(For SSC Jr. Engg. Electrical)
Full Marks – 70 Time – 40 minutes
Q. 1. Power in AC circuit is measured as
A. RMS value B. Avg. value
C. Instantaneous value D. Any of the above Q. 2. Power factor(p.f.) is defined as
A. 𝐴𝑝𝑝𝑎𝑟𝑒𝑛𝑡 𝑝𝑜𝑤𝑒𝑟
𝑅𝑒𝑎𝑐𝑡𝑖𝑣𝑒 𝑝𝑜𝑤𝑒𝑟 B.
𝑇𝑟𝑢𝑒 𝑝𝑜𝑤𝑒𝑟 𝑅𝑒𝑎𝑐𝑡𝑖𝑣𝑒 𝑝𝑜𝑤𝑒𝑟
C. 𝑇𝑟𝑢𝑒 𝑝𝑜𝑤𝑒𝑟
𝐴𝑝𝑝𝑎𝑟𝑒𝑛𝑡 𝑝𝑜𝑤𝑒𝑟 D. None of the above
Q. 3. The connection used of 11kV/400V distribution transformer is A. Delta-Delta B. Delta-Star C. Star-Delta D. Star-Star
Q. 4. In short-circuit test of transformer iron losses are neglected because A. Mutual flux is small B. Primary current is small C. Secondary current is small D. Copper loss is high Q. 5. The speed-time curve used for main line traction is
A. Trapezoidal B. Quadrilateral C. Triangular D. Rectangular
Q. 6. The ratting of lightning arrestor used for protecting 132kV transformer is A. 132kV, 5kA B. 120kV, 10kA
C. 120kV, 5kA D. 76.2kV, 10kA Q. 7. Which type of motor is used in mixers?
A. Universal motor B. Single phase induction motor C. Hysteresis motor D. Stepper motor
Q. 8. Which of the following rules is used for determining direction of rotation of DC motor?
76
A. Flaming’s Right-hand Rule B. Flaming’s Left-hand Rule C. Lenz’s Law D. Faraday’s Law
Q. 9. Resistance switching is generally used in case of
A. Oil CB B. Vacuum CB
C. Air blast CB D. Air break CB
Q. 10. In the circuit given below, the value of R required for the transfer of maximum power to the load having a resistance of 3 Ω is
A. 3 Ω B. 0 Ω
C. 6 Ω D. ∞ Ω
Q. 11. Buchholz relay is ___________ actuated relay and used in only ___________ cooled transformer.
A. oil, oil B. oil, air
C. gas, air D. gas, oil
Q. 12. Find the RMS value of the current given by 𝑖 = 10 + 10 sin ωt A.
A. 5 6𝐴 B. 5𝐴
C. 5 2𝐴 D. 10𝐴
Q. 13. Diversity factor of a power plant is always
A. equal to one B. less than one
C. greater than one D. depends on the type of load Q. 14. Eddy current loss of a transformer depends on
A. both supply voltage & frequency
B. only supply voltage, but not on frequency C. only frequency, but not on supply voltage D. Any of the above
77
Q. 15. Number of independent KVL equations in a network having 6 branches, 3 nodes is
A. 6 B. 3
C. 4 D. 9
Q. 16. A system with transfer function, 𝑇 𝑠 = (𝑠−1)
(𝑠2+𝑠−2) is –
A. stable B. unstable
C. marginally stable D. stability can’t be determined Q. 17. The Laplace transform of 𝑒−2𝑡sin 2𝑡 is –
A. 4 (𝑠+2)2+4 B. 4 𝑠4+4 C. 2 𝑠2+4𝑠+8 D. 2 𝑠4+4
Q. 18. Application of derivative control to a system improves its – A. steady state response B. transient response C. total response D. step response Q. 19. A system having transfer function 𝐺 𝑠 = 1
2(𝑠+0.5) is subjected to unit step input, the
steady state value of the output is –
A. 1 B. 2 C. 1/2 D. 1/10
Q. 20. The solution of the differential equation 𝑑
2
𝑥 𝑑𝑡2+ 2
𝑑𝑥
𝑑𝑡+ 2𝑥 = 1 is –
A. critically damped B. over damped C. under damped D. steady Q. 21. Crossover distortion is found in which type of amplifier?
