Fourth Semeter

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END TERM EXAMINATIONFOURTH SEMESTER •TECH. - MAY2011

Paper Code: ETEE202 Subject: Electromechanical Energy Conversion-IITime: 3 Hours Maximum Marks: 75Note: Attemptfive questions including Q.no.l which is compulsory. Graphpapersflog

table/ calculator are required.

Q 1 (a) Answer thc following questions briefly:- (2x5=10)(i) What are the advantages of introducing resistance in the rotor circuit

of a three phase wound rotor induction motor?(ii) Why an auxiliary winding is required for the operation of a single

phase induction motor?(iii) What are the effects of armature reaction in an alternator at (A) zero

leading pf and (B) unity power factor loads?(iv)A synchronous motor designed to operate in USA is brought in India.

If in USA it runs at 1800rpm, at what speed it will run in India?(v) An induction motor is running at 50Hz at a speed of 1440 rpm. Motor

has 4 poles. At what speed in space will the field produced by rotor,rotate?

(b) (i) Make the most suitable choice out of the following:- (2x5=lO)(A) A universal motor will operate successfully only when its field

winding is connected in parallel with armature.(B) Above motor will operate successfully only when its field winding is

connected in series with the armature.(C) Above motor will operate successfully under both the conditions

mentioned at (i) and (ii).(D) Above motor will operate successfully when both shunt and series

field windings are present in the motor.(ii) A three phase synchronous motor may be employed-

(A) For constant speed application and not for power factor correction.(B) For power factor correction and not for constant speed application.(C) For both, constant speed application as well as for power factor

correction.(D) Neither for constant speed application not for power factor

correction.(iii)Thc torque developed by a repulsion motor at no load is maximum

whcn space angle between pole axis and brush axis is-(A) 900 (B) 450 (C) 150 (D) None of the above

(iv) In a steam driven large turbo alternator the poles are-(A) Salient pole type(B) Smooth cylindrical type(C) It makes no difference whether salient pole type or smooth

cylindrical type hence these could be of any type.(D) When it is 11kV it will be smooth cylindrical but when it is 33kV it

will be salient pole type. '(v) An induction generator can develop electric power-

(A) Only when connected to grid. .(13) Only when a suitable capacitor bank is connected across its

terminals.(C) Either when connected to grid or when a suitable capacitor bank is

connected across its terminals.(D) None of the above is true.

(e) Mention whether following statements are true or falsc:- (lx5=5)(i) A deep bar rotor is used in an induction motor to increase its speed,(i i] An ac series motor has its amature laminated but field structure

unlaminated.(iii)Two reaction theory of three phase alternators is applicable to smooth

cylindrical rotor machines only.

Northern India Engineering College, New Delhi

P.T.O.[-2-]

(iv)'V' curves of a synchronous motor are the curves between fieldcurrent and armature applied voltage.

(v) S.C. test on a synchronous machine is normally performed at fullarmature voltage.

Q2 (a) Explain the production of rotating magnetic field in a three phaseinduction motor. (6.5)

(b) A IJ pole, 50Hz 3 phase induction motor develops a maximum torque of200Nm at 1400rpm. Find the torque at a slip of 5%. Neglect statorimpedance. (6)

OR(a) Describe the various methods of speed control of threeinduction motors.

(b) A 6 pole, 3 phase, 60Hz induction motor takes 48kW1I-lOrprn. The stator core loss is 1.4kW, stator core lossmechanical losses are lkW. Find motor efficiency.

phase slip ring(6.5)

input power at1.6kWandrotor

(6)

Q3 (a) With the help of the torque-slip characteristic explain why single phaseinduction motor is not inherently self starting? (6.5)

(b) Explain various types of single phase induction motor alongwith thetechniques used for their starting. (6)

OR(a) Develop the equivalent circuit of a single phase induction motor. (6.5)(b) Describe the construction and working of a universal motor and give itsapplications. (6)

QIJ (a) Derive the emf equation of a concentrated full pitch winding. (6.5)(b) Calculate the distribution factor for a 3 phase distributed single layerwinding of the armature of an alternator. The alternator has 2 poles anda total of 18 slots. (6)

'OR(a) Explain the synchronous impedance method of finding the voltageregulation of a three phase alternator. Give the circuits to perform testsrequired for the same. (6.5)

(b) A 3 phase star connected cylindrical rotor synchronous generator ratedat 10kVA and 230volts has a synchronous reactance of 1.2ohms perphase and an armature resistance of Oi Sohm per phase. Calculate thepercentage voltage regulation at full load with 0.8 lagging power factor. (6)

Q5 (a) Discuss the effect of saliency and explain the two reaction theory forsalient pole synchronous machine. (6.5)

(b) A 2:WOv, three phase, 60Hz Y connected cylindrical-rotor synchronousmotor has a synchronous reactance of ll.ohrns per phase. When itdelivers 200hp, the efficiency is found to be 90% excluding the field loss.The power angle is 15 electrical degrees. Neglecting the ohmic resistance,determine-(i) The induced excitation voltage per phase, Er. (3)(ii) The line current. (3)

OR(a) Explain hunting phenomenon in synchronous motors. How can it bereduced, describe in detail. (6)

(b) Describe the principle of operation of a reluctance motor giving suitableconstructional diagrams. State its various applications. (6.5)

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END TERM EXAMINATIONFOURTH SEMESTER .TECH. - MAy 2011

Paper Code: ETEE204 Subject: Analog Electronics·IITime: 3 Hours Maximum Marks: 75Note: Attemptfive questions including Q.no.l which is compulsory. Internal choice is

indicated.

