Full-Length Mock Test 9 — RRB JE CBT 2 Technical Abilities Pattern (100 MCQs)

Section A: Circuit Fundamentals and AC/DC Basics (20 Questions)

1. The unit of electric charge is the:
   (a) Coulomb (b) Ampere (c) Volt (d) Farad
2. The unit of electric potential difference is the:
   (a) Volt (b) Ampere (c) Coulomb (d) Ohm
3. The unit of electric current is the:
   (a) Ampere (b) Volt (c) Coulomb (d) Watt
4. The unit of electrical resistance is the:
   (a) Ohm (b) Ampere (c) Volt (d) Farad
5. The unit of electrical power is the:
   (a) Watt (b) Joule (c) Newton (d) Coulomb
6. The unit of electrical energy consumed by a household, as billed, is the:
   (a) Kilowatt-hour (kWh) (b) Watt (c) Ampere-hour (d) Volt-second
7. A resistor's colour code with bands "brown-black-red" indicates a resistance value of:
   (a) 1000 Ω (1 kΩ) (b) 100 Ω (c) 10 Ω (d) 10,000 Ω
8. Resistivity of a conducting material is defined per unit:
   (a) Length and cross-sectional area (resistance × area / length) (b) Volume only, with no area or length term (c) Mass only (d) Current only
9. The resistance of a conductor increases with increasing temperature for most:
   (a) Metals (positive temperature coefficient) (b) Insulators exclusively (c) Semiconductors exclusively, with metals showing the opposite trend (d) None of the materials, as resistance is temperature-independent
10. The temperature coefficient of resistance for most pure metals is:
    (a) Positive (resistance increases with temperature) (b) Negative (resistance decreases with temperature) (c) Zero (no change with temperature) (d) Undefined
11. Semiconductors like silicon typically show a temperature coefficient of resistance that is:
    (a) Negative (resistance decreases with increasing temperature) (b) Positive, identical to metals (c) Zero, identical to insulators (d) Infinite
12. The "superposition theorem" in circuit analysis applies only to circuits containing:
    (a) Linear bilateral elements (b) Only nonlinear elements (c) Only a single source with no other components (d) Only capacitors, never resistors or inductors
13. Thevenin's theorem allows a complex linear network, as seen from two terminals, to be replaced by:
    (a) A single voltage source in series with a single resistance (b) A single current source in parallel with an inductor only (c) An infinite network with no simplification possible (d) A network with no equivalent representation at all
14. Norton's theorem allows a complex linear network, as seen from two terminals, to be replaced by:
    (a) A single current source in parallel with a single resistance (b) A single voltage source in series with a capacitor only (c) An infinite network with no simplification possible (d) A network with no equivalent representation at all
15. Maximum power transfer from a source to a load occurs when the load resistance equals the:
    (a) Source's internal (Thevenin) resistance (b) Load's own reactance, unrelated to the source (c) Zero value regardless of source resistance (d) Infinite value regardless of source resistance
16. A "star-delta" transformation is used to simplify networks containing:
    (a) Three-terminal resistor/impedance networks not reducible by simple series-parallel combination (b) Only two-terminal single-resistor networks (c) Only capacitor banks with no resistors (d) Only inductor banks with no resistors
17. In a balanced three-phase star (Y) connection, the line voltage is related to the phase voltage by a factor of:
    (a) √3 (b) 3 (c) 1/√3 (d) 1
18. In a balanced three-phase delta connection, the line current is related to the phase current by a factor of:
    (a) √3 (b) 3 (c) 1/√3 (d) 1
19. In a balanced three-phase star connection, the line current equals the:
    (a) Phase current (b) Phase current multiplied by √3 (c) Phase current divided by √3 (d) Phase current multiplied by 3
20. In a balanced three-phase delta connection, the line voltage equals the:
    (a) Phase voltage (b) Phase voltage multiplied by √3 (c) Phase voltage divided by √3 (d) Phase voltage multiplied by 3

Section B: Electrical Machines (20 Questions)

