ACE/12/EE/MG2

EE 1/24

ACEEngineering Academy

MOCK GATE (2012) – 2EE: ELECTRICAL ENGINEERING

Time : 3 hours Maximum Marks : 100

Read the following instructions carefully.

1. This question paper contains 20 printed pages including pages for rough work.Please check all pages and report discrepancy, if any.

2. Candidates have to answer in the Optical Response Sheet(ORS) by darkening the bubbles using ablack ink ballpoint pen only.

3. Write your registration number, name and other details at the specified locations on theORS using Black ink ballpoint pen only.

4. All the questions in this question paper are of objective type.

5. Questions must be answered on Objective Response Sheet (ORS) by darkening theappropriate bubble (marked A, B, C, D) using Black ink ballpoint pen against thequestion number on the ORS. Each question has only one correct answer. Since bubblesdarkened by the black ink ball point pen cannot be erased, candidates should darken the bubblesin the ORS very carefully.

6. Questions 01 through 25 (25 questions) are 1-mark questions and questions 26 through 55 (30questions) are 2-mark questions.

7. The question pairs (48, 49) and (50, 51) are the common data questions. The questionpairs (52, 53) and (54, 55) are questions with linked answers. The answer to the secondquestion of the linked question pairs will depend on the answer to the first question of thepair. If the first question in the linked pair is wrongly answered or is un attempted, thenthe answer to the second question in the pair will not be evaluated.

8. Questions 56 through 60 (5 questions) are 1-mark questions and questions 61 through 65(5 questions) are 2-mark questions.

9. Un-attempted questions will result in zero mark and wrong answers will result in NegativeMarks. For Q1 to Q25 and Q56 to Q60, 0.33 mark will be deducted for each wrong answer. ForQ26 to Q51, Q61 to Q65, 0.66 mark will be deducted for each wrong answer. The question pairs(Q.52, Q.53), and (Q.54, Q55) are questions with linked answers. There will be negative marksonly for wrong answer to the first question of the linked answer question pair, i.e. for Q.52 andQ.54, 0.66 mark will be deducted for each wrong answer. There is no negative marking for Q.53and Q.55.

10. Calculator is allowed whereas charts, graph sheets or tables are NOT allowed in the examinationhall.

11. Cell / Mobile phones or any other electronic gadgets are prohibited in the examination hall.12. Rough work can be done on the question paper itself. Additional blank pages are given at the end

of the question paper for rough work.

Name

Registration Number EE

ACE/12/EE/MG2

EE – MG2 2/20

Q. 1 – Q. 25 carry one mark each.

Q01. For what values of ‘a’ and ‘b’ the simultaneous equations,

x + y + z = 1, x + 2y + 3z = 4 x + 2y +az = b

have no solution ?

(A) a = 3 & b ≠ 4 (B) a ≠ 3 & b = 4

(C) a = 3 & b = 4 (D) a = 4 & b = 4a

Q02. Which of the following substitutions reduces the non Linear differential equation

0QyPydxdy 4 to linear form (P and Q are functions of x) ?

(A) y–2 = V (B) y–3 = V (C) y–1 = V (D) y–4 = V

Q03. The volume of solid of revolution generated by the curve y = x , 0 x 4 about

x –axis is

(A) 4 (B) 8 (C) 6 (D) 10

Q04. A and B are alternatively tossing a coin. One who gets the head first wins the game.

If A starts the game what are winning chances of player B in second trial?

