(dee 311) - anucde1. (a) how crossover dissolution eliminated in class ab amplifier? (b) what is...

(DEE 311)

B.Tech. DEGREE EXAMINATION, MAY 2012.

(Examination at the end of Third Year Third Semester)

Electricals and Electronics

Paper I — LINEAR CONTROL SYSTEMS

Time : Three hours Maximum : 75 marks

Answer Question No. 1 Compulsorily. (15 × 1 = 15)

Answer ONE question from each Unit. (4 × 15 = 60)

1. (a) Explain the principles of superposition.

(b) Define sensitivity.

(c) Name the major parts of a closed loop control system.

(d) What is the effect of positive feedback on stability?

(e) State mason's gain formula.

(f) How are feedback control systems classified?

(g) What are the time domain specifications?

(h) What are the frequency domain specifications?

(i) How are the locations of roots of characteristic equation related to stability?

(j) What is constant N circle?

(k) State the necessary condition for the Routh's criterion for stability.

(l) What is positional coral coefficient?

(m) State Nyguist criterion of stability.

(n) Name and sketch three typical tests inputs in a control system.

(o) What do you understand by breakaway paints in root locus technique?

UNIT I

2. (a) Obtain the transfer function )(

)(

sX

sY of the SFG shown in fig.

Or

(b) For the electrical network shown in fig. Obtain the transfer function. Deduce the

result when R1 = R2= R and C1=C2=C.

Or

3. (a) Explain the mason's gain formula.

(b) Draw a signal flow graph for the following set of linear equations

053 321 =++ yyy

042 321 =−+ yyy

032 =−− yy

Also obtain the overall transfer function.

UNIT II

4. (a) Show that the transfer function of a system with unit step response by

tettC 2

2

55

2

5)( −−+= is given by

)2(

)1(10

)(

)(

++

=SS

S

sR

sC.

(b) For the system show in fig, find the value of ‘a’ such that the damping ratio is 0.5.

Determine the rise time, peak time, maximum overshoot and settling time, is the

unit step response.

Or

5. Explain the following:

(a) Absolute stability

(b) Relative stability

(c) Bounded input – Bounded output

(d) Rowth- Hurwitz criterion.

UNIT III

6. (a) Sketch the root locus for )1)(1(

)3)(2()().(

−+++

=SS

SSHSHSG

Or

(b) Sketch the Bode plot for a unity feedback system characterized by the loop transfer

function )005.01)(001.01(

)025.01)(2.01()(

3 SSS

SSKSG

++

++

Show that the system is conditionally stable. Find the range of values of K for

which the system is stable.

UNIT IV

7. (a) Write short notes on lead-lag compensation.

(b) Explain the necessity of a compensator

Or

8. A system is characterized by the following state space equation.

0;1

0

02

13

2

1

.

2

.

1 >

+

−

−=

tu

x

x

x

x

[ ]

=

2

101x

xy

(a) Find the TF of the system.

(b) Compute the state transition matrix.

(c) Solve the state equation for a unit step input under Zero initial condition.

——————

(DEE 312)


(Examination at the end of Third Year Third Semester )


Paper II — ELECTRONIC CIRCUITS — II


Answer Question No. 1 compulsorily. (15 × 1 = 15)


1. (a) How crossover dissolution eliminated in class AB amplifier?

(b) What is class B Amplifier?

(c) What is the mex.V due of conversion efficiency for series fed class - A Amplifier?

(d) What are the applications of power amplifiers?

(e) What is the effect of employing –ve feed backon voltage and current gain of

parallel amplifiers?

(f) What is the Barkhausen Criterion?

(g) How the stability can improved in oscillators?

(h) Why LC oscillators are not suitable?

(i) What are the applications of formed amplifiers?

(j) Why double-tuning employed in temed amplifiers?

(k) Classify multivibrators.

(l) What are the factors affecting the load voltage in a regulator?

(m) What is meant by Thermal Protection?

(n) What is a performance factor of Regulator?

(o) List various sweep circuits.