21. The "commutator" in a DC machine functions to:
    (a) Convert the AC induced in the armature into DC at the brushes (or vice versa for a motor) (b) Regulate the field current alone, with no role in armature current (c) Cool the armature winding, with no electrical function (d) Serve purely as a mechanical support with no electrical function
22. "Armature reaction" in a DC machine refers to the effect of:
    (a) Armature current's magnetic field distorting/weakening the main field flux (b) The field winding's resistance alone (c) The commutator's mechanical wear alone (d) The brush material's colour
23. Interpoles (commutating poles) in a DC machine are used primarily to:
    (a) Improve commutation and reduce sparking at the brushes (b) Increase the main field flux permanently (c) Serve only a structural/mechanical support function (d) Reduce the number of main poles required
24. A DC compound motor combines:
    (a) Both series and shunt field windings (b) Only a series field winding (c) Only a shunt field winding (d) No field winding at all
25. In a "cumulative compound" DC motor, the series and shunt field MMFs:
    (a) Aid (add to) each other (b) Oppose each other (c) Have no relation to each other (d) Cancel each other out completely at all loads
26. In a "differential compound" DC motor, the series and shunt field MMFs:
    (a) Oppose each other (b) Aid each other (c) Have no relation to each other (d) Are always exactly equal, cancelling completely
27. The speed of a DC shunt motor can be controlled by varying the:
    (a) Field current (flux control) or the armature voltage (b) Only the frequency of the DC supply, which has no meaning for DC (c) Only the number of poles physically, in real time (d) Only the commutator segments' width
28. Starting a DC motor directly across full supply voltage without a starter is undesirable because:
    (a) The armature current would be excessively high due to low back EMF at standstill (b) The armature current would be zero at standstill, preventing starting (c) The motor would run at reduced speed only, with no current concern (d) The field current would become zero
29. A three-phase induction motor's rotor can be of which two main types?
    (a) Squirrel cage and wound (slip-ring) rotor (b) Only squirrel cage, with no other type existing (c) Only wound rotor, with no other type existing (d) Only permanent-magnet rotor
30. A slip-ring (wound-rotor) induction motor allows external resistance to be added to the rotor circuit, primarily to:
    (a) Improve starting torque and control starting current (b) Reduce running efficiency deliberately at all times (c) Increase no-load speed to unsafe values (d) Prevent the motor from starting at all
31. The "crawling" phenomenon in a squirrel cage induction motor refers to the motor:
    (a) Running stably at a low speed (around 1/7th of synchronous speed) due to harmonic effects (b) Running at exactly synchronous speed under all conditions (c) Failing to run at any speed whatsoever (d) Running only in reverse direction
32. "Cogging" (magnetic locking) in an induction motor refers to the motor's:
    (a) Refusal to start at all, due to stator and rotor slot number interaction (b) Tendency to run above synchronous speed (c) Tendency to reverse direction spontaneously during normal running (d) Tendency to vibrate only after being switched off
33. A single-phase induction motor is not self-starting because a single-phase winding produces:
    (a) A pulsating (not rotating) magnetic field at standstill (b) A perfectly rotating field identical to a three-phase motor (c) No magnetic field whatsoever (d) A field that rotates only when the motor is already running
34. A capacitor-start induction motor uses a capacitor in series with the starting winding to:
    (a) Create a phase difference for starting torque (b) Filter out DC components from the AC supply (c) Store energy for use after the motor has started, with no role during starting (d) Increase the running winding's resistance
35. A synchronous motor's power factor can be controlled by varying its:
    (a) Field (excitation) current (b) Armature resistance alone (c) Number of stator slots dynamically (d) Frequency of the DC field supply, which has no meaning
36. An "over-excited" synchronous motor operates at a power factor that is:
    (a) Leading (b) Lagging (c) Exactly unity always (d) Zero
37. An "under-excited" synchronous motor operates at a power factor that is:
    (a) Lagging (b) Leading (c) Exactly unity always (d) Zero
38. A synchronous condenser is essentially a synchronous motor operated:
    (a) Over-excited, at no mechanical load, purely to supply reactive power (b) Under-excited, at full mechanical load (c) At exactly synchronous power factor with no reactive power role (d) Only as a generator, never as a motor
39. The efficiency of a transformer is typically highest at a load level:
    (a) Where copper losses equal iron losses (b) At exactly zero load, with no current flowing (c) At exactly twice the rated load (d) Independent of the loss balance entirely
40. An auto-transformer differs from a two-winding transformer in that it has:
    (a) A single winding common to both primary and secondary, with electrical connection between them (b) Two completely electrically isolated windings, like a standard transformer (c) No winding at all (d) Only a rotating part, unlike a standard transformer

