(dee 311) - anucde7. (a) explain how stability of a system can be assessed using polar plots. (b)...
TRANSCRIPT
(DEE 311)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012.
(Examination at the end of Third Year of 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) What is a control system?
(b) What is a non-linear system?
(c) Define Discrete data.
(d) Give an example for time varying system.
(e) Differentiate between pole and zero.
(f) What is steady state error?
(g) What is magnitude criterion in a root locus?
(h) Define BIBO stability.
(i) Give an application of high pass filter.
(j) Write the relationship between frequency and resonant magnitude.
(k) Draw the frequency characteristics of lag compensator.
(l) What is the advantage of polar plot?
(m) What is the significance of Eigen value?
(n) Define phase variable.
(o) State Mason’s gain formula.
UNIT I
2. (a) Distinguish between open loop and closed loop systems.
(b) Develop the block diagram for the system given as
Or
3. (a) Explain the signal flow graph and usage of Mason’s gain formula.
(b) Obtain the transfer function of the following system :
UNIT II
4. (a) Explain the effect of adding a pole to a given system.
(b) Determine the range of ‘k’ for the system to be stable :
021520 234 =++++ kssss .
Or
5. (a) Explain how the special cases are solved in RH criterion.
(b) Obtain the response of a unity F.B. system whose open loop transfer function is
)4(
3)(
+=
sssG for a unit step input.
UNIT III
6. Draw complete root locus of the system )2(
)3()()(
++
=ss
sksHsG .
Or
7. (a) Explain how stability of a system can be assessed using polar plots.
(b) Sketch Bode plots and comment on stability
)50(
)5(80)()(
2 +
+=
ss
ssHsG .
UNIT IV
8. (a) Derive the transfer function for a lead-lag compensator.
(b) Derive an expression to find the state transition matrix in Laplace domain.
Or
9. (a) List the factors to be considered in selection of a compensator.
(b) Obtain the state model of the system given as
———————
(DEE 312)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012
(Examination at the end of Third Year Third Semester)
Electricals and Electronics
Paper II — ELECTRONIC CIRCUITS – II
Time : Three hours Maximum : 75 marks
Answer Question No.1 compulsorily. (15 × 1 = 15)
Answer ONE question from each Unit. (4 × 15 = 60)
1. Write short notes on :
(a) What are the applications of power amplifier?
(b) Define efficiency of a power amplifiers.
(c) Draw the circuit diagram of a phase inverter.
(d) State the disadvantages of using transformers in a push-pul amplifier.
(e) What are the temperature considerations of power amplifiers?
(f) What are the features of large signal amplifiers?
(g) State the demerits of negative feedback in amplifiers.
(h) What are feedback amplifiers?
(i) What is Barkhausen criterion?
(j) Define the term damping oscillations.
(k) Define Bustained oscillations.
(l) State two applications of an oscillator.
(m) Discuss the advantages of single tuned amplifier.
(n) Define the term ‘current charging’.
(o) List various sweep circuits.
UNIT I
2. (a) Explain why a power amplifier is also known as a large-signal amplifier.
(b) State the advantages achieved by using a push-pull amplifier circuit, instead of
connecting the two transistors in parallel.
Or
3. Explain the following terms in connection with power amplifiers :
(a) Collector dissipation rating.
(b) Harmonic distortion.
(c) Class-A, Class-B and Class-C - operation.
UNIT II
4. Derive an expression to illustrate that the voltage gain in an amplifier circuit with
negative feedback is somewhat stable even if the ‘β’ of transistor changes due to its
replacement.
Or
5. (a) Explain the principle of working of the Wein bridge oscillator circuit. Draw the
phase shift network that determines the frequency of oscillations.
(b) The RC network of a Wein bridge oscillator consists of resistors and capacitors
of values R1 = R2 = 220 kΩ and C1 = C2 = 250 PF. Determine the frequency of
oscillations.
UNIT III
6. Explain the following :
(a) Tuned primary amplifier.
(b) Tuned secondary FET amplifier.
Or
7. Write short notes on the following :
(a) Schmitt trigger circuit.
(b) The Bistable multivibrator.
UNIT IV
8. (a) Explain the switching mode power supplies.
(b) Explain the series and shunt voltage regulators.
Or
9. Write short notes on the following :
(a) Voltage sweep circuits.
(b) Current sweep circuits.
