from a 220 V, 60 Hz single phase source. If the coil is modeled by a series RL circuit, find i) The complex power in the coil and ii) The values of R and L.
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Derive the expression for RMS value of alternating current wave I = ImSin ωt.
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Derive the relation between phase and line voltages and currents in balanced three phase star connection.
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Explain regulation of a transformer with phasor diagrams.
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Derive the condition for maximum efficiency in a single phase transformer.
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Explain the operation of an auto transformer with a neat diagram.
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What are the advantages of 3-phase Transformers?
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Explain the speed control of 3-Φ induction motor using Rotor resistance control.
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Sketch the Torque-slip characteristics of Induction motor and explain.
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Explain the principle of production of rotating magnetic field in a 3-phase induction Motor.
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Derive the condition for maximum torque under running condition of 3-phase Induction Motor.
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What is ELCB? Explain the working principle of ELCB.
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Mention advantages and disadvantages of ELCB.
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What are the different types of wires and cables? Explain.
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Give applications of the primary and secondary batteries.
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