Section C: Power Systems and Protection (20 Questions)

41. India's electrical power system predominantly operates at a frequency of:
    (a) 50 Hz (b) 60 Hz (c) 25 Hz (d) 100 Hz
42. The standard three-phase distribution voltage commonly supplied to Indian domestic low-tension consumers (line-to-neutral, single-phase) is approximately:
    (a) 230 V (b) 110 V (c) 440 V (d) 11 kV
43. The standard three-phase low-tension line voltage in India is approximately:
    (a) 400 V (b) 230 V (c) 11 kV (d) 33 kV
44. Extra-high-voltage (EHV) transmission in India commonly uses voltage levels such as:
    (a) 220 kV, 400 kV, and 765 kV (b) Only 230 V (c) Only 11 kV (d) Only 1.5 V
45. A "bus bar" in a substation serves as a:
    (a) Common junction/collection point for incoming and outgoing feeders (b) Protective relay device only (c) Type of insulator used only on overhead lines (d) Type of underground cable exclusively
46. An "isolator" (disconnector) switch, unlike a circuit breaker, is designed to:
    (a) Open only when the circuit is already de-energized (no-load), for isolation purposes (b) Interrupt full load or fault current safely, exactly like a circuit breaker (c) Operate automatically upon fault detection, exactly like a relay (d) Serve only as a decorative panel indicator
47. A "sectionalizer" in a distribution feeder works together with an upstream breaker/recloser to:
    (a) Isolate a faulted section after a preset number of the recloser's operations (b) Directly interrupt fault current on its own, without any coordination (c) Serve only a metering function (d) Increase fault current levels deliberately
48. The neutral point of a power system may be earthed via a "Petersen coil" primarily to:
    (a) Limit earth fault current in systems prone to single-line-to-ground faults (b) Increase the earth fault current level deliberately for faster detection (c) Serve only a voltage-boosting function (d) Prevent any current from flowing in the neutral under any condition
49. A "solidly earthed" neutral system connects the neutral to earth:
    (a) Directly, with no intentional impedance (b) Through a high resistance only (c) Through a reactor tuned to the system capacitance only (d) Never, as solid earthing means no earth connection at all
50. Load forecasting in power system planning is used to:
    (a) Estimate future electricity demand for capacity planning (b) Determine the colour of transmission towers (c) Set tariff rates exclusively, with no technical planning role (d) Replace the need for any generation capacity planning
51. "Economic load dispatch" in power system operation aims to:
    (a) Allocate generation among available units to minimize total operating cost while meeting demand (b) Maximize fuel consumption regardless of cost (c) Distribute load randomly among generating units (d) Ignore transmission losses entirely by design
52. A "tap changer" on a power transformer is used to:
    (a) Adjust the transformation ratio to regulate output voltage (b) Change the transformer's cooling method only (c) Change the transformer's core material physically during operation (d) Serve only a mechanical locking function
53. An "on-load tap changer" (OLTC), unlike an off-load tap changer, can change taps:
    (a) While the transformer remains energized and carrying load (b) Only after the transformer is fully de-energized and isolated (c) Only once during the transformer's entire service life (d) Only manually, with no automatic operation ever possible
54. A "protective relay" is best described as a device that:
    (a) Detects abnormal conditions and initiates a trip signal to the circuit breaker (b) Physically interrupts the fault current itself, without any breaker (c) Only measures energy consumption for billing (d) Only provides illumination indication with no protective function
55. The "primary protection" of a power system element refers to protection that:
    (a) Operates first, directly covering that specific element (b) Operates only as a last resort, after all backup schemes fail (c) Has no defined zone of operation (d) Only applies to generators, never to lines or transformers
56. "Backup protection" is provided in addition to primary protection to:
    (a) Operate if the primary protection fails to clear the fault (b) Replace the need for primary protection entirely (c) Operate before the primary protection, always ahead of it (d) Serve only a cosmetic redundancy with no functional role
57. A "current transformer" (CT) used with protective relays is designed to:
    (a) Step down high line currents to a standard low secondary current suitable for relays/meters (b) Step up currents for use in extra-high-voltage transmission (c) Measure voltage directly, with no relation to current (d) Serve only as a mechanical support structure
58. A "potential transformer" (PT/VT) is designed to:
    (a) Step down high system voltage to a standard low secondary voltage for meters/relays (b) Step up currents for extra-high-voltage transmission (c) Measure current directly, with no relation to voltage (d) Serve only as a mechanical support structure
59. Under IS/international colour codes commonly followed in India for LT wiring, the earth wire is typically:
    (a) Green (or green-yellow) (b) Red (c) Black (d) Blue
60. The phase (line) conductors in Indian three-phase LT wiring are commonly colour coded as:
    (a) Red, yellow, and blue (b) Only green throughout (c) Only white throughout (d) Only black throughout