——————
(DEE 313)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012
(Examination at the end of Third Year Third Semester)
Electricals and Electronics
Paper III — GENERATION OF ELECTRICAL POWER
Time : Three hours Maximum : 75 marks
Answer Question No.1 compulsorily. (15 × 1 = 15)
Answer ONE question from each Unit. (4 × 15 = 60)
1. Write brief note on :
(a) What is meant by base load?
(b) What is load duration curve?
(c) Define hydrographs.
(d) What is meant by economizers.
(e) Define Mass curves.
(f) What is Penstock?
(g) Define load factor.
(h) Define diversity factor.
(i) Define Plant use factor.
(j) List the various types of equipment that can came power quality problem.
(k) Define thermal efficiency of gas plant.
(l) What is solar pond?
(m) What are different types of tariff?
(n) Define Power factor.
(o) What is the principle of operation for wind energy?
UNIT I
2. Draw and explain of typical layout of thermal power plant describe the function of a
coal and ash handling plant.
Or
3. (a) Write short notes on effect of variable on plant operation and design.
(b) Explain the size of generator units.
UNIT II
4. (a) Briefly discuss about the characteristics of turbines and governing of turbines.
(b) Explain the classification of hydroelectric plants.
Or
5. Draw a typical layout of gas turbine plant and describe the function of different
components of their plant.
UNIT III
6. (a) Draw a typical layout of solar thermal power plants.
(b) Explain the principle operations of wind power.
Or
7. (a) Explain the generating power from tidal energy.
(b) Write short notes on the improvement of thermal efficiency of gas plant.
UNIT IV
8. (a) Briefly explain the what factors affecting cost of generation.
(b) Write short notes on Reduction of cost by inter connected statious.
Or
9. Explain the following terms :
(a) Methods of improving powerfactor considerations.
(b) Phase advancing and generation of reactive KVAR.
——————
(DEE 314)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012
(Examination at the end of Third Year Third Semester)
Electricals and Electronics
Paper IV — ELECTRICAL MEASUREMENTS
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) What are the main parts of a moving coil instrument?
(b) What is the material generally used for control spring?
(c) Which meter, the ammeter (or) voltmeter has high resistance?
(d) Which value of current r.m.s. (or) maximum is measured by M.I. instruments?
(e) How the temperature error can be minimised?
(f) What is the working principle of Dynamometer type instrument?
(g) How many current coils are there in a single phase wattmeter?
(h) What do you understand by the exciting coil?
(i) How many terminals are taken out from the energy meter?
(j) What do you understand by the term creeping?
(k) What are the types of the frequency meters?
(l) How the e.m.f. is induced in the moving coil?
(m) How the power factor of high voltage line is measured?
(n) How the torque is developed in case of powerfactor meter?
(o) List the application of Wein bridge.
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. (a) Describe the constructional details and working of an electrodynamometr type
instrument.
(b) Describe the construction and working three phase field power factor meter.
UNIT II
4. (a) Draw the equivalent circuit and phasor diagram of a current transformer.
Derive the expressions for ratio and phase angle errors.
(b) A current transformer with a bar primary has 300 turns in its secondary
winding. The resistance and reactance of the secondary circuit are 1.5 Ω and
1.0 Ω respectively including the transformer winding with 5A flowing in the
secondary winding, the magnetizing mmt is 100 A and the iron loss is 1.2 W.
Determine the ratio and phase angle errors.
Or
5. Derive the equations of balance for an Anderson’s bridge. Draw the phasor diagram
for conditions under balance. Discuss the advantages and disadvantages of the
bridge.
UNIT III
6. Describe the working of kV voltage schering bridge. Derive the equations for
capacitance and dissipation factor. Draw the phasor diagram of the bridge under
conditions of balance.
Or
7. Write short notes on the following :
(a) Ballistic galvanometer.
(b) B-H loop
(c) Flux meter.
UNIT IV
8. Describe the construction and working of :
(a) DVM’s.
(b) LCD’s.
Or
9. Write short notes on the following :
(a) Applications of CRO.
(b) Thermo Couple.
(c) Strain Guage.
——————
(DEE 315)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012.
(Examination at the end of Third Year Third Semester)
Electricals and Electronics
Paper V — TRANSMISSION AND DISTRIBUTION
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) Define GMD.
(b) What is the main use of GMD method of inductance calculations?
(c) What is surge impedance loading?
(d) Define ferranti effect.
(e) Define regulation of transmission line.
