JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year BASIC ELECTRICAL ENGINEERING Previous Question Paper (September/October - 2023 - R15)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
What are the differences between independent and dependent sources?
Answer
An independent source provides a specified voltage or current that is independent of any other circuit variable. A dependent (controlled) source provides a voltage or current whose value depends on the voltage or current elsewhere in the circuit.
State and explain the maximum power transfer theorem.
Answer
The Maximum Power Transfer Theorem states that for a linear, active, bilateral network, the maximum power is transferred from the source to the load when the load impedance is the complex conjugate of the Thevenin equivalent impedance of the network as seen from the load terminals.
This means the load resistance must equal the Thevenin resistance (R_L = R_th) and the load reactance must be equal in magnitude but opposite in sign to the Thevenin reactance (X_L = -X_th).
Define power factor of an a.c circuit.
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The impedance of an electrical circuit is (30 -j50) ohms. Determine (i) the resistance, (ii) the capacitance, and (iii) the magnitude of the impedance, when the circuit is connected to a 240 V, 50 Hz supply.
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Define transformation ratio of transformer.
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What is the working principle of transformer?
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What is the condition for maximum efficiency of a DC machine?
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What are the different types of DC Generators?
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Differentiate gravity and spring control mechanisms used in measuring instruments.
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What are the advantages and limitations of MI type instruments.
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Part B
Using method of superposition, determine the current through the 5kΩ resistors for the circuit in Figure 1.
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Explain the Kirchhoff’s laws.
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State and explain Thevenin’s theorem.
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Determine the current I in the network shown in Figure 2 by using Thevenin’s theorem.
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An alternating voltage expressed as i= 14.14 sin (314t+φ). Determine a) Time period b) Frequency c) rms value of current d) Average value of current e) peak factor f) form factor
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A resistance of 10Ω connected in series with a 50mH inductance across a 230V, 50Hz supply. Find a) impedance b) current c) power factor d) Phase angle e) voltage across resistor and inductor
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Describe how the open circuit test is conducted on the single phase transformer.
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Explain about transformer regulation.
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Explain about various losses of Single phase transformer? How to minimize them?
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State the various parts of a transformer and their function.
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Explain the working principle of D.C. Motor with neat sketches.
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Three phase induction motor is wound for four poles and is supplied from 50 Hz supply. Calculate i) Synchronous speed ii) the speed of the rotor when the slip is 3% and iii) the rotor frequency when the speed of the rotor is 900rpm.
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Enumerate the different types of losses in a DC motor?
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Summarize the various effects utilized in different types of measuring Instruments.
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Explain the working Principe of repulsion type Moving Iron Instrument.
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Explain the working of Moving coil Permanent magnet instruments.
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What are the different damping mechanisms provided to the measuring instruments? Explain in brief.
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