Section D: Measurements, Electronics, Control, and Power Electronics (20 Questions)

61. A dynamometer-type wattmeter can measure power in:
    (a) Both AC and DC circuits (b) Only DC circuits (c) Only AC circuits, never DC (d) Neither AC nor DC circuits
62. An energy meter (electricity meter) used for billing typically measures cumulative:
    (a) Energy consumption in kWh (b) Instantaneous power only, with no cumulative record (c) Voltage only (d) Frequency only
63. A CRO (cathode ray oscilloscope) is primarily used to:
    (a) Visually display and measure waveforms of electrical signals (b) Measure only DC resistance values (c) Measure only mechanical vibration with no electrical function (d) Serve only as a power supply unit
64. A "true RMS" meter, unlike an average-responding meter calibrated for sine waves, correctly measures the RMS value of:
    (a) Any waveform shape, including distorted/non-sinusoidal waveforms (b) Only pure sine waves, with no advantage for other waveforms (c) Only DC values (d) Only square waves, and no other waveform
65. A field-effect transistor (FET) is generally considered a:
    (a) Voltage-controlled device (b) Current-controlled device exclusively, like a BJT (c) Device with no control terminal at all (d) Purely mechanical switching device
66. In a MOSFET, the three terminals are named:
    (a) Source, drain, and gate (b) Emitter, base, and collector (c) Anode, cathode, and grid (d) Plate, cathode, and control grid
67. An operational amplifier (op-amp) in an "ideal" analysis is assumed to have:
    (a) Infinite open-loop gain and infinite input impedance (b) Zero open-loop gain and zero input impedance (c) Exactly unity gain with no input impedance consideration (d) Negative input impedance
68. A comparator circuit, often built using an op-amp, is used to:
    (a) Compare two input voltages and output a high/low signal accordingly (b) Amplify a signal linearly with no comparison function (c) Store digital data permanently (d) Convert AC to DC exclusively
69. A "flip-flop" in digital electronics is a basic memory element that can store:
    (a) One bit of binary information (b) An entire program's instructions (c) Only analog voltage levels, never binary data (d) Only a fixed decimal number
70. A "logic gate" such as an AND, OR, or NOT gate operates on:
    (a) Binary (digital) input signals to produce a binary output per its logic function (b) Only continuously varying analog signals (c) Only mechanical inputs, never electrical signals (d) Only audio frequency signals
71. In closed-loop control system terminology, the "plant" (or process) refers to:
    (a) The physical system being controlled (b) Only the controller's internal circuitry (c) Only the feedback sensor (d) Only the reference input signal generator
72. A "sensor" (transducer) in a control system is used to:
    (a) Convert a physical quantity into a measurable electrical signal for feedback (b) Amplify the control signal with no sensing function (c) Store energy for backup power only (d) Serve only a structural/mechanical support function
73. An "open-loop" control system, unlike a closed-loop system, operates:
    (a) Without feedback from the output to correct the input (b) With continuous feedback correction at all times (c) Only in AC circuits, never in DC applications (d) Only when the plant itself has no dynamics
74. A soft starter for an induction motor limits starting current primarily by:
    (a) Gradually ramping up the applied voltage using thyristor-based control (b) Physically adding external rotor resistance, exactly like a slip-ring motor starter (c) Increasing supply frequency abruptly at start (d) Disconnecting the motor from supply entirely during starting
75. A chopper circuit is used to convert:
    (a) Fixed DC into variable DC (b) Fixed AC into variable AC directly, with no rectification (c) DC into a purely mechanical output (d) AC into a purely thermal output only
76. An inverter circuit is used to convert:
    (a) DC into AC (b) AC into DC (c) AC into a fixed different AC frequency without any switching devices (d) Mechanical energy into DC directly
77. A rectifier circuit is used to convert:
    (a) AC into DC (b) DC into AC (c) DC into a purely mechanical output (d) AC into a purely thermal output only
78. A "freewheeling diode" placed across an inductive load in a switching circuit serves to:
    (a) Provide a path for the inductor's stored current when the main switch turns off, protecting the switch (b) Increase the switch's voltage rating requirement (c) Block current flow entirely at all times (d) Serve only a decorative/indicator function
79. Pulse Width Modulation (PWM) is a technique used to control the effective output voltage/power by varying the:
    (a) Duty cycle (on-time ratio) of switching pulses (b) Supply frequency of the incoming AC mains only (c) Physical size of the switching device (d) Colour of the indicator lamp
80. A power diode used in high-current rectifier applications differs from a small-signal diode primarily in its:
    (a) Higher current-carrying capacity and voltage rating (b) Complete absence of any p-n junction (c) Operation only in reverse bias, never forward bias (d) Function only as a light-emitting device