UNIT I

2. (a) Explain the operation of complementary by symmetry class B Amplifier with neat circuit diagram.

(b) Derive the expression for efficiency of a transformer coupled class A amplifier.

Or

3. (a) A complementary symmetry class B Amplifier. Supplied output to load of 3Ω from the supply voltage of 20 V. calculate Max. power output, power output, power dissipation rating of each transistor?

(b) Prove that the maximum efficiency of a series fed, directly coupled class ‘A’ Amplifier in just 25%?

UNIT II

4. (a) Draw the circuit diagram of a voltage shunt feedback using BJT and derive the

expression for voltage gain with feed back.

(b) With the help of general block diagram explain the term feedback.

Or

5. (a) In a transistoligel Hatley oscillator the two inductances are 2 mH and 20 mH

while the frequency to be changed from 950 kHz to 2050 kHz. Calculate their

range over which the capacity is to be varied.

(b) Explain the operation Wein bridge oscillator with help of neat diagram.

UNIT III

6. (a) Explain the operator of astable multivibrator with help of neat circuit diagram.

(b) Draw and explain the circuit of double tuned Amplifier with the help of frequency

response?

Or

7. (a) Draw and explain the tapped single tuned capacitance coupled amplifier.

(b) 3m band width for double temed amplifier is 10 kHz. Calculate the bandwidth if

such three stages are cascaded. Also calculate the bandwidth for four stages.

UNIT IV

8. (a) Explain with block diagram, the basic types of voltage regulator circuits.

(b) Draw and explain transistorized can start current sweep generation circuit.

Or

9. (a) Draw neat circuit diagram, of a series regulator and explain its working.

(b) Explain the operation of voltage sweep circuits.

———————

(DEE 313)




Paper III — GENERATION OF ELECTRICAL POWER




Write brief on:

1. (a) Define mass curve.

(b) Define load duration curve.

(c) What is penstock?

(d) Define hydrographs.

(e) What is the principle of working hydroelectric plant?

(f) What is Super heater?

(g) What is a tariff?

(h) Define power factor.

(i) Define diversity factor.

(j) Define load factor.

(k) List the various types of equipment that can came power quality problem.

(l) Define depreciation reserve.

(m) Define solar pond.

(n) What is meant by fuel cell?

(o) What are control rods in the nuclear power plant?

UNIT I

2. Draw and explain of typical layout of thermal power plant describe the functions of a

coal and ash handling plant.

Or

3. Write short notes on:

(a) Boiler (b) Economizers (c) Size of generator Units.

UNIT II

4. Write Short notes on:

(a) Classification of Hydroelectric plants

(b) Characteristics of turbines and governing of turbines.

Or

5. Write short notes on:

(a) Boiling water reactor

(b) Liquid metal cooled reactor.

UNIT III

6. Draw a typical layout of a gas turbine power plant and describe the functions of

different components of this plant.

Or

7. What is wind power? Explain the principles operation of wind power. Discuss various

factors on which the power depends.

UNIT IV

8. Explain the reasons why power factor tariff is imposed. Explain clearly the procedure for

finding out the capacity of the shunt capacitor required for an existing installation for

improvement of power factor.

Or

9. (a) Derive an expression for the most economic power factor.

(b) A consumer consumes 1 * 106 Kwhrs per year and his yearly load factor is 40%.

The tariff is Rs. 100 per kw per year + paise 25 per unit. Determine the saving in

his energy cost annually is he improves his load factor to 100% percent.

–––––––––––

(DEE 314)




Paper IV — ELECTRICAL MEASUREMENTS




1. (a) What is the material generally used for control spring?

(b) What type of damping is used in M.C. type instrument?

(c) What do you mean by the damping force?

(d) Which meter, the ammeter (or) voltmeter has high resistance?

(e) Which magnetic property is used in repulsion type in instrument?

(f) What are the common errors in all instruments?

(g) How the temperature error can be minimised?

(h) What type of coils are there in a dynamometer type instrument?

(i) How many current coils are there is a single phase wattmeter?

(j) How the damping force is produced?