Ql (a) Define the term "Common mode rejection ratio". Explain how to measure it?(b) What is an active load? Where it is used?(c) Determine the range of variable inductance, if frequency of oscillation is to vary

between 950KHz to 2050KHz. Assume C]=7500PF and C2=100PF.(d) Explain the two conditions for oscillation in feedback amplifier.(e) Explain the difference between a voltage amplifier and a power amplifier by

giving an example.(f) Why class B and class C amplifier have more efficiency than class A amplifier?(g) What do you mean by precision rectifier, explain with circuit?(h) Explain why active filter preferred over passive filters?(i) Explain an all pass filter.Ul Define the terms free running frequency, capture range and pull in time.(2.5x10=25)

Q2 (a) Find the output of a given circuit in fig(l). (6)to 1e.'1. 20\<.. fL

S"iwl r-'VN----. ~

\J !>-_\/W __Ll~ \ lOj<"JL . II "sv \ ~---"---'-v..;-, _ I

I' /' 1 'I ~·I·t -'--±. ~0~~_,1 I ,--- .\JJ.~ "-v ;

(b) Explain the difference between constant current bias and current mirror. (6.5)OR

Q3 (a) Draw and explain the operation of a voltage to current converter when load isgrounded. Is there any limitations on the size of the load when grounded? (6.5)

(b) I~xplain the working of differentiator and it is excited by the input shown infig(2). Find the output voltage if Rr=2Kn, Cl=O.lIlF. (6)

\1.", I'--i

Q4 (a) Explain the operation of an astable multivibrator and derive the expression forfrequency of oscillations. (6.5)

(b) Explain how the triangular wave generator can be converted into a Rampgenerator? (6)

ORQ5 (a), Explain the working of Wein Bridge Oscillator and derive the expression for the

frequency of oscillation. (6.5)(b) Discuss the applications of OTAas programmable voltage amplifier. (6)

Q6 (a) Explain how push-pull configuration reduce the harmonic distortion in anamplifier? (6)

(b) Explain the advantage of Schmitt Trigger over basic comparator. How it willconvert Sine wave into square wave. (6.5)

ORQ7 (a) Define conversion efficiency. Determine the maximum value of conversion

efficiency for a series fed class A power amplifier. (6)(b) Explain how two analog voltages are multiplied and divided by using log and

antilog amplifier? (6.5)

Q8 (a) Design the band pass filter so that cut off frequency fc=1KHz Q=20 and Ar=10.Assume C=lIlF. (6)

(b) Explain the operation of 723 regulator. (6.5)OR

Q9 (a) Design a first order low pass filter for a high cut off frequency of 2KHz and passband gain is 2. (6)

(b) Explain the operation of VCO with the help of block diagram. (6.5)************


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END TERM EXAMINATIONFOURTH SEMESTER •TEcH. - MAy 2011

Paper Code:ETEE206 Subject: Power System·ITime: 3 Hours MaximumMarks: 75

Note: Attemptfive questions including Q.no.l which is compulsory. Select onequestion from each unit.

Q1 (a) Give the concept of reactive power in a power system. Why is itnecessary to control it in a power system?

(b)What is surge impedance of a Line? Give its importance. What issurge impedance loading?

(c) Give the different methods of equalizing the potential in overheadLine insulators.

(d)Distinguish between overhead lines and cables.(e) Give a representative list of all the equipment installed in a power

network. Give one application of each. (SxS=2S)

UNIT-IQ2 (a) Explain the advantages of transmission of power at high voltage or

extra high voltage, keeping in view the conductor section, linelosses, per unit voltage drop and length of the line. (5)

(b)What are the advantages of 3-:phase transmission system oversingle phase transmission system? (4)

(c)What is the importance of power factor in power systems? (3.5)

Q3 With respect to transmission lines discuss the following:-(a) Types of conductors(b)Bundle conductors(c) Skin effect(d)Proximity effect(e) Bus bars

(12.5)

UNIT-IIQ4 Determine the mirumum inductancey'km of a transposed double

circuit, 3-phase lines shown in fig.I. The diameter of each conductoris 2cm. (12.5)

1- 9"", -9/

@ T5"~

~ +s:~@ 1

Q5 (a) What is the difference between nominalequivalent circuit of a transmission line?

(b)A short 3-phase 150Hz, 132KV line has alO+j40 ohm/phase. Calculate -(i) Sending-end voltage(ii)The load angle(iii)Linelosses and draw a phasor diagram.

1t or equivalent rt-

(3)senes impedance of

(9.5)

P.T.O.


[-2-]

UNIT-IIIQ6 (a)Why are the overhead line insulators glazed? (2.5)

(b)A 3-phase overhead line is supported on 4 disc suspensioninsulators. The voltage across the second and the third discs fromthe line end are 18KVand 13.2kV respectively. Calculate the linevoltage and string efficiency. Given mutual capacitance/earthcapacitance=m. (10)

Q7 (a)What is corona? On what factor does the occurrence of coronadepends? Explain how the on set of corona is reduced with the useof bundle conductors. (8)

(b)Write a short note on electrostatic and electromagneticinterference. (4.5)

UNIT-IVQ8 At a river crossing an overhead line has a span of 300m with supports

of conductors at 30m and 70m above the water level. The weight ofthe conductor is O.4kg/m. If the tension of the conductor is adjusted r=>.

to 1200kg, determine the clearance of the conductor above water at apoint 100m from the base of taller tower. Derive any relation used. (8.5+4)

Q9 (a)What is capacitance grading in cables? What are its advantages? (4)(b)Howthe capacitance of a 3-core cable determined by tests? (5)(c) Calculate the capacitance per km of a cable if conductor diameter

is 2cm, sheath diameter 5cm and Er=4. (3.5)

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END TERM EXAMINATIONPaper Code: ETME 206

MA Y - JUNE 2011Subject: Manufacturing Machines

Time: 3 Hours Maximum Marks: 75Note: Attempt any four questions.a.1 is compulsory.

Q.1 (a) Differentiate between single purpose and special purpose machines alongwith example? (3x5=15)

(b) Enlist various cutting tool materials giving their properties & applications?(c) Explain Eccentric Turning?(d) How is material removal rate in a shaping machine calculated.(e) What is the difference between counter boring and countering operations?

