ELECTRICAL ENGINEERING

. Allowed ifhree, Hours I. lMaximum Marks:.'300 I

-INSTRUCTIONS,
Each question, is print"ed-bo"thin' Hindi ,and in English.
Answers muSt" be written ih medium
•c

spe'CiMcl in the' AC1iiiission 'Certificate -issued to you; wHich must be clearly on the couer of the answer'::book in 'the space provided for the purpose. No marks-will be given, for: the'.a1J.S.tpers,written: in, a medium other that., in,-the Admission

Candidc;Ltes, should' attempt Question Nos. 1 .and 5 which are ct;Jmpulsory, and any three
.
remaining selecting',fIt least one .question fr9m SectiQ.1)..
All -questions 'carry equal-marks.,
Marks 'assigned to each part of the question are indicated at the end ofthe
Assume" .suitable data considered necessary and indicate the same clearly.­
",SYlJlbols/NotationS" .¥suaZ, l?1eanings; unless othenvise, indicated.



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Section-A
What are the difficulties associated with measurement of low resistances?
Describe nowi low resistance is "measured accurately. by Kelvin's double bridge.' 'Derive the formula. 15
A 110-kV;.rSO':Hz·, 200-tan long line resistance and resistance of 40 ohms and 80 ohms phase respectively.. The capacitance of each conductor' to neutral is 1·68" if the receiving end voltage .is 116 kV at 0:0 load;, compute the sending-end voltage at no load;
the line" charging: current
the kVA supplied to the line;
the open-circuit power loss in the line. Assume a nominal-pie circuit for the line. 20
Explain the steps involved,in interfacing, a stepper motor to the 855. ,Draw the ,interface schematic. 10 •
Indicate the steps ,involved in designing an, 8255 output port using partial decoding such that the port maps ·to any' address between 80 H and .FF'H. Show also the hardware schematic: 10
2. The diagram of a speed control system is given below: <img src='./qimages/1064-2a.jpg'> ·The generator-e.m:f. eg is 2000 volts per field· ampere and the e.m.f. em is 1-5 volts,rad se_c The .motor torque KT is -0·5 Nm per armature ampere 'and inertia of motor and ,load,· is 10-4kg-m., Assuming negligible friction,. determine the transfer function omega(s)/vin(s).
State and briefly explain the basic requirements essential qualities of protective relying. 20
discuss consideration of transmision losses in economic operation of thermal power plants.
for a system consisting of two plants,the incremental costs are given by
dc1/dp1=o.o1p1+20 /mwhr
dc2/dp2=0.015p2+22.5/mwhr
the system is running under optimal schedule with p1=p2=100mw
if dowpl/dowp2=0.2,find the penalty factor of the plants
3. The..output/error. transfer .function of a control ,system with unit feedback loop is
K k/s2(1
Sketch the Nyquist locus and hence .determine. the stability of the system (note: the diagram is to be drawn on the answer book itself) 20
Explain what you understand by steady-state stability and steady state stability limit. 6
methods' to improve transient stability of power system. 14
(c)Discuss in brief the physical, chemical and electrical properties ofSF6 gas with respect to its application in high-voltage circuit breakers. 20
Briefly .explain· the. working principle,... of.a CRO with the help of a block diagram.
(ii)·The voltage .across horizontal deflection plates of a eRO is V1 sin(omega t+02 and 'that across vertical plates ",V2 sin(rot Prove that the. trace on the screen is an ellipse. 'Define the equation interpret,..its meaning.
How is error detection handled in data transfer using checksums and cyclic redundancy characters Explain the concepts.
Suppose the following.data bytes are received and the last byte is the checksum character
(iii)Calculate the data polYnominal forthe16-bit data stream 26FO H. Write the generator polynomial for bisync SDLC protocols .
What is the theoretical:bandwidth required to transmit a digital ,signal? ,Justify your answer How can you related and width to bit What IS Inter-Symbol Interference .(ISI)?-·HOw· 'Can be tackled? What-is the. ,importance of Eye­diagram? How,is)t
what is inter-symbol interference how can this be tackled? what is the importance of eye. diagram? how is it generated?
5. Using Routh-Hurwitz criteria, determine the maximum value of .K for which the following control system is sable: 10
<img src='./qimages/1064-5a1.jpg'>
For the following control system with . sinusoidal input signal.determine the 'frequency at which the output magnitude Is maximum: 10
<img src='./qimages/1064-5a2.jpg'>