(f) What are the stringing charts?
(g) How the substations are classified?
(h) What is the difference between feeder and distribution?
(i) State kelvin's law.
(j) Define impulse ratio.
(k) Define corona.
(l) What are the different types of insulators?
(m) What are the methods for improving string efficiency?
(n) What are the factors on which sag depends on?
(o) Define critical disruptive voltage.
UNIT I
2. (a) Derive an expression for capacitance/phase of a 34 unsymmetrical spaced line
with lives fully transposed.
(b) Derive the expression for inductance of a double circuit 34 line.
Or
3. (a) Explain clearly the skin effect and the proximity effects when referred to
overhead lines.
(b) The three conductors of a 34 line are arranged at the corners of a triangle if
sides 2.5m, 3m, 3.5m. Calculate the inductance per km of the line when the
conductors are regularly transposed. The diameter of each conductor is 1.24 cm.
UNIT II
4. Write short notes on the following
(a) Propagation constant
(b) Characteristic impedance
(c) ABCD constants.
Or
5. (a) Derive the expression for sending end voltage in nominal Π method and end
condenser method.
(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) Explain why the transmission line are 34, 3 wire circuit while distribution lines
are 34, 4 wire circuits.
(b) Derive the expression for voltage regulation in an uniformly distributed loads
on feeders.
Or
7. (a) Explain briefly the different types of bus bars.
(b) Explain the following
(i) Underground substation.
(ii) Distribution substation.
UNIT IV
8. (a) What is an underground cables? Write short notes on ''classification'' cables.
(b) In a string of 5 insulator discs, capacitance between each unit and earth is 1/6
of the mutual capacitance. Find the string efficiency.
Or
9. (a) Explain the inter sheath grading of cables.
(b) Estimate the charging correct drawn by a cable with 3 cores and protected by a
metalic sheath when switched on to an 11 kg, 50 hz supply. The capacitance
between two cores with the third core connected to the sheath is measured to be
3.7 mf.
——————————
(DEE 316)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012.
(Examination at the end of Third Year Third Semester)
Electricals and Electronics
Paper VI — ELECTRO MECHANICS - III
Time : Three hours Maximum : 75 marks
Answer Question No. 1 compulsorily. (15 × 1 = 15)
Answer ONE question from each Unit. (4 × 15 = 60)
1. Write brief notes on the following:
(a) Why synchronous motors are not self-starting?
(b) Damper windings are used in salient-pole structure why?
(c) What is a synchronous condenser?
(d) Why voltage regulation of an alternator is negative for leading power factor
loads?
(e) Define synchronous Impedance?
(f) Define coil span factor.
(g) What are the conditions for parallel operation?
(h) Give the applications of cylindrical alternators.
(i) Give the applications of AC series motors.
(j) Define 'V' curves.
(k) Define Hunting. Methods to prevent.
(l) Applications of Reluctance motors.
(m) Applications of Linear induction motor.
(n) Draw the characteristics of universal motor.
(o) Give the principle of variable reluctance stepper motor.
UNIT I
2. (a) Give the constructional details of rotor of both salient pole and cylindrical rotor
synchronous machines. (8)
(b) A 6 pole alternator rotating at 1000 rpm has a single phase winding housed in 3
slots per pole, the slots in groups of three being 200 apart. If each slot contains
10 conductors, and the flux per pole is 2 × 10-2 wb , calculate the voltage
generated, assuming the flux distribution to be sinusoidal. (7)
Or
3. (a) Explain how the voltage regulation can be predicted by using 7PF method.
(8)
(b) What is armature reaction? Explain the effect of armature reaction on the
terminal voltage of an alternator at various power factors and draw the phasor
diagrams. (7)
UNIT II
4. (a) What are conditions for parallel operation of 3-φ alternators? What is the need
of parallel operation? (7)
(b) Discuss Blondel's two reaction theory of salient pole synchronous machines.