Section E: General Awareness, Computer Applications, and Current Affairs (20 Questions)

81. The Central Board of Irrigation and Power (CBIP) in India is primarily concerned with:
    (a) Technical development in the power and water resources sectors (b) Railway safety standards exclusively (c) Currency and banking regulation (d) Postal service standards
82. NTPC Limited, a major Indian public sector enterprise, is primarily engaged in:
    (a) Power generation (b) Railway rolling stock manufacturing (c) Postal services (d) Airline operations
83. POWERGRID (Power Grid Corporation of India) is primarily responsible for:
    (a) Bulk power transmission across India (b) Local retail electricity billing only (c) Coal mining operations (d) Railway electrification exclusively
84. The term "Discom" commonly refers to a:
    (a) Power distribution company (b) Railway coach manufacturing unit (c) Telecom regulatory body (d) Banking ombudsman office
85. In computer terminology, "CPU" stands for:
    (a) Central Processing Unit (b) Central Program Utility (c) Computer Peripheral Unit (d) Central Power Unit
86. In computer terminology, "GUI" stands for:
    (a) Graphical User Interface (b) General Utility Interface (c) Global Unified Index (d) Graphic Unit Identifier
87. A computer "virus" is best described as:
    (a) Malicious software that can replicate and spread, potentially harming data/systems (b) A hardware component that improves processing speed (c) A type of antivirus protection program (d) A type of authorised system update
88. In MS Excel, a "cell reference" like "B5" refers to:
    (a) The cell at the intersection of column B and row 5 (b) Only the entire column B (c) Only the entire row 5 (d) A named range with no fixed location
89. The full form of "PDF" (a common document file format) is:
    (a) Portable Document Format (b) Personal Data File (c) Printed Document Format (d) Program Data Format
90. Cloud computing refers to the delivery of computing services (storage, processing, software) primarily over the:
    (a) Internet, from remote servers (b) A dedicated local cable with no internet involvement (c) Postal mail system (d) Landline telephone network only, with no data component
91. The Pradhan Mantri Sahaj Bijli Har Ghar Yojana is more commonly known by which name (mentioned earlier)?
    (a) Saubhagya (b) UDAY (c) DDUGJY (d) IPDS
92. The Integrated Power Development Scheme (IPDS) primarily focuses on:
    (a) Strengthening sub-transmission and distribution networks in urban areas (b) Rural road construction (c) Airport modernisation (d) Railway signalling upgrades
93. The Deendayal Upadhyaya Gram Jyoti Yojana (DDUGJY) primarily focuses on:
    (a) Rural electrification and feeder separation (b) Urban metro rail construction (c) National highway development (d) Digital payment infrastructure
94. India's installed renewable energy capacity target set under various national announcements has emphasised rapid growth in which sources?
    (a) Solar and wind energy (b) Only coal-based thermal power (c) Only nuclear power (d) Only large hydroelectric power
95. The International Solar Alliance (ISA), co-founded by India, aims to promote:
    (a) Solar energy deployment and cooperation among member countries (b) Coal trade agreements (c) Railway technology exchange (d) Postal service cooperation
96. "Green hydrogen" refers to hydrogen produced using:
    (a) Renewable energy-powered electrolysis of water (b) Coal gasification exclusively (c) Natural gas reforming exclusively, with no renewable input (d) Nuclear fission by-products exclusively
97. The National Green Hydrogen Mission of India aims to promote green hydrogen production and:
    (a) Reduce dependence on fossil fuel imports while cutting carbon emissions (b) Increase coal imports exclusively (c) Phase out all renewable energy sources (d) Eliminate the electricity grid entirely
98. A "phasor measurement unit" (PMU) in modern power systems is used to provide:
    (a) Synchronised, real-time measurement of electrical quantities across the grid (b) Only manual meter readings taken monthly (c) Only mechanical vibration data with no electrical measurement (d) Only billing information with no technical measurement
99. The term "Make in India" initiative, relevant to domestic electrical equipment manufacturing, primarily aims to:
    (a) Boost domestic manufacturing and reduce import dependence (b) Increase equipment imports exclusively (c) Discourage all domestic manufacturing (d) Apply only to the textile sector
100. Energy conservation in India is promoted through standards and labelling (star rating) administered by:
     (a) Bureau of Energy Efficiency (BEE) (b) Bureau of Indian Standards (BIS) exclusively (c) Central Electricity Authority (CEA) exclusively (d) Reserve Bank of India (RBI)

