MPPSC AE 2017: State Engineering Service Examination, Electrical Engineering Paper-II
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600041
RoU No.
Candidate should write his/her Roll No. here.
Total No. of Questions : 7 No. of Printed Pages : 7
SE]V[-2017(02)-II
ELECTRICAL ENGINEERING
Paper—^11
Time : 3 Hours ] [ Total Marks : 300
Instructions to the candidates:
m
Please read each of thefollowing instructions carefully before [m]
attempting questions.
0^
Candidates should attempt FIVE questions in all. Question No. 1 is compulsory.
Out ofremaining SIX questions, attempt any FOUR.
All questions carry equal marks. The number of marks carried by a part ofa question
is indicated against it.
Answers must be written in ENGLISH only.
Unless otherwise mentioned, symbols and notations have their usual standard meanings.
Assume suitable data, if necessary and indicate the same clearly.
Neat sketches should be drawn wherever required.
All parts and sub-parts ofa question are to be attempted together in the answer book.
Any pages left blank in the answer book must be clearly struck out.
SEM-2017/EE-2 [ P-T.O.
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1. Answer the following questions 6x10=60
{a) What do you mean by information capacity, bits and bit rate? Write the
expression for Shannon limit for information capacity.
(b) Explain briefly the various methods of arc extinction in a circuit breaker.
(c) Explain the process of building up of voltage in a d.c. shunt generator and
-V
give the conditions of self-buildup voltage.
(d) Discuss the properties of Gaussian process.
(e) A 12500 kVA load is supplied at a power factor of 0-8 lagging by a 3-phase
1— voltage is to be maintained at 33 kV at both ends.
transmission line whose OL
Determine the capacity of the sjmchronous condenser to be installed for
1
voltage regulation. Given that the line resistance and reactance per phase
1
are 4 £2 and 12 £2 respectively.
(f) What is the effect of the curvature of the earth on direct and reflected
radio waves?
(g) Explain why field control is employed for getting speeds higher than rated
and armature voltage control is employed for getting speeds less than
rated.
(h) Determine the transfer matrix for the system given below :
'0 3" '1 r "2 1' "Xi"
= + u[t) and y-
X2 _X2_ 1 1 1 0 _X2_
(i) Explain why a single-phase induction motor is not self-starting.
(j) Differentiate between peripheral-mapped I/O and memory-mapped I/O.
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2. (a) (i) Derive the expression for moment of inertia of the fljrwheel required
for load equalization. 10
(ii) A motor equipped with a flywheel is to supply a load torque of
1000 N-m for 10 sec followed by a light load period of 200 N-m long
enough for the flywheel to regain its steady-state speed. It is desired
to limit the motor torque to 700 N-m. What should be the moment of
inertia of the flywheel? The motor has an inertia of 10 kg-m . Its
no-load speed is 500 r.p.m. and the slip at a torque of 500 N-m is 5%.
Assume speed-torque characteristic of motor to be a straight line in
the region of interest. 10
(b) An electric train weighing 500 tonnes climbs up gradient with G = 8 and
following speed-time curve :
(i) Uniform acceleration of 2-5km/hr/sec for 60 sec
(ii) Constant speed for 5 min
(Hi) Coasting for 3 min
(iv) Dynamic braking at 3 km/hr/sec to rest
The train resistance is 25 N/tonne, rotational inertia effect 10% and
combined efficiency of transmission and motor is 80%. Calculate the
specific energy consumption. 20
(c) Explain the principle of dielectric heating. What are the problems
associated with it? Also give the applications of dielectric heating. 20
3. (a) Draw the architecture diagram of 8085 microprocessor and explain the
functions of each block in detail. 20
(b) (i) Explain all the steps required to perform an interrupt process in
8085 microprocessor. . 10
(ii) What are the different modes of data transfer in microprocessor?