(A) 5/16 (B) 1/4 (C) 3/4 (D) 1/16

Q05. The inverse Laplace Transform of log2s 1

s(s 1)

(A) t1 (2sin t 1 e )t

(B) t1 (1 e 2cos t)t

(C) 1 + e–t + 2 cost (D) None

Q06. No. of minterms present at the output of n – bit EX – OR gate is

(A) 2n (B) 2n 1 (C) 2n 1 (D) 2n

Q07. A 10 – bit Digital to Analog converter has a resolution of 10 mV/bit. The analog

output voltage for digital input of 1 1 1 1 0 1 0 1 is

(A) 2.45 V (B) 2.55 V (C) 2.02 V (D) 1.85 V

Q08. The value of SP after executing the following instructions isSP = 0 0 0 0H

(1) Push PSW

(A) 0 0 0 0H (B) F F F FH (C) 0 0 0 2H (D) F F F EH

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ZC

V

S is closed

+1 K

Vi V0

+

D2

D1

6.6 V

0.6 V6.6 V

0.6 V

V0

Vi0

5.3 V

5.3 V

6.6 V

6.6 V

V0

Vi0

Q09. Assume that the diodes D1 and D2 have Cutin Voltage of 0.6 V under forward bias.For the Zener Diodes, VZ = 6 V. The i/p – o/p characteristic curve is

(A) (B)

(C) (D)

Q10. The Refracted current of the transmission line is

(A)CZ

V

(B)CZV

(C) Zero

(D)CZ

V2

0.6 V6.6 V

0.6 V

V0

Vi

6.6 V

0

6.6 V

6.6 V

6.6 V

V0

Vi

6.6 V

0

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Q11. Consider the following Statements regarding HVDC Power transmission:

1. The Modern HVDC systems use 12 pulse converters.

2. DC systems never use ground or sea return.

3. Most of present – Day D.C. schemes are two-terminal links.

Which of the statements given above is/are correct?

(A) 1, 2 and 3 (B) 1 only (C) 2 and 3 only (D) 1 and 3 only

Q12. If a fixed amount of power is to be transmitted over a certain length with fixed power

loss, it can be said that volume of conductor is

(A) Inversely proportional to magnitude of the voltage and power factor of

the load.

(B) Inversely proportional to square of the voltage and square of power factor of the

load.

(C) Proportional to square of voltage and power factor of the load.

(D) Proportional to magnitude of the voltage only.

Q13. When hot spots occur at core joints in a transformer, the gases liberated are

(A) Acetylene, Hydrogen (B) Acetylene, Methane, Hydrogen

(C) Methane, Ethane, Propane (D) Methane, Ethane, Hydrogen

Q14. In a Transformer, eddy current loss is 100 W which is half of the total iron loss. If

both thickness of laminations and frequency are increased by 10%, the new iron loss

would be

(A) 256.41 W (B) 231 W (C) 267.41 W (D) 242 W

Q15. Semi closed slots or totally closed slots are used in induction motor, essentially to

(A) improve starting torque

(B) increase pull out torque

(C) increase efficiency

(D) reduce magnetizing current and improve power factor

Q16. A Cumulative compound DC motor delivers fixed rated load power at rated speed. Ifthe series field is short circuited then(A) Both armature current and speed increases(B) Armature current remains constant but speed increases(C) Armature current increases and speed decreases(D) Both decrease

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Q17. A synchronous machine is operating on busbar at constant load and at unity power

factor. If its excitation is increased, then which of the following statements are

correct?

The machine operates as

1. a generator at leading power factor

2. a motor at leading power factor

3. a generator at lagging power factor

4. a motor at lagging power factor

5. exporter of reactive power

6. absorber of reactive power

(A) 2, 4, 6 (B) 2,3,5 (C) 2,3,5 (D) 3,4,6

Q18. Consider the following network

The current i(t) is

(A) 7.5 sin (1000 t) A

(B) 7.5 sin (1000 t) A

(C) 7.5 cos (1000 t) A

(D) 7.5 cos (1000 t) A

Q19. The Q – factor of a parallel resonance circuit consisting of an inductance 1 m H,

capacitance of 105 F and a resistor of 100 is

(A) 1 (B) 10(C) 20 (D) 100

Q20. Open loop transfer function of an unity feedback system,5s

10G

.

