Full-Length Mock Test 3 — RRB JE CBT 2 Technical Abilities Pattern (100 MCQs)
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Section A: Circuit Fundamentals and AC/DC Basics (20 Questions)
- Kirchhoff's Voltage Law can be applied to:
(a) Any closed loop in a circuit, linear or non-linear (b) Only purely resistive circuits, never circuits with inductors/capacitors (c) Only DC circuits, never AC circuits (d) Only circuits with exactly one component - Kirchhoff's Current Law applies at:
(a) Any node/junction in a circuit (b) Only the source terminals (c) Only a single, specific "official" node designated in advance (d) Only in AC circuits, never DC - A "node" in circuit analysis is a point where:
(a) Two or more circuit elements are connected (b) Only a single element exists with no connection (c) Only a voltage source is present (d) Only a resistor is present, never any other element - "Mesh analysis" in circuit theory uses:
(a) Loop currents as the primary unknowns to be solved (b) Only node voltages, never loop currents (c) Only Ohm's Law with no simultaneous equations (d) Only graphical methods with no equations - "Nodal analysis" in circuit theory uses:
(a) Node voltages as the primary unknowns to be solved (b) Only loop currents, never node voltages (c) Only Ohm's Law with no simultaneous equations (d) Only graphical methods with no equations - The reciprocity theorem in linear circuits states that:
(a) The ratio of response to excitation remains the same if source and response (ammeter) positions are interchanged (b) No relationship exists between any two circuit points (c) Only non-linear circuits satisfy this theorem (d) Only circuits with a single element satisfy this theorem - Millman's theorem is used to find:
(a) The voltage across a common node connected by multiple parallel branches with different sources (b) Only the current through a single resistor (c) Only the magnetic flux in an inductor (d) Only the capacitance value of a capacitor - A "practical" voltage source, unlike an ideal voltage source, has:
(a) A non-zero internal resistance causing terminal voltage to drop under load (b) Infinite internal resistance (c) Zero internal resistance under all conditions (d) No terminal voltage at all regardless of load - A "practical" current source, unlike an ideal current source, has:
(a) A finite (non-infinite) internal (shunt) resistance (b) Zero internal resistance (c) Infinite internal resistance under all conditions (d) No current output at all regardless of load - In an AC circuit, "instantaneous power" varies:
(a) With time, as the product of instantaneous voltage and current (b) Never; it is always constant regardless of time (c) Only in DC circuits, never AC (d) Only when the circuit contains no reactive elements - A "delta-connected" three-phase load has each phase winding connected:
(a) Between two line terminals directly (b) From each line terminal to a common neutral point (c) In series across all three lines simultaneously as one winding (d) Only to earth with no line connection - A "star-connected" three-phase load has each phase winding connected:
(a) From a line terminal to a common neutral/star point (b) Between two line terminals directly with no neutral point (c) Only to earth with no line connection (d) In series with a capacitor exclusively - Power factor correction using capacitors works by supplying:
(a) Leading reactive power to offset the lagging reactive power of inductive loads (b) Additional lagging reactive power to inductive loads (c) Only additional real power with no reactive component (d) No practical effect on the system's reactive power balance - The unit of frequency is:
(a) Hertz (b) Ohm (c) Farad (d) Henry - Angular frequency (ω) relates to frequency (f) by:
(a) ω = 2πf (b) ω = f/2π (c) ω = f² (d) ω = πf/2 - In a purely resistive AC circuit, the power factor is:
(a) Unity (1) (b) Zero (c) Negative (d) Undefined - In a purely reactive (inductive or capacitive) AC circuit, the power factor is:
(a) Zero (b) Unity (1) (c) Negative one exactly always (d) Undefined and impossible to determine - Which of the following best describes a "balanced" three-phase system?
(a) Equal magnitude voltages/currents in each phase, with 120-degree phase displacement (b) Completely unequal magnitudes with no defined phase relationship (c) A system with only a single phase (d) A system with no phase relationship at all - A neutral conductor in a three-phase four-wire system primarily carries:
(a) The unbalance current in an unbalanced load condition (b) The full-rated current of all three phases combined at all times (c) No current under any condition (d) Only DC current, never AC - Which network theorem is particularly useful for simplifying a portion of a circuit into a single equivalent voltage source and series resistance, for analysing the effect of a variable load?