(k) How the current is lead in the instrument?

(l) What do you understand by the exciting coil?

(m) What are the applications of induction type instrument?

(n) What is the electrical resonance frequency meter?

(o) How the emf is induced in the moving coil?

UNIT I

2. Describe the construction and working of PMMC instrument. Derive the equation for

deflection if the instrument is spring controlled. Describe the method of damping used

in these instruments.

Or

3. Describe the constructional details of an attraction type moving iron instrument with

the help of a neat diagram. Derive the equation for deflection if spring control is used

and comment upon the shape of scale.

UNIT II

4. Draw the equivalent circuit and phasor diagram of a current transformer. Derive the

expressions for ratio and phase angle errors.

Or

5. Describe the working of Hay’s bridge for measurement of inductance. Derive the

equations for balance and draw the phasor diagram under conditions of balance. Why is

this bridge suited for measurement of inductance of wish ‘Q’ coils?

UNIT III

6. Write short notes on the following:

(a) Ballistic galvanometer (b) Flux meter

Or

7. Write short notes on the following:

(a) Measurement of permeability (b) Epstein’s square.

UNIT IV

8. (a) Explain the functioning of a time base generator in a CRO.

(b) Describe an overview of applications of a CRO.

Or

9. Describe the construction and working of

(a) LVOT (b) Thermister.

———————–––

(DEE 315) B.Tech. DEGREE EXAMINATION, MAY 2012.



Paper V — TRANSMISSION AND DISTRIBUTION


All questions carry equal marks.

Answer Question No. 1 Compulsorily. (15 × 1 = 15)


1. (a) Explain bounded conductors.

(b) What is an ACSR conductor?

(c) Give the expression for the disruptive critical voltage.

(d) Give the limitations of Transposition.

(e) What is the necessity for a double circuit line?

(f) What are the factors affecting corona?

(g) What is Ferranti effect?

(h) What is sag template?

(i) What are the important considerations in the mechanical design of overhead lines?

(j) What are dampers?

(k) What are the factors on which sag depends on?

(l) What is the difference between 3 phase, 3 wire and 3 phase, 4 wire distribution

systems?

(m) What is the importance of minimum potential on the distributor?

(n) What are the advantages of suspension insulators?

(o) What is shackle insulator?

UNIT I

2. (a) Discuss the concept of GMR and GMD in the calculation of transmission line

inductance.

(b) A two conductor single phase line operates at 50 Hz. The diameter of each

conductor is

20 mm and the spacing between the conductors is 3 m. Determine the capacitance

of the line taking into account the effect of ground. The height of conductors above

ground is 6 m.

Or

3. (a) Derive the expression for the inductance of a 3φ double circuit line, in which the

sub-conductors are placed at the corners of a regular hexagon.

(b) The three conductors of a 3-φ line are arranged at the corners of a right angled

triangle. If two sides of this triangle is 2 m, find line-to-neutral capacitance per

km. Take the diameter of each conductor as 1.24 cm. The conductors are

transposed at regular intervals.

UNIT II

4. (a) Derive the expression for sending end voltage in nominal T method and end

codenser method.

(b) In a 3 φ line with 132 kV at the receiving end, the following are the transmission

constants :

°== 398.0DA , °= 75110B Ω , °= 880005.0C v.

If the load at the receiving end is 50 MVA at 0.8 lagging pf determine the value of

the sending end voltage.

Or

5. (a) To prove that the conductor takes the shape of a catenary between two equal

supports.

(b) An overhead line has a span of 250 m. Find the weight of the conductor if the

ultimate tensile strength is 5788 kg, sag is 1.5 m and factor of safety is 2.

UNIT III

6. (a) A single phase load of 5 MW is transmitted by a pair of overhead conductors. If a

third conductor of the same cross section and material be added and 3-phase

supply be thus substituted for the original single phase, calculate the 3-phase load

which can now be transmitted if the voltage between the conductors and the

percentage loss in the lines remains unchanged.