(8)
Or
5. (a) What are various methods of synchronizing of alternators? Why bright lamp of
synchronizing is preferred over dark lamp method? (8)
(b) Two 1000 KVA 3φ alternators are operating in parallel and supply a load of
1500 KVA at 0.8 lagging power factor. If one of the machines is operating at 0.4
lagging power factor and supplying 800 KVA, find the output of the other
machine and the power factor at which it is operating. (7)
UNIT III
6. (a) Explain the principle of operation of a 3φ synchronous motor. (8)
(b) What are V-curves of a synchronous motor? What are the main characteristics
of a synchronous motor? (7)
Or
7. (a) Explain why a synchronous motor does not have starting torque. Explain one
method of starting a synchronous motor. (8)
(b) A 3000V, 3φ synchronous motor running at 1500 rpm has its excitation kept
constant corresponding to no-load terminal voltage of 3000V. Determine the
power input, power factor and torque developed for an armature current of
250A if the synchronous reactance is 5 Ω per phase and armature resistance is
neglected? (7)
UNIT IV
8. (a) Write a short notes on operations of AC series motor. (8)
(b) Explain the operation of repulsion motor and give its applications? (7)
Or
9. (a) Explain the principle of operation of Linear induction motor. (7)
(b) Write a short notes on stepper motor. (8)
————————
(DEE 321)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012
(Examination at the end of Third Year Fourth Semester)
Electricals and Electronics
Paper I — LINEAR IC’s AND APPLICATIONS
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) Draw the Block diagram of operational amplifier.
(b) Define slew rate.
(c) What are the Bandwidth limitations?
(d) Define the summing amplifier.
(e) Define precision rectifiers.
(f) What are the different types of oscillators?
(g) Mention some of the linear applications of op-amps.
(h) Draw the circuit of a phase shift oscillator.
(i) What is window detector?
(j) What is a sample circuit?
(k) What is Ramp converters?
(l) Explain the term Schmitt trigger.
(m) Define voltage regulators.
(n) What do you mean by clipping circuits?
(o) Explain the Band Stop filters.
UNIT I
2. Explain the following :
(a) Op-Amp error sources.
(b) Frequency compensation and stability.
Or
3. Draw the circuit diagram of Op-Amp differentiator, integrator and derive an
expression for the output in terms of input.
UNIT II
4. (a) Explain the principle of working of the Wien bridge oscillator circuit.
(b) A vacuum tube phase-shift oscillator uses three identical RC sections is the
feedback network. The values of the components are R = 100 kΩ and
C = 0.01 µF. Calculate the frequency of oscillation.
Or
5. (a) Explain how a comparator can be used as a zero crossing detector.
(b) Write short notes on Schmitt trigger.
UNIT III
6. Write short notes on the following :
(a) Positive and negative clippers.
(b) Positive and negative clampers.
Or
7. (a) Explain the R-2R ladder type DAC.
(b) Write short notes on Tracking A/D converters.
UNIT IV
8. (a) Draw the Block diagram of monostable multivibrator using 555 timer and
derive an expression for its frequency of oscillation.
(b) Explain the Monolithic PLL’s.
Or
9. Write short notes on the following :
(a) All pass filters.
(b) State variable filters.
——————
(DEE 322)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012.
(Examination at the end of Third Year Fourth Semester)
Electricals and Electronics
Paper II — MICROPROCESSORS AND INTERFACING
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) What is a microprocessors?
(b) What is a micro computers?
(c) What is a control bus?
(d) What is a assembler macros?
(e) What is the meaning of addressing memory?
(f) What is meant by multi programming?
(g) Explain the SDK 86.
(h) Define ports in microcomputers system.
(i) What is DMA?
(j) What is interrupt Repouses?
(k) What is EQU directive?
(l) What is the first statement in assembly language program?
(m) What is a register?
(n) What is the purpose of segment registers in 8086?
(o) Write the internal block diagram of 8251.
UNIT I
2. Explain the briefly 8086 microprocessor family. (15)
Or
3. Write short notes on the following (8+7)
(a) Instruction descriptions
(b) Assembler directives.
UNIT II
4. (a) Explain the program development steps. (8)
(b) Explain the constructing the machine codes for 8086 instructions. (7)
Or
5. Write short notes on the following
(a) Writing programs for use with an assembler.
(8)
(b) Assembly language program development tools. (7)
UNIT III
6. (a) Explain the 8086 Interrupts. (8)
(b) Write short notes on Interfacing a microprocessor to keyboards. (7)
Or
7. Explain the following (8+7)
(a) D/A converter operation
(b) Interfacing and applications
UNIT IV
8. (a) Write short notes on the 8086 maximum mode. (8)
(b) Explain the Rs 232 C serial data standard. (7)
Or
9. Explain the internal block diagram of 8253 and 8259. (15)
——————
(DEE 323)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012.