Q.2 (a) Define machining. Give the classification of machining processes? Also enlistthe various elements of machine tools. (6)

(b) Explain in brief the working principle of a lathe machine? (8)A workpiece of 250mm diameter and 500mm length is to be turned down to235 mm dia. for the entire length. The suggested feed is Lmm Zrev. andcutting speed is 135m/min. The maximum allowable depth of cut is 5.0mm.Calculate

(i) Spinde R.P.M. (ii)MRR (iii) Feed Speed

Q.3 (a) Explain briefly how quick return motion mechanism for a shaper isaccomplished, also discuss the feed mechanism used in shaper. (7.5)

(b) Explain with a diagram Apron mechanism in Lathe. (7.5)

Q.4 (a) How are 'drills' classified? Discuss briefly 'Twist Drill Nomenclature' withneat sketches. (7)

(b) Differentiate in brief bench drilling machine and radial drilling machine. (8)A hole of 25 mm diameter and 62.5mm depth is to be drilled. The suggestedfeed is 1.25mm/rev. and cutting speed is 60m/min. Assuming tool approachand tool overtravel as 5 mm,Calculate(i)Spindle RPM (ii)Fee Speed (iii)Cutting Time

Q.5 (a) What is milling? Draw the block diagram of a horizontal milling machine andexplain brief its various parts. (7.5)

(b) Define Indexing? Index for 87 divisions and explain the steps. (7.5)

Q.6 [ajCompare boring and reaming operation? Explain briefly ajig boringmachine, with a neat sketch. (7.5)

(b) What is grinding wheel? Explain briefly with neat sketches various types ofsurface grinding machines. (7.5)

Q.7 Write short notes on any five:(a) "Bar feed mechanism' used in Turret and capstan lathe.(b) Drill holding devices(c) Classify dividing heads.(d) Gear shaping and Gear Hobbing(e) Compare Lapping, Honing & Superfinishing(1)CNC Lathe & Conventional Lathe

(3x5=15)

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END TERM EXAMINATIONFOURTH SEMESTER B.TEcH. -MAY 2011

Paper Code: ETEE20B Subject: Control Engineering-ITime: 3 Hours Maximum Marks: 75

Note: Attemptfive questions including Q.no.l which is compulsory. I

Q 1 (a) Write two major differences between an open loop and closed loopsystem. Also, give two examples of each system. (2)

(b) What is the transfer function of a linear time invariant (LTI) system? Givethe major limitation of transfer function modeling approach of thesystem. (2)

(c) Write the transfer function Xo (s) for the system shown in fig.I. (2)X;(s)

k, (';r;J~L}l-1~c

~/ (Z.,}1.

(d) Write the transfer function, C for the signal flow graph shown in fig.2. (2)R

§-H3-H

Rls) 1 •.• "~_ •..~ • t7C~.J

'----- .~ il2-

----.Ih•••.H-.1- F;:J.2-

(e) What are the two characteristic parameters of a first order system? Howto determine them? (2)

(f) Represent a standard IInd order system in the form of a unity feedbackform and write its closed loop transfer function. (2)

(g) What are the type and order of the system shown in fig.3? (2)

R.~S) ..L.+ rs .L: Ccr)-r S T

(h) For the system with characteristi:'~~~ation S3 - 4S2 + S + 6 = O. Howmany roots lie in left half S-plane? (2)

(i) For the system shown in fig.4, the input x(t) =:: S int, determine thesteady-state response of the system. (2)

?t(f) ~ -fn )-~ j{f;)I

. SU) Sketch the polar plot for the transfer function G(s)H(S) = --. (2)

]+ST(k) What should be the value of K for the system having a characteristic

equation given by S3 + 3KS2 + (K + 2)S + 4 = 0 to be stable? (3)(1) Derive the condition under which the following transfer function

Kll + S)represent a lead compensator G(S) =: ( . ;; -. (2)

ll+t;)P.T.O.


[-2-]Q2 Write the differential equations for the mechanical system shown in fig.S and

draw an electrical analog circuit based on force voltage analogy. (12.5)

t,L; !W, f S,~F/' "

F;~.S-.

Q3 (a) For the block diagram shown in fig.6, draw an equivalent signal flow

graph and determine overall transfer function C. (6.5)R

R i'

c

F-'(1'b'

(b) Derive the transfer function of an armature controlled DC servometerrelating output speed w(s) with armature voltage VatS). Assume armatureinductance negligible. (6)

Q4 For a proto-type standard second order system, with natural frequency rox

and damping ratio ~, derive expression for rise time, peak overshoot andsettling time. Assume ~<l. (12.5)

Q5 (a) The open loop transfer function of a servo system with unity feedback is10

G(S):.c; ( ). Evaluate the static error constant (Kp, x., Ka) for theS O.lS + I

system. Obtain the steady state error of the system when subjected to an?

. ( ) a.t:input given by r t = ao + ai' + -- -2

(b) The open loop, transfer function of a unity feedback system is given by

G(S) :::=-(S + 2Xs + 4XS2 + 6S + 25)' Determine the value of K. Which will

cause sustained oscillations in the system? What are the correspondingoscillation frequencies? (6.5)

(6)

Q6 (a) A unity feedback control system has an open loop transfer functionK

G(S)-c (X X ) . Sketch the root locus plot of the systemS+l S+2-j S+2+j

by determining, centroid, number and angle of asymptotes, angle ofdeparture and value of K at which root locus cross the jo-axis. (6.5)

(b) Draw a schematic diagram of a position servomechanism and represent itin the form of a block-diagram. Introduce a PD controller in this systemand discuss it effect of the time response of the position servomechanism. (6)

Q7 Sketch the Bode magnitude and phase plots for the unity feedback control. G(S) 10(1+ 0.5S)system gIVen by = ( X ) . From the plot determine the

S 1+ O.IS 1+ 0.2Sgain cross and phase cross-over frequency, GM and PM. (12.5)

Q8 Write short notes on any two of the following:-(a) AC servo motor(b) Synchronous motor(c] Nyquist stability criterion(d) M & N circles

(6+6.5)

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END TERM EXAMINATIONFOURTH SEMESTER .TECH. - MAyJUNE 2011 .