A. Class A B. Class B
C. Class C D. Class D
Q. 22. If a sine wave is given as an input to a Schmitt Trigger the output will be a A. sine wave B. square wave
C. triangular wave D. none of the above Q. 23. For any transistor(BJT) emitter, base & collector are respectively
78 A. heavily, lightly & moderately doped B. lightly, heavily & moderately doped C. heavily, lightly & moderately doped D. heavily, moderately & lightly doped
Q. 24. If in a 3-phase power measurement by two-wattmeter method, W1=200W and W2=100W for a load. The total reactive power drawn by the load will be
A. 100 3 VAR B. 100 VAR
C. 100/ 3 VAR D. 150 VAR
Q. 25. The equation 𝛻 × 𝐸 = −𝜕𝐵
𝜕𝑡 represents
A. Faraday’s Law B. Gauss’s Law C. Ampere’s Law D. Any of the above Q. 26. In case of gravity control instrument the controlling torque(Tc) is
A. ∝ 𝜃 B. ∝ 1/ sin 𝜃
C. ∝ sin 𝜃 D. ∝ 1/𝜃
Q. 27. A voltmeter gives 120 oscillations per minute when connected to the rotor of a slip ring induction motor. The stator frequency is 50Hz.The slip of the motor is
A. 2% B. 2.5%
C. 4% D. 5%
Q. 28. The number of electrical degrees passed through in one revolution of a six pole synchronous alternator is
A. 360 B. 720
C. 1080 D. 2160
Q. 29. In case the field of a synchronous motor is under excited, the power factor will be
A. leading B. lagging
C. zero D. unity
Q. 30. The damping winding in a synchronous motor is generally used A. to provide starting torque only
79 B. to reduce noise level
C. to reduce eddy currents
D. to prevent hunting and provide the starting torque Q. 31. IGBT is used for applications in
A. Low power B. Medium power C. High power D. All of the above Q. 32. The Snubber circuit is used in thyristor circuits for
A. Triggering B. dV/dt protection C. dI/dt protection D. phase shifting Q. 33. In a thyristor, ratio of latching current to holding current is
A. 0.4 B. 1.0
C. 2.5 D. 6.0
Q. 34. “An isolator can be used as a circuit breaker”. The above statement is
A. right B. wrong
C. depends upon the system D. can be used beyond 33kV Q.35. Transposition is done to avoid
A. unequal voltage at different phases B. interference with communication lines C. unequal distance between transmission lines D. all of these
Q. 36. Circuit breaker used in A.C. is rated for
A. average voltage B. R.M.S. voltage C. peak-to-peak voltage D. all of these Q. 37. Root locus diagram can be used to determine
A. absolute stability B. relative stability C. conditional stability D. none
80
A. RMS value B. Avg. value
C. Instantaneous value D. Any of the above
Q. 39. A device which has VI-characteristics very close to current generator is A. Zener diode B. P-N junction diode
C. Field effect transistor D. None of the above Q. 40. Codes: a b c d A. 4 3 2 1 B. 4 1 2 3 C. 3 2 1 4 D. 3 2 4 1
Q. 41. The insulation of modern EHV lines are designed based on A. the lightning voltage B. switching voltage C. both A & B D. none of the above Q. 42. Graphite is used in nuclear power plant as a
A. coolant B. control rod element C. moderator D. electrode
Q. 43. Spinning reserve is
A. the reserve generating capacity which is available for service but not in operation
B. the reserve generating capacity which is connected to the bus and is ready to take load
81 D. none of the above
Q. 44. The material extensively used for those portions of the magnetic circuit which carry steady flux and need superior mechanical properties is
A. Stainless steel B. Cast iron
C. Aluminium D. Any of the above Q. 45. The electrical conductivity of metal is of the order of
A. 107 B. 10-4
C. 105 D. 10-6
Q. 46. For producing sinusoidal waves we use
A. Wien-Bridge oscillator B. Colpitt’s oscillator C. Relaxation oscillator D. None of the above Q. 47. Household energy meter is
A. integrating instrument B. indicating instrument C. recording instrument D. Any of the above Q. 48. Flip-flop circuit is
A. Astable B. Bistable
C. Unstable D. Both A & B Q. 49. 8085-microprocessor has
A. 8-bit data bus & 8-bit address bus B. 8-bit data bus & 16-bit address bus C. 16-bit data bus & 8-bit address bus D. 16-bit data bus & 16-bit address bus Q. 50. The reflection coefficient(𝜌𝑣) for a open ended transmission line is
A. -1 B. ∞
C. 0 D. 1
Q. 51. If an energy meter disc rotates at 5 rpm for a continuously supplied load of 25 KW for 2 hours, then the meter constant is
A. 6 B. 10
82
Q. 52. Number of comparator needed in a parallel conversion type 8-bit A to D converter is
A. 256 B. 128
C. 255 D. 127
Q. 53. Fuses are used in a electrical circuit for protection up to
A. 5 Amp B. 50 Amp
C. 100 Amp D. 200 Amp
Q. 54. If 100 MΩ is the insulation resistance of a 50 KM long underground cable, then what will be the resistance for a 100 KM long cable?