Answer Key with Explanations

1.(a) The coulomb is the unit of electric charge.

2.(a) The volt is the unit of potential difference.

3.(a) The ampere is the unit of current.

4.(a) The ohm is the unit of resistance.

5.(a) The watt is the unit of power.

6.(a) Billed household energy is measured in kilowatt-hours.

7.(a) Brown-black-red = 1-0-×100 = 1000 Ω.

8.(a) Resistivity relates resistance to length and cross-sectional area.

9.(a) Most metals have a positive temperature coefficient.

10.(a) Pure metals show positive temperature coefficient of resistance.

11.(a) Semiconductors typically show negative temperature coefficient.

12.(a) Superposition applies to linear bilateral circuits.

13.(a) Thevenin's theorem gives an equivalent voltage source in series with resistance.

14.(a) Norton's theorem gives an equivalent current source in parallel with resistance.

15.(a) Maximum power transfer occurs when load resistance equals source's Thevenin resistance.

16.(a) Star-delta transformation simplifies three-terminal networks.

17.(a) In star, line voltage = √3 × phase voltage.

18.(a) In delta, line current = √3 × phase current.

19.(a) In star, line current = phase current.

20.(a) In delta, line voltage = phase voltage.

21.(a) The commutator converts AC in the armature to DC at the brushes.

22.(a) Armature reaction is the armature MMF's distorting effect on main flux.

23.(a) Interpoles improve commutation and reduce brush sparking.

24.(a) A compound motor has both series and shunt fields.

25.(a) In cumulative compound, series and shunt MMFs aid each other.

26.(a) In differential compound, series and shunt MMFs oppose each other.

27.(a) DC shunt motor speed is controlled by field or armature voltage variation.

28.(a) Direct starting causes excessive current since back EMF is zero at standstill.

29.(a) Induction motor rotors are squirrel cage or wound (slip-ring) type.

30.(a) External rotor resistance improves starting torque/current in slip-ring motors.

31.(a) Crawling is stable low-speed running near 1/7th synchronous speed due to harmonics.

32.(a) Cogging is refusal to start due to slot number interaction.

33.(a) A single-phase winding produces a pulsating, not rotating, field at standstill.

34.(a) A series capacitor with the start winding creates phase difference for starting torque.

35.(a) Synchronous motor power factor is controlled via field excitation.

36.(a) Over-excited synchronous motor operates leading.

37.(a) Under-excited synchronous motor operates lagging.