The time constant of the corresponding closed loop system is

(A) 0.20 sec (B) -0.25 sec(C) -5 sec (D) 0.1 sec

Q21. The open loop transfer function of an unity feedback system is)2s(s

10

.

The Phase Margin (PM) of the system is in the range of

(A) 0 < PM < 900 (B) 0 < PM <1800

(C) 0 < PM < 2250 (D) can’t be determined

+

150 sin 1000 t V 0.02 H

i(t)

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Q22. A L.T.I continuous – time system has the frequency response H(). It is known

that the input, x(t) = 1 + 4 cos (2t) + 8 sin (3t 900) produces the response,

y(t) = 2 2 sin (2t). Then H() at = 3 is

(A) 2 (B) 0

(C) 0.5 ej/2 (D) 8

Q23. The range of firing angle in Thyristor Controlled Rectifier (TCR) is

(A) 00 - 900 (B) 900 - 1800

(C) 00 - 1800 (d) 00 - 450

Q24. A single phase current source inverter is feeding a purely capacitive load. The inverter

is operated with a current source of 100 A with capacitance of 10 mF. The output is

required with 50 Hz alternations of supply. The peak to peak output voltage would be

(A) 50 V (B) 100 V

(C) 25 V (D) 200 V

Q25. A Dual slope integrating type digital voltmeter has a read out range from 0 to 39999

counts. The resolution of this voltmeter in 40V range of operation is

(A) 4 mV (B) 0.1 mV

(C) 1 mV (D) 0.4 mV

Q. 26 to Q. 55 carry two marks each.

Q26. i2

o

2 dzz along2xy is

(A) i235 (B) i2

35

(C) i331 (D) 3 + i

Q27. The value of

0

xsin dxe by Simpson’s rule with 2 sub intervals, is

(A) )e21(3

(B) )e21(2

(C) )e42(3

(D) )e42(2

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Q28. The solution of the following differential equation is2

2d g 0dt , g is a constant, (0) = a and d (0) 0

dt

(A) = a sin(gt)

(B) = a cos (gt)

(C) = sin ( g t)

(D) = a cos ( g t)

Q29. In a binary communication system either ‘0’ or 1 is transmitted. Because of noise in

the system a ‘0’ can be received as a ‘1’ with probability ‘p’ and a ‘1’ can be received

as a ‘0’ with probability (1-p). Assuming that the probability that a ‘0’ is transmitted

is p0 and 1 is transmitted q0. Then the probability that a ‘1’ was transmitted when 1 is

received, is

(A)00

0

ppqq)p1(

(B)pp)p1(q

pp

00

0

(C)00

0

pp)p1(q)p1(q

(D)000

00

pppqqp

Q30. The logical expression for glowing the LED in the following logic circuit in terms of

P, Q and R is

(A) P Q R (B) RQP (C) P + Q + R (D) RQP

+ 5 V

33 K

100

P

QR

1

2

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1.8 K

+

+

1K

5V

RL

1K

15V

A1

A2 1.5V+

Q31. Which of the following Flip – Flops is represented by digital circuit given below ?

(A) S R F F with A = S and B = R (B) J K F F with A = J and B = K

(C) J K F F with A = K and B = J (D) S R F F with A = R and B = S

Q32. Calculate RL for op-amp circuit shown :

(A) 500 (B) 1 K (C) 6 K (D) 9 K

Q33. Match List-I (Equipment) with List-II (Application) and select the correct answerusing the codes given below the list.

List – I List – IIA. Metal oxide Arrester 1. Protects generator against short circuit faults.B. Isolator 2. Improves transient stability.C. Auto – Reclosing CB 3. Allows CB maintenanceD. Differential Relay 4. Provides Protection against surges.