I Paper Code: ETEE210 Subject: Electromagnetic Fields TheoryTime: 3 Hours Maximum Marks: 75c=- Note: Q.no.l is compulsory. Attempt one question from each unit. I

Ql (a) Find ~ unit vector normal to the surface X2 + y2 = Z2 at the point (1,0, -1). (4)

(b)Derive an expression for the energy density of a parallel-platecapacitor. (5)

(c) State and explain Biot-Savart's law in magnetostatics. Give itsintegral form. (4)

(d)Find the frequency at which the conduction current density anddisplacement current density are equal in sea water, where(J",4.0Slm and Er=80Eo' (4)

(e) A lossless transmission line is A./8Iong.State and explain whetherit will be inductive or capacitative if it is terminated in a (i) short-circuited (ii)open-circuit. (4)

(f) Explain the followingterms:- (4)(i) The propagation constant(ii] The intrinsic impedance and the attenuation constant.

UNIT-IQ2 (a)Define curl of a vector. State and prove Stoke's Theorem. (5)

(b)Given the vector field F(x,y,z) = 5xyzQx + y2ay + YZQz. Verify Stoke'sTheorem by evaluating over the open surface S defined by five sidesof a cube measuring 1m on a side and about the closed curve C, asshown in the figure. i! (7.5)

'1'1

c

1M

'i.-- 1 ? ,(- -Q3 (a] Given the vector E =4Sin-¢Qr' Evaluate the integral rE.dS over the

rregion lying between the spherical surfaces r=2 and r=4. (5)

(b)Transform the vector C = ZSin¢Qp - pC'os¢Q¢ + 2pZQz to Cartesiancoordinates. (7.5)

UNIT-IIQ4 [a] Define electric flux. State and prove Gauss's law in electrostatics in

integral and differential form. (6.5)(b)A volume charge distribution in cylindrical coordinates is given by

p(r,<jJ,z) = Po(~) 0< r < a where Po is a constant. Determine0; a < r < OC!

electric field intensity at all points using Gauss's Law in integralform. (6)

P.T.O.


[-2-]

Q5 (a) State the boundary conditions that the vectors ii(orB)must satisfyat the boundary between two different media. (6.5)

(b)A uniform line charge of 2J.!C/mis located on the z-axis. Find theelectric field in Cartesian coordinates at the point P(1,2,3) if thecharge extends from 2=-4 to 2=4. (6)

UNIT-IIIQ6 (a) Derive an expression for intrinsic impedance of a lossy medium.

What is the phase difference between the electric and magneticfields in a good conductor? (8)

(b)A lossless dielectric medium has 0" = 0, u, = 1and s, = 4. Anelectromagnetic wave has magnetic field components expressed asfL.;:; --O.lCos(wt - z)ox + 0.5Sin(w[ - z)oyA 1m. Find the components ofelectric field intensity of the wave. (4.5)

Q7 (a) Prove that if a plane electromagnetic wave is incident normallyfrom medium 1 to medium 2, then the reflection coefficient 0" andtransmission coefficient T are related as T =: 1-I- r . Discuss thecase when medium 1 is a perfect dielectric and medium 2 a perfectconductor. . (9)

(b)In free spaceH=0.lCos(2xl08t-kx)oyAlm. Calculate (i) k, A, T. (ii)The time t it takes forthe wave to travel A/8 distance. (3.5)

UNIT-IVQ8 (a) Prove that the input impedance, Zi, of a finite lossless line having

length 1, is given by Zi = ZO[ZI. -I- jZo tan f31]. The symbols have theirZo -I- jZI. tan f31

usual meaning. (8)(b)In a lossless transmission line, the velocity of propagation is

2.5xl08m/s. If the capacitance of the line is 30pF1m, find-(i) L(ii)Zo(iii)~ at lOOMHz and (iv) reflection coefficient if the line is

terminated by a resistive load of 500. (4.5)

Q9 (a)Write an elaborate note on an open-circulated transmission line. (6)(b)Prove that quarter wave (A / 4) line acts as an impedance inverter. (3)(c) Discuss the basic idea of impedance matching in transmission

lines. Explain how it is achieved? (3.5)

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END TERM EXAMINATIONFOURTH SEMESTER MAy JUNE 2011

Paper Code: ETEE212 Subject: Power Station PracticeTime : 3Hours Maximum Marks: 75

Note: Attempt all the five questions. Internal choice is indicated. I

Ql Comment with sufficient reasons, on the following:- (5x3=lS)(a) It is always economical to improve the p.f. to unity of an electric installation.(b) In order to have lower cost of electrical energy generation, the load factor and

diversity factor should be low.(c) The pH value of water used for boilers is 7.(d) The moderator used in fast breeder reactor is heavy water.(e) For low head and high discharge, Kaplan turbine is used in Hydro-electric

stations.

Q2

Q3 (a)

(b)

(a)

(b)

Q4 (a)

(b)

(a)

(b)

Q5 (a)

(b)

(a)

(b)

(a) What is tariff? Discuss and compare various tariffs used in practice by electricutilities. (9)

(b) What is geothermal power? Discuss various precautions to be taken duringoperation of a geothermal power plant. (6)

OR(a) What are 'Load Curves' and Load Duration Curves? Discuss their importance in

the economics of generation. (6)(b) What is wind power? Discuss various factors on which this power depends?

