JNTU B.Tech II NETWORK THEORY Previous Question Paper (April - 2018 - R15)

What is a phase sequence and what is its importance in 3-phase AC circuits?

What are the differences between balanced and unbalanced 3-phase systems?

What is an initial condition?

Under what conditions, response of RLC series circuit for step input is: i) under damped ii) over damped. Draw typical responses.

What is difference between driving point function and transfer function?

Define poles and zeros of a network function. Draw pole-zero plot for the network function

What are 2-port parameters? How are these parameters helpful in describing a 2-port network?

Give expressions for symmetry and reciprocity of Z and Y parameters.

Give expressions for trigonometric and exponential form of Fourier series.

What is the need of filter in electrical network? What are its characteristics?

With a neat circuit and phasor diagram explain the three phase power measurement by two wattmeter method and also derive the expression for Power Factor.

A 3-phase delta connected load has Zab = 100 ohms, Zbc = -j100 ohms and Zca = (70.7 -j70.7) ohms is connected to a balanced 3 phase 400V supply. Determine the line currents Ia, Ib and Ic. Assume the phase sequence abc.

For a star connected three phase system, derive relationship between (i) phase voltages and line voltages (ii) phase currents and line currents.

A 3-phase, three-wire, 208 V, ABC systems supplies a delta-connected load of Zab=5∠0, Zbc=4∠30, Zca=6∠-15 ohms. Find the line currents and total power consumed in the system.

A source voltage of 50 V is applied across a series RL circuit with R=8 ohms and L=5 H at t = 0. Using Laplace Transform method, determine the circuit current i(t) for all t ≥ 0. Assume zero initial conditions.

A series R-L circuit has R=20 ohms and L=8 H. The circuit is connected across a DC voltage source of 120 V at t=0. Calculate the time at which voltage drops across R and L are same.

An R-L-C series circuit with R=2 ohms, L=2 H, C=2 F, are excited by an AC voltage of v(t)=20 sin 2t. Find the current in the network for t>0. Assume at t=0- the network was unenergized.

For a source free RLC series circuit, the initial voltage across C is 10V and initial current through L is zero. If L = 20 mH, C=0.5 µF and R=100 ohm. Evaluate current in the circuit for all t ≥ 0.

Determine driving point impedance Z(s) of a network comprising 5 mH inductor connected in series with a parallel combination of a 5 ohm resistor and 100 µF capacitor. State all critical frequencies of Z(s).

Consider circuit shown in Figure 1. The input to circuit is voltage of voltage source, vi(t). The output is voltage across 8 Ω resistor, vo(t). The network function that represents this circuit is H(s) = Vo(s)/Vi(s) = (30+jω)/(1+j0.66ω). Determine value of inductance, L.

Discuss necessary conditions for driving point and transfer functions.

The transform voltage V(s) of a network is given by V(s) = 3s / ((s+2)(s+2+j2)(s+2-j2)). Plot pole-zero diagram in s-plane and obtain time domain response v(t).

Derive impedance parameters in terms of transmission parameters.

Find ABCD parameters of the network shown in figure 2.

Two 2-port networks A and B are connected in parallel. Each of these networks has their own y-parameters. Show that resultant y-parameters of the combined parallel network is sum of y-parameters of the individual networks A and B.

Determine Z-parameters for network shown in Figure 3.

Discuss about time scaling, duality and time shifting properties of Fourier transform.

Design a constant-K low pass filter with cut-off frequency of 1 kHz and design impedance is 600 ohms.