(Examination at the end of Third Year Fourth Semester)
Electricals and Electronics
Paper III — DIGITAL SIGNAL PROCESSING
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) Define stability.
(b) Define causality.
(c) What is LTI system?
(d) Explain region of convergence.
(e) State Cauchy’s integration theorem.
(f) Define Discrete Fourier transform.
(g) Define DFT.
(h) What is meant by linear phase filter?
(i) Explain Bilinear transformation.
(j) Define Ladder realizations.
(k) Determine z -transform of ( )2−nu .
(l) Find the final value, ( )21
1
8.08.11
2−−
−
+−=
zz
zzy .
(m) ( ) ( )1−= nnunx , then ( )zx .
(n) What is a unit impulse function?
(o) Define phase delay.
UNIT I
2. (a) Explain about BIBO stability of LTI system.
(b) Check the following systems are stability, causality, linearity and time
invariance
(i) ( ) ( )( )txedt
dty t−=
(ii) ( ) ( )txty −= 2 .
Or
3. (a) Define z -transforms. Explain the property of z -transforms.
(b) ( ) ( ) ( )nununx
n
n
+=
2
132 . Find ( )zx .
UNIT II
4. (a) Explain properties of DFS and DFT.
(b) ( ) nanx = , 1<a , find ( )iweX . Obtain the amplitude and phase spectrum.
Or
5. Write short notes on the following :
(a) Decimation in time FFT algorithms
(b) Computation of inverse DFT.
UNIT III
6. Write short notes on the following :
(a) Properties of IIR filters
(b) Design of digital butterworth filters using bilinear transformation.
Or
7. Write short notes on the following :
(a) Impulse invariance transformation methods
(b) Design of digital filters using frequency transformation method.
UNIT IV
8. (a) Define IIR and FIT systems. Briefly explain the comparison of IIR and FIR
filters.
(b) Explain the rectangular window and Hanning window.
Or
9. (a) Write short notes on canomic, cascade relizations.
(b) Obtain the cascade relization of
( ) ( )( )
−
+
+
++=
−−−
−−
111
11
4
11
8
11
8
11
311
zzz
zzzH .
———————–––
(DEE 324)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012.
(Examination at the end of Third Year Fourth Semester)
Electricals and Electronics
Paper IV — POWER ELECTRONICS
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) What is a thyristor?
(b) What is snubber circuit?
(c) What is meant by forward blocking mode?
(d) What is the meaning of TRIAC?
(e) Explain the term DIAC.
(f) Define firing angle.
(g) What is SCS?
(h) What is meant by line commutation?
(i) Explain the basic principle of inverter.
(j) What are different types of inverters?
(k) What is a three phase inverter?
(l) What is meant by modulation index?
(m) Draw the control characteristics of type –D choppers.
(n) What is dual converter?
(o) What is meant by series inverter?
UNIT I
2. (a) Explain the static V-I characteristics of a thyristors and different modes of
operation. (8)
(b) It is required to operate 200A SCR, in parallel with 300A SCR, with their
respective on stage voltage drops of 1.4V and 1.2 V. Calculate the value of
resistance to be connected in series with each SCR. So that they share the total
load of 500A in proportion to their current voltages. (7)
Or
3. Writ short notes on the following :
(a) Series and parallel operation of SCR's (8)
(b) TRIAC triggering and turn off methods. (7)
UNIT II
4. (a) Explain the operation principle of 34 full converters with associated waveforms.
(7)
(b) Describe the working principle of single phase semiconverter for RL load with a
neat sketch. (8)
Or
5. (a) Write short notes on 'pulse width modulation control for PF improvement.
(8)
(b) A 34 half wave rectifier is operating in the inverting mode connected to a 440V
(line) supply. If the angle of firing advance is 18º and the overlap is 4.2º, find
the mean voltage at the load. (7)
UNIT III
6. Explain the operating of MC murracy full bridge inverter in detail with reference to
different modes of operation. What are its applications? (15)
Or
7. (a) Explain the operation of a parallel inverter and mention the merits. (7)
(b) With a neat circuit diagram, explain the principle of operation of a single phase
half bridge inverter. (8)
UNIT IV
8. (a) Explain the operating principle of both step up and step down choppers
involving different modes with the neat circuit diagrams. (8)
(b) A step up chopper is used to deliver load voltage of 400 V from a 220V Dc
source. If the blocking period of thyristor is 60 M sec. Compute the requires
pulse width. (7)
Or
9. Explain the operation of 14 step down Cycloconverter for continuous load currents
with the help of neat wave forms and briefly describe their applications. (15)
—————
(DEE 325)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012.