Show the schematic diagram of a power line carrier protection scheme for a transmission line. 8
Which are the components you consider most vital in the scheme? 4
Using. the principle of phase comparision explain how the scheme ·works.
How is regeneration in digital communication different from amplification in analog communication? .In .what way' regeneration is better? . 5
Draw the block diagram of a PCM receiver and show .how a .transmitted ,sinusoidal ',signal is
reconstruction in the receiver.. 5
(iii)Distinguish between virtual circuit and datagram·.-in data-networks, 5
What is the rationale. behind error control coding? Distinguish between linear codes and non­linear codes:' ". .. 5
Explain the carrier type a.c.signal conditioning system With the helpJ of a 'block diagram., 10
Describe the .circuit l of a 3-amplifier configuration of an instrumentation amplifier. Discuss how this offers a :ve.ry high inp:ut
Draw the block diagram of a microprocessor based process control system making use of data acquisition systems, sensor 'inputs outputs connected to relays DACs. Explain the scheme briefly
Design an interface to a micro .using the LM334 temperature sensor, and LM393 analog comparator. A logic 1 i/p should indicate a temperature of greater than 100 of. (Corresponding voltage for this sensor is 3.11 volts.) 8
The information in an analog signal voltage waveform is to be transmitted over',a PCM system ,W!tJ1. ·an, .accuracy 9f ±0·10,.1, (full scale). The analog voltage wave form has a bandwidth of 100 Hz and an amplitude range of 10Vto +10V.
determine the maximum sampling rate required.
(2)Determine the number of bits in each PCM word.
Determine the minimum bit rate required in the PCm signal.
(4)Determine the minimum absolute channel bandwidth required for the transmission. 12
(ii)Why do we need a MODEM to access Internet over telephone line? How does it work? What is the role of a ROUTER in a data network? 8
7 What are capacitive transducers? 5
What are the different uses of capacitive transducers? 5
A pressure-measuring instrument uses.a capacitive transducer having a spacing of 4mm ,between its diaphragms. A pressure of 5.00, produces an· aVerage deflection of 0·25mm of the diaphragm the. transducer. T1J.e transducer capacitance of 300 'pFbefore application of the pressure. was 'connected to an oscillator circuit having a frequency of "lOa0kHz. Determine i the .change in frequency of oscillator after the pressure is applied to the. transducer. 10
What are .the 'features three sources .of ·interrupts. that 8086 has? 6
What are the three operations possible in the string group? What are the, registers used by the instructions. in this group? 6
Write the block diagram indicating how 8255A PPI is interfaced to 8086 max mode CPU' module, USIng two 8255As for 16-bit I/O operation. 8
Distinguish among the following terms: 6
Forward error correction and
Error detection method
(2)RanClom error and Burst error
Block code s and Convolutional
codes.
If c· is valid code vector then prove that ,CHT where HT is the transpose of the parity check matrix 10
List the merits and demerits of delta modulation. 4
A PID control system is shown below:
<img src='./qimages/1064-8a.jpg'>
for: K1=0 .find the values.of Kp and KD so that the. system has no steady-state error With' step iiipuf, has a damping ratio of O-g and the dominant time constant of 1. 20

A line-to-ground fault occurs on-phase of a three-phase I synchronous generator grounded through an impedance Zn and operating without load, Derive sequence network representation for this fault and determine the current in phase 12
The positive, negative and zero .sequence reactances of a 13.2-kV, 50-MVA synchronous generator are 0·3' pu, 0'2· and Q. pu A line:.;to-ground fault occurs on phase 'a'.Neglecting all resistances; determine: the fault current.
The figure below shows the single-line diagram .of a part of a t power system. It provided with distance relays at A and B. CIJ C2 C3 and C4 are circuit breakers. The impedances of the sections of the,line are shown.in ohms:
<img src='./qimages/1064-8c.jpg'>
A fault occurs at f1 as· shown in . impedance se.en by-the relay installed at A. Will
this relay operate before the circuit breaker: at has tripped?'S,

Will the relay atB trip for' fault at F1 before the circuit-breaker at A has tripped? 5
If the circuit breaker 62 fails for a .fault at will the fault be cleared by the relays at A and 5
How will the fault at F 2 be, cleared? 5