ELECTRICAL MEASUREMENTS

Code No: R05310202 Set No. 1
III B.Tech I Semester Regular Examinations, November 2008
ELECTRICAL MEASUREMENTS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Give the classification of electrical measuring Instruments.
(b) Explain the working principle of PMMC instrument with a neat sketch.
(c) State the advantages and dis-advantages of PMMC instrument. [5+6+5]
2. Draw the equivalent circuit and phasor diagram of a potential transformer. Derive
the expressions for its ratio error. State the assumptions made for derivation of
this error. [16]
3. (a) Give the constructional details of electrodynamometer type wattmeter with a
neat sketch.
(b) Prove that the true power= COS
COS .COS( − )
× Actual wattmeter reading for
electrodynamometer type of wattmeters, where cosφ =p.f of the circuit, β =
tan−1 􀀀wL
R where L and R are the inductance and resistance of the pressure
coil of the circuit. [8+8]
4. Derive the expression for deflecting torque in single phase induction type Energy
water. Show that deflection is maximum when the phase angle between two fluxes
is 900 and when the disc is purely non-inductive. [16]
5. (a) How a co-ordinate type A.C. potentiometer is standardized? Explain how an
unknown voltage can be measured by using this potentiometer?
(b) What are the sources of errors in the above potentiometer? [10+6]
6. (a) What are the different difficulties encountered in the measurement of high
resistances? Explain how these difficulties are overcome?
(b) A highly sensitive galvanometer can detect a current as low 0.1 nano-Amperes.
This galvanometer is used in a wheat-stone bridge as a detector. The resistance
of galvanometer is negligible. Each arm of the bridge has a resistance of 1K
.
The input voltage applied to the bridge is 20V. Calculate the smallest change
in resistance, which can be detected. The resistance of the galvanometer can
be neglected as compared with the internal resistance of bridge. [10+6]
7. (a) State the advantages and disadvantages of Anderson’s bridge.
(b) Draw the phasor diagram for Anderson’s bridge under balance conditions.
(c) A bridge consists of the following:
Arm ab - a choke coil having a resistance R1 and inductance L1
Arm bc - a non-inductive resistance R3.
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Code No: R05310202 Set No. 1
Arm cd - a mica condenser C4 in series with a non-inductive resistance R4.
Arm da - non-inductive resistance R2.
When this bridge is fed from a source of 500 Hz, balance is obtained under
following conditions.
R2=2410
; R . 3=750
; C . 4=0.35 μF ; R4 = 64.5
. The series resistance of
capacitor is 0.4
. Calculate the resistance and inductance of the choke coil.
The supply is connected between a and c and the detector is between b and
d. [6+4+6]
8. Explain the construction and working principle of a ballistic galvanometer with a
neat sketch. [16]
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Code No: R05310202 Set No. 2
III B.Tech I Semester Regular Examinations, November 2008
ELECTRICAL MEASUREMENTS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Explain the constructional details of PMMC instrument with neat sketch.
(b) Explain why PMMC instruments are the most widely used instruments? Ex-
plain their advantages and disadvantages. [8+8]
2. (a) Explain the constructional details of different types of current transformers.
(b) A 100/5A, 50 Hz current transformer has a bar primary and a rated sec-
ondary burden of 12.5VA. The secondary winding has 196 turns and a leakage
inductance of 0.96mH. With a purely resistive burden at rated full load, the
magnetizing mmf is 16AT and the loss excitation required 12A. Find ratio and
phase angle errors. [8+8]
3. (a) Explain the working of a 3-phase wattmeter. Draw a neat sketch of the
wattmerter and also its connections. Also, explain how the mutual effects
between the two elements of the wattmeter are eliminated.
(b) A voltage: 100 sinwt+40cos(3wt-30o)+50sin(5wt+50o)V is applied to the pres-
sure circuit of a wattmeter and through the current coil is passes a current of
8 sin wt+6 cos (5wt-120o)A. What will be the reading of the wattmeter?
[10+6]
4. Explain the functions of the following in a single phase induction type Energymeter.
(a) Shunt and series magnets
(b) Moving disc
(c) Permanentmagnet
(d) Shading bands and holes in disc. [4+4+4+4]
5. Explain the following in A.C. potentiometer:
(a) Drysdale phase shifting Transformer.
(b) Transfer instrument. [8+8]
6. Explain the following:
(a) Why is Kelvin’s double bridge superior to the wheat-stone bridge for the
purpose of low resistance measurement?
(b) How the difficulties associated with the measurement of a very high resistance
are over come?
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Code No: R05310202 Set No. 2
(c) How the effects of contact resistance and resistance of the connecting leads
are eliminated in the measurement of resistance by Kelvin’s double bridge?
(d) Why is the Voltmeter-Ammeter method unsuitable for the precise measure-
ment of the low resistance? [4+4+4+4]
7. (a) Draw the circuit diagram and phasor diagram of Owen’s bridge under balance
conditions. Derive the equations under balance conditions.
(b) An owen’s bridge is used to measure the properties of a sample of sheet steel
at 2KHz. At balance, arm ab is test specimen; arm bc is R3 =100
; arm cd
is C4 = 0.1 μF. Calculate the effective impedance of the specimen under test
conditions. [10+6]
8. (a) What is ballistic galvanometer? What are its special features?
(b) Explain the theory and working principle of ballistic galvanometer? [6+10]
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Code No: R05310202 Set No. 3
III B.Tech I Semester Regular Examinations, November 2008
ELECTRICAL MEASUREMENTS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) What are the different effects used in producing deflecting torque in an analog
instruments. State the examples, in which these effects are used?
(b) Define the terms “indicating instruments”, “recording instruments” and “in-
tegrating instruments”. Give examples of each case.
(c) Derive the equation for deflection if the instrument is PMMC spring controlled.
[5+5+6]
2. Explain the constructional details and working of a single phase electrodynamome-
ter type of powerfactor meter. Prove that the special displacement of moving
system is equal to the phase angle of the system. [16]
3. (a) Draw the possible methods of connection the pressure coil of a wattmeter and
compare the errors. Explain the meaning of “Compensation winding” in a
Wattmeter and show how they help to reduce the error.
(b) A dynamometer type wattmeter has a field system which may be considered
long compared with its moving coils. The flux density is 0.012T, the mean
diameter of the moving coil is 3 cm and the moving coil turns are 500. The
current through the moving coil is 0.05A and power factor of the circuit of
which power is measured is 0.866. Calculate the torque when the axis of the
field and moving coils are [8+8]
i. 30o
ii. 90o.
4. Explain the constructional details of a single phase induction type energy meter.
Explain, why the phase of shunt flux is made exactly in quadrature with that of
applied voltage so as to produce a deflecting torque exactly proportional to power.
[16]
5. (a) Draw the circuit of d.c. potentiometer. Explain how you can calibrate the
same against a standard cell. Discuss the effect of room temperature on this
calibration.
(b) Explain how the potentiometer may be used for precise measurement of voltage
(240V d.c.). [10+6]
6. (a) Explain how insulation resistance of a cable can be measured with a help of
loss of charge method?
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Code No: R05310202 Set No. 3
(b) The following results were obtained by loss of charge method of testing cable:
discharged immediately after charging the deflection = 200 divisions;
discharged 30 seconds after charging the deflection = 125 divisions;
discharged 30 seconds after charging, when in parallel with a resistance of 10
M
, the deflection = 100 divisions. Calculate the insulation resistance of the
cable. [8+8]
7. (a) Explain the working of Hay’s bridge for measurement of inductance with a
circuit diagram. Derive the equations for balance and draw the phasor diagram
under balanced conditions.
(b) The four arms of a Hay’s bridge are arranged as follows: AB is a coil of
unknown impedance; BC is a non-reactive resistor of 100
; CD is a non-
reactive resistor of 833
 in series with a standard capacitor of 0.38μF; DA is
non-reactive resistor of 16800
. If the supply frequency is 50 Hz, determine
the inductance and the resistance at the balanced conditions. [10+6]
8. Explain the construction and working principle of flux meter with a neat diagram.
[16]
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Code No: R05310202 Set No. 4
III B.Tech I Semester Regular Examinations, November 2008
ELECTRICAL MEASUREMENTS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Explain the construction and working of an attracted disc type kelvin absolute
electrometer.
(b) What are the advantages and disadvantages of the above instrument?
(c) Can it be used for measurement of low voltages such as 100 V? Give the reason.
[6+6+4]
2. Derive the expressions for ratio and phase angle error of a potential transformer.
State the assumptions made for derivation of these errors. [16]
3. (a) Draw the necessary circuit diagram for measurement of three phase power
by two wattmeter method. Make necessary derivations. In case of balanced,
discuss the effects of the following load power factors on the two wattmeter
readings.
i. zero
ii. unity
(b) The power to a 3-phase induction motor was measured by this method, and
the readings were 3,400 and ?1,200 watts respectively. Calculate the total
power and power factor. [10+6]
4. (a) Explain the different sources of errors in single phase induction type ener-
gymeter.
(b) A 50 A, 230 V meter on full load test makes 61 revolutions in 37 seconds. If
the normal disc speed is 520 revolutions per Kwh, find the percentage error.
[10+6]
5. (a) Describe the steps when D.C. crompton’s potentiometer is used to measure
an unknown resistance?
(b) A basic slide wire potentiometer has a working battery voltage of 3 volts with
negligible internal resistance. The resistance of slide wire is 400
 and its
length is 200 cm. A 200 cm scale is placed along the slide wire. The slide wire
has 1 mm scale divisions and it is possible to read upto of a division. The
instrument is standardized with 1.018 V standard cell with sliding contact at
the 101.8 cm mark on scale. Calculate:
i. Working current
ii. The resistance of series rheostat
iii. The measurement range and
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Code No: R05310202 Set No. 4
iv. The resolution of the instrument. [10+6]
6. (a) Draw the circuit diagram of a Wheatstone bridge and derive the conditions
for balance.
(b) The four arms of a Wheat shone bridge are as follows: AB = 100
; BC = 10

; CD = 4
; DA = 50
. The galvanometer has a resistance of 20
 and is
connected across BD. A source of 10V d.c. is connected across AC. Find the
current through the galvanometer. What should be the resistance in the arm
DA for no current through the galvanometer? [8+8]
7. (a) What is the difference between L.V. schering bridge and H.V. schering bridge?
(b) Draw the circuit diagram of H.V. schering bridge.
(c) A capacitor bushing forms arm ab of a schering bridge and a standard capac-
itor of 500 pF capacitance and negligible loss, forms arm ad. Arm bc consists
of a noninductive resistance of 300
. When the bridge is balanced arm cd
has a resistance of 72.6
 in parallel with a capacitance of 0.148 μF. The
supply frequency is 50 Hz. Calculate the capacitance and dielectric loss angle
of capacitor. Derive the equations for balance and draw the phasor diagram
under conditions of balance. [4+3+9]
8. (a) Explain the theory of flux meter with a neat sketch.
(b) A flux density =0.05 W/m2; turns on moving coil=40; area of moving coil=750
mm2 If the flux linking with a 10 turn search coil of 20 mm2 area connected
to the flux meter is reversed in a uniform field of 0.5 W/m2, calculate the
deflection of the flux meter. [10+6]
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LINEAR AND DISCRETE SYSTEMS ANALYSIS

Code No: R05310205 Set No. 1
III B.Tech I Semester Regular Examinations, November 2008
LINEAR AND DISCRETE SYSTEMS ANALYSIS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Obtain the state variable model for a system described by the following dif-
ferential equation.
10d3y
dt3 + 5d2y
dt2 + 2dy
dt + 3y = 20dx
dt + 10x
(b) Determine the state transition matrix for the state matrix.
A =