(Examination at the end of Third Year Fourth Semester)
Electricals and Electronics
Paper V — UTILIZATION OF ELECTRICAL POWER
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) Define load equalization.
(b) Define continuous rating of motor.
(c) What do you mean by Electric braking?
(d) What is tractive effort?
(e) What is Plugging
(f) Mention the requirements of an ideal traction system.
(g) Bring out the advantages of electrical heating.
(h) Mention the requirements of good heating element.
(i) What are the different types of arc welding?
(j) What are the requirements of ac welding equipments.
(k) State inverse square law.
(l) Define Reduction factor.
(m) Define Luminous intensity.
(n) What do you mean by tractive effect?
(o) Define polar curves.
UNIT I
2. Write short notes on the following:
(a) Heating and cooling of motors.
(b) Regenerative braking applied to traction motors.
Or
3. (a) Explain briefly how the motor capacity is selected for continuous duty.
(b) Write short notes on ‘Selection of capacity for short time and intermittent
periodic duty’.
UNIT II
4. Sketch the typical speed–time curve for
(a) Main line service and,
(b) Suburban service with electric traction
Or
5. (a) Discuss the advantages of series parallel control of starting as compared to the
rheostatic starting for a pair of dc traction motors.
(b) Explain various methods of electric breaking. State the condition to be fulfilled
for each method of braking.
UNIT III
6. (a) State and explain the Stefan’s law.
(b) With neat sketches, describe the construction, principle of operation,
application and control methods of direct and indirect arc furnaces.
Or
7. Explain the following
(a) Resistance arc welding
(b) Metallic arc welding
UNIT IV
8. (a) Derive relation between E, I and L for a uniform diffuse source.
(b) Discuss laws of illumination and its limitations in actual practice.
Or
9. Define the terms:
(a) Solid angle
(b) Luminous flux
(c) Lumen
(d) Candle power
(e) Uniform diffuse source
(f) Illumination
(g) MSCP
(h) MHCP.
–––––––––––
(DEE 326)
B.Tech. DEGREE EXAMINATION, DECEMBER 2012.
(Examination at the end of Third Year Fourth Semester)
Electricals and Electronics
Paper VI — SWITCH GEAR AND PROTECTION
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) What is protective relay?
(b) What is primary protection?
(c) What is back up protection?
(d) What are thermal relays?
(e) What is offset mho relays?
(f) Define are quenching?
(g) What are the different types of fault and abnormal conditions expected in
alternator?
(h) What is the importance of arc resistance?
(i) Define current chopping.
(j) Define restriking voltage.
(k) What is use of ground wire?
(l) Define resistance grounding.
(m) What is solid resistivity?
(n) Define PSM in over current relay.
(o) What is neutral grounding?
UNIT I
2. What is universal torque equation? Using this equations derive the following
characteristics
(a) impedance relay
(b) reactance relay
(c) mho relay.
Or
3. Describe the operation of following relays with neat sketches
(a) Shaded pole type induction relay
(b) Watt hocermeter type induction relay
(c) Induction cup type relay.
UNIT II
4. (a) Explain the term active recovery voltage, restricting voltage and RRRV.
(b) Derive an expression for restricting voltage in terms of system capacitance and
inductance.
Or
5. (a) Explain the construction principle and working of an oil circuit breaker with a neat sketch.
(b) A circuit breaker is rated at 1200 A, 1550 MUA, 33 KV, 2 Sec, 3φ 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.
UNIT III
6. (a) Make a list of faults, which may occur on an alternator. State the protection to be used for each of faults.
(b) Explain biased differential protection for faults.
Or
7. (a) Explain the working of Are suppression oil.
(b) A 11 KV, 100 MUA alternators is provided with differential protection. The percentage of winding to be protected against phase to ground fault is 85%. The relay is set to operate when there is 20% out of balance current. Determine the values of the resistance to be places in the neutral to ground connection.
UNIT IV
8. (a) Explain the basic principle working and characteristics of static relay.
(b) What do you understand by amplitude comparator and phase comparator?
Prove that duality between them with the help of phasor diagrams.
Or
9. (a) Draw and explain the circuit diagram of static differential relay.
(b) What are the merits and demerits of static relay over electromagnetic relay?
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