(b) A dc 3-wire system with 460 V across outers supplies 250 kW on the positive and

400 kW on the negative side, the voltages being balanced. Calculate the voltage on

the positive and negative sides respectively. If the neutral wire becomes

disconnected from the balancer set.

Or

7. Write short notes on the following :

(a) Sectionalized double busbar system.

(b) Protection against travelling waves.

UNIT IV

8. (a) Explain the methods of improving string efficiency.

(b) The potential across the 6 units of a string is equalized by using graded insulators.

If the capacitance of the top insulator is 8 C and that of pin to earth is C, calculate

the capacitance of the other units. If instead of graded insulators, a guard ring is

used to equalize the potential, calculate the capacitance of each link to conductor.

Assume the insulators used in the string are similar to that of the top.

Or

9. A single core 66 kV cable working on a 3 phase system, has a conductor diameter of 2 cm

and a sheath of inside diameter 5.3 cm. If two inter sheaths are introduced in such a

way that the stress varies between the same maximum and minimum in the three layer,

find

(a) Positions of inter sheaths

(b) Voltage on the inter sheaths

(c) Maximum and minimum stress.

———————–

(DEE 316)

B.Tech. DEGREE EXAMINATION, APRIL/MAY 2012.



Paper VI — ELECTRO MECHANICS – III




1. Write brief notes on the following

(a) What is armature reaction?

(b) Define synchronous impedance.

(c) Define regulation of a synchronous generator.

(d) Write e.m.f. equation of synchronous generator.

(e) Explain harmonics in generated voltage.

(f) What are the applications of salient pole alternator?

(g) What is the limitation of Potier triangle method?

(h) Define synchronizing power.

(i) What is the meaning of load sharing?

(j) Define inverted V curves.

(k) What are the applications of synchronous condenser?

(l) What are the applications of Repulsion motor?

(m) What is synchronous capacitor?

(n) Draw the load characteristics of universal motor.

(o) Give the two applications of stepper motor.

UNIT I

2. (a) Write the expression, showing the relationship between speed, frequency and

number of poles of a synchronous machine.'

(b) The speed of rotation of the turbine driving an alternator is 166.7 rpm. What

should be the number of poles of the alternator if it is to generate voltage at 50Hz.

Or

3. Explain the voltage regulation can be predicated using emf and mmf methods.

UNIT II

4. (a) State the need for parallel operation of alternators.

(b) What are the conditions for parallel operation of three – phase alternators.

Or

5. (a) Explain effect of change of excitation of a synchronous generator connected to an

infinite bus – bar.

(b) What should be done to cause an alternator to share load after synchronisation?

UNIT III

6. (a) Explain why a synchronous motor does not have starting torque. Explain one

method of starting a synchronous motor.

(b) Explain the effect of change of excitation of a synchronous motor on its armature

current.

Or

7. (a) What are the causes of Hunting and how if it is prevented?

(b) Explain the power distribution in a syn. motor.

UNIT IV

8. Write short notes on the following :

(a) Reluctance motor (b) Hysteresis motor.

Or

9. (a) Explain the principle operation of linear induction motor.

(b) Write short notes on repulsion motor.

———————–––

(DEE 321)


(Examination at the end of Third Year

Fourth Semester)


Paper I — LINEAR IC'S AND APPLICATIONS




1. (a) Define CMRR.

(b) What is a cascade amplifier?

(c) What are the factors that effect the electrical parameters of op-amp?

(d) List two special cases of inverting amplifier.

(e) What are the two requirements for oscillations?

(f) What is frequency stability?

(g) Give applications that require a VCO.

(h) What is the difference between clippers and clampers?

(i) What is a sample-and-hold circuit?

(j) Define the term resolution for D/A converter.

(k) What is a window detector?

(l) List the advantages of a switching regulator.

(m) What is a PLL?

(n) What is a power booster?

(o) What are the basic operating modes of 555 timer?

UNIT I

2. (a) With help of block diagram. Explain the operational amplifier indicating the

various building blocks.

(b) Explain the operation of summing amplifier with circuit diagram.

Or

3. (a) What are the three differential amplifier configurations? Explain briefly.

(b) Give the frequency compensation techniques adopted in operational amplifiers.

UNIT II

4. (a) Draw the schematic diagram of RC phase shift oscillator using op-amp? Explain its

operation.

(b) Explain the operation of non inverting comparator with neat circuit diagram.

Or

5. (a) Draw the circuit diagram of regenerative comparator using op-amp? Explain.

(b) Explain how the op-amp can be used as sewtooth wave generator.

UNIT III

6. (a) Explain the successive approximation A/D converter.

(b) What is a sample-and-hold circuit? Explain in detail.

Or

7. (a) Explain the operational D/A converter with binary weighted resisters.

(b) Draw the circuit diagram of peck detector and explain.

UNIT IV

8. (a) Explain how astable multivibrator act as a free-running ramp generator.

(b) Design a first-older low pass filter for a high cut-off-frequency of 2 kHz and pass

band genin of 2.

Or

9. (a) Explain passive filter and differentiate between active and passive filters.

(b) Explain the working of PLL with help of block diagram.

–––––––––––

(DEE 322)



Fourth Semester)


Paper II — MICROPROCESSORS AND INTERFACING


Answer Question No. 1 compulsory. (15 × 1 = 15)


1. (a) What is an over flow?

(b) What is the purpose of the pointer register?

(c) Which jump instruction is 5-byte long?

(d) How big is the flag of the 8086?

(e) What is REP prefix?

(f) What is the use of lock prefix?

(g) What do you mean by addressing modes?

(h) What is meant by Hand shaking?

(i) What is Band rate?

(j) What are the DOS function calls?

(k) What is a linker?

(l) Macro means what?

(m) What is a DMA?

(n) What is a address bus?

(o) What is 8086 maximum mode?

UNIT I

2. (a) Draw and discuss the internal block diagram of 8086.

(b) Draw and discuss a typical minimum and maximum mode 8086 system.

Or

3. (a) Explain the physical memory organization in an 8086 system.

(b) State and explain the different instruction formats of 8086.

UNIT II

4. (a) Write an ALP to convert a four digit octal number to decimal numbers.

(b) What is the significance of the assembly language program development tools?

Explain in detail.

Or

5. (a) Explain different program development steps for writing 8086 ALP.

(b) Explain the coding template for 8086 ‘MOV’ instruction to mole data between

memory location and register.

UNIT III

6. (a) Draw and discuss interrupt structure of 8086 in details.

(b) What is the difference between hardware and software interrupt?

Or

7. (a) Explain in structure of interrupt vector table of 8086.

(b) Explain the interrupt response sequence of 8086.

UNIT IV

8. (a) Draw and discuss the different mode of operation of 8253.

(b) Explain the working of USART 8251 with net block diagram.

Or

9. (a) Explain serial data transmission methods and standards.

(b) How does 8259 A differentiate between an 8-bit and 16-bit processors?

———————–

(DEE 323)



Fourth Semester)


Paper III — DIGITAL SIGNAL PROCESSING




1. (a) What is a causality condition for LTI system?

(b) Define convolution sum.

(c) What is a time-invariant system?

(d) State Parseval’s relation in z- transform.

(e) Define system function.

(f) What is meant by Region of convergence?

(g) Find the z-transform of a digital impulse.

(h) What is the N-point DFT of a sequence ( )nx ?

(i) What is meant by radix-Z FFT?

(j) What is bilinear transformation?

(k) What is warping effect?

(l) What is the general form of IIR filter?

(m) What are the design techniques of FIR filters?

(n) Draw the impulse response of an ideal low pass filter.

(o) What is Gibbs phenomenon?

UNIT I

2. (a) Determine the stability of the system.

( ) ( ) ( ) ( ) ( )1212

5−−=−+−− nxnxnynyny .

(b) Find the inverse Z-transform of

( )143 2 +−

=zz

zzX for the region of convergence.

(i) 1>z

(ii) 3

1<z

(iii) 13

1<< z .

Or

3. (a) Determine the inverse Z-transform by the partial fraction expansion method.

( )372

22 +−

+=

zz

zzX if the ROC are.

(i) 3>z (ii) 2

1<z

(iii) 32

1<< z .

(b) State and prove periodic convolution of discrete Fourier Series. UNIT II

4. (a) Determine the 8-point DFT of the signal ( ) 0,0,0,1,1,1,1,1=nx and sketch its

magnitude and phase.

(b) Explain about methods to evaluate circular convolution of two sequences. Or

5. (a) Draw the flow graph of 16-point DIT-FFT.

(b) Given ( ) nnx 2= and 8=N , find ( )KX using DIT-FFT algorithm.

UNIT III

6. (a) Design a Butter worth high pass fitter satisfying the following specifications. 3.0=pf Hr ; 5.0=pα dB

16.0=sf Hz ; 30=sα dB ; Hzf 1= .

(b) Compare Digital filters and Analog filters.

Or

7. (a) Design a Chebyshev filter for the following specifications

( ) 18.0 ≤≤ jweH π2.00 ≤≤w

( ) 2.0≤jweH ππ ≤≤w6.0

Using impulse -invariance method.

(b) Write about warping effect.

UNIT IV

8. (a) Design an approximation to an ideal high pass filter with magnitude response

( ) 0=jweH 3

0π

≤≤ w

1= otherwise.

(b) Give the comparison between FIR & IIR filter.

Or

9. (a) Compare different windows.

(b) Obtain the direct form –I realization for the system described by difference

equation

( ) ( ) ( ) +−−−= 225.015.0 nynyny

( ) ( )14.0 −+ nnnx .

——————

(DEE 324)


(Examination at the end of Third Year Fourth Semester)


Paper IV — POWER ELECTRONICS




1. (a) What is DIAC?

(b) What is SCS?

(c) What is LASER?

(d) What do you mean by voltage commutation?

(e) Define Firing circuit.

(f) What is meant by pulse number of a converter?

(g) What is dual converter?

(h) Define Resistance control.

(i) What are the disadvantages of frequency modulation scheme?

(j) What are the disadvantages of pulse width modulation scheme?

(k) Define load commutation.

(l) Define Peak capacitor voltage.

(m) Write the expression for Design of inductance (L).

(n) Explain the concept of Dead zone.

(o) What are the advantages of pulse with modulation control?

UNIT I

2. Describe the different modes of operation using static V-I characteristic of the thyristor.

What is the effect of gage current on their characteristic? Explain various applications of

the thyristorised power controllers.

Or

3. (a) What is UJT firing circuit and explain it with suitable waveform?

(b) SCRs with rating of 1200 V and 250 A are used in a string to handle 5 kV and 2

kA. Calculate the number of series and parallel units required in case derating

factor is

(a) 0.2 (b) 0.4.

UNIT II

4. Briefly explain the single phase half wave controlled converter with R load.

Or

5. Explain the three phase half wave converters and three phase full wave converters.

UNIT III

6. (a) Explain the basic principle of inverter. What do you mean by voltage fed and current fed inverters?

(b) A three phase inverter is supplied from a 660 V source. For a star connected resistive load of 20 Ω /phase, find the RMS load current, the load power and the thyristor ratings for

(i) 120° conduction and

(ii) 180° conduction.

Or

7. Explain the operations of MC Murray full bridge inverter in detail with reference to different modes of operation. What are its applications?

UNIT IV

8. (a) Derive an expression for output voltage in terms of duty cycle for a setup, step down and step down/up chopper.

(b) Discuss the methods of controlling the output voltage of a chopper.

Or

9. Briefly explain the principle operation of single phase cyclo converters and their applications.

——————

(DEE 325)



Fourth Semester)


Paper V — UTILIZATION OF ELECTRICAL POWER




1. (a) Explain heating of motors.

(b) Define load equalization.

(c) What are the advantages of plugging?

(d) Define Stefans law.

(e) Mention the requirements of an ideal traction system.

(f) Explain the system of fraction with merits.

(g) Draw a typical speed time curve for main line.

(h) Define polar curves.

(i) Define illumination.