−1 1 0
0 −1 1
0 0 −2

 [8+8]
2. The input to the circuit of figure 2(a) is a rectified sine wave as shown in figure
2(b).
Determine the current following through 1 ohm resistor. ω = 1 rad/sec. Draw the
magnitude spectrum and find out the nth harmonic of i(θ). [8+4+4]
(a) & (b) Figure 2
3. (a) Show that a periodic signal can be expressed as continuous sum of everlasting
exponentials.
(b) Find the F.T. of
i. δ(t − t0)
ii. rect t/τ . [8+8]
4. (a) Explain the graphical interpretation of convolution with the following func-
tions. As shown in figure 4a.
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Code No: R05310205 Set No. 1
Figure 4a
(b) A voltage
−t
e u(t) is applied to a series RC network as shown in figure 4b.
Figure 4b
Find the voltage V0(t) using frequency domain analysis.
5. (a) State and explain the properties of positive real function.
(b) Check whether given polynomial H(s) = 2s4 +5s3 +6s2 +2s +1 is Hurwitz
or not. [8+8]
6. Find the networks for the following functions in one Foster and one Cauer form
(a) Y (s) = (s+1)(s+3)
(s+4)(s+2)
(b) Z(s) = 2(s+0.5)(s+4)
s(s+2) . [2 × 8]
7. (a) The signals m1(t) = 10cos100πt and m2(t) = 10cos50πt are both sampled
with fs = 75 Hz. Show that the two sequences of samples so obtained are
identical.
(b) The signal g(t) = cos10 πt+0.5cos 20 πt is sampled with the interval between
samples is Ts. Find the maximum allowable time for Ts.
(c) Determine the sampling rate for the band pass signal whose centre frequency
fc is 5 fm with a signal band width of 2fm. [5+5+6]
8. How many different sequences have a Z-transform given by
H(z) = 1−2z−1+3z−2
(1−
1
8 z−1+1
4 z−2)(1+1
3 z−1) . [16]
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Code No: R05310205 Set No. 2
III B.Tech I Semester Regular Examinations, November 2008
LINEAR AND DISCRETE SYSTEMS ANALYSIS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Develop the state variable model equation for the circuit as shown in figure
1a.
Figure 1a
(b) A system matrix is given by
A = −1/2
−5/2
1/2
−7/5
obtain the state transition matrix. [8+8]
2. A rectangular waveform of magnitude 10V,duty ratio 75% and frequency 50Hz
is applied across a resistance of 1ohm in series with an inductance of 100mH.
Determine the steady state current in the circuit. Also find the power and P.F of
the load current. [8+4+4]
3. (a) Use the duality property of F.T, find the transform of
g(t) = A
1+(at)2
(b) Using the superposition and time shifting properties, Find the F.T. of the
signals shown in figure 3b. Sketch the amplitude spectrum assuming τ<< To.
[8+8]
Figure 3b
4. (a) Find the LT of the following functions.
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Code No: R05310205 Set No. 2
i. f(t) = Kt K is a real constant >1
ii. f(t) = tδ′(t)
(b) The impulse response of a certain linear system is given by
h(t) =
−2t
e u(t) t 0
= 0 t < 0
using the convolution integral, determining the response y(t) due to the ramp
input
x(t) = 0 t < 0
= t t 0. [8+8]
5. (a) List the properties of positive real function.
(b) A function is given by N(s) = s3+5s2+9s+3
s3+4s2+7s+9 .
Determine the positive realness of the function. [8+8]
6. (a) Given the driving-point impedance function
Z(s) = s(s2+2)
(s2+1)(s2+4)
Synthesize a ladder network of the first Cauer form for this impedance func-
tion.
(b) A network is made up of a series connection of an RL network and RC network.
Assuming that neither of the networks is a short circuit find the location of
poles and also the location of zeros. What is the behavior at the origin and
at infinity? [8+8]
7. Find the mean square value of the output voltage vo(t) of an RC network shown
in figure 7 if the input voltage has a power density spectrum Si(ω) given by
(a) Si (ω)= k
(b) Si (ω)= G2(ω) [gate function with cutoff at ω=1]
(c) Si (ω)= π [δ(ω + 1)+δ(ω − 1)]
In each case, also calculate the power of the input signal. [16]
Figure 7
8. For a causal discrete-time LTI system, if the input x(n) is
x(n) = 1/2 n
u(n) − 1/4 1/2 n−1
u(n − 1)
Then the output is y(n) = 1/3 n
u(n)
(a) Determine the impulse response h(n) and the system function H(z)
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Code No: R05310205 Set No. 2
(b) Find the difference equation that characterizes this system. [2 × 8]
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Code No: R05310205 Set No. 3
III B.Tech I Semester Regular Examinations, November 2008
LINEAR AND DISCRETE SYSTEMS ANALYSIS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Show that the inductor current iL(t) in the circuit as shown in figure 1a is
given by
iL (t) = −3
1 − 20t/3 −
−20t/3
e 
 u(t).
Figure 1a
(b) A dynamical system is described ... by the differential equation
y + 4y¨+ 5y˙ + 2y = u
show that the state variable formulation is

x˙ 1
x˙ 3
x˙ 2

= 

0 1 0
0 0 1
−2 −5 −4
 x1
x2
x3

+ 

0
0
1

u [8+8]
2. (a) Derive an expression for the effective value of non-sinusoidal periodic waveform.
(b) A periodic current source given by i(t) = 5+3 cos (100t + 45◦)+2 cos (200t − 10◦)
is applied to a parallel RL circuit as shown in figure 2b. Calculate the response
V(t) and average power. [8+8]
Figure 2b
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Code No: R05310205 Set No. 3
3. (a) Determine the F.T. of a trapzoidal function and triangular RF pulse f(t) shown
in figure 3(a)i and figure 3(a)ii. Draw its spectrum.
i. Figure 3(a)i
Figure 3(a)i
ii. figure 3(a)ii
Figure 3(a)ii
(b) Show that a normalized Gaussian pulse is its own fourier transform. [8+8]
4. (a) Find the convolution for the signals.
i. x(t) = 1 0 < t < T
0 otherwise
ii. h(t) = t 0 < t < 2T
0 otherwise
(b) Given LT, how do you obtain its F.T. [8+8]
5. Given z(s) = (s2+Xs)
s2+5s+4
(a) What are the conditions on ‘X’ for Z(s) to be a positive real function?
(b) Find ‘X’ for Re (Z (jω)) to have a second order zero at ω = 0. [8+8]
6. (a) Given the driving point admittance function Y (s) = s(s2+1)(s2+4)
s(s2+2) . Synthesize
ladder network of the first Cauer form.
(b) State and explain Foster’s reactance theorem for LC networks. [8+8]
7. (a) How does flat top sampling differ from impulse sampling? Discuss the merits
and drawbacks of both types of sampling.
(b) Show that the continuous time signal xa(t) = A cos (ωot+φ) can be uniquely
recovered from its sampled version x[n]=xa(nT) if the sampling frequency is
ωs = 2 π/T > 2wo. [8+8]
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Code No: R05310205 Set No. 3
8. The output y(n) of a discrete-time LTI system is found to be 2(1/3)nu(n) when the
input x(n) is u(n)
(a) Find the impulse response h(n) of the system.
(b) Find the output y(n) when the input x(n) is 􀀀1
2 n
u(n). [8+8]
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Code No: R05310205 Set No. 4
III B.Tech I Semester Regular Examinations, November 2008
LINEAR AND DISCRETE SYSTEMS ANALYSIS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Write the state equation for the circuit as shown in figure 1a.
Figure 1a
(b) Find the state response of the system shown in figure 1b.
x˙ 1
x˙ 2 = 0 1
−1 0 x1
x2 + 0
1
x1(0)
x2(0) = 0
0
[8+8]
Figure 1b
2. Find the trigonometric form of the following voltage waveform shown figure 2 and
hence compute average power and power factor of the load if voltage is applied to
series RL circuit with R = 1
, L = 1H. [8+4+4]
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Code No: R05310205 Set No. 4
Figure 2
3. (a) State and prove the time scaling property of F.T.
(b) Find the fourier transform of the pulse functions shown in figure 3b.
Figure 3b
4. (a) Evaluate the following convolution integrals.
i. u(t)
−t
e u(t)
ii. u(t) tu(t)
(b) Find the Inverse LT of the following function
F(s) = S+4
2S2+5S+3 . [8+8]
5. (a) Explain Sturm’s theorem.
(b) Test whether the following function is a positive real function and the poly-
nomials are Hurwitz or not using Sturm’s test.
F(s) = 2s4+7s3+11s2+12s+4
s4+5s3+9s2+11s+6 . [8+8]
6. Indicate which of the following functions are either RC, RL, or LC impedance
functions. Give reasons.
(a) Z(s) = (s+1) (s+3)
s(s+4)
(b) Z(s) = (s+3) (s+7)
(s+2) (s+5)
(c) Z(s) = s2+4s+3
s2+6s+8
(d) Z(s) = s2+5s+6
s2+s . [4 × 4]
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Code No: R05310205 Set No. 4
7. For a low pass signal with a bandwidth of 6000Hz, what is the minimum sampling
frequency for perfect reconstruction of the signal? What is the minimum required
sampling frequency if a guard band of 200Hz is required? What is the minimum
required sampling frequency and the value of ‘K’ for perfect reconstruction if the
reconstruction filter has the following frequency response
H(f) =

K, |f| < 7000
K − K(|f| − 7000)/3000, 7000 < |f| < 10000
0, otherwise
. [16]
8. Using the relation anu(n) $ z
z−a , |z| > |a|. Find the Z-transform of the following:
(a) x1(n) = nan−1u[n]
(b) x2(n) = n(n − 1)an−2u[n]
(c) x3(n) = n(n − 1)......(n − k + 1)an−ku[n]. [5+5+6]
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POWER ELECTRONICS

Code No: R05310206 Set No. 1
III B.Tech I Semester Regular Examinations, November 2008
POWER ELECTRONICS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) What is the importance of Surge current rating of a thyristor, explain in detail.
(b) A thyristor has half-cycle surge current rating of 1000mA for a 50Hz supply.
Calculate its one-cycle surge current rating and I2t rating. [10+6]
2. A single phase fully controlled converter is connected to a load comprised of 2 ohms
resistance and 0.3H inductance. The supply voltage is 230V at 50Hz. Estimate the
average load voltage, average load current and input power factor for a firing angle
of 200. Assume continuous and ripple free load current, draw load voltage waveform.
[5+5+4+2]
3. A three phase, half wave controlled converter is connected to a 380V (line) supply.
The load current is constant at 32A and is independent of firing angle. Find the
average load voltage at firing angle of 00 and 450, given that the thyristors have
a forward voltage drop of 1.2V. What value of current and peak reverse voltage
rating will the thyristor require and what will be the average power dissipation in
each thyristor. [4+4+4+4]
4. A single phase ac voltage controller feeds power to a resistive load of 4 ohms from
230V, 50Hz source. Determine
(a) The max. values of average and rms thyristor currents for any firing angle α.
(b) The minimum circuit turn-off time for any firing angle α.
(c) the max. value of di/dt occurring in the thyristors. [6+6+4]
5. Explain the operation of single phase midpoint cyclo converter with R-L load s for
continuous conduction with relevant circuit diagram nd necessary output waveforms
for f0 = 1/3 fs. [4+6+6]
6. A load commutated chopper, fed from a 230V dc source has a constant load current
of 50A. For a duty cycle of 0.4 and a chopping frequency of 2 KHz, Calculate
(a) the value of commutating capacitance
(b) average output voltage
(c) circuit turn-off time for one SCR pair
(d) total commutation interval [4+4+4+4]
7. Draw and explain the simple SCR series inverter circuit employing class A type
commutation. With the help of important waveforms. State the limitations of this
inverter. [8+4+4]
1 of 2
Code No: R05310206 Set No. 1
8. (a) What are the different pulse width modulation techniques used for inverters.
(b) Which of the schemes gives better quality of voltage and current. [10+6]
⋆ ⋆ ⋆ ⋆ ⋆
2 of 2
Code No: R05310206 Set No. 2
III B.Tech I Semester Regular Examinations, November 2008
POWER ELECTRONICS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. The latching current of a thyristor with d.c. voltage source of 100V is 50mA.
Calculate the value of minimum width of the gate pulse current when connected
to a pure inductive load of 1H. Compute the effect, if a resistance of 10 ohms is
connected in series with the load. [8+8]
2. Explain the operation of a singe phase half wave converter for R-load with neat
circuit diagram and necessary waveforms. Also derive the output average voltage
and current for α = 300. [12+4]
3. A three phase, fully controlled converter is connected to a resistive load. Show that
the average output voltage is given by
Vdc=3p3
2 VmCosα for 0 < α < π/3 and
Vdc = 3p3
2 Vm [1 + Cos(α + π/3)] for π/3 < α < 2π/3 [8+8]
4. Explain the operation of a single phase ac voltage controller with neat circuit dia-
gram and output waveforms with respect to source voltage waveforms at α = 600
for Resistive load. [4+8+4]
5. Discuss the working of a single phase mid point cyclo converter with R-L loads and
for discontinuous operation with neat circuit diagram and output rms voltage and
current waveforms for f0=1/3 fs. [4+7+5]
6. Derive the expression for minimum and maximum values of load current for a type
- A chopper and also derive the current ripple. [10+6]
7. Draw and explain the simple SCR series inverter circuit employing class A type
commutation. With the help of important waveforms. State the limitations of this
inverter. [8+4+4]
8. A single phase full bridge inverter uses a uniform PWM with two pulses per half
cycle for voltage control. Plot the distortion factor, fundamental component, and
lower order harmonics against modulation index. [5+5+6]
⋆ ⋆ ⋆ ⋆ ⋆
1 of 1
Code No: R05310206 Set No. 3
III B.Tech I Semester Regular Examinations, November 2008
POWER ELECTRONICS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. A 200A thyristor operates in parallel with a 300A thyristor. Their ON state voltage
drops are respectively 1.5V and 1.0V. Calculate the value of the resistance to be
inserted in series with each thyristor so that they share a load of 500A in proportion
to their respective current ratings. [16]
2. (a) Compare mid-point converters and bridge type converters and bring out im-
portant features.
(b) Compare discontinuous and continuous current modes of operation of convert-
ers and bring out salient features. [8+8]
3. A three phase, fully controlled converter is connected to a resistive load. Show that
the average output voltage is given by
Vdc=3p3
2 VmCosα for 0 < α < π/3 and
Vdc = 3p3
2 Vm [1 + Cos(α + π/3)] for π/3 < α < 2π/3 [8+8]
4. The ac voltage controller uses on-off control for heating a resistive load of R = 4
ohms and the input voltage is Vs = 208V, 60Hz. If the desired output power is P0
= 3KW, determine the
(a) duty cycle δ
(b) input power factor
(c) sketch waveforms for the duty cycle obtained in (a) [5+6+5]
5. For a single phase mid-point cyclo-converter, explain the operation of the circuit
when fed to R-load with the help of neat circuit diagram and relevant output
waveforms for α = 300 and α = 1200 for f0 = 1/4 fs. [4+8+4]
6. Explain the time ratio control and current limit control strategies used for choppers,
with necessary waveforms and circuit. [8+8]
7. Draw and explain the simple SCR series inverter circuit employing class A type
commutation. With the help of important waveforms. State the limitations of this
inverter. [8+4+4]
8. What are the methods for voltage control within the inverters. Explain in detail
with waveforms. [16]
⋆ ⋆ ⋆ ⋆ ⋆
1 of 1
Code No: R05310206 Set No. 4
III B.Tech I Semester Regular Examinations, November 2008
POWER ELECTRONICS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. Explain in detail various voltage ratings and current ratings of a thyristor. [16]
2. (a) Compare mid-point converters and bridge type converters and bring out im-
portant features.
(b) Compare discontinuous and continuous current modes of operation of convert-
ers and bring out salient features. [8+8]
3. A six pulse thyristor converter connected on the secondary of the 6.6KV/415V,
50Hz transformer is supplying to 460V, 200A a.c, load. Calculate
(a) Converter firing angle
(b) DC power delivered by the converter
(c) ac terminal power
(d) ac line current [4+4+4+4]
4. Two SCRs are connected back-to-back have a load resistance of 400 ohms and a
supply of 110V ac. If firing angle is 600, find
(a) the rms output voltage
(b) average power. [10+6]
5. Discuss the working of a single phase bridge type cyclo converter with RL loads and
for discontinuous operations with relevant output waveforms and circuit diagram
for f0 = 1/2 fs. [4+6+6]
6. For the ideal type A-chopper circuit, following conditions are given, Edc = 220V,
chopping frequency, = 500 Hz, duty cycle δ=0.3 and R = 1 ohm, L = 3mH and Eb
= 23V. Compute the following quantities.
(a) Check whether the load current is continuous or not.
(b) Average output current
(c) maximum and minimum values of steady state output current [6+4+6]
7. Draw and explain the simple SCR series inverter circuit employing class A type
commutation. With the help of important waveforms. State the limitations of this
inverter. [8+4+4]
1 of 2
Code No: R05310206 Set No. 4
8. Calculate the output frequency of a series inverter circuit with following parameters,
L = 10mH, C = 0.1 μF, R = 400 ohms, toff = 0.2 msec. Also determine the
attenuation factor. [16]
⋆ ⋆ ⋆ ⋆ ⋆
2 of 2

LINEAR & DIGITAL IC APPNLICATIOs

Code No: V3110/R07 Set No. 1
III B.Tech I Semester Regular Examinations, November 2009
POWER SYSTEMS-II
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What is the method of images? How can it be used to take into account the
presence of ground in calculating the capacitance of a single phase line?
(b) Two conductors of a single phase line, each of 2cm diameter, are arranged in
a vertical plane with one conductor mounted 2m above the other. A second
identical line is mounted at the same height as the first and space horizontally
0.5m apart from it. The two upper and the lower conductors are connected
in parallel. Determine the inductance per km of the resulting double circuit
line. [8+8]
2. (a) Discuss the terms voltage regulation and transmission efficiency as applied to
transmission line.
(b) A balanced 3-phase load of 30 MWis supplied at 132 kV, 50Hz and 0.85 p.f lag
by means of a transmission line. The series impedance of a single conductor
is (20+j40) ohms and the total phase-neutral admittance is 315 × 10−6 mhos.
Use nominal - T to determine
i. A, B, C, D constants of the line,
ii. Vs and
iii. regulation of the line. [6+10]
3. (a) Derive the expressions for voltage and current distribution over a long line.
Explain the significance of characteristic impedance loading in connection with
the long lines. Deduce the above voltage and current relations in the hyper-
bolic form and obtain the element values of an equivalent to represent the long
lines.
(b) Determine the auxiliary constants of a 3-phase, 50Hz. 200km long transmis-
sion line having resistance, inductance and capacitance per phase per km of
0.15 ohm, 3.5mH and 0.009μF respectively. [8+8]
4. (a) Draw equivalent circuit for finding the transmitted voltage and current surges
on a forked line. Derive expressions for the transmitted voltage and currents.
(b) A transmission line has an inductance of 0.93 H/km and a capacitance of
0.0078 μF/km. This overhead line is connected to an underground cable hav-
ing an inductance of 0.155 mH/km and a capacitance of 0.187 μF/km. If a
surge of crest 100 kV travels in the cable towards its junction with the line,
find the surge transmitted along the line. [8+8]
1 of 2
Code No: V3110/R07 Set No. 1
5. (a) Derive an equation for calculating the maximum electric intensity on the con-
ductor surface of a 3-phase single circuit horizontal configuration line with two
sub-conductors per phase.
(b) In a 3-phase overhead line, the conductors have an overall diameter of 3.0
cm each and are arranged in delta formation. Assuming a critical disruptive
voltage of 250 kV between lines and an air density factor of 0.90 and m0 =
0.95, find the minimum spacing between conductors allowable, assume fair
weather conditions. [8+8]
6. (a) What is guard ring which is being used in the suspension string type insulator?
Deduce the relation for determining the capacitance formed by the ring.
(b) A three phase over head line is being supported by tree discs suspension in-
sulators, the potential across the first and second insulators are 12 and 18 kV
respectively. Calculate
i. the line voltage,
ii. the ratio of capacitance between pin and earth to self-capacitance of each
unit,
iii. the string efficiency. [8+8]
7. (a) Is sag desirable or an evil for a transmission line? Discuss the various conduc-
tor material used for overhead lines.
(b) An overhead line has a conductor of cross-section 2.5 cm2 and a span length
of 150 meters. Determine the sag which must be allowed if the tension is not
to exceed one-fifth of the ultimate strength of 4,175 kg/cm2
i. In still air,
ii. With a wind pressure of 1.3 kg/meter and an ice coating of 1.25 kg/m.
iii. Determine also the vertical sag in the latter case. [6+10]
8. (a) Show that for the same dimensions of a cable with an intersheath can with-
stand a working voltage of 33% higher than a non-intersheath cable. Assume
same homogeneous dielectric and most economical designs for both cables.
(b) A 3-phase, single core 66 kV cable has a conductor diameter of 3 cm and a
sheath of inside diameter 6 cm. If two intersheaths are introduced in such a
way that the stress varies between the same maximum and minimum in the
three layers. Find
i. Positions of intersheaths
ii. voltage on the intersheaths
iii. Maximum and minimum stress. [8+8]
? ? ? ? ?
2 of 2
Code No: V3110/R07 Set No. 2
III B.Tech I Semester Regular Examinations, November 2009
POWER SYSTEMS-II
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What are bundled conductors? Discuss the advantages of bundled conductors,
when used for overhead lines.
(b) Calculate the capacitance (phase-to-neutral) of a three-phase 100 km long
double circuit line shown in Figure 1b, with conductors of diameter 2.0 cm
each arranged at the corners of an hexagon with sides measuring 2.1 m. [8+8]
Figure 1b
2. (a) Define regulation of a short 3-phase transmission system and develop an ex-
pression for approximate voltage regulation.
(b) A balanced 3-phase load of 30MW is supplied at 132kV, 50Hz and 0.85 p.f.
lagging by means of a transmission line. The series impedance of a single
conductor is (20 + j52) ohms and the total phase-neutral admittance is 315
× 10−6 mho. Using nominal-T method, determine:
i. The A, B, C and D constants of the line,
ii. Sending end voltage,
iii. Regulation of the line. [16]
3. (a) Derive the equivalent ABCD constants of a transmission line connected in
series with an impedances at both ends.
(b) The per-unit-length parameters of a 215kV, 400km, 60Hz, three phase long
transmission line are y = j3.2 × 10−6 mhos per km per phase and z = (0.1
+ j 0.5) ohm/km. The line supplies a 150 MW load at unity power factor.
Determine
i. the voltage regulation
ii. the sending-end power and
1 of 2
Code No: V3110/R07 Set No. 2
iii. the efficiency of transmission. [8+8]
4. (a) Derive the travelling wave equations in a lossless transmission line.
(b) The ends of two long transmission lines, A and C are connected by a cable
B, 1km long. The surge impedances of A, B, C are 400, 50 and 500 ohms
respectively. A rectangular voltage wave of 25 kV magnitude and of infinite
length is initiated in A and travels to C, determine the first and second voltages
impressed on C. [6+10]
5. (a) Write a short notes on radio interference due to corona.
(b) Determine the disruptive critical voltage and the visual critical voltages for
local and general corona on a 3-phase overhead transmission line consisting of
three stranded copper conductors spaced at 2.5 meters apart at the corners
of an equilateral triangle. Air temperature and pressure are 210C and 73.5
cm of Hg respectively. Conductor diameter is 1.8 cm, irregularity factor (m0)
0.85, and surface factors (mv) 0.7 for local and general corona 0.7 and 0.8
respectively. Breakdown strength of air is 21.1 kV (r.m.s) / cm. [6+10]
6. (a) Explain why suspension type of insulators are preferred for high voltage over-
head lines. Sketch a sectional view of one unit of the suspension type insulator
and describe the construction.
(b) An insulator string containing five units has equal voltage across each unit by
using disc of different capacitances. If the top unit has a capacitance of C and
pin to tower capacitance of all units is 20 percent of the mutual capacitance
of top unit. Calculate mutual capacitance of each disc in a string. [8+8]
7. (a) Discuss in brief, the factors on which sag of the overhead line depends. Write
the expression of sag and explain the terms with units.
(b) An overhead transmission line has span of 220 metres, the conductor weighing
604kg/km.Calculate the maximum sag if the ultimate tensile strength of the
conductor is 5758kg. Assume a factor of safety of 2. [8+8]
8. (a) What are all the insulating materials used in underground cables? Explain in
detail about different kinds of insulating materials.
(b) A single core 66 kV cable working on 3-phase system has a conductor diameter
of 2 cm and a sheath of inside diameter 5.5 cm. If the two inter sheaths are
introduced in such a way that the variation of stress is in between the same
maximum and minimum in the three layers. Determine the following:
i. Positions of intersheath
ii. Voltage on the intersheath
iii. Maximum and minimum stresses. [8+8]
? ? ? ? ?
2 of 2
Code No: V3110/R07 Set No. 3
III B.Tech I Semester Regular Examinations, November 2009
POWER SYSTEMS-II
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What is the method of images? How can it be used to take into account the
presence of ground in calculating the capacitance of a single phase line?
(b) Two conductors of a single phase line, each of 2cm diameter, are arranged in
a vertical plane with one conductor mounted 2m above the other. A second
identical line is mounted at the same height as the first and space horizontally
0.5m apart from it. The two upper and the lower conductors are connected
in parallel. Determine the inductance per km of the resulting double circuit
line. [8+8]
2. A 3-phase, 50Hz overhead transmission line 100km long has the following constants:
Resistance/km/phase = 0.1 ohm
Inductive reactance/km/phase = 0.2 ohm
Capacitive susceptance /km/phase = 0.04 × 10−4 mho
Determine
(a) the sending end current
(b) sending end voltage
(c) transmission efficiency when supplying a balanced load of 10000 kW at 66kV,
p.f. 0.8 lagging. Use nominal-T method. Draw the phasor diagram to illus-
trate your calculations. [16]
3. (a) Deduce expression for the magnitude of incident and reflected voltages at any
point on a transmission line interms of voltage and current at receiving end,
characteristic impedance and propagation constant of the line.
(b) A three-phase transmission line is 300km long and delivers a load of 150MVA,
0.8p.f lag at 220kV. The ABCD constants of the line are A=D=0.86 1.80;
B=1506 880; C =0.0026 900mhos. Determine the following under full load and
no load conditions [8+8]
i. Sending-end line to neutral voltage,
ii. The sending-end current, and
iii. The percent voltage regulation.
4. (a) When the transmission line is terminated by the inductive load, how do you
find out the expressions of reflected voltage and current wave.
(b) A battery with an emf E and a resistance R is connected at t = 0 to the
sending end of a lossless transmission line which is open circuited at the far
end. Plot the sending end current as a function of time for R=Z0/3. The time
required for a wave to travel the full length of the line is T0. [8+8]
1 of 2
Code No: V3110/R07 Set No. 3
5. (a) Explain the methods of reducing corona loss.
(b) Find the disruptive critical voltage and critical voltages for visual corona of
a 3-phase, 200 km long line consisting of three stranded copper conductors
(7/4.75) mm, area 120 mm2 spaced in a 4 metre delta arrangement, tempera-
ture 32 oC and barometric pressure 73 cm. If this line operates on 200kV at 50
Hz. Calculate fair weather and storm loss for the line. Assume any additional
data, if required. [8+8]
6. (a) Explain why suspension type of insulators are preferred for high voltage over-
head lines. Sketch a sectional view of one unit of the suspension type insulator
and describe the construction.
(b) An insulator string containing five units has equal voltage across each unit by
using disc of different capacitances. If the top unit has a capacitance of C and
pin to tower capacitance of all units is 20 percent of the mutual capacitance
of top unit. Calculate mutual capacitance of each disc in a string. [8+8]
7. (a) Explain the factors affecting the mechanical design.
(b) An over head line with stranded copper conductor is supported on two poles
200 meters apart having a difference in level of 10 m the conductor diameter is
2 cm and weighs 2.30 kg/m square meter of the projected area and the factor
of safety is 4. The maximum tensile strength of the copper is 4220 kg/square
meter. [6+10]
8. (a) Derive a formula for the electric stress in a single core cable. Where is the
stress maximum? Where it is minimum?
(b) The inner and outer diameters of a cable are 3 cm and 8cm. The cable is insu-
lated with two materials having permittivity of 5 and 3.5 with corresponding
stresses of 38kV/cm and 30 kV/cm. Calculate the radial thickness of each
insulating layer and the safe working voltage of the cable. [8+8]
? ? ? ? ?
2 of 2
Code No: V3110/R07 Set No. 4
III B.Tech I Semester Regular Examinations, November 2009
POWER SYSTEMS-II
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What are bundled conductors? Discuss the advantages of bundled conductors,
when used for overhead lines.
(b) Calculate the capacitance (phase-to-neutral) of a three-phase 100 km long
double circuit line shown in Figure 1b, with conductors of diameter 2.0 cm
each arranged at the corners of an hexagon with sides measuring 2.1 m. [8+8]
Figure 1b
2. A (medium) single phase transmission line 100km long has the following constants:
Resistance/km = 0.25 ohm
Reactance/km = 0.8 ohm
Susceptance/km = 14 × 10−6 mho
Receiving end line voltage = 66,000 V
Assume that the total capacitance of the line is localized at the receiving end alone;
determine
(a) the sending end current
(b) the sending end voltage
(c) regulation and
(d) supply power factor. The line is delivering 15000kW at 0.8 power factor lag-
ging. Draw the vector diagram to illustrate your calculations. [4+4+4+4]
3. (a) Starting from the first principles, deduce expressions for ABCD constants of
a long line in terms of its parameters.
(b) A three-phase, 50 Hz, 150 km long transmission line has three conductors each
of 0.7 cm radius spaced at the corners of triangle of sides 2 m, 3.5m and 4.5m.
1 of 2
Code No: V3110/R07 Set No. 4
The resistance of each conductor is 0.4 ohms per km and the line delivers 50
MVA at 132 kV and at a lagging p.f. of 0.85. Determine ABCD constants as
long line (both real and complex angle methods) [8+8]
4. (a) Draw equivalent circuit for finding the transmitted voltage and current surges
on a forked line. Derive expressions for the transmitted voltage and currents.
(b) A transmission line has an inductance of 0.93 H/km and a capacitance of
0.0078 μF/km. This overhead line is connected to an underground cable hav-
ing an inductance of 0.155 mH/km and a capacitance of 0.187 μF/km. If a
surge of crest 100 kV travels in the cable towards its junction with the line,
find the surge transmitted along the line. [8+8]
5. (a) Explain the methods of reducing corona loss.
(b) Find the disruptive critical voltage and critical voltages for visual corona of
a 3-phase, 200 km long line consisting of three stranded copper conductors
(7/4.75) mm, area 120 mm2 spaced in a 4 metre delta arrangement, tempera-
ture 32 oC and barometric pressure 73 cm. If this line operates on 200kV at 50
Hz. Calculate fair weather and storm loss for the line. Assume any additional
data, if required. [8+8]
6. (a) Explain why suspension type of insulators are preferred for high voltage over-
head lines. Sketch a sectional view of one unit of the suspension type insulator
and describe the construction.
(b) An insulator string containing five units has equal voltage across each unit by
using disc of different capacitances. If the top unit has a capacitance of C and
pin to tower capacitance of all units is 20 percent of the mutual capacitance
of top unit. Calculate mutual capacitance of each disc in a string. [8+8]
7. (a) Is sag desirable or an evil for a transmission line? Discuss the various conduc-
tor material used for overhead lines.
(b) An overhead line has a conductor of cross-section 2.5 cm2 and a span length
of 150 meters. Determine the sag which must be allowed if the tension is not
to exceed one-fifth of the ultimate strength of 4,175 kg/cm2
i. In still air,
ii. With a wind pressure of 1.3 kg/meter and an ice coating of 1.25 kg/m.
iii. Determine also the vertical sag in the latter case. [6+10]
8. (a) Find expressions for capacitance, insulation resistance and dielectric stress of
a single core cable.
(b) An H-type cable, 30km long has a capacitance per km between any two con-
ductors of 0.45μF. The supply voltage is 3-phase, 33kV, and 50Hz. Determine
the charging current. [8+8]
? ? ? ? ?
2 of 2
Code No: V3116/R07 Set No. 1
III B.Tech I Semester Regular Examinations, November 2009
DYNAMICS OF MACHINERY
(Mechanical Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What is meant by piston effort and crank effort?
(b) A horizontal axle AB 80cms long is pivoted at its centre. It carries a weight
of 35N at B & a rotor weighing 60N at A. The rotor rotates at 800 rpm in
clockwise direction looking from the front. Calculate the angular velocity of
precision taking the radius of gyration of the rotor to be 35cms. [4+12]
2. (a) What do you mean by angle of repose?
(b) A turn buckle, with right and left hand single head start threads, is used to
couple two wagons. Its thread pitch is 12 mm and the mean diameter 40
mm.The coefficient of friction between the nut and the screw is 0.16.
i. Determine the work done in drawing the wagons together a distance of
240 mm, against a steady load of 2500 N.
ii. If the load increases from 2500 N to 6000 N over a distance of 240
mm.What is the work to be done? [4+12]
3. (a) Describe with neat sketch the prony brake dynamometer.
(b) A single block brake is shown in figure 3 the diameter of drum is 250mm and
the angle of contact is 120 degrees. If the operating force of 900N is applied
at the end of a lever and the coefficient of friction between the drum and
the lining is 0.45 determine the torque that may be transmitted by the block
brake. [6+10]
Figure 3
4. (a) State how the size of the flywheel calculated.
(b) A single cylinder four stroke oil engine develops 15kW at a speed of 400 rpm
and drives a machine at 750 rpm. the engine shaft carries a flywheel with
a moment of inertia of 114 kg-m2.The machine shaft also carries a flywheel
1 of 2
Code No: V3116/R07 Set No. 1
with the moment of inertia of 8 kg-m2. If the fluctuation of energy is 80If the
coefficient of fluctuation of speed is required to be lowered to a total value of
1%, what is the moment of inertia of the additional rotating mass to be fitted
to the machine shaft? [6+10]
5. A governor of the Proell type has each arm 250 mm long. The pivots of the upper
and lower arms are 25 mm, from the axis. The central load acting on the sleeve has
a mass of 25 kg and each rotating ball has a mass of 3.2 kg when the governor sleeve
is in mid position, the extension link of the lower arm is vertical and the radius of
path of rotation of the masses is 175 mm. the vertical height of the governor is 200
mm. if the speed of governor is 160 rpm, when in mid position, find:
(a) Length of the extension link and
(b) Tension in the upper arm. [16]
6. Four masses m1, m2, m3 and m4 having 100, 175, 200 and 25 kg are fixed to cranks
of 20 cm radius and revolve in places 1, 2, 3 and 4. The angular position of the
cranks in planes 2, 3 and 4 with respect to the crank in plane 1 are 750, 1350 and
2000 taken in the same sense. The distance of planes 2, 3 and 4 from plane 1 are
60 cm, 186 cm and 240 cm respectively. Determine the position and magnitude of
the balance mass at a radius of 60 cm in plane L and M located at middle of the
plane 1 and 2 and the middle of the planes 3 and 4 respectively. [16]
7. A 2-Cylinder uncoupled locomotive with cranks at 900 has a crank radius of 32.5
cms. The distance between centers of driving wheel is 150 cms. The pitch of
cylinders is 60 cms. The diameter of Freads of driving wheels is 180 cms. The
radius of center of gravity of balance weights is 65 cms. The pressure due to dead
load on each wheel is 4 tones. The weight of reciprocating and rotating parts per
cylinder are 330 kg respectively. The speed of locomotive is 60kmph. Find:
(a) The balancing weights both in magnitude and position required to be placed
in the planes of driving wheels to balance whole of the revolving and 2/3 of
reciprocating masses.
(b) Swaying couple.
(c) The variation of tractive force.
(d) The maximum and minimum pressure in rails. What is the maximum speed
at which it is possible to run the locomotive, in order that the wheels are not
lifted from the rail? [16]
8. A 1200 kg machine mounted on four identical springs of total spring constant K
and having negligible damping. The machine is subjected to a harmonic external
force of amplitude F0 = 490 N and frequency 180 rpm. Determine the amplitude if
motion of the machine and maximum force transmitted to the foundation because
of the unbalanced force when K = 1.96×106 /m. [16]
? ? ? ? ?
2 of 2
Code No: V3116/R07 Set No. 2
III B.Tech I Semester Regular Examinations, November 2009
DYNAMICS OF MACHINERY
(Mechanical Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What are the conditions for a body to be in equilibrium under the action of
two forces and a torque?
(b) In four link mechanism ABCD, The link AB revolves with an angular veloc-
ity of 10 Rad/s and angular acceleration of 25 Rad S2 at the instant when
it makes an angle of 450 with AD, the fixed link.The lengths of links are
AB=CD=800mm, BC=1000mm, AD=1500mm. The mass of the links is
4kg/m length. Determine the torque required to overcome the inertia forces,
neglecting the gravitational effects. Assume all links to be uniform cross sec-
tions. [4+12]
2. (a) Explain that the coefficient of friction for film or viscous friction depends upon
the square root of velocity of body and inversely proportional to the intensity
of bearing pressure.
(b) A screw jack has a screw thread, 7.5 cm mean diameter and 1.5 cm pitch.
The load on the jack revolves with the screw. The coefficient of friction at the
screw threads is 0.05.
i. Find the tangential force to be applied to the jack at 36 cm radius so as
to lift a load of 600 N.
ii. State whether the jack is self-locking.If it is, find the torque necessary to
lower the load.If not, find the torque which must be applied to keep the
load from descending. [6+10]
3. (a) What do you mean by an absorption dynamometer.
(b) A differential band brake acting on the 3/4th of the circumference of a drum
of 450mm diameter is to provide a braking torque of 250Nm. One end of the
band is attached to a pin 100mm from the fulcrum of the lever and the other
end to another pin 25mm from the fulcrum on the other side of it where the
operating force is also acting. If the operating force is applied at 500mm from
the fulcrum and the coefficient of friction is 0.2 find the two values of the
operating force corresponding to the two directions of rotation of the drum.
[4+12]
4. A gas engine is provided with 2 flywheels of 5kN each and the radius of gyration
of each is 60 cm. Cylinder diameter is 20 cm. stroke 25 cm. and the mean rpm
is 200 the mean pressure above the atmospheric during the firing stroke is 0.6 M
Pa during the compression stroke is 0.11 MPa. During the exhaust stroke is 0.03
MPa. During the suction stroke is 0.016 MPa below atmospheric. If the engine has
1 of 2
Code No: V3116/R07 Set No. 2
one working stroke during four strokes and if the resistance is constant determine
the % fluctuation of speed. [16]
5. A governor of the Proell type has each arm 250 mm long. The pivots of the upper
and lower arms are 25 mm, from the axis. The central load acting on the sleeve has
a mass of 25 kg and each rotating ball has a mass of 3.2 kg when the governor sleeve
is in mid position, the extension link of the lower arm is vertical and the radius of
path of rotation of the masses is 175 mm. the vertical height of the governor is 200
mm. if the speed of governor is 160 rpm, when in mid position, find:
(a) Length of the extension link and
(b) Tension in the upper arm. [16]
6. A, B, C and D are four masses carried by a rotating shaft at radii of 10 cm, 12.5
cm, 20 cm and 15 cm respectively. The planes in which the masses revolve are 60
cm apart and the mass of B, C and D are 10 kg, 5 kg and 4 kg respectively. Find
the required mass A and the relative angular setting of the four masses so that the
shaft is in complete balance. (Assuming the plane of mass as the reference plane.)
[16]
7. A four coupled-wheel locomotive with two inside cylinders has reciprocating and
revolving parts per cylinder as 300 kgf and 250 kgf respectively. The distance
between planes of driving wheels is 150 cms. The pitch of cylinders is 60cms. The
diameter of tread and driving wheels is 190 cms and the distance between planes
of coupling rod cranks in 190 cms. The revolving parts for each coupling rod crank
are 125 kgf. The angle between engine cranks is 900 and the length of coupling
rod crank 22 cms. The angle made by coupling rod crank with adjustment crank
is 180. The distance of center of gravity of balance weights in planes of driving
wheels from a scale center is 75 cms. Crank radius is 32 cms. Determine:
(a) The magnitude and position of balance weights required in leading and trailing
wheels to balance 2/3 of reciprocating and whole of revolving parts if half of
the required reciprocating parts are to be balanced in each pair of coupled
wheels.
(b) The maximum variation of tractive force and hammer blow when locomotive
speed is 100kmph. [16]
8. (a) Determine natural frequency of the pendulum system.
(b) Define:
i. Free vibrations
ii. Forced vibrations
iii. Damping. [16]
? ? ? ? ?
2 of 2
Code No: V3116/R07 Set No. 3
III B.Tech I Semester Regular Examinations, November 2009
DYNAMICS OF MACHINERY
(Mechanical Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Define and explain the super position theorem as applicable to a system of
forces acting on a mechanism.
(b) A horizontal axle AB 150cms long is pivoted at its centre. It carries a weight
of 50N at B & a rotor weighing 80N at A. The rotor rotates at 1500 rpm in
clockwise direction looking from the front. Calculate the angular velocity of
precision taking the radius of gyration of the rotor to be 45cms. [4+12]
2. (a) Derive the expression for the friction torque in flat collar bearing considering
uniform wear.
(b) The spindle of a screw jack has single start square threads with an outside
diameter of 45 mm and pitch of 10 mm. The spindle moves in a fixed nut. The
load is carried on a swivel head but is not free to rotate. The bearing surface
of the swivel head has a mean diameter of 60 mm.The coefficient of friction
between the nut and the screw is 0.12 and that between the swivel head and
the spindle is 0.10.Calculate the load which can be raised by efforts of 100 N
each applied at the end of two levers each of effective length of 350mm. also
determine the velocity ratio and the efficiency of the lifting arrangement.
[6+10]
3. (a) Describe with neat sketch the fottinger torsion dynamometer.
(b) A simple band brake is operated by a lever of length 500mm. The brake
drum has a diameter of 500mm and the brake band embraces 5/8th of the
circumference. One end of the band is attached to the fulcrum of the lever
while the other is attached to a pin on the lever 100mm from the fulcrum. If
the effort applied to the end of the lever is 3kN and the coefficient of friction
is 0.25, find the maximum braking torque on the drum. [6+10]
4. The following data refer to a steam engine:
Diameter of the piston= 24 cm
Stroke= 48 cm
Length of connecting rod= 90 cm
Weight of the reciprocating parts= 1500N
Weight of connecting rod= 1000N
Speed = 150 rpm
Center of gravity of the connecting rod from the crank pin= 32cm
Radius of gyration of connecting rod about the center of gravity=40 cm
Determine the magnitude and direction of the inertia torque on the crank shaft
when the crank has turned through 45 degrees from the inner dead center. [16]
1 of 2
Code No: V3116/R07 Set No. 3
5. A governor of the Proell type has each arm 250 mm long. The pivots of the upper
and lower arms are 25 mm, from the axis. The central load acting on the sleeve has
a mass of 25 kg and each rotating ball has a mass of 3.2 kg when the governor sleeve
is in mid position, the extension link of the lower arm is vertical and the radius of
path of rotation of the masses is 175 mm. the vertical height of the governor is 200
mm. if the speed of governor is 160 rpm, when in mid position, find:
(a) Length of the extension link and
(b) Tension in the upper arm. [16]
6. Two weights of 8 kg and 16 kg rotate in the same plane at radii of 1.5 and 2.25
m respectively. The radii of these weights are 600 apart. Find the position of the
third weight of the magnitude of 12 kg in the same plane which can produce static
balance of the system. [16]
7. The following data relate to a single cylinder reciprocating engine.
Mass of reciprocating parts = 40 kg
Mass of revolving parts = 30 kg at 180mm radius.
Speed = 150 rpm
Stroke length = 350 mm
If 60% of the reciprocating parts and all the revolving parts to be balanced, deter-
mine the
(a) Balanced mass required at a radius of 320 mm.
(b) The unbalanced force when the crank has turned 450 from the top dead center.
[16]
8. A mass weighing 85 kgf is supported on springs which deflects 1.8 cm under the
weight of the mass. The vibration of the mass are constrained to be linear and
vertical and are damped by a dashpot which reduces the amplitude to one-quarter
of its initial value in two complete oscillations, find:
(a) The magnitude of the damping force at unit speed and
(b) Periodic time of damped vibrations. [16]
? ? ? ? ?
2 of 2
Code No: V3116/R07 Set No. 4
III B.Tech I Semester Regular Examinations, November 2009
DYNAMICS OF MACHINERY
(Mechanical Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Discuss the equilibrium of two and three force members.
(b) In a four link mechanism the dimensions of the links are given below.
Fixed link AD=60mm, driving link AB=50mm, coupler BC=100mm, driven
link DC=80mm, and DE=40mm. The driving link is making an angle 1200
with AD. The driven link is acted upon by a force of 80 6 1500 N on link DC
at E. Determine the input torque T on the link AB. [4+12]
2. (a) What is meant by the following? Friction, friction force, coefficient of friction,
limiting friction, angle of friction and angle of repose.
(b) The thrust on the propeller shaft of a marine engine is taken up by 8 collars
whose external and internal diameters are 660 mm and 420 mm respectively.
The thrust pressure is 0.4 MN/mm2 and may be assumed uniform. The coef-
ficient of friction between the shaft and collars is 0.04. If the shaft rotates at
90 r.p.m.: find
i. total thrust on the collars: and
ii. power absorbed by friction on the bearing. [6+10]
3. A sample band brake is applied to a drum of 560mm diameter, which rotates at
240 rpm. Angle of contact of band is 270 degrees. One end of the band is fastened
to a fixed pin and the other end of the brake lever 140mm from the fixed pin. The
brake lever is 800mm long and is placed perpendicular to the diameter that bisects
the angle of contact. The coefficient of friction is 0.3; determine the necessary pull
at the end of the lever to stop the drum if 40 kW of power is being absorbed. Also
find the width of the band if its thickness is 3mm and the maximum tensile stress
is limited to 40N/mm2. [16]
4. A high speed has connecting rod length 5 times the crank which is 6 cm. It weighs
30 N has a center of gravity 10 cm from the big end bearing. When suspended in
bearing it makes 50 complete oscillations in 52 seconds. The reciprocating parts
weigh 15 N. Determine the torque exerted on the crank shaft due to the inertia of
the moving parts when the crank makes an angle of 135 degrees with the top dead
center when the speed of rotation is 1200 rpm. [16]
5. A governor of the Proell type has each arm 250 mm long. The pivots of the upper
and lower arms are 25 mm, from the axis. The central load acting on the sleeve has
a mass of 25 kg and each rotating ball has a mass of 3.2 kg when the governor sleeve
is in mid position, the extension link of the lower arm is vertical and the radius of
path of rotation of the masses is 175 mm. the vertical height of the governor is 200
mm. if the speed of governor is 160 rpm, when in mid position, find:
1 of 2
Code No: V3116/R07 Set No. 4
(a) Length of the extension link and
(b) Tension in the upper arm. [16]
6. Four masses m1, m2, m3 and m4 having 100, 175, 200 and 25 kg are fixed to cranks
of 20 cm radius and revolve in places 1, 2, 3 and 4. The angular position of the
cranks in planes 2, 3 and 4 with respect to the crank in plane 1 are 750, 1350 and
2000 taken in the same sense. The distance of planes 2, 3 and 4 from plane 1 are
60 cm, 186 cm and 240 cm respectively. Determine the position and magnitude of
the balance mass at a radius of 60 cm in plane L and M located at middle of the
plane 1 and 2 and the middle of the planes 3 and 4 respectively. [16]
7. The following data relate to a single cylinder reciprocating engine.
Mass of reciprocating parts = 40 kg
Mass of revolving parts = 30 kg at 180mm radius.
Speed = 150 rpm
Stroke length = 350 mm
If 60% of the reciprocating parts and all the revolving parts to be balanced, deter-
mine the
(a) Balanced mass required at a radius of 320 mm.
(b) The unbalanced force when the crank has turned 450 from the top dead center.
[16]
8. (a) Determine natural frequency of the pendulum system.
(b) Define:
i. Free vibrations
ii. Forced vibrations
iii. Damping. [16]
? ? ? ? ?
2 of 2
Code No: V3120/R07 Set No. 1
III B.Tech I Semester Regular Examinations, November 2009
LINEAR IC APPLICATIONS
(Electronics & Communication Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) For the given differential amplifier using ideal op-amp. Find the output voltage
Vo .
Figure 1:
(b) For the given circuit in the above figure1 show that the output corresponding
to common-mode voltage Vc = V1+V2
2 is zero if R0
R = R2
R1
. Find Vo in that case.
[10+6]
2. (a) Explain with a neat circuit diagram the working of voltage to current converter
with floating load.
(b) Design a circuit to convert a 4 mA-to 20mA input current to 0V-to-10V output
voltage. The circuit is powered from ±15V regulated supplies. [8+8]
3. (a) In the differentiator circuit the input is a sine wave with a peak-to-peak am-
plitude of 3V at 200 Hz. Sketch the output waveform.
(b) Determine the output voltage produced by the cascaded integrator. At t =
0.5 sec. [8+8]
4. (a) Design a first order band pass filter with lower cutoff frequency of 100Hz and
a higher cutoff frequency of 1KHz. The pass band gain should be 4. Calculate
the ‘Q’ of the filter.
(b) Determine f1 and f2 for a second order band pass filter with a centre frequency
of 1 KHz and band width = 200Hz. [8+8]
5. (a) List the conditions for oscillation in all the three types of oscillators, namely,
RC phase shift, wien- bridge and quadrature oscillators.
(b) Explain the difference between a signal generator and a function generator.
1 of 2
Code No: V3120/R07 Set No. 1
(c) Justify the name for quadrature oscillator. [8+8+4]
6. (a) Draw the dc voltage versus phase difference characteristic of balanced modu-
lator phase detector of a PLL indicating all important regions.
(b) Draw the dc out put voltage of VCO versus frequency characteristic of a PLL
indicating the capture and lock range clearly.
(c) State the relationship between lock range and capture range through a math-
ematical expression. [6+6+4]
7. (a) Explain the operation of a multiplying DAC and mention its applications.
(b) A 12-bit D to A converter has a full-scale range of 15 volts. Its maximum
differential linearity error is ± 1/2 LSB.
i. What is the percentage resolution?
ii. What are the minimum and maximum possible values of the increment in
its output voltage? [8+8]
8. (a) What are the basic blocks preceding an Analog to Digital converter in a typical
application like digital audio recording?
(b) Explain the functioning of a sample & hold circuit.
(c) Suggest improvement in basic sample & hold circuit. [6+6+4]
? ? ? ? ?
2 of 2
Code No: V3120/R07 Set No. 2
III B.Tech I Semester Regular Examinations, November 2009
LINEAR IC APPLICATIONS
(Electronics & Communication Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) For the given differential amplifier using ideal op-amp. Find the output voltage
Vo .
Figure 1:
(b) For the given circuit in the above figure1 show that the output corresponding
to common-mode voltage Vc = V1+V2
2 is zero if R0
R = R2
R1
. Find Vo in that case.
[10+6]
2. (a) Draw the circuit diagram of a practical log amplifier and obtain an expression
for its output voltage.
(b) Explain how to range the input Vi to an arbitrary power by cascading log and
antilog amplifiers. [8+8]
3. (a) Design a non-inverting comparator with output levels stabilizes at ±5V and
VTL= 0 and VTH= 2.5V (TL: Lower threshold, TH: upper threshold) as shown
in the figure2
(b) For the given inverting Schmitt trigger, calculate its higher and lower trigger
levels. [8+8]
4. Design a wide band-reject filter using first-order high pass and low pass filters
having fL = 2KHz and fH = 400Hz respectively. [16]
5. (a) Describe operation of a quadrature oscillator.
(b) Design a quadrature oscillator, oscillating at 318 Hz using Mc1458/μA741 IC.
[8+8]
6. (a) Draw the dc voltage versus phase difference characteristic of balanced modu-
lator phase detector of a PLL indicating all important regions.
1 of 2
Code No: V3120/R07 Set No. 2
Figure 2:
(b) Draw the dc out put voltage of VCO versus frequency characteristic of a PLL
indicating the capture and lock range clearly.
(c) State the relationship between lock range and capture range through a math-
ematical expression. [6+6+4]
7. (a) Explain the operation of a multiplying DAC and mention its applications.
(b) A 12-bit D to A converter has a full-scale range of 15 volts. Its maximum
differential linearity error is ± 1/2 LSB.
i. What is the percentage resolution?
ii. What are the minimum and maximum possible values of the increment in
its output voltage? [8+8]
8. Describe in detail the functioning of various integrating type Analog to Digital
converters and compare them in all aspects. [16]
? ? ? ? ?
2 of 2
Code No: V3120/R07 Set No. 3
III B.Tech I Semester Regular Examinations, November 2009
LINEAR IC APPLICATIONS
(Electronics & Communication Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) List and explain the characteristics of an ideal op-amp.
(b) Calculate the exact closed loop gain of the inverting amplifier of the figure1
shown, if AOL = 2,00,000, Ri = 2M­ and Ro = 75­.
Figure 1:
(c) Draw the pin diagram of μA741 op-amp. [8+4+4]
2. (a) What is the principle used in the design of an antilog amplifier explain?
(b) Draw the basic logarithmic multiplier circuit and explain how it multiplies two
voltages. [8+8]
3. (a) Design a non-inverting comparator with output levels stabilizes at ±5V and
VTL= 0 and VTH= 2.5V (TL: Lower threshold, TH: upper threshold) as shown
in the figure2
(b) For the given inverting Schmitt trigger, calculate its higher and lower trigger
levels. [8+8]
Figure 2:
4. Draw and explain the working principle of first order high pass filter. Derive the
expressions for gain and phase angle of the above filter. [16]
1 of 2
Code No: V3120/R07 Set No. 3
5. (a) Derive the expression for frequency of oscillation of a square wave generator.
(b) Design a square wave oscillator for an oscillator frequency of 2KHz. Assume
suitable values stating the necessary assumptions. Use op.Amp μA 741 oper-
ating with ±15Volt power supplies. [8+8]
6. (a) Draw the dc voltage versus phase difference characteristic of balanced modu-
lator phase detector of a PLL indicating all important regions.
(b) Draw the dc out put voltage of VCO versus frequency characteristic of a PLL
indicating the capture and lock range clearly.
(c) State the relationship between lock range and capture range through a math-
ematical expression. [6+6+4]
7. (a) With a suitable circuit diagram using NE 565 PLL IC, explain implementation
of a FSK demodulation.
(b) What are the standard frequencies used for mark and space to originate and
answer in FSK teletypewriter signal transmission. [12+4]
8. Write short notes on
(a) Noise rejection in dual slope type Analog to Digital converter.
(b) Operation of Flash type Analog to Digital converter. [8+8]
? ? ? ? ?
2 of 2
Code No: V3120/R07 Set No. 4
III B.Tech I Semester Regular Examinations, November 2009
LINEAR IC APPLICATIONS
(Electronics & Communication Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) An op-amp has a slew rate of 2V/μs. What is the maximum frequency of an
output sinusoid of peak value 5V at which the distortion sets in due to the
slew rate limitation.
(b) If the sinusoid of 10V peak is specified, what is the full power band width?
[8+8]
2. In some measurements it is necessary to sense current from a transducer and convert
it into voltage. For a three op-amp realization of a current input instrumentation
amplifier, derive the expression for Vo. [16]
3. (a) Determine VTHand VTLand hysteresis of the inverting comparator shown in
the below figure1.
Figure 1:
(b) Distinguish between astable, bistable and monostable multivibrators. [8+8]
4. (a) Design a wide band-pass filter with fL = 200Hz, fH = 1KHz and the pass band
gain = 4; also calculate the value of Q of the filter.
(b) Draw the frequency response plot of the above filter. [10+6]
5. Write short notes on:
(a) Sawtooth waveform generator
(b) Voltage-to-Frequency converter. [8+8]
6. Draw the functional diagram of a 555 time IC and explain the function of each
internal block to obtain astable multivibrator operation. [16]
1 of 2
Code No: V3120/R07 Set No. 4
7. (a) With a neat circuit diagram explain the functioning of an inverted R-2R ladder
type Digital to Analog converter.
(b) The LSB of a 10-bit DAC is 20 m volts.
i. What is its percentage resolution?
ii. What is its full-scale range?
iii. What is the output voltage for an input, 10110 01101? [8+8]
8. (a) Define the terms ‘Accuracy’ and ‘settling time’ of an Analog to Digital con-
verter.
(b) Explain in detail with a neat circuit diagram the operation of a parallel com-
parator type Analog to Digital converter. [6+10]
? ? ? ? ?
2 of 2
Code No: V3126/R07 Set No. 1
III B.Tech I Semester Regular Examinations, November 2009
SOFTWARE TESTING METHODOLOGIES
( Common to Computer Science & Engineering and Information
Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Discuss how software testing will ensure the quality of a developed software.
(b) Discuss the trade - off between quality assurance costs and manufaturing costs.
[10+6]
2. (a) Discuss about “Traversal marker” form of path instrumentation.
(b) What is meant by coincidental correctness? Give an example. [8+8]
3. (a) Discuss the following strategies of data flow testing with suitable examples:
i. All-predicate-uses(APU) strategy
ii. All-computational (ACU) strategy
(b) Compare the path flow and data-flow testing strategies. [8+8]
4. Discuss in detail the Domains and Interface testing. [16]
5. Explain the procedure to find the maximum number of different paths possible and
fewest number of paths possible with an illustration. [16]
6. What is decision table and how is a decision table useful in testing? Also explain
with the help of an example. [16]
7. (a) Write designers comments about state graphs.
(b) Write Testers comments about state graphs. [8+8]
8. (a) Write Partitioning Algorithm.
(b) Write an algorithm for All Pairs Paths using Matrix Operations. [8+8]
? ? ? ? ?
1 of 1
Code No: V3126/R07 Set No. 2
III B.Tech I Semester Regular Examinations, November 2009
SOFTWARE TESTING METHODOLOGIES
( Common to Computer Science & Engineering and Information
Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Distinguish between functional testing and structural testing.
(b) State whether the designer and tester are same? If not in what phases of
testing the designer and tester will be different? Why? [6+10]
2. Consider the following flow graph Figure 2
Figure 2
Select optimal number of paths to achieve C1+C2 (statement coverage + branch
coverage). [16]
3. (a) Discuss the following strategies of data flow testing with suitable examples:
i. All-predicate-uses(APU) strategy
ii. All-computational (ACU) strategy
(b) Compare the path flow and data-flow testing strategies. [8+8]
4. (a) What is meant by a nice domain? Give an example for nice two-dimensional
domains.
(b) Discuss the following terms: [8+8]
i. Linear domain boundarees
ii. Non linear domain boundaries
iii. Complete domain boundaries
iv. Incomplete domain boundaries
5. Explain applications of Paths, Path Products and Regular Expressions. [16]
6. (a) How set of paths can be characterized in the flow graph through the set of
test cases? Explain each of them.
1 of 2
Code No: V3126/R07 Set No. 2
(b) How can we obtain Boolean equations from the flow graph with loops? [8+8]
7. Explain:
(a) Finite state machine
(b) State graph inputs and outputs
(c) Transitions and state tables. [16]
8. (a) Define maximum element and minimum element of a graph?
(b) Explain parallel reduction and loop reduction? [8+8]
? ? ? ? ?
2 of 2
Code No: V3126/R07 Set No. 3
III B.Tech I Semester Regular Examinations, November 2009
SOFTWARE TESTING METHODOLOGIES
( Common to Computer Science & Engineering and Information
Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Why is it impossble for a tester to find all the bugs in a system? Why might
it not be necessary for a program to be completely free of defects before it is
delivered to its customers?
(b) To what extent can testing be used to validate that the program is fit for its
purpose? Discuss. [10+6]
2. (a) State and explain various kinds of predicate blindness with suitable examples.
(b) What are link counters? Discuss their use in path testing. [8+8]
3. (a) What are the transaction flows? Discuss their complications.
(b) What is meant by Data-flow testing? Discuss its significance. [8+8]
4. (a) Discuss the procedure for rectifying boundary closures of ugly domains.[8+8]
(b) Explain the domain testing strategy.
5. (a) Flow graph are abstract representation of programs. Justify?
i. Distributive laws
ii. Absorption Rule. [8+8]
6. (a) How set of paths can be characterized in the flow graph through the set of
test cases? Explain each of them.
(b) How the Boolean expressions can be used in the test case design? [8+8]
7. The behavior of a finite-state machine is invariant under all encodings. Justify.
[16]
8. (a) What operations does a toolkit consist for the representation of graphs?
(b) How can a relation matrix be represented and what are the properties of
relations? [8+8]
? ? ? ? ?
1 of 1
Code No: V3126/R07 Set No. 4
III B.Tech I Semester Regular Examinations, November 2009
SOFTWARE TESTING METHODOLOGIES
( Common to Computer Science & Engineering and Information
Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Why is it impossble for a tester to find all the bugs in a system? Why might
it not be necessary for a program to be completely free of defects before it is
delivered to its customers?
(b) To what extent can testing be used to validate that the program is fit for its
purpose? Discuss. [10+6]
2. Discuss the following terms in detail
(a) Predicates
(b) Path predicates
(c) Achievable paths [5+5+6]
3. (a) Discuss the following strategies of data flow testing with suitable examples:
i. All-predicate-uses(APU) strategy
ii. All-computational (ACU) strategy
(b) Compare the path flow and data-flow testing strategies. [8+8]
4. (a) What is meant by a nice domain? Give an example for nice two-dimensional
domains.
(b) Discuss the following terms: [8+8]
i. Linear domain boundarees
ii. Non linear domain boundaries
iii. Complete domain boundaries
iv. Incomplete domain boundaries
5. Discuss all the rules in path representation of graphs. [16]
6. (a) Explain knowledge-based systems and decision tables?
(b) What are the rules of Boolean algebra? [8+8]
7. (a) Mention design guidelines for building finite state machines into code.
(b) Write short notes on:
i. Switches, Flags and unachievable paths.
ii. Essential and Inessential finite state behavior. [6+5+5]
1 of 2
Code No: V3126/R07 Set No. 4
8. (a) Write an algorithm for Node Reduction.
(b) Illustrate the applications of Node Reduction algorithm. [8+8]
? ? ? ? ?
2 of 2
Code No: V3145/R07 Set No. 1
III B.Tech I Semester Regular Examinations, November 2009
LINEAR & DIGITAL IC APPLICATIONS
( Common to Bio-Medical Engineering and Electronics & Computer
Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Draw the pin diagram and schematic symbol of a typical Op-amp IC741 and
explain the function of each pin. [6+6+4]
(b) Discuss the three basic types of linear IC packages and briefly explain the
characteristics of each.
(c) State the two types of integrated circuits classified according to their mode of
operation and briefly explain the significance of each.
2. (a) Write short notes on non inverting comparator.
(b) For the given (figure 2b) inverting Schmitt trigger, calculate its higher and
lower trigger levels. [8+8]
Figure 2b
3. (a) What are the conditions to be satisfied by a circuit to produce oscillations?
(b) Give the classification of filters. Explain the frequency response of all filters.
[6+10]
4. (a) Write short notes on :
i. Balanced Modulator.
ii. Voltage Controlled Oscillator.
iii. Digital Phase Detector.
(b) Give any one applications of PLL and explain it in detail. [4+4+4+4]
5. (a) Draw and compare the conversion times for tracking and successive approxi-
mation ADC devices.
(b) A dual slope ADC uses a 12bit counter and a 8 MHz clock rate. The max
input voltage is +10V. The maximum integrator o/p voltage should be -8V,
when the counter has cycled through 2n counts. The capacitor used in the
integrator is 0.1μF. Find the value of the resistor of the integrator. [8+8]
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Code No: V3145/R07 Set No. 1
6. List out standard TTL Characteristics and explain them briefly with necessary
diagrams. [16]
7. (a) Implement the following Boolean function using 8:1 multiplexer
F(ABCD) = ABD + ACD + BCD + ACD
(b) Design a 32 to 1 multiplexer using four 74×151 multiplexers and 74×139
decoder? [8+8]
8. (a) Design a modulo-100 counter using two 74×163 binary counters?
(b) Design an 8-bit parallel-in and serial-out shift register? Explain the operation
of the above shift register with the help of timing waveforms? [8+8]
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Code No: V3145/R07 Set No. 2
III B.Tech I Semester Regular Examinations, November 2009
LINEAR & DIGITAL IC APPLICATIONS
( Common to Bio-Medical Engineering and Electronics & Computer
Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What are the three factors that affect the electrical parameters of an Op-amp.
(b) Derive the expression for CMRR for the first stage differential amplifier.
[8+8]
2. (a) What is Gyrator circuit? Explain its operation with a neat circuit diagram.
(b) What is a sample and hold circuit? Why is it needed? With neat circuit
diagram, describe the operation of an Op-amp based sample and hold circuit.
[6+10]
3. (a) Design a II order Butterworth Low-pass filter for a cut off frequency of 1KHz
and for a given normalized polynomial of S2+1.414S+1. Assume necessary
data.
(b) In the above circuit given (figure 3(b)ii) if the integrator components are
R1=120 K
 and C1 = 0.01μF,R3= 6.8 K
 R2= 1.2K
, determine
i. Peak-to-peak triangular output amplitude.
ii. The frequency of triangular wave. [8+8]
Figure 3(b)ii
4. (a) Design a 555 Astable multivibrator to operate at 10 KHz with 40% duty cycle.
(b) Explain in which the 555 timer can be used as Astable multivibrator. [8+8]
5. (a) In which type of Analog to Digital converter, a Digital to Analog converter is
used? Explain its operation in detail.
(b) List important specifications of Analog to Digital and Digital to Analog con-
verters indicating their typical values. [8+8]
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Code No: V3145/R07 Set No. 2
6. (a) Explain how to estimate sinking current for low output and sourcing current
for high output of CMOS gate?
(b) Analyze the fall time of CMOS inverter output with RL = 1K
 VL = 2.5V
and CL = 100PF. Assume VL as stable state voltage. [8+8]
7. (a) Design a full subtractor with logic gates.
(b) Design a 4 bit parallel adder using full adder? [8+8]
8. (a) Draw the logic diagram of binary counter and explain its operation?
(b) Draw the internal structure of synchronous SRAM and explain the operation?
[8+8]
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Code No: V3145/R07 Set No. 3
III B.Tech I Semester Regular Examinations, November 2009
LINEAR & DIGITAL IC APPLICATIONS
( Common to Bio-Medical Engineering and Electronics & Computer
Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What are the three factors that affect the electrical parameters of an Op-amp.
(b) Derive the expression for CMRR for the first stage differential amplifier.
[8+8]
2. (a) What is Gyrator circuit? Explain its operation with a neat circuit diagram.
(b) What is a sample and hold circuit? Why is it needed? With neat circuit
diagram, describe the operation of an Op-amp based sample and hold circuit.
[6+10]
3. (a) For the all-pass filter, determine the phase shift between the input and output
at f = 2KHz. To obtain a positive phase shift, what modifications are necessary
in the circuit?
(b) How are filters classified? What is pass band and stop band for a filter?[8+8]
4. (a) Describe the operation of an analog phase detector.
(b) Analyze the behavior of an analog phase detector through necessary circuit
diagram, waveforms, mathematical expressions and characteristic curves.[8+8]
5. (a) Explain the operation of a multiplying DAC and mention its applications.
(b) A 12-bit D to A converter has a full-scale range of 15 volts. Its maximum
differential linearity error is ± 1/2 LSB.
i. What is the percentage resolution?
ii. What are the minimum and maximum possible values of the increment in
its output voltage? [8+8]
6. (a) Draw the circuit of two input NAND gate with totem-pole output and do the
static analysis when output is HIGH & Output is low.
(b) Explain why two totem pole outputs can’t be tied together.
(c) With neat circuit explain the concept of open collector O/P with pull-up.
resistor. [6+6+4]
7. (a) Write short notes on look ahead carry generator.
(b) Design a full adder with minimum number of NAND gates. [8+8]
8. (a) Write short notes on synchronous up counter.
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Code No: V3145/R07 Set No. 3
(b) Explain the operation of Synchronous SRAM with the help of its internal
Architecture. [8+8]
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Code No: V3145/R07 Set No. 4
III B.Tech I Semester Regular Examinations, November 2009
LINEAR & DIGITAL IC APPNLICATIOs
( Common to Bio-Medical Engineering and Electronics & Computer
Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What are the three differential amplifier configurations? Compare and con-
trast these configurations.
(b) What is a level translator circuit? Why is it used with the cascaded differential
amplifier used in Op-amps?
(c) Explain the term“Slew Rate” and how it affects the frequency response of an
Op-amp? [10+3+3]
2. (a) Explain with a neat circuit diagram the working of voltage to current converter
with floating load and grounded.
(b) Design a circuit to convert a 4 mA to 20mA input current to 0V to 10V output
voltage. The circuit is powered from ±15V regulated supplies. (Assume
necessary data) [10+6]
3. Write short notes on the operation of any two:
(a) Quadrature oscillator.
(b) Voltage controlled oscillator.
(c) Wien - bridge oscillator. [16]
4. (a) Explain the operation of Astable multivibrator using 555 timer.
(b) Design a Monostable multivibrator using 555 timer to produce a pulse width
of 200 ms. [10+6]
5. (a) Explain the operation of a dual slope type Analog to Digital converter.
(b) A dual slope Analog to Digital converter uses a 16-bit counter and operates
at 4 MHz clock rate. The maximum input voltage is +8volts. Find the value
of integrator resistor ‘R’ if the maximum output voltage of the integrator is
-6V after 2n counts for an integrator capacitor of 0.1μF. [8+8]
6. (a) Compare different logic families and mention their advantages and disadvan-
tages?
(b) Which is the fastest non-saturated logic gate? Draw the circuit and explain
its functions. [8+8]
7. (a) Design the 32 input to 5 output priority encoder using four 74LS148 and gates?
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Code No: V3145/R07 Set No. 4
(b) Design a CMOS transistor circuit with the functional behavior [8+8]
F(X) = (A + B)(B + D)(A + D).
8. (a) Design a conversion circuit to convert a T flip-flop to D flip-flop?
(b) Explain the operation of parallel in parallel out shift register? [8+8]
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LINEAR SYSTEMS ANALYSIS