Describe briefly the characteristics of the generator used for harnessing thisform of energy. (9)

Describe briefly the construction and principle of operation of the following in athermal power plant;- (8)(i) Electrostatic precipitator (ii) Economizer (iii) Feed water systemDraw a typical layout of a gas turbine power plant and describe briefly thefunctions of different components of this plant. (7)

ORDraw a typical layout of a thermal power plant and describe briefly the functionsof the following components:- (8)(i) Coal and ash handling plants (ii) Steam generating plant.Describe with a neat diagram the principle of operation and application of a gasturbine power plant. Discuss its advantages over a thermal power plant. (7)

What are various types of turbines used in hydro-stations? Discuss theapplication of each one of therewith, in regard to head, discharge, etc andcompare their performance. (12)Using block diagram, draw layout for a diesel power plant indicating variouscomponents and list various auxiliary equipment required. (3)

ORDraw a typical layout of a hydro station and explain the function of the followingcomponents:- (12)(i) Reservoir (ii) Forebay (iii) Penstock (iv)Surge tankExplain the operation and applications of a Diesel power plant. (3)

Explain clearly how the operation of nuclear reactor is controlled for generationof electrical power? (9)Draw a line diagram of an indoor substation and list out various equipment inthe substation. (6)

ORWhat are various control rods used in a nuclear reactor? Describe the functionof each of these. Also, explain what you mean by critical mass of a reactor? (10)Describe briefly various bus bar arrangements and compare their performance. (5)

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~. (Plea e write your Exam Roll No.) EXIlm Roll No•............•....•....

Q1 i (a) Explain, why the po er factor of an inductiop motor operating at noload is very low? (5x5=25)

I (b) For a slip(S) and lin frequency f1, prove that the frequency of rotoremf in an induction otor is 'Sji'.

(c) Explain the working f capacitor start single phase induction motor.(d) Explain the nature f armature reaction in a synchronous machine

for unity power facto and zero power factor lagging.(e) What are V-curves? raw and explain V-curve for synchronous motor.

Q2 (a) A, 3-phase, 400V, 5at its full load speethe friction and winloss, shaft power an

(b) Draw and explainmotor.

UNIT-IHz induction motor takes a power input of 35kWof 890rpm. The total stator losses are 1kW and

age losses are 1.5kW. Calculate slip, rotor ohmicefficiency. (7.5)he torque-slip characteristics of an induction

(5)Q3 (a) From the equivalent ircuit of a polyphase induction motor, obtain the

following relation 1, ,. = MI+ (~; r l where 12MT is the stator load

component of curre t at maximum torque. Neglect stator resistance. (6.5)(b) Explain auto-trans rmer starting and star-delta starting for an

induction motor. (6)

UNIT-IIQ4 (a) Draw and explain e equivalent circuit of single phase induction

motor. (6)(b)What is double revo 'ng field theory show that single phase induction

motor does not have starting torque? (6.5)

Q5 (a) A universal motor as a 2 pole armature with 960 conductors. At acertain load the mo r speed is 5000rpm and the armature current is4.6A, the armature erminal voltage and input are respectively lOOVand 300W. Comput the following, assuming an armature resistanceof 3.50. (7.5)(i) Effective armatu e reactance(ii)Maximum value f useful flux/pole.

(b) Write short note 0 any two methods for starting a single phaseinduction motor. (5)

UNIT-IIIQ (a) Explain with the h lp of neat diagram, the constructional details of

salient pole synchro ous machine. (5)(b) Explain how the p tier triangle can be drawn with the help of acc

and any two point on the ZPFC. Explain the difference betweenpotier reactance xp d armature leakage reactance Xa,. (7.5)

P.T.O.

~\


Q7 {a) A 6.6kV Istar conn cted 3-phase synchronous motor works atconstant voltage an constant excitation. Its synchroflOus impedanceis 1.5+j12 Q per ph se. When the input power is 1000kW, the pf is0.8 leading. Find th pfwhen input is increased to 1500kW. (6.5)

(b) An altemator, conn cted to infinite bus, is operating at unity powerfactor at half load. ith the field current remaining constant, steam

, input is increased 11alternator begins to operate at full load. Underthis condition, disc ss what happens to power factor and reactivepower flow. (6)

UNIT-IVQ (a) Explain the two- eaction theory as applied to salient pole

synchronol!s mach ne and draw its phasor diagram for a laggingpower factor load. (6)

(b)A salient pole s chronous generator has the following per unitparameter Xct=1.2, Xq=0.8 and ra=0.025. Compute the excitationvoltage Ef on a per nit basis, when generator is delivering rated KVAat rated voltage an a pI of 0.8 lagging. (6.5)

Q(a) Draw and explain the voltage phasor diagram" for a synchronous

motor operating at .5 lagging pf (5)(b)The [u11load curre t of a 3.3kV, star connected synchronous motor is

160A at 0.8pf lagg"ng. The resistance and synchronous reactance ofthe motor are 0.8 and 5.5 Q per phase respectively. Calculate theexcitation emf, tor ue angle, efficiency and shaft output of the motor.Assume the mech ical stray load loss to"be 30kW. (7.5)

************


(Pie e write your Exam Roll No.)

ENDTFOUR

Pap f Code; ETEC204/ETE1E204Pap rId: 28204Tim: 3 Hours

ote: Attempt one question from

Exam Roll No .

RM EXAMINATION

Maximum Marks :75ach unit. Q.1 is compulsory. Internal choice is indicated.

Q 1 (a) Explain the function of all the basic building blocks of an op-amp.(b)What is the import nce of current mirror? Draw the circuit of the

basic current mirror d explain its working.(c) List the important fe tures of an Instrumentation amplifier. Draw the

circuit of a practical nstrumentation amplifier and find·an expressionfor its output voltage

(d)What types of fixe voltage regulators are available? Show thestandard representa .on and discuss main characteristics.

(e) Draw the circuit of All-Pass filter and find its transfer function.Give an application f All-Pass filter. (5x5=25)

Wilson current source and show that its outputal to the reference current. (5)

ORcompensating techniques used in op-amps.

ance. (6.5)

(b)Draw the circuit ofcurrent is almost eq

(a) Discuss the externCompare their perfor

Q3

UNIT-IQ2 (a) Draw the circuit of MOSFET source coupled differential amplifier.

Derive an expression for its CMRR. (6.5)

(b)The time constant RC) of an op-amp integrator circuit is O.lms.