(a) Thevenin's Theorem (b) Only KCL with no theorem application (c) Only KVL with no theorem application (d) None; no theorem addresses this situation
Section B: Electrical Machines (20 Questions)
- A "self-excited" DC generator obtains its field excitation from:
(a) Its own armature output (b) An entirely separate, independent DC source (c) An AC supply exclusively, with no DC field current (d) No excitation source at all - A "separately excited" DC generator obtains its field excitation from:
(a) An independent external DC source (b) Its own armature output exclusively (c) An AC supply exclusively, with no DC involved (d) No excitation source at all - A DC motor's "starting current" without any starter would generally be:
(a) Very high, since back EMF is zero at standstill (b) Very low, since back EMF is at its maximum at standstill (c) Exactly equal to the rated running current always (d) Zero, since motors cannot draw current at standstill - A DC motor starter primarily functions to:
(a) Limit starting current by inserting resistance in the armature circuit initially (b) Increase starting current deliberately (c) Replace the need for any armature winding (d) Convert the motor to AC operation - The direction of rotation of a DC motor can be reversed by:
(a) Reversing either the armature connections or the field connections (but not both simultaneously) (b) Reversing both armature and field connections simultaneously, which has no net effect on direction (c) Increasing the supply voltage only (d) Increasing the motor's physical size only - A transformer's "regulation" (voltage regulation) is defined based on the difference between:
(a) No-load and full-load secondary voltage (b) Primary and secondary turns ratio only (c) Core loss and copper loss only (d) Physical weight at no-load and full-load - A transformer's efficiency is generally highest when operating at a load level where:
(a) Copper losses equal iron losses (b) The transformer is significantly overloaded beyond rating (c) The transformer carries zero load (d) The transformer's core is completely removed - "Sumpner's test" (back-to-back test) on transformers is used to determine:
(a) Full-load performance/heating characteristics using two identical transformers without high power supply (b) Only the transformer's physical weight (c) Only the transformer's colour (d) Only the transformer's cost - A "power transformer," compared to a "distribution transformer," is generally used for:
(a) Higher-voltage, bulk transmission-level applications rather than end-consumer distribution (b) Only very low-voltage household applications exclusively (c) Only DC applications, never AC (d) Only decorative display purposes with no real electrical function - An induction motor's power factor at light load, compared to at full load, is generally:
(a) Lower (poorer) at light load (b) Higher (better) at light load (c) Identical regardless of load (d) Always exactly unity regardless of load - Which of the following methods can be used for speed control of a three-phase induction motor?
(a) Varying supply frequency (VFD) (b) Only varying the motor's paint colour (c) Only varying the motor's physical weight (d) Only varying the ambient humidity - Pole-changing as an induction motor speed control method works by:
(a) Physically/electrically changing the number of stator poles to alter synchronous speed (b) Changing the rotor's physical material composition (c) Changing the motor's paint colour (d) Changing the ambient temperature - A synchronous motor's "V-curves" show the relationship between armature current and:
(a) Field excitation, at constant load (b) Only the motor's physical weight (c) Only the motor's paint colour (d) Only ambient humidity - An alternator's short-circuit ratio (SCR) is a parameter related to:
(a) The machine's field current requirements and inherent stability characteristics (b) Only the machine's physical dimensions (c) Only the machine's manufacturer (d) Only the machine's colour - "Armature winding" in an AC synchronous generator is typically located on the:
(a) Stator, in most modern large synchronous machines (b) Rotor exclusively, in all synchronous machines without exception (c) Neither stator nor rotor; it is external to the machine (d) The machine's outer casing exclusively, with no winding at all - The "field winding" of a large synchronous generator is typically located on the:
(a) Rotor, excited by a DC supply (typically via an exciter or brushless system) (b) Stator exclusively, in all synchronous machines without exception (c) Neither stator nor rotor (d) The machine's outer casing exclusively - A "brushless exciter" system for a synchronous generator's field supply avoids the need for:
(a) Brushes and slip rings for field current supply (b) Any field winding at all (c) Any rotor at all (d) Any stator winding at all - Three-phase induction motors are generally preferred over single-phase motors for higher-power industrial applications primarily due to:
(a) Self-starting capability and generally higher efficiency/power density (b) Complete inability to start under load (c) Requirement for exclusively DC supply (d) Complete absence of any starting torque - A "linear induction motor" produces:
(a) Linear (straight-line) motion rather than conventional rotary motion (b) Only rotary motion, identical to a standard induction motor (c) No motion at all under any condition (d) Only oscillatory vibration with no net displacement - Overall, understanding both DC and AC machine principles is emphasised in RRB JE Electrical preparation because:
(a) Both machine types remain relevant across different real-world electrical applications (b) Only DC machines are ever used in modern practice (c) Only AC machines are ever used in modern practice (d) Neither machine type has any practical relevance today
Section C: Power Systems and Protection (20 Questions)
- India's electricity generation mix has historically been dominated by which fuel-based source, though renewables are growing?
(a) Coal-based thermal generation (b) Purely nuclear generation (c) Purely tidal generation (d) Purely geothermal generation - A "combined cycle power plant" improves overall efficiency by:
(a) Using waste heat from a gas turbine to generate additional steam-turbine power (b) Using no turbine at all (c) Operating only at exactly zero load (d) Discarding all waste heat with no recovery - Which of the following best describes a "pumped storage" hydroelectric scheme?
(a) A scheme that pumps water to a higher reservoir during low demand and generates power from it during peak demand (b) A scheme that only ever generates power, with no pumping capability (c) A scheme unrelated to electricity generation (d) A purely theoretical concept with no real-world implementation - Nuclear power plants generate heat through:
(a) Controlled nuclear fission (b) Combustion of fossil fuel (c) Wind-driven mechