(DEE 311) - · PDF file... (DEE 311) UNIT II ... Explain the operation of Carey Fosters slide...

(DEE 311)

B.Tech. DEGREE EXAMINATION, JUNE 2010.

(Examination at the end of Third Year)

Electricals and Electronics

Paper I — LINEAR CONTROL SYSTEMS

Time : Three hours Maximum : 75 marks

Answer Question No. 1 compulsorily.

Answer ONE question from each Unit.

1. (a) What is a control system?

(b) What is closed loop system?

(c) What is a time invariant system?

(d) Draw the basic waveform of a ramp signal.

(e) What are zeros of a system?

(f) Define rise time.

(g) What is high pass filter?

(h) What are the co-ordinate axes for polar plot?

(i) What is eBod (phase) plot?

(j) What is the use of lag compensation?

(k) Define state variable of a system.

(l) Write the state model of a system.

(DEE 311) 2

(m) What are eigen vectors?

(n) What are M and N circles?

UNIT I

2. (a) What are the limitations of open loop

system?

(b) Obtain transfer function for the following

system.

Or

3. (a) What are the limitations of transfer function

representation?

(b) Obtain the transfer function.

(DEE 311) 3

UNIT II

4. (a) What are time domain specifications and

define them.

(b) The response of a system has an overshoot of

30% for a step input and overshoot takes

place 0.05 seconds later after the excitation

in applied. Find the transfer function of the

system. (2nd order).

Or

5. Check the stability of the following systems with

char, equation.

(a) 0643 =+− rss

(b) 031545816422 34 =++++ ssssr .

UNIT III

6. Draw root locus of the system whose forward path

transfer function in )3)(2(

)(++

=sss

KsG and

comment on stability.

Or

7. Draw eBod plot for the system,

)10)(4(

)2(200)(

++±=sss

ssG .

(DEE 311) 4

UNIT IV

8. (a) Explain the effect of lead compensation on

system’s response.

(b) What are the advantages of state variable

representation?

Or

9. (a) If

=

10

00A find state transition matrix.

(b) Explain the term observability.

—————————

(DEE 312)




Paper II — ELECTRONIC CIRCUITS — II



(1 × 15 = 15)


(4 × 15 = 60)

1. (a) Amplifier are classified on what basis.

(b) In class B amplifier Q point is set at.

(c) What is the other name of the phase inverter

circuit?

(d) Negative and positive feedbacks are also

called as.

(e) ‘ Aβ ’ in a feedback amplifier is called.

(f) Define desensitivity and write an expression.

(g) Define stability of a negative feed back

(h) Define a multivibrator.

(DEE 312) 2

(i) The multivibrator is also called as

(j) Define Barskhausen criterion.

(k) What is stagger tuned Amplifier?

(l) Draw the circuit of series voltage regulator.

(m) Define sweep speed error.

(n) Give some protection techniques.

(o) Draw the voltage sweep ckt.

UNIT I

2. (a) How the power amplifiers are classified,

describe their characteristics?

(b) Derive the general expression for output

power in a class A power Amplifier.

Or

3. (a) Distinguish between small signal and large

signal amplifier.

(b) Why do we use a tuned ckt as a loading for

class-C amplifier?

(DEE 312) 3

UNIT II

4. (a) Describe the operation of RC phase shift

oscillator and find the expression for

frequency.

(b) Write briefly about crystal oscillator.

Or

5. (a) Draw the h-parameter equivalent ckt for

transistor amplifier in three configurations.

(b) Write in detail about Barkhausen criterion.

UNIT III

6. (a) Give the detailed description of the working

of bistable multivibrator.

(b) Explain the operation of Schmitt trigger.

Or

7. (a) How are tuned amplifier are classified?

(b) Draw the ckt for the double tuned amplifier

and explain its working.

(DEE 312) 4

UNIT IV

8. (a) What is SMPS and what is its significance?

(b) Compare SMPS and UPS.

Or

9. (a) Explain the generation of a trapezoidal wave

forms and what are its applications.

(b) Briefly explain voltage and current sweep

circuits.

——————

(DEE 313)




Paper III — GENERATION OF ELECTRICAL POWER



(1 × 15 = 15)


(4 × 15 = 60)

1. (a) Define peak load.

(b) What is load curve?

(c) What is the use of a condenser in thermal

plants?

(d) What is economiser in steam plants?

(e) Define Run-off.

(f) What is meant by spillway?

(g) What are the advantages of nuclear power

stations?

(h) List some nuclear fuels.

(i) What is cold reserve?

(DEE 313) 2

(j) Define plant use factor.

(k) What is meant by Running Charges?

(l) How the power factor can be improved?

(m) What is the function of super heater?

(n) What is Cavitation?

(o) Define capacity factor.

UNIT I

2. (a) Briefly explain various stages in Coal

handling.

(b) What is meant by feed water treatment?

Explain.

Or

3. (a) Explain the working of water tube boiler.

(b) Briefly discuss turbo generators.

UNIT II

4. (a) Explain how the site is selected for hydro

electric stations.

(b) Explain the working of pumped storage plant

for peak-load.

Or

5. (a) With a neat sketch, explain the working of

CANDU reactor.

(DEE 313) 3

(b) Explain types of nuclear reactions.

UNIT III

6. (a) Explain various components of gas turbine

plants.

(b) Explain the construction and working of a

solar cell.

Or

7. (a) Derive an expression for the torque and total

power generated in wind turbines.

(b) Explain how the power is extracted from the

tides.

UNIT IV

8. (a) Discuss various factors affecting cost of

generation.

(b) A thermal station has an annual fixed cost of

Rs. 350.40 per KW of installed capacity. The

fuel and operating costs are 4 paise per KWh

generated. Find the cost of electric energy

generated per KWh for station load factors of

25, 50, 75 and 100%. Plot a curve showing

the variation of cost of energy with load

factor.

Or

9. Discuss the causes, effects of low pF. Explain

various methods of power factor improvement.

(DEE 313) 4

———————

(DEE 314)




Paper IV — ELECTRICAL MEASUREMENTS


Answer Question No.1 compulsorily and ONE question

from each Unit.

1. (a) What is the physical effect used in MI

instruments?

(b) What for electro static instruments are used?

(c) What is the purpose of control torque in

indicating type instruments?

(d) What is the purpose of Epstein's square?

(e) Why PMMC instruments are not suitable for

a.c measurements?

(f) What is thermo-couple?

(g) Why does a CT not give very high voltage in

secondary?

(DEE 314) 2

(h) What is the purpose of Synchroscope?

(i) What is the purpose of Maxwells Bridge?

(j) What is the use of Kelvins double bridge?

(k) Name the transducer used for weight.

(l) Define a transducer.

(m) What is the principle of operation of DVM's?

(n) What is the principle of MI meters?

(o) Define Permeability.

UNIT I

2. (a) Explain different torques required for

satisfactory operation of Indicating

instruments.

(b) How to minimize different errors in PMMC

instruments?

Or

3. (a) Explain the operation of Synchroscope.

(b) Explain the principle and Operation of Power

factors meter.

(DEE 314) 3

UNIT II

4. (a) Explain the advantages of Instrument

Transformers over other multipliers and

shunts?

(b) Explain the operation of Carey Fosters slide

wire bridge.

Or

5. (a) Explain the operation of Heauisides Bridge.

(b) Explain the operation of Kelvins double

bridge.

UNIT III

6. (a) Explain the operation of Ballistic

galvanometer.

(b) Explain the principle of operation of flux

meter.

Or

7. Explain the calibration of Ballastic galvanometer

by Hibberts method.

(DEE 314) 4

UNIT IV

8. Explain the construction of CRO with neat

diagram.

Or

9. (a) Explain the principle of operation of LVDT.

(b) Explain the principle of operation of strain

Gauge.

