JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II NETWORK THEORY Previous Question Paper (April/May - 2023 - R13)
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
Define phase sequence.
Answer
The phase sequence is the specific order in which the individual phase voltages of a balanced three-phase system reach their respective maximum positive values. In a standard three-phase system, the sequence is typically denoted as positive phase sequence (R-Y-B or A-B-C), where each phase is displaced by 120 degrees in time, or negative phase sequence (R-B-Y or A-C-B), depending on the order of rotation.
What is line voltage? What is its significance?
Answer
Line voltage is defined as the potential difference measured between any two of the three supply lines in a three-phase electrical system. In a star (Y) connection, it is the voltage between two phase terminals, while in a delta (Δ) connection, it is the voltage across each phase winding.
The significance of line voltage lies in its role as the standard measure for power distribution and equipment rating. It determines the magnitude of power delivered to loads and dictates the insulation requirements for electrical apparatus. In industrial and commercial applications, the line voltage is the primary parameter used to specify the capacity of transmission lines and the operational voltage of three-phase motors and transformers.
How an inductor behaves for sudden changes in current?
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What is the behavior of capacitor in steady state?
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Define pole and zero of a network.
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What is a one-port network? Give example
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Define short circuit admittance parameters.
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How to find ABCD parameters?
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Define line spectra.
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What is odd symmetry in Fourier series?
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Part B
Derive the relationship between phase and line currents in a balanced three phase delta connected system with resistive load.
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A 3-phase, star connected system with 230 V between each phase and neutral has resistances of 1 Ω, 2 Ω and 6 Ω respectively in the three phases. Estimate the current flowing in each phase and the neutral current. Find the total power absorbed by the load.
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How to measure three phase active power? Explain with neat circuit diagram.
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In a 4-wire, 3-phase system, two phases have currents of 9A and 5A at lagging power factors of 0.866 and 0.5 respectively, while the third phase is open circuited. Calculate the current in the neutral and draw the phasor diagram.
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Explain the transient behavior of current in series RC circuit excited by DC supply with the help of necessary derivations.
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In the circuit below figure 1, find the expression for the voltage ‘v’ for t > 0.
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Explain the transient behavior of current in series RLC circuit excited by DC supply with the help of necessary derivations.
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For the circuit shown below figure 2, find the current ‘i’ for t > 0.
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Explain the concept of complex frequency with an example.
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What are the properties of transfer functions? Explain in detail.
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What is a transformed circuit? Explain with examples.
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What are the necessary conditions for driving point functions? Explain in detail.
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Derive the relationship between Z and hybrid parameters.
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For the network below figure 3, determine admittance parameters.
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Derive the relationship between Y and ABCD parameters.
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Find the hybrid Parameters of the following two port network (figure 4).
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What is a low pass filter? Explain it in detail.
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A periodic waveform is described as follows f(t) = 3t for 0 ≤ t ≤ 2 and f(t) = 0 for 2≤t≤5 and repeats. Evaluate the Fourier series coefficients.
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What is a band pass filter? Explain it in detail.
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Find the Fourier transform of the following function.
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