Code No: R7310206 1
III B.Tech. I Semester(R07) Regular Examinations, December 2009
LINEAR SYSTEMS ANALYSIS
(Electrical & Electronics Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE questions
All questions carry equal marks
? ? ? ? ?
1. (a) Explain what is meant by state variable and mention the advantages of state space ap-
proach.
(b) The transfer function of a system is G(s) = 2
(s+1)(s+3) obtain the state variable represen-
tation of the system.
(c) Write the state equation for the circuit shown in ¯gure 1.
Figure 1:
2. (a) The input voltage in volts to a series RL circuit is
e(t) = 180 sin(314t + 100) + 56 sin(942t + 350) + 18
The value of R and L are 18­ and 0.0413H. Determine:
i. The expression for the current.
ii. The rms value of voltage and current.
iii. The power factor of the circuit.
(b) Find the trigonometric series for the wave form shown in ¯gure 2.
Figure 2:
3. (a) Obtain the Fourier transform of unit step function.
(b) State and explain the properties of Fourier transform.
(c) Show that the Fourier transform of ±(t), the impulse function has constant magnitude.
Page 1 of 2
4. (a) Find the Laplace transform of the following waveform shown in ¯gure 3.
Figure 3:
(b) For the network shown in ¯gure 4 ¯nd the voltage across the inductor 4H.
Figure 4:
5. (a) State the properties of Hurwitz polynomial.
(b) Check whether the following functions are positive real function or not.
i. Z(s) = s+3
s+2.
ii. Z(s) = s2+7s+70
s(s+10) .
6. (a) Obtain the second Foster form for a network has impedance.
Z(s) = s(s2+10)
(s2+4)(s2+16)
(b) Explain how the removal of pole at in¯nity of an impedance Z(S) can realize an element
in the network.
7. (a) State and explain Sampling Theorem.
(b) What are the e®ects of Under Sampling?
(c) Write short notes on the reconstruction of signal from its sample.
8. (a) State the properties of the Region Of Convergence(ROC).
(b) Find the Z-transform of the following:
i. Unit step function.
ii. Unit impulse function.
(c) Find the inverse Z-transform of the following:
X(Z) = 1+2Z+3Z2+4Z3+5Z4
Z4 .
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Code No: R7310206 1
Page 2 of 2
Code No: R7310206 2
III B.Tech. I Semester(R07) Regular Examinations, December 2009
LINEAR SYSTEMS ANALYSIS
(Electrical & Electronics Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE questions
All questions carry equal marks
? ? ? ? ?
1. (a) What are the state variables chosen in analysis of electrical circuits?
(b) Write state variable equation for the following di®erential equations:
d2y
dt2 + 5dy
dt + 6y = sin t + 5e¡t.
(c) Obtain the state variable equation for the network shown in ¯gure 1.
Figure 1:
2. (a) Find the RMS and average values of the periodic function shown in ¯gure 2.
Figure 2:
(b) The voltage V (t) = 4
¼ £sin 2¼t
1 + sin 6¼t
3 + sin 10¼t
5 + :::::::::::::::::1¤is applied to circuit of R =
4­ in series with an inductance of L = ¡1
¼ ¢H.
Calculate the average power and power factor.
3. (a) State and explain any four properties of Fourier transform.
(b) Obtain the Fourier transform of the following:
i. Signum function.
ii. Rectangular pulse.
iii. Ramp signal.
Page 1 of 2
4. (a) Obtain the L.T. of the following waveform shown in ¯gure 3.
Figure 3:
(b) Find the current through the resistance R2 if the applied voltage is Vi = V ¡at
e to the circuit
shown in ¯gure 4.
Figure 4:
5. (a) Test whether the following polynomial is Hurwitz or not.
i. H(S) = S4 + S3 + 5S2 + 3S + 4.
ii. H(S) = S3 + 2S2 + 3S + 6.
(b) Test whether the following function is a positive real function or not.
N(s) = s3+s2+3s+5
s2+6s+8 :
6. (a) Synthesis given function in II Cauer form
F(S) = 2(s+1)(s+3)
S(S+2) .
(b) State the properties of RL impedance of RC admittance functions.
7. Write short notes on the following:
(a) Sampling theorem.
(b) Aliasing.
(c) Properties of correlation function.
8. (a) What are the di®erences between continuous and discrete time signals?
(b) Find the sequence corresponding to the following Z-transformed function given by
X(Z) = Z3¡4:8
Z(Z¡0:2)(Z¡0:4) .
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Code No: R7310206 2
Page 2 of 2
Code No: R7310206 3
III B.Tech. I Semester(R07) Regular Examinations, December 2009
LINEAR SYSTEMS ANALYSIS
(Electrical & Electronics Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE questions
All questions carry equal marks
? ? ? ? ?
1. (a) Why are the currents through the resistances and voltage across a conductance not chosen
as state variables.
(b) Find eAt for A = · ¡1 ¡1
0 1 ¸.
(c) Obtain the state equation for the circuit shown in ¯gure 1.
Figure 1:
2. (a) An alternator gives an output of 100 sin !t + 30 sin !t + 20 sin 5!t
Where ! = 100. If this voltage is applied to a load of 10­ series with 0.01H, ¯nd the current,
average power and power factor of the alternator.
(b) Obtain the RMS and average values of the following functions.
i) f(t) = sin2 t. ii) f(t) = sin t + 20 cos 3t + 3 sin(5t + £¼
4 ¤).
3. (a) State and explain Parseval's theorem.
(b) Obtain the Fourier transform of the decaying exponential function. Also draw the magnitude
and phase spectra of exponential function.
4. (a) State the convolution theorem and determine the Laplace transform of the given function
by using convolution theorem.
G(S) = S
(S+1)(S+3) .
(b) A voltage pulse of 10V magnitude and 5¹ sec duration is applied to the RC network shown
in ¯gure 2. using LT method.
Figure 2:
Page 1 of 2
5. (a) Test whether the following function is positive real function or not.
N(S) = S3+4s2+7s+3
s3+3s2+5s+6 .
(b) i. Check whether the polynomial s4 + s3 + 7s2 + 6 is Hurwitz or not.
ii. Find the range of values `a' so that
H(S) = S4 + S3 + aS2 + S + 3 is Hurwitz polynomial.
6. (a) Obtain the ¯rst Cauer form of Z(S) = (S+2)(S+4)
(S+1)(S+3) .
(b) Explain the realization of ¯rst foster form of R-c equivalent network deriving necessary
expressions.
7. (a) What is the necessity of sampling process?
(b) What are the di®erent types of sampling methods?
(c) Write short notes on correlation of energy signals.
8. (a) Find the Z-transform of the following:
i) f(t) = t2. ii) F(S) = 1
S(s+a) .
(b) Find the inverse Z-transform of the following:
i) F(Z) = Z
Z+a . ii) F(Z) = Z¡4
(Z¡1)(Z¡2)2 .
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Code No: R7310206 3
Page 2 of 2
Code No: R7310206 4
III B.Tech. I Semester(R07) Regular Examinations, December 2009
LINEAR SYSTEMS ANALYSIS
(Electrical & Electronics Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE questions
All questions carry equal marks
? ? ? ? ?
1. (a) What are the properties of state transition matrix?
(b) Evaluate the state transition matrix eit, for the following system equation
X(t): = · 0 1 0
0 0 1
1 0 0 ¸X(t) + · 0
0
1 ¸u(t)
(c) Write state equation in matrix form for the circuit shown in ¯gure 1.
Figure 1:
2. (a) Find the exponential Fourier series for the waveform shown in ¯gure 2.
Figure 2:
(b) The current waveform shown in ¯gure 3 is applied to a circuit containing of 0:01¹F in parallel
with 1K­ through a ¯lter that allows frequencies between 13 and 14 KHz. Find the average
power delivered to 1K­.
Figure 3:
3. (a) State the properties of positive real function.
(b) Check whether the following functions are Hurwitz or not.
i. H(S) = S4 + 6S3 + 2S2 + S + 1.
ii. H(S) = S5 + 4S4 + S3 + 2S2 + S + 1.
4. (a) Synthesize the network in ¯rst foster form
Z(S) = 2(S2+1)(S2+9)
S(S2+4) .
(b) State and explain the properties of L-C immittance functions, deriving necessary expressions.
Page 1 of 2
5. (a) Find the Fourier transform of the time signal shown in ¯gure 4.
Figure 4:
(b) Obtain the Fourier transform of the double sided exponential signal.
6. (a) Find the voltage across 2­ resistor in the circuit shown in ¯gure 5 using L-T method.
Figure 5:
(b) Find the Laplace transform of the following ¯gure 6.
Figure 6:
7. Explain the following with suitable examples.
(a) Impulse sampling.
(b) Natural and °at top sampling.
(c) Band pass sampling.
(d) Power density spectrum.
8. (a) Find the Z-transform of the following:
i. e¡at = f(x)
ii. F(s) = 1
((s(s+1))
(b) Obtain the inverse Z-transform of the following :
i. X(Z) = 10
(Z¡1)(Z¡2)
ii. X(Z) = 1+Z¡1+Z¡2
1¡Z¡1
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Code No: R7310206 4
Page 2 of 2