Determine the outpu response for the following input signals:- (6)

(i) 1V peak sine wav

(ii)Step voltage Vi=1 for 0 s t s .5ms .

(iii)2VP-P square wa e of 5KHz.

Draw the input and utput waveforms.

UNIT-IIQ4 (a) Draw the circuit of a multivibrator which can generate a single output

pulse of duration T. xplain the working and derive the expression forthe pulse width T. (6.5)

(b)Draw the circuit of op-amp oscillator to generate radio frequencysignals. Determine e expression for the frequency of oscillation andthe condition for osc llation. (6)

ORQ5 (a) Explain the workin of a square waveform generator and derive an

expression for the requency of oscillation. Suggest a method forobtaining asymmetri al square wave. (6.5)

(b)For an RC-phase hift oscillator, derive the expression for thefrequency of oscillati n and condition for sustained oscillation. (6)

P.T.O.

\


[-2-]

.UNIT-III'..' : 6 (a) For the circuitsh wn in fig.I, find the output voltage waveform for a

sine wave input si nal. (6.5)

... ~.. ,f 'W~'-,

Fig.!

IJ·t

(b) Draw the circuit f a log amplifier and derive the expression for theoutput voltage. Is he circuit independent of temperature? (6)

ig.2

.~ (b) Draw and explain the working of a complementary .symmetry push-: j pull amplifier. De ve an expression for its efficiency. (6)

OR,7 (a) A comparator circ it using positive feedl?ack is shown in fig.2. A sine

wave input is app ied, Derive the output response. Explain Hysterisisin this circuit. . (6.5)

9

UNIT-IV8 (a) Draw the circuit of a second-order low-pass filter and derive an

expression for its transfer function for a maximally flat response inthe pass band. (6.5)

(b)Draw the block s hematic of a PLL and explain the function of eachblock. (6)

OR(a) Draw the circuit of a notch filter and derive an expressIOn for its

transfer function. (6)(b) Draw a block sch matic of voltage controlled oscillator (VeO). Explain

its working and d rive an expression for its frequency. (6.5)

*********.**

.~

.j


Attempt any five ques .ons:- (2.5xlO=25}(a) Explain thc choice f voltage for a transmission system.(b) State the advanta s of high transmission voltage.(c) What is skin effect?(d) Explain the term s rge impedance loading of a transmission lines.(e) What is the effect 0 line capacitance on the line performance?(f) Explain the need of transposition of transmission lines.(g) On what factors do s the insulation resistance of a cable depend?(h) Is sag a necessity 0 an evil? Discuss.(i) What are the factor which affect corona?m Why are suspen ion insulators preferred for high voltage power

transmission?

tease write your Exam Roll No.)

ENDfJper Code: ETEE206'fJperId: 49206ime:3 Hours

Exam Roll No ............•..........

ERM EXAMINATIONSubject: Power System~~

Maximum Marks :75pulsory. Select one question from each unit.

(6)(6.5}

(a) Explain the import ce of reactive power in a power system.(b) Givc a comparison etween ac and dc transmission.

UNIT-II(a) Derive an expressio for inductance of single phase two wire line. (6.5)(b) Determine the indu tance of a 3-phase symmetrical line whose conductors

are placed at the orners of an equilateral triangle of sides meter. Thediameter of each co ductor is 20mm. (6)

UNIT-I2 What is elective pow r supply system? Discuss different types of supply

systems and give their omparison. (12.5)

5 A lOOlan long 3-phas ,50Hz transmission line has following line constants.Resistancejphasejkm= .10, Reactancejphasejkm=O.5Q,Susceptancej phase j =lOxl0-6S. If the line supplies load of 2011Wat O.9pf.lagging at 66kv at the r ceiving end. Calculate by nominal1t method- (12.5)(i) Sending end power f: ctor (ii)Regulation (iii)Transmission efficiency.

UNIT-IIIExplain the phenomen n of corona. Discuss the methods of reducing coronaand interference. State e advantages and disadvantages of corona. (12.5}

(a) Define string efficie cy. Explain the methods of improving string efficiency. (6.5)(b) An insulator string consists of three units, each having a safe working

voltagc of 15kv. Th ratio of self-capacitance to shunt capacitance of eachunit is 8: 1. Find m . urn safe working voltage of string. Also, find stringefficiency. (6)

(6}(6.5}

UNIT-IVsag in overhead lines when supports are at

(6.5)(6)

(a) Derive the expressi n forunequal levels.

(b) Write short notes on the following:-(i) Sag template (ii)vibration dampers

(a) Write a brief note on oil-filled cables.(b) Explain capacitance ading of cables.

************


Exam Roll No •••••......•..•..••.•..

ENDT·write your Exam Roll No.)

SEMESTER B.TECH. MAy-tOtOSubject: Control Engineering

Maximum Marks :75Hte: Q.1 is compulsory. Attempt ny five questions from the remaining questions. Assume

su table missing data if any.

(f)

~Q....

Fig.l shows the polar (i) --- (ii) _I (iii) jw (iv) (I + jwT)1+ jwT jw

(g) Open loop transfer fun tion is G(s)H(s) = 2 I . The system is-s (Ts + 1)(i) Stable (ii)Unsta Ie (iii)Marginally stable (iv)Conditionally stable

(h) Addition of pole to the pen loop transfer function has the effect of-(i) Pulling root locus t right (ii) Pulling root locus to left(iii)Pulling root locus d wn (iv)Pulling root locus up

(i) Which of the following compensator will be used to increase the damping ofa complex roots which are badly under damped-(i) Phase lead (ii) Ph se lag (iii) Phase lag-lead (iv)Anyone

(j) A second order system exhibits 100% overshoot, its damping coefficient is-(i) Zero (ii)Uni (iii)Less than unity (iv)More than unity

Ql Tick the correct answer:- (lOxl=lO)(a) If unit step input is ap lied to first-order system. The steady state error will

be(i) Zero (ii)Time co st. (T) (iii)Vary with time (iv)None of the above

(bJ If a pole of a system is n jw axis, the system is-(i) Stable (ii) Unstabl (iii)Marginally unstable (iv)None of the above

(c) Velocity feedback incr ases the damping ratio without affecting undampednatural frequency of th system-(i) True (ii) False

(d) Given two systems _C( ) = _1_ .....(i) C(S) = _I_ .....(ii)R() S + 1 R(S) 3S + I

(i) First system has les rise time.(ii) Second system has ess rise time.(iii)Both have equal ris time.(iv)Data is insufficient.