Explain different conditions under which microprocessor controlled
data transfer can take place. 10
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(C) (i) Explain the different addressing modes supported by 8085 instruction
set and explain each one with the help of suitable example. 10
(n) Explain the operation of the following instructions in
8085 microprocessor : 3+3+4=10
(1) RRC
(2) CMPR
(3) LDAX Rp
4. (a) (i) Explain the various parameters that influence the design of a satellite
communication link. 10
(ii) With the help of a block diagram, briefly describe the functions of the
important constituent parts of a typical large size earth station. 10
(b) (ii Briefly describe different digital modulation techniques. Which is the
most commonly used one and why.is that so? 10
(ii) What is the use of multiplexing techniques? Explain briefly the
various multiplexing techniques. 10
(cj (i) Draw the schematic diagram of an IMPATT diode and fully explain the
two effects that combine to produce a 180° phase difference between
the applied voltage and the resulting current. 10
Sketch and explain the block dia^am of pulse code modulation. Also
give its applications. 10
5. (a) (i) Use the Routh-Hurwitz array to determine the location (right-half
plane, left-half plane or on imaginary axis) of the closed-loop poles of
the following control system : 10
s-7
s+2
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(ii) The step response of a second-order system is shown in the figure
below for an input of 2u(t). Determine the open-loop and closed-loop
transfer functions. Assume unity feedback ; 10
(b) The overall transfer function of a control system is given by
C(s) _ 16
R{s) +1-63+16
It is desired that the damping ratio be 0-8. Determine the derivative rate
feedback constant and compare rise time, peak time, maximum
overshoot and steady-state error for unit ramp input without and with
derivative feedback control. 20
(c) (i) Explain the stepwise procedure for plotting root locus. 10
(ii) Determine the overall transfer function relating C and R for the
system whose block diagram is shown below : 10
G3
+x
R +. c
>
^6^ "A
H2 ^
Hi ^
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6. (a) A 15 kVA, 2300/230 V, 50 Hz, single-phase transformer gave the following
test data :
Open-circuit test : =2300V,.I^ = 0-21 A, =50 W
Short-circuit test : Vg = 47 V, /^ = 6 •0 A, Wg =160 W
(i) Find the equivalent circuit referred to high-voltage side. 5
(ii) Calculate the full-load voltage regulation at 0-8 p.f. lagging when the
load voltage is held at 220 V. 5
(Hi) What is the efficiency at half the rated load at unity power factor? 5
(iv) Find the maximum efficiency and corresponding output power. 5
(b) (i) Derive the torque equation of a d.c. machine. 10
(ii) A 230 V d.c. shunt motor with constant field drives a load whose
torque is proportional to the speed. When running at 750 r.p.m. it
takes 30 A. Find the speed at which it will run if a 10 £2 resistance is
connected in series with its armature. The resistance of armature
may be neglected. 10
(c) A 25 hp, 400 V, 50 Hz, 4-pole, star-connected induction motor has the
following impedances per phase in ohms referred to the stator side :
i?g =0-641, Ry =0-332, =1-106, Xy =0-464 and X„^^ =26-30
Rotational losses are assumed constant and are 1 -1 kW and the core losses
are assumed negligible. If the slip is 2-2% at rated voltage and frequency,
find (i) speed, (ii) stator current, (in) power factor and (iv) output and input
power. 20
7. (a) (i) Why is load flow study essential for a power system? Starting from
the fundamentals, derive static load flow equations in polar
coordinates for n bus system. Also write the nature of these
equations. 10
(ii) What are the various tiqjes of HVDC link? Explain each of them
with the help of diagram and also mention the advantages and
disadvantages of each. 10
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(b) (i) Discuss the advantages of digital relays. Describe the basic functional
blocks of a digital relay. 10
(ii) Explain the principle of -working of distance relays. 10
(c) (i) Explain the construction, principle and working of an oil circuit
breaker with a neat sketch. 10
(ii) Describe the trip circuit diagram of 3-zone distance relay used for the
protection of a transmission line. Why are 3 zones necessary? How
their reach setting and time setting is done? 10
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Source: Madhya Pradesh Public Service Commission. Question paper published by Madhya Pradesh Public Service Commission.