———————

(DEE 315)




Paper V — TRANSMISSION AND DISTRIBUTION



(1 × 15 = 15)


(4 × 15 = 60)

1. (a) What are transmission line parameters?

(b) Define transposition.

(c) Write the expression for inductance of

3-φ double circuit line with symmetrical

spacing.

(d) What are the advantages bundled

conductors?

(e) Define GMR.

(f) Define the efficiency of transmission line.

(g) Write the expression for voltage at sending

end.

(h) What are limitations of nominal π method?

(DEE 315) 2

(i) Define propagation constant.

(j) What is the order of power loss due to

charging current?

(k) Where are the circle diagrams useful?

(l) What is Ferranti effect?

(m) What are factors affecting sag?

(n) Why are insulators used in overhead lines?

(o) What are the advantages of underground

cables?

UNIT I

2. (a) Derive the expression for inductance of a 3-φ

transposed transmission line.

(b) A transposed 3-φ line has conductors of

diameter 2 cm and spaced at distance of 3.65,

5.5 and 8.2 m between the centres. Calculate

the inductance per phase per km of line

length.

Or

3. (a) Derive the expression for capacitance of a

3-φ symmetrical transmission line.

(b) A 3-φ double circuit line has its vertices of a

regular hexagon of side 2 m. The conductor

radius is 1.25 cm. Find the capacitance per

phase per km.

(DEE 315) 3

UNIT II

4. (a) What is a receiving end power circle

diagram? How can it be drawn? What

information does it provide?

(b) Find no load sending end voltage and voltage

rise from the sending end to the receiving

end for a 50 Hz, 300 km long line if the

receiving end voltage is 200 kN.

Or

5. (a) What is sag template? What is its use? Also

write a short note on conductor vibrations.

(b) An overhead line has a span of 152 m and is

supported on level supports. The conductor

has an effective diameter of 2.068 cm, cross-

sectional area is 3.065 sq.cm. and weighs

2.292 kg/m. The line is subjected to a wind

pressure of 39.063 kg/sq.m. of project area.

Assuming a maximum stress of 1054.63

kg/sq.cm, find sag under given conditions.

Also find vertical component of sag.

UNIT III

6. (a) Explain the single bus bar arrangement, its

merits and demerits.

(b) Write short notes on Kelvin’s law for most

economical cross section.

Or

(DEE 315) 4

7. Prove that the total voltage drop in a uniformly

loaded distributor fed at one end is equal to drop

produced by the whole load assumed contracted at

the midpoint of the distributor.

UNIT IV

8. (a) Name the different types of insulators used

in power systems. Give the application of

each insulator.

(b) Describe the main constructional features of

pin and string insulators.

Or

9. (a) Derive a formula for insulation resistance

and capacitance of a single core cable.

(b) How are cables classified? Give the

application of each cable.

——————

(DEE 316)




Paper VI — ELECTRO MECHANICS — III


Answer question No. 1 compulsorily.

(1 × 15 = 15)


(4 × 15 = 60)

1. (a) What are the major parts of an alternator?

(b) Mention aay one application where salient

pole type alternators are employed.

(c) Write the expression for frequency.

(d) Define breadth factor.

(e) What is this significance of synchronous

method?

(f) What are the various losses occurens in

alternators?

(g) What type of field windings used in salient

pole synchronous machines?

(DEE 316) 2

(h) What is the other name of zero power factor

method?

(i) Mention any condition for proper

synchronization of alternators.

(j) What is synchronizing power?

(k) Why is a synchronous motor is not

inherently self starting?

(l) Write the expression for Maximum power

developed

(m) What is synchronous condenser?

(n) What is the preventive measure for hunting?

(o) What is variable reluctance stepper motors?

UNIT I

2. (a) Explain about the MMF method with neat

figures.

(b) A 3-φ , 1000 KVA, 11 KV star connected

alternator has resistance of 1.5 Ω /phase and

synchronizing reactance of 25 Ω /phase. Find

the percentage regulation for a load of 600

kW at 0.8 leading power factor.

Or

3. (a) Explain in detail about the armature

reaction. Draw the vector diagram.

(b) Discuss about the various losses in an

alternator and devise the efficiency equation.

(DEE 316) 3

UNIT II

4. (a) A 400 KVA, 6-pole alternator runs at

1000 rpm in parallel with other machines on

3300 V bus bars. The synchronous reactance

is 25%. Calculate the synchronizing power

for one mechanical degree of displacement

and the corresponding synchronizing torque.

(b) Derive the expression for synchronising

power and also synchronising torque with

neat phasor diagrams.

Or

5. (a) Derive the expression for regulation of

salient pole machines.

(b) Discuss in detail about effect of variation of

excitation and mechanical input on parallel

operation.

UNIT III

6. (a) Explain ‘V’ and inverted ‘V’ cures of a

synchronous motor.

(b) Derive the expression for maximum and

minimum powers for a given excitation by

explaining the power circles.

Or

(DEE 316) 4

7. (a) What is hunting? Explain in detail and also

explain how to prevent.

(b) Explain about synchronous condenser.

Mention its application.

UNIT IV

8. (a) Explain in detail about principle of operation

of reluctance motor.

(b) Explain the operation of Repulsion motors.

Mention its applications.

Or

9. (a) Explain the principle of operation of

permanent magnet stepper motor.

(b) Explain how a linear induction motor is used

in the application of transportation.

——————

(DEE 321)




Paper I — LINEAR IC's AND APPLICATIONS


Answer Question No.1 Compulsorily.

(1 × 15 = 15)


(4 × 15 = 60)

All questions carry equal marks.

1. (a) What is Slew Rate?

(b) Define CMRR.

(c) Define input Bias current.

(d) Define Thermal Drift.

(e) Draw the circuit diagram for current to

voltage converter.

(DEE 321) 2

(f) Draw the CKT diagram for Astable

Multivibresor.

(g) List the applications of PLL.

(h) What are the advantages of Negative

feedback?

(i) What is the function of peak detector circuit?

(j) Define Duty cycle.

(k) Write out put expression of Resistive

weighted D/A converter.

(l) Define Bark Hausen estiteria in oscillators.

(m) Draw the Response of Band pass filter and

give the cut off frequencies formula.

(n) Draw the circuit diagram for All pass fitter.

(o) Define Resolution.

UNIT I

2. (a) Explain Instrumentation amplifiers.

(b) Explain voltage to current converter using

op-amp.

Or

(DEE 321) 3

3. (a) Derive the expression for Integrator using

op-amp.

(b) Explain about Precision Rectifiers using

op-amp.

UNIT II

4. (a) Derive the output expression for wein Bridge

oscillator using op-amp.

(b) Explain about saw tooth wave generator.

Or

5. (a) Explain about Zero-crossing detector.

(b) Explain precision type comparators.

UNIT III

6. (a) Explain R-2R ladder D/A converter.

(b) Explain about positive clampers.

Or

7. (a) Explain dual slope A/D converter.

(b) Explain Resistive weighted D/A converter.

(DEE 321) 4

UNIT IV

8. (a) Explain 555 timer act as a Monostable.

Multivibrator.

(b) Explain Band stop fitter.

Or

9. (a) Explain 723 voltage Regulator.

(b) Find the Expression for cut off frequency for

Low pass fitter.

———————

(DEE 322)




Paper II — MICROPROCESSORS AND

INTERFACING



(1 × 15 = 15)


(4 × 15 = 60)

1. (a) What are the different addressing modes of

8086?

(b) Which instruction of 8086 can be used for

lookup table manipulations?

(c) What is bus cycle?

(d) What is minimum mode of operation in

8086?

(e) What is the control word format of 8085 in

I/O and BSR mode?

(f) Explain the function of (i) XLAT

(ii) MOVSB.

(DEE 322) 2

(g) What do you mean by HANDSHAKING?

(h) What are the various interrupts in 8086?

(i) What are the uses of delay subroutines?

(j) What is the purpose of 8251?

(k) What is the purpose of 8279?

(l) What are the different modes of operation of

8255?

(m) What are the stack operations in 8086?

(n) What is the function of the following signals

in 8086

(i) DT/R (ii) QSO, QSI.

(o) List the 16-bit flag register.

UNIT I

2. (a) Draw the register organization of 8086

explain the application of each register.

(b) Explain why memory is divided into

segments in 8086.

Or

3. (a) Explain the conditional and control flags of

8086.

(b) Explain the different addressing modes of

8086 with an example.

(DEE 322) 3

UNIT II

4. (a) Write an ALP using 8086 to find the factorial

of a number.

(b) Which instructions in 8086 can be used for

lookup table manipulations justify?

Or

5. (a) How does 8086 identify between 8 bit and

16 bit operations?

(b) What are assembler directives?

UNIT III

6. (a) Describe the interrupt sequence of 8086.

(b) Interface a DAC 0800 to 8086. How do you

generate a triangular waveform.

Or

7. (a) Explain the interfacing of a keyboard and

microprocessor.

(b) Explain the operation of dual slope ADC.

(DEE 322) 4

UNIT IV

8. (a) Design a microprocessor based stop watch

using 8253 and 8255.

(b) Explain 8086 based system configured in

minimum mode. Draw a neat block diagram.

Or

9. (a) Draw the memory read bus cycle in

minimum mode of operation of 8086.

(b) What are the criteria considered before

interfacing memory to the processor?

——————

(DEE 323)




Paper III — DIGITAL SIGNAL PROCESSING


Answer question No. 1 compulsorily.

Answer any ONE question from each Unit.


1. (a) What are the advantages of Digital signal

processing?

(b) Define the shift-invariance applied to a

discrete time system.

(c) What is meant by Regional convergence?

(d) What is parseval’s relation?

(e) Compare static and dynamic systems.

(f) What is the sufficient condition for the

existence of DTFT?

(g) Write the convolution property of the

z-transform.

(h) Explain the meaning of the statement “DFT

supports circular convolution”.

(DEE 323) 2

(i) What are the uses of zero padding?

(j) Distinguish between DFT and DTFT.

(k) Why FFT is needed?

(l) What are the disadvantages, of FIR filters?

(m) What are the desirable characteristics of the

window?

(n) What are the properties of bilinear

transformation?

(o) Define Discrete Fourier Series.

UNIT I

2. (a) Determine the convolution sum of two

sequences, ( ) 2,1,2,3=nx ( ) ↑

= 2,1,2,1xh

(b) Determine if the system described by the

following equations are causal on non-causal

(i) ( ) ( ) ( )1

1

−+=

nxnxxy

(ii) ( ) ( )2nxxy = .

Or

3. Find the z-transform of the following discrete-time

signals, and find ROC for each.

(a) ( ) ( ) ( ) ( )283

1188

2

1 −−−+= nnnnx

(DEE 323) 3

(b) ( ) ( ) ( )nunnx

n

+=3

15.0

(c) Find the inverse z-transform of

( )21

1

231

31−−

−

+++=

zz

zzχ .

UNIT II

4. (a) Draw the signal flow graph for 16-point DFT

using DIT algorithm.

(b) Find 8-point DFT of the following sequence

( ) 0,0,0,0,1,1,1,1=nx .

Or

5. (a) Distinguish between linear and circular

convolution of two sequences.

(b) Find the circular convolution of the sequence

( ) ;3,2,1,11 −=nx ( ) 3,2,1,02 =nx .

UNIT III

6. (a) Apply bilinear transformation to

( ) ( )( )21

2

++=

SSSH and 1=τ sec find

( )2H .

(DEE 323) 4

(b) Using impulse invariance with 1=τ sec

determine ( )ZH if ( )12

12 ++

=SS

SH

Or

7. (a) By locating the poles, determine the transfer

function of the normalised Butter worth

filter of order 2.

(b) Compare FIR and IIR filters.

UNIT IV

8. (a) Using the window method with a Hamming

window to design a 5-tap differentiator.

(N = 5).

(b) Explain about the characteristics of

windows.

Or

9. Write short notes on the following :

(a) Canonic realization.

(b) Bartlett window.

(c) Kaiser window.

———————

(DEE 324)




Paper IV — POWER ELECTRONICS



Answer Question No. 1 compulsory.


1. (a) What is meant by spread time of SCR?

(b) What is a thyristor?

(c) Define LASER and IGBT.

(d) Give the significance of dv/dt in SCR.

(e) What is the necessity of RC triggering

circuit?

(f) What is the effect of source Inductance on

converters?

(g) What is meant by pulse width modulation?

(h) Give the application of inverters?

(i) What is extinction angle?

(DEE 324) 2

(j) In dc choppers, if Ton is the on-period and ‘f’

in the chopping frequency, then give the

expression the output voltage interms of

input voltage Vs.

(k) Specify any two application of cyclo

converters.

(l) What are the necessary conditions for

turning ON of an SCR?

(m) Why it is necessary to remove the harmonics

from the output of an inverter?

(n) Justify the use of chopper circuit for speed

control of dc motors.

(o) Define derating factor.

UNIT I

2. (a) Draw the static characteristic of an UJT and

explain its working.

(b) What are the practical problems related to

series, parallel operation of SCR? Discuss.

Or

3. (a) Discuss the two transistor model of a

thyristor. Using this model, describe the

various mechanisms of turning - on thyristor.

(b) Discuss about turn-off methods?

(DEE 324) 3

UNIT II

4. (a) Explain the operation of a 3 phase fully

controlled rectifier with RL load and free

wheeling diode?

(b) A resistive load of 10Ω is connected through

a half wave SCR circuit to 220V, 50 Hz,

single-phase source. Calculate the power

delivered to load for a firing angle of 60°.

Or

5. (a) Explain about φ−1 half wave circuit with

resistive R and inductive L load and derive

expression for power factor.

(b) Explain the circulating and non circulating

current modes of operation.

UNIT III

6. (a) Describe the Mc-Murray Bed ford Inverter

with appropriate voltage current wave

forms?

(b) Explain the operation of 3 phase in meter in

180° mode of operation.

Or

(DEE 324) 4

7. (a) With the help of circuit diagram and

waveform explain the operation of single

phase bridge inverter and obtain the

expression for output voltage.

(b) Compare voltage source and current source

Inventoried.

UNIT IV

8. (a) Discuss about different types of chopper

circuits?

(b) What are the advantages and disadvantages

of cyclo converters over phase controlled

inverter circuits?

Or

9. (a) Explain the principle of operation of class-A

chopper. Draw the load voltage wave form.

(b) A step up chopper has input voltage of 220V

and output voltage of 660V. If non

conducting time of thyristor in 100 µ sec,

compute pulse width of output voltage. If

pulse width is halved for constant frequency

operation, find new output voltage.

———————

(DEE 325)




Paper V — UTILIZATION OF ELECTRICAL POWER



(15 marks)


(4 × 15 = 60) 1. (a) What is regenerative braking?

(b) What is short time loading?

(c) What is overload capacity of inducting

motors?

(d) What is traction systems?

(e) What is the purpose of tramways?

(f) What is Kando system?

(g) Why the field diverter used for control of

speed of DC series motor designed for high

inductance?

(h) Define Schedule speed of locomotive.

(i) What is the advantage of dielectric heating?

(j) What is Stefan's Law?

(DEE 325) 2

(k) What is submerged arc welding?

(l) Define luminous intensity.

(m) Define luminance.

(n) What is MHCP?

(o) What is resistance welding?

2. (a) What factor govern the selection of motor for

particular application.

(b) A motor driving a Colliery winder has the

following load cycle.

Accelerating period 0-15 sec - load rising

uniformly from 0 to 1050 h.p.

Full speed period 15 to 85 sec - load constant

at 600 h.p.

Decelerating period 85 to 95 sec - h.p.

returned to line falls uniformly 200 to zero.

Decking period 95 to 120 sec - Motor

stationary.

Estimate the size of the continuous rated

motor suitable for above load cycle.

Or

(DEE 325) 3

3. (a) Discuss various types of braking. Describe in

detail d.c and a.c dynamic braking as applied

to dc motors.

(b) What are the advantages of load

equivalisation and how this is done.

4. (a) Discuss various factors an which final choice

of traction system depends.

(b) A train at an average speed of 50 kmph

between stations situated 2.5 km apart. The

train accelerates at 2 kmphps and retards at

3 kmphps. Find its maximum speed

assuming specified trapezoidal speed time

curve. Draw the speed time curve for the run

and calculate also the distance travelled by it

before the brakes are applied.

Or

5. (a) Explain how the direction of rotation of

traction motor is reversed.

(b) What is Kando system? Explain the

potentialities of this systems for its being

adopted.

6. (a) Explain the construction and working of A

jax-wyatt furance.

(b) Estimate the energy required to melt one

tonne of brass in a single phase induction

furnace.

If the melt is to be carried out in 411 Hrs,

What must be the average power input to the

furnace?

Or

(DEE 325) 4

7. (a) What are different types of electric welding

explain?

(b) What is the effect of welding lime of

resistance welding on the quality of weld.

8. (a) What are the advantages and disadvantages

of sodium and high pressure mercury

lighting over that of filament lamp.

(b) What is the effect of increasing the space

height ratio of lamp over recommended

values of the illumination?

Or

9. (a) What are the objects to be achieved for good

street lighting and what are main faults to

be avoided?

(b) Describe the construction and working of

cold cathode discharge tube used for signs.

What safety precautions are taken?

———————

(DEE 326)




Paper VI — SWITCH GEAR AND PROTECTION


Answer question No. 1 compulsory.

(15)


(4 × 15 = 60)

1. (a) What are the basic requirements of

protective relay?

(b) Define operating torque of a relay.

(c) Define TMS.

(d) What is meant by secondary zone of

protection?

(e) What is a circuit breaker?

(f) Define recovery voltage.

(g) Define making capacity of circuit breaker.

(h) Why SP6 circuit breakers are preferred?

(DEE 326) 2

(i) What is NPs protection of alternators?

(j) What is the advantages of reactance of

grounding?

(k) Define soil resistivity.

(l) What is the advantage of phase

comparators?

(m) What is instantaneous over current relay?

(n) What is characteristic angle of relay?

(o) What is IDMT relay?

UNIT I

2. (a) Explain how the relays are classified.

(b) Explain the working of Buchholz’s relay.

Or

3. (a) Explain the construction and working of over

current relay.

(b) An over current relay of current rating 5 A

and setting 150% is connected to the

secondary of CT of ratio 300 : 5. Calculate

the current in lines for which the relay

picks up.

(DEE 326) 3

UNIT II

4. (a) Explain the principle of interrupting

capacitive currents.

(b) Classify air circuit breakers. Explain the

working of one of them.

Or

5. (a) Explain the arc quenching properties of

SF6 gas. What are the advantages of SF6

breakers over other circuit breakers?

(b) Explain the construction of working of SF6

circuit breakers.

UNIT III

6. (a) Explain the biased differential protection

scheme employed for protection of

alternators.

(b) Explain the protection scheme for generator-

transformer unit protection.

Or

7. (a) Explain the reasons leading to the general

practice of earthing the neutral point of a

power system and discuss the relative merits

of earthing it (i) solidly (ii) through a

resistance.

(b) Discuss the various protection schemes

employed for the protection of feeders.

(DEE 326) 4

UNIT IV

8. (a) Classify static relays and explain them.

(b) Explain the working of static over current

relay.

Or

9. (a) Explain amplitude and phase comparators.

(b) Explain the scheme of static distance relay.

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