Codes:

A B C D(A) 4 3 2 1(B) 3 4 1 2(C) 4 3 1 2(D) 3 4 2 1

1

2

3 T Q

QAB

Clk

ACE/12/EE/MG2

EE – MG2 9/20

X = 0.3 X = 0.2

V= 1.00E = 1.1

Q34. A synchronous generator working at 50 Hz is connected to an infinite bus through a

line as shown in Fig. The inertia constant is 3 MW – sec/MVA. If the generator is

loaded to 75% of its maximum power transfer capacity and a small perturbation is

given, the new natural frequency of oscillations is

(A) 9.62 Hz

(B) 1.53 Hz

(C) 8.72 Hz

(D) 1.39 Hz

Q35. The current rating of a relay is 5A. The relay is set at 150% and connected throughCT of 400/5. For the Fault current of 6000A, find PSM?(A) 60 (B) 50 (C) 10 (D) 15

Q36. A 100 KVA transformer is provided with tap changer on primary side. The puleakage impedance of Transformer is (0.0075 + j 0.09) . The tap setting formaintaining rated voltage on secondary side of Transformer at a load of 100 KW at0.8 p.f lag is(A) 6.5% down (B) 6.5% up (C) 7.5% down (D) 7.5% up

Q37. A starting torque of 80 Nm is developed in an induction motor by an auto-transformerstarter with a tapping of 30%. If the tapping of auto-transformer starter is 60%, thenthe starting torque will be(A) 40 Nm (B) 160 Nm (C) 240 Nm (D) 320 Nm

Q38. A 230 V D.C series motor takes 30 A when it delivers its rated output at 1200 rpm.Its resistance is 0.4 . The resistance that must be added to obtain rated torque at800 rpm is(A) 7.2 (B) 1.2 (C) 2.42 (D) 5.62

Q39. Consider the following network

The power dissipated across 4 resistor is

(A) 0.188 W (B) 0.288 W (C) 0.388 W (D) 0.488 W

+2 V

1 2 3

3

4

0.5 A

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IdealSampler

Ts s/2

x(t) y(t)Ts

s/2

Q40. The phasor diagram shown in fig. is valid for a two element series circuit having

(A) R and C, with tan = 1.3367

(B) R and C, with tan = 4.2635

(C) R and C, with tan = 1.1918

(D) R and C, with tan = 0.2345

Q41. Characteristic equation of a system is s3 + 20 s2 + 16 s + 320 = 0.

The undamped natural frequency in rad/sec is

(A) 2 (B) 2 (C) 4 (D) 16

Q42. The input to the following system is x(t) = 2 + cos (50t) . If it is sampled at

Ts = 0.01 secs, then the expression for the output signal y(t) is

(A) 2 + cos (50t) (B) 2 + cos (5t)(C) cos (50t) (D) 2 + cos (30t)

Q43. A step down chopper is feeding an inductive load, whose output current is assumed tobe ripple free. The ratio of average currents through chopper and free wheeling diodeis

(A) 4

(B) 0.25

(C) 0.8

(D) 1.25

Q44. A single phase 230 V, 50 Hz ac mains fed step down transformer (2 : 1) is supplyingpower to a full – wave bridge uncontrolled ac – dc converter. The converter is usedfor charging a battery with 12 V dc with the series limiting resistor being 20 . If oneof the diodes gets open circuited then average charging current is(A) 2 A (B) 1 A (C) 1.65 A (D) 2.3 A

V

500

103.20

I

CH

F.DVS = 100 V

+

LOAD

I0

Duty cycle =0.8

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Q45. A single phase fully controlled bridge rectifier with a free-wheeling diode feeds aninductive load. The load resistance is 15.53 and it has a large inductance providingconstant load current. Input to converter is fed from an ideal 230 V, 50 Hz singlephase source. For a firing angle delay of 60, the average values of thyristor currentand source current are respectively.(A) 3.33 A, 3.33 A (B) 5.77 A, 0(C) 5.77 A, 5.77 A (D) 3.33 A, 0

Q46. A dynamometer type wattmeter with its voltage coil connected across the load side ofthe instrument reads 250W. The voltage coil has a resistance of 2000 . If the loadvoltage is 200 V, the power taken by the load is(A) 250 W (B) 230 W(C) 200 W (D) 20 W

Q47. An oscilloscope is operated in X-Y display mode.List-I suggests Y- i/p & X - i/p signals.List-II describes corresponding Lissajious figures displayed.Match List-I & List-II using codes given below.

