Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II NETWORK THEORY Previous Question Paper (May - 2019 - R15)
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 a three phase electric system and give the common configurations of it.
Answer
A three-phase electric system is a polyphase system consisting of three circuits carrying alternating currents of the same frequency but displaced in phase by 120 degrees from each other. The common configurations are Star (Y) and Delta (Δ) connections.
Draw the circuit diagram for measuring reactive power by using a single wattmeter.
Answer
To measure reactive power using a single wattmeter, the current coil is connected in series with one line, and the potential coil is connected across the other two lines. This creates a 90-degree phase shift between the voltage and current applied to the wattmeter, allowing it to measure reactive power (Q = V_L I_L sin φ).
Define transient response or natural response.
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How do you relate and understand the response as over damped, under damped and critically damped?
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Explain the physical interpretation of complex frequency.
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How do you define Driving point impedance and admittance?
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State the application of h-parameters in electronic circuits.
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Derive z-parameters in terms of ABCD parameters.
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Draw the frequency response characteristic of constant K low pass filter.
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State the design parameters of Band pass filter.
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PART - B
Derive the relationship between line and phase voltages and currents in a Delta connection.
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A 20 HP induction motor is supplied from a 400 V, 3 phase, 50 Hz power system. The efficiency being 90%, the power factor of operation is 0.8. Obtain i) the active power consumed ii) the apparent power iii) the reactive power and iv) the line current.
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A delta connected load has following impedances ZRY = j10Ω, ZYB = 10Ω, ZBR = - j10Ω. If the load be connected across a three phase 415V supply (balanced), obtain the line currents. Draw the vector diagram.
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Derive the transient response for a series RC circuit with Sinusoidal excitation.
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Find the current in a series R-L circuit having R = 2Ω and L=10 H while a dc voltage of 100 V is applied. What is the value of this current after 5 seconds of Switching On?
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Derive the expression for circuit current of a series RLC circuit excited by DC as input.
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Derive the conditions for symmetry and reciprocity in terms of Y-Parameters.
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Find the y-parameters of the network shown in figure 1.
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Derive the condition for Reciprocity and symmetry in a two port ABCD parameter representation.
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Find the z-parameters of the network shown in figure 2.
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Explain the conditions to be fulfilled for interconnection of two port networks.
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Find voltage and current transformation ratio shown in the figure 3.
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Explain the concept of poles and zeros in a network function. Locate the poles and zeros of a transfer function G(s) = (s+2) / ((s+3)(s+4)).
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State and explain the properties of transfer functions.
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Compare between Laplace and Fourier transform.
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Find the exponential Fourier series for the following wave form shown in figure 4.
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Obtain the Fourier series for the waveform shown in figure 5.
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Draw the T and π-network representation of Band elimination filter.
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