A. 200 MΩ B. 100 MΩ
C. 50 MΩ D. data insufficient
Q. 55. For the transient stability of a power system A. 𝑑𝛿 𝑑𝑡 = 0, 𝑑𝑃 𝑑𝛿 = 0 B. 𝑑𝛿 𝑑𝑡 < 0, 𝑑𝑃 𝑑𝛿 < 0 C. 𝑑𝛿 𝑑𝑡 = 0, 𝑑𝑃 𝑑𝛿 > 0 D. 𝑑𝛿 𝑑𝑡 > 0, 𝑑𝑃 𝑑𝛿 = 0 where, P & δ
have their usual meaning.
Q. 56. The p.u. impedance of a 100 KVA, 50 Hz, 1-phase transformer is 0.8 p.u.. Now with 200 KVA as base the new p.u. impedance will be
A. 1.6 p.u. B. 0.4 p.u.
C. 0.8 p.u. D. 3.2 p.u.
Q. 57. When four resistances of 2W & 1W; 5W & 2W; 10W & 5W and 15W & 10 W are connected in parallel, the greatest power is absorbed by
A. 2 W & 1 W in parallel B. 5 W & 2 W in parallel C. 10 W & 5W in parallel D. 15 W & 10 W in parallel Q. 58. The cut-in voltage of a silicon diode is approx.
A. 0.7 volt B. 0.3 volt
C. 1.4 volt D. None of the above.
Q. 59. Two equal resistors R connected in series across a voltage source V dissipate power P. What would be the power dissipated in the same resistors when they are connected in parallel across the same voltage source?
83
A. 4P B. P
C. 2P C. 16P
Q. 60. Specific resistance is measured in
A. mho D. ohm/cm
C. ohm – cm D. ohm/cm
Q. 61. The Boolean expression, (A + AB) gets simplified to
A. A + B B. A
C. B D. AB
Q. 62. The slip of an induction motor normally does not depend on A. rotor speed B. synchronous speed C. shaft torque D. core-loss component
Q. 63. A simple phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is
A. 86.7% B. 88.26%
C. 88.9% D. 87.8%
Q. 64. A three-phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3 s. The symmetrical breaking current is
A. 1200 A B. 3600 A
C. 35 kA D. 104.8 kA
Q. 65. The period of the signal x t = 8sin(0.8πt +π
4) is
A. 0.4π s B. 0.8π s
C. 1.25 s D. 2.5 s
Q. 66. The inductance of a long solenoid of length 1000 mm wound uniformly with 3000 turns on a cylindrical paper tube of 60 mm diameter is
A. 3.2 μH B. 3.2 mH
C. 32.0 mH D. 3.2 H
84
A. 12 V B. 30 V
C. 24 V D. 44 V
Q. 68. An ideal op-amp has
A. Infinite input impedance B. Infinite voltage gain C. Infinite CMRR D. All of the above
Q. 69. The most important criterion for the parallel operation of two transformers is A. Both of them must have same voltage ratio
B. Both of them must have same polarity C. Both of them must have same X/R ratio D. Any of the above
Q. 70. Inflammable articles like plastic, wooden materials etc. are generally heated using A. Induction heating B. Dielectric heating
C. Resistance heating D. None of the above
85