List-I List-II

1. 10 cos (100 t)V & 5 sin (100 t) V

2. 10 sin (100 t+450) V & 10 sin (100 t) V

3. 5 cos (100 t) V & 10 sin (100 t) V

4. 10 sin (100t) V & 10 cos (100 t) V

1 2 3 4(A) Q S P R(B) Q P S R(C) R Q P S(D) S P R Q

P.

Q.

R.

S.

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Common Data Questions

Common Data for Questions 48 and 49:

A 2000V, 3-phase, 4-pole, star connected synchronous motor runs at 1500 rpm. The

excitation is kept constant corresponding to an open circuit voltage of 2000V. The

resistance is negligible in comparison with synchronous reactance of 3.5 /phase.

Armature current is 200 A.

Q48. The torque (or load) angle is

(A) 17.650 (B) 35.30

(C) 16.650 (D) 450

Q49. The power factor is

(A) 0.816 lag (B) 0.816 lead

(C) 0.953 lag (D) 0.953 lead

Common Data for Questions 50 and 51:

A synchronous generator is rated 20MVA, 13.8 KV. It has X1 = 0.25 PU,

X2 = 0.35PU and X0 = 0.1 PU. The neutral is solidly grounded. The Machine is on

no-load and is operating at rated voltage when a double line to ground fault occurs at

its terminals.

Q50. The Sub-Transient fault current in KA is

(A) 57.6 (B) 45.5

(C) 11.52 (D) 28.65

Q51. The Sub-Transient current in phase B in KA is

(A) 4.85 (B) 6.45

(C) 31.12 (D) 18.42

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Linked Answer Questions :

Statement for Linked Answer Questions 52 and 53 :

In the circuit shown, the switch is moved from position ‘a’ to position ‘b’ at t = 0. The

switch was in position ‘a’ for a long time, and the current i1(t) achieved steady state

of 2 A with a time constant of 0.2 sec.

Q52. The values of R1 and L are respectively.(A) R1 = 1 , L = 0.2 H (B) R1 = 0.5 , L = 0.1 H(C) R1 = 2 , L = 0.5 H (D) R1 = 4 , L = 1 H

Q53. If the poles of the circuit for t > 0 lie at s = 1 and 2, the values of R2 and C arerespectively.(A) R2 = 0.5 , C = 1 F (B) R2 = 0.3 , C = 10 F(C) R2 = 0.3 , C = 5 F (D) R2 = 4 , C = 5 F

Statement for Linked Answer Questions 54 and 55 :

The transfer function of a system is given by

2s3s6

)s(U)s(Y

2

Its state space model is given by

xcy,uba

xK00K

x2

1

where x is the state vector.

Q54. The values of K1 and K2 are

(A) 1, 2 (B) 1, 2 (C) 3, 2 (D) 3, 2

Q55. The State Transition Matrix (STM) is given by

(A)

0ee0

t3

t2

(B)

t2

t3

e00e

(C)

t2

t

e00e

(D)

t2

t

e00e

i2(t)

C

R2

i1(t)

V1 = 1 V

b

Fig.

L

+

aR1

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General Aptitude (GA) Questions :

Q. 56 to Q. 60 carry one mark each.

Q56. Choose the most appropriate word from the options given below to complete the

following sentence

The visitor was of an______age; white-haired but baby-faced, he might havebeen twenty-five or fifty.(A) assiduous (B) unalterable(C) indecorous (D) indeterminate

Q57. The question below consists of pair of related words followed by four pairs of words.

Select, the pair that best expresses the relation in the original pair.