(e) Gain margin in dB of 9 unity feedback system whose open loop transfer

function 1 is giv n by (i) 0 (ii) 1 (iii) -1 (iv)InfiniteS(S + 1)

Q2 (a) For the given electrical circuit as shown in fig.2. Obtain the transfer functionEo (s)IE; (s) by use of bl ck diagram approach. (6)

P.T.O.


[-2-)(b) For the given electri al system as shown in fig.2. Obtain the tr

function by using Mas n's Gain formula.

Q3 (a.)The system shown in fig.3 consists of a unity feedback loop containing aminor rate feedback lop. (6)

(blWithout any rate fee back (b=O)determine the damping factor, undampednatural frequency an overshoot of the system.

~t' ~ \t;;, CIS)Y lS,(S-I-q

L-:·'oSJ

Determine the rate f edback constant ~hich will increase the equivalentdamping factor of the ystem 0.8. (7)

(7)

\-(S \.<;~\)\sr-1'-'S

-\'\~

\-\t..~

.r~~~4- .alf the value found in 4(al and study the relative

(7)

(13)

d determine the stability for given open-loop transferK

(S~ + 1)(ST2 + 1)

1O(S + 3) th . I .d h d .___ , Draw e NyqUlst p ot an t en etermmeS(S -1)

loop system. (6)the stability of close

(b) Consider G(S)H(S)

20(S + 10)Open loop transfer func ion is given by G(S)H(S) = 2 • DrawS(S + l)(S + 2S + 2)

the Eoge plot and find g 'n margin (GMIand phase margin (PM). (13)

(al Draw the polar plot

function G(S)H(S) =

Sketch the root-loci of th system shown in fig.5.Q.\Sj

(b) Reduce the gain tostability of the syste

(a) Feedback control sys m is shown in fig.4. The process transfer function is

G(S) = K(S + 40) and the sensor transfer function is JJ(S) = _1 __ .S(S + 10) S + 20

Find the gain K that result in marginal stability. Determine ,the oscillationfrequency. R\s) \5) (6)

C:n.\~)

Q

Q

Q5

Q4

Q Write short notes on an two of the following:-(al LAG-LEADcompens tion(b) PID Controller(c) Steady state Error c nstraints(d) Synchros

(6.5x2=13)

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Exam Roll No•.......•..•...........

RM EXAMINATIONSEMESTER B.TEen. MAY-2010

Subject: Electromagnetic Field TheoryMaximum Marks :75

Note: Q.1 is compul ory. Attempt one question from each unit.

write your Exam Roll No.)

Code: ETEE2103 Hours

Ql (a) If the electric potential at point is zero. Does it follow that electrical fieldintensity is also zero at hat point. Explain.

(b) If V2U = O. Why does it ot follow that U is identifying zero?(c) Why is electrostatic pot ntial is continuous at a boundary?

- -(d) Express E and B in te s of potential function V and A.(e) Under what condition will be Reflection Coefficient and Transmission

coefficient for perpendi ular polarization will be same as that of parallelpolarization.

(f) What is meant by ski depth of a conductor? How is it related to theattenuation constant? ow does it depend on cr and 8?

(g) What is the essential d fference between transmission line and an ordinaryelectric network?

(h) What is smith chart d where is the point representing a short circuit onsmith admittance chart

(i) Obtain approximate ex ression for r and Zo for a Lossy Transmission Line atvery low frequency suc that roL«<R, roC«<G.

Ul Define SWR. How is it r lated to voltage and current reflection coefficient?( l0x2.5=25)

UNIT·I

Q2 (a) Determine the charge j[ r2

)_ 20r+- ar

ensity p in both regions. If D = 35 ~--a

138r r

r::;2

r>2

in cylindrical co-ordina es. (6)(b) Distinguish between pLacian of scalar and vector function. Find the

Laplacian of (i) V = 1 (cylindrical co-ordinate) (6.5)reo t/J

(ii) A=x2 zax+xy2Zay+xyz2az'OR

Q3 (a) Transform the vector B = zax + (1- x)ay + Y az into cylindrical co-ordinates. (4)x

(b) Define the terms gradie t, divergence and curl of vector. (6)(c) Find the constant b so that vector F=t(x+3y)+ )(y-2x)+k(x+bz)is

solenoidal. (2.5)

UNIT-IIQ4 (a) Solve Laplace equat on for the region between cones. Given at

() = (}j, V = ~ and at () (}2' V = 0 . The cone vertices are isolated at r=O. (6)(b) In cylindrical co-ordin es two <j>=constantplanes are insulated along z-axis.

Neglect fringing and c culate Ebetween planes assuming that V=lOOvoltfor t/J = a and V = 0, t/J 0 . (6.5)

ORQ5 (a) Write the boundary c nditions that exist at interface of free space and a

magnetic material of in mite permeability. (6)(b) Define current densi vector J. Using Ampere's Circuital Law, derive

relationship between Band J. (3)(c) Explain the terms ener density and energy stored in magnetic field. (3.5)

P.T.O.