38.(a) A synchronous condenser is over-excited, unloaded, supplying reactive power.

39.(a) Transformer efficiency peaks where copper losses equal iron losses.

40.(a) An auto-transformer has a single winding common to primary and secondary.

41.(a) India's power system operates at 50 Hz.

42.(a) Standard domestic single-phase voltage in India is about 230 V.

43.(a) Standard LT three-phase line voltage in India is about 400 V.

44.(a) EHV transmission uses levels like 220 kV, 400 kV, 765 kV.

45.(a) A bus bar is a common junction point for feeders.

46.(a) An isolator opens only under no-load conditions for isolation.

47.(a) A sectionalizer isolates a faulted section after preset recloser operations.

48.(a) A Petersen coil limits earth fault current in ground-fault-prone systems.

49.(a) Solid earthing connects neutral to earth directly, with no intentional impedance.

50.(a) Load forecasting estimates future demand for capacity planning.

51.(a) Economic load dispatch minimizes generation cost while meeting demand.

52.(a) A tap changer adjusts transformation ratio to regulate voltage.

53.(a) An OLTC can change taps while the transformer remains energized.

54.(a) A protective relay detects abnormal conditions and signals the breaker to trip.

55.(a) Primary protection directly covers and operates first for its element.

56.(a) Backup protection operates if primary protection fails.

57.(a) A CT steps down high line current to a standard low secondary current.

58.(a) A PT steps down high voltage to a standard low secondary voltage.

59.(a) The earth wire is conventionally green (or green-yellow).

60.(a) Phase conductors are commonly colour coded red, yellow, and blue in India.

61.(a) A dynamometer wattmeter measures power in both AC and DC.

62.(a) An energy meter measures cumulative energy in kWh.

63.(a) A CRO displays and measures waveforms visually.

64.(a) A true-RMS meter correctly measures RMS for any waveform shape.

65.(a) An FET is a voltage-controlled device.

66.(a) A MOSFET's terminals are source, drain, and gate.

67.(a) An ideal op-amp is assumed to have infinite gain and input impedance.

68.(a) A comparator compares two voltages and outputs high/low accordingly.

69.(a) A flip-flop stores one bit of binary information.

70.(a) A logic gate operates on binary inputs per its logic function.

71.(a) The "plant" is the physical system being controlled.

72.(a) A sensor converts a physical quantity into a measurable electrical signal.

73.(a) Open-loop control has no feedback correction.

74.(a) A soft starter ramps up voltage via thyristor control to limit starting current.

75.(a) A chopper converts fixed DC into variable DC.

76.(a) An inverter converts DC into AC.

77.(a) A rectifier converts AC into DC.

78.(a) A freewheeling diode provides a path for inductor current when the switch turns off.

79.(a) PWM controls output by varying the duty cycle of switching pulses.

80.(a) A power diode has higher current/voltage rating than a small-signal diode.

81.(a) CBIP deals with technical development in power and water resources.

82.(a) NTPC is primarily engaged in power generation.

83.(a) POWERGRID handles bulk power transmission across India.

84.(a) A "Discom" is a power distribution company.

85.(a) CPU stands for Central Processing Unit.

86.(a) GUI stands for Graphical User Interface.

87.(a) A computer virus is malicious, replicating software that can harm systems/data.

88.(a) "B5" refers to the cell at column B, row 5.

89.(a) PDF stands for Portable Document Format.

90.(a) Cloud computing delivers services over the internet from remote servers.

91.(a) The scheme is more commonly known as Saubhagya.

92.(a) IPDS focuses on strengthening urban sub-transmission/distribution networks.

93.(a) DDUGJY focuses on rural electrification and feeder separation.

94.(a) India has emphasised rapid growth in solar and wind energy.

95.(a) The ISA promotes solar energy deployment and cooperation.

96.(a) Green hydrogen is produced via renewable-powered electrolysis of water.

97.(a) The National Green Hydrogen Mission aims to cut fossil fuel imports and emissions.

98.(a) A PMU provides synchronised real-time grid measurements.

99.(a) "Make in India" aims to boost domestic manufacturing, reducing import dependence.

100.(a) Energy conservation labelling (star rating) is administered by the Bureau of Energy Efficiency.