HIBERNATION : ACTIVITY ::

(A) joint : rope (B) molecule : crystal(C) infringement : law (D) interregnum : government

Q58. Choose the word from the options given below that is most nearly opposite in

meaning to the given word:

CANONICAL :

(A) infelicitous (B) irrefutable(C) heterodox (D) minuscule

Q59. Choose the most appropriate word from the options given below to complete the

following sentence:

Medieval kingdoms did not become constitutional republics overnight; on thecontrary, the change was _______(A) unpopular (B) unexpected (C) advantageous (D) gradual

Q60. If the two digits of the age of Mr. Manoj are reversed then the new age so obtained is

the age of his wife.111 th of the sum of their ages is equal to the difference between

their ages. If Mr. Manoj is older than his wife then find the difference between theirages.(A) 8 years (B) 10 years (C) 9 years (D) 7 years

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Q. 61 to Q. 65 carry two marks each.

Q61. There are two containers : The first contains 500ml, of alcohol, while the second

contains 500ml of water. Three cups of alcohol from the first container is taken out

and is mixed well in the second container. Then, three cups of this mixture is taken

out and is mixed in the first container. Let A denotes the proportion of water in the

first container and B denotes the proportion of alcohol in the second container. Then,

(A) A > B (B) A < B (C) A=B (D) cannot be determined

Q62. The average temperature of the town in the first four days of a month was 58 degrees.

The average for the second, third, fourth and fifth days was 60degrees If the

temperatures of the first and fifth days were in the ratio 7 :8, then what is the

temperature on the fifth day?

(A) 64 degrees (B) 232 degrees (C) 240 degrees (D) None of these

Q63. Aqua regia is a mixture containing 50percent concentrated HCL and 70 percent

concentrated HNO3 in the ratio 1:3 respectively. Aqua regia is to be formed with 15

lit, of HCL of 80 percent concentration and 56 lit, of HNO3 of 90 percent

concentration by adding water as a diluting agent. Another mixture ‘X’ having

40percent concentrated HCL and 30percent concentrated H2SO4 in the ratio 5:7

respectively is added to the aqua regia to form a solution of 111 lit. Find the ratio of

HCL to water in the solution. Only water is used as a diluting agent.

(A) 3:8 (B) 4:7 (C) 2:5 (D) 1:3

Q64. Select the correct alternative from the given choices

Statement :

A study on effects of coffee consumption on the sleeping pattern has found out that

those who have coffee at least twice a day have a sound sleep.

Which of the following contradicts the findings reported in the above statement ?

(A) Children have the most sound sleep even though they do not consume coffee.

(B) Caffeine contained in coffee, is used in manufacturing ayurvedic sleeping pills.

(C) It is found that those who do not consume coffee are able to sleep long hours than

those who consume coffee.

(D) It is found that those who consume coffee are likely to dream more frequently in

sleep than those who do not consume coffee.

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Q65. Directions for question No . 65: Answer the question on the basis of the information

given below. Table A below provides data about ages of children in a school. For the

age given in the first column, the second column gives the number of children not

exceeding the age. For example, first entry indicates that there are 9 children aged 4

years (or) less. Table B and C provide data on the heights and weights respectively of

the same group of children in a similar format. Assuming that an older child is always

taller and weights more than a younger child, answer the following question.

Table A Table B Table CAge (years) Number Height (cm) Number Weight (kg) Number4 9 115 6 30 85 12 120 11 32 136 22 125 24 34 177 35 130 36 36 288 42 135 45 38 339 48 140 53 40 4610 60 145 62 42 5411 69 150 75 44 6712 77 155 81 46 7913 86 160 93 48 9114 100 165 100 50 100

What is the number of children of age 9 years or less whose height does not

exceed 135 cm ?

(A) 48 (B) 45

(C) 3 (D) cannot be determined

END OF THE QUESTION PAPER

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SPACE FOR ROUGH WORK