(6).~.j

Q

Q

( t;

uJi~~m " '(a) Fa; normal incid nee upon the dielectric-dielectric interface \,..\ ..

f-Ll' = f-L2 = f-Lo' we defi e Rand T as the reflection and transrmsSl0n coeffic~for average p wer i.e. Pr = ~ , p, = Tp' Prove that;0." t7"7 {TO"'Il twg

R __(111 - 112)2 al1d T __ 411,112___ when nl and n2 are refractive index.111 + 112 (111+ 112Y

(b) State Poynting Theorem. In a non-magnetic materialH = 30Cos(2Jr xl 08 t 6x)a r mA / m. Find (i) I~trinsic Impedance (ii) Poynting

" vector (iii) Time ave age power crossing the surface x=l, 0<y<2, 0<2<3m. (6.5)OR

(a) Derive the followin general expression of the attenuation and phase

constant for can ucting media a = @ P2EUI+ (:Er -I)NPf m and

[J=@ ~2E(1+(:)' +l}adfm (6)

(b) A 3GHz y-polarized uniform plane wave propogate in the +x direction in anon-magnetic medi m having a dielectric constant 2.5 and a loss tangent10.2. (6.5)(il Determine the istance over which the amplitude of propogating wave

will be out in hal .(ti) Determine intri sic impedance the wavelength, the phase velocity and

group velocity of wave in the medium.

(iii)Ass.uming E :::a x 50Sin( 60Jr x 109 t + ~) at x=O. Write the expression for H

for all t and x.

. UNIT-IV-r2- ~~~--t

v;;.(a)

Consider the two art network shown in fig(a). The relation between the

, ' [V] [A DB][_V/22]forinput and output v riables can be written in matrix I::: ,II C

(

cash yf 20 sinh yf]Lossy Line in fig(b), show that ABCD matrix is _1_ sinh yf cosh yf . (6.5)

20 '

•(b) A 600 air Line operating at 20MHz is 10m long. If .the input impedance is90+j 1500. Calcula 2 L ' r and S. (6)

OR(a) The input imped ce of an open short circuited Lossy Transmission Line

has both a resistiv and reactive component. Prove that input impedance ofa very short secti n e of a slightly' Lossy Line (ae «< 1, {Jf «< 1)0 isapproximately. (4.5)(i) 2

m= (R + jwL)e ith a short circuit termination.

(ii) 2 = G - jOJC with an open circuit termination.In G2 + (OJC)

(b) The open-circuit d short circuit impedance measured at ~nput terminal ofa transmission I ne 4 meter long are respectively 250 L. -500g and360 L. 2000. (i) De rmine Zo, a. and 13. (iiI Determine R, L, G and C. (8)

9

8

.~.j

---.

...............


Exam Roll No .•..••.......•..••....•

ERM EXAMINATIONFOu rnSEMESTER B.TECH. MAY~OlO

Subject: Power Station PracticeMaximum Marks :75

pt remainIng questions as per internal choice indicated.

er Code: ETEE212e:3 Hours

Note: Q.1 is compulsory. Atte

Identify correct or inc rrect for each of the following statement:-(1x25=25)(a) Loud curve depicts energy demand per day.(b) Sometimes alterna ors are Hydrogen Cooled.(c) Steam pressure in PP is of the order of 20kgf / cm2.

(d)Capital cost of a GTPP is lower than that of steam PP for samecapacity.

(e) Kaplon turbine is axial flow turbine.(f) Stainless steel is ost widely used material in solar cells.(g) Main byproduct of a Biogas plant is organic manure.(h) Substations are si ply switching stations.(i) Power station swit hgears are not manufactured in India.(j) 50% Power Gener tion Capacity in India is Hydro.(k) Graphite is never sed as moderator in NPP.(1) 1 watt=lJoule/sec.(m) Low p.f. range eans p.f.>0.9.(n)Largest constitue t of Biogas is C02.(0) Cost of per MWT installation in India is approximate Rs. 5 crores.(p)Wind power plant are most efficient at wind velocity of 10-15Kmph.(q) SI engines are use to drive portable D.G.sets.(r) Gas turbines are elf-starting.(s) Typcicallife of a ydro Power Plant is 20 years.(t) Super Thermal Po er Plants have capacity larger than 2000MW.(u) Diesel Power Plan s are used as Peak Load Plants.(v)Largest Hydro Pot ntial in India is in Himachal Pradesh.(w)Calorific value of oal used in T.P.P. is 5000Kcal/kg.(x)No MHD power pI nt was ever exerted in India.(y)Ash-handling pIa t is a sub system of Coal-Handling plant in T.P.P.

2 Discuss the salient features of a Steam Power Plant and explain thefactors leading to ch ice of its location. (12.5)

OR(a) Explain the impo tance of 'Moderator' in Nuclear Power Plant. (5)(b)Calculate the am unt of nuclear fuel used per year, in a 100MW NPP

working at 90% oad factor, if lkg of processed fuel produces energyequivalent of 25 illion KWH,assuming conversion efficiency of 80%.(7.5)

Q3 How could wind ene gy be tapped for Power Generation? Draw schematicdiagram of a Wind ower Plant and explain functioning of its importantsystems. (12.5)

ORCompare the meri s and demerits of a Diesel generator and a GasTurbine used for po er generation, explaining their fields of operation. (12.5)

Q4 Explain the govemi g system of a reaction type hydro turbine. Can thesame system be us d in a micro-hydal plant? (12.5)

OR

P.T.O.


.~I

[-2-]

N.P.S.6000/-10%10%0.150.25

H.P.S.5000/-10%5%0.051.00

S.P.S.RS.4000/-

10%15%

Rs.0.20RS.0.25

Sketch Layout of a ical Electric Substation located .in, an IndustrialArea. Describe briefl equipment installed therein. (12.5)

ORA turbine is to opera e under a head of 25m at 200 rpm. The discharge is8.5m3/sec and over 1efficiency is 90%. Determine (a) type of turbine (b)Powrer generated an (c)Specific speed of turbine. (12.5)

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Using following data, calculate overall cost/kwh in respect of steam,hydro and nuclear ower stations:- .Maximum Load demand=100MW,Load factor=O.4.

S.DO. Cost(i) Capital/kw(ii) Interest(iii) Depreciatio(iv) OP. Expens s/kwhv T&D cost h

5

.~,_I

I I


Fourth Semeter

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