(j) Define mean spherical candle power.

(k) Define luminous intensity.

(l) What is welding?

(m) Define plane angle.

(n) Define crest speed.

(o) What are the advantages of direct internal combustion engine system?

UNIT I

2. Briefly explain the plugging, rheostatic and regenerative braking applied to DC motors.

Or

3. Write short notes on the following

(a) Selection of motor capacity for continuous duty.

(b) Applications in load equalization.

UNIT II

4. What is speed time curve and deduce expressions to get the relationship between

various quantities using

(a) Trapezoidal

(b) Quadrilateral speed time curves.

Or

5. (a) Explain the methods of speed control of traction motors.

(b) Explain the suitability of AC motors and linear motor for traction work.

UNIT III

6. (a) Give the construction of resistance ovens and explain direct and indirect resistance

heating.

(b) How efficiency of resistance furnace is estimated, explain.

Or

7. (a) Explain IPOT welding in detail.

(b) Determine the efficiency of a high frequency induction furnace which takes 10

minutes to melt 2 kg of aluminium, the input to the furnace being 5 kw and the

melting and initial temperatures are 660°C and 15°C respectively. Specific heat of

aluminium = 0.212 latent heat of fusion of aluminium = 76.8 K cal/kg.

UNIT IV

8. Explain the principle, construction and working of the following lamps.

(a) Fluorescent lamps

(b) Sodium vapour lamp

(c) Mercury vapour lamp.

Or

9. Write short notes on the following

(a) Factory lighting

(b) Flood lighting

(c) Street lighting.

——————————

(DEE 326)



Fourth Semester)


Paper VI — SWITCH GEAR AND PROTECTION




1. (a) What are the basic requirement of protective relays.

(b) Explain the need for protective relays.

(c) Define picking.

(d) Define operating force.

(e) Explain backup relay.

(f) Write the expression for relay equation.

(g) Draw the curve between time current characteristic of a typical attracted armature

relay.

(h) Define plus setting multiplier.

(i) Define time setting multiplier.

(j) What is a circuit breaker?

(k) Define the term active recovery voltage.

(l) What is the importance of are resistance?

(m) Define current chopping.

(n) Define soil resistivity.

(o) Define translay relay.

UNIT I

2. Explain the principle of working of distance relays. Describe with neat sketches the

following type of relays.

(a) Impedance relay

(b) Admittance relay

(c) Reactance relay

(d) MNO relay.

Or

3. (a) Explain the difference between definite characteristic and inverse characteristic of

relays.

(b) Describe the construction and working of a buchholz relay and it use.

UNIT II

4. (a) Explain the terms restricting voltages and RRRV.

(b) A circuit breaker is rated at 1200A, 1550 MUA, 33 KV, 3 sec; 3 phase oil circuit

breaker. Determine

(i) rated normal current

(ii) breaking capacity

(iii) rated symmetrical breaking current

(iv) rated making capacity

(v) short time rating and

(vi) rated service voltage.

Or

5. (a) Derive an expression for restricting voltage in terms of system capacitance and

inductance.

(b) What are the advantages and disadvantages and compassed to bulk oil circuit

breaker?

UNIT III

6. (a) What are the roots faults in the alternator? For such faults give their causes and

suggest protective measures.

(b) A 34 transformer having a line voltage ratio of 400/3300 KV is Ster/Delta

connected. The CTS on the 400KV side have a ratio of 800/5 Amps. What must be

the ratio of CTS on 3300V side?

Or

7. (a) Explain biased differential protection for faults.

(b) Explain the working are suppression oil.

UNIT IV

8. Show that the amplitude and phase comparator are due to each others. Explain

operations of circulating current type rectifier bridge amplitude comparator. What do

you understand by them directional? Explain 90°, 60° and 30° connections.

Or

9. (a) What are the merits and demerits of static relay over electromagnetic relay?

(b) Draw and explain circuit diagram of static inverse time over current relay.

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(dee 311) - anucde1. (a) how crossover dissolution eliminated in class ab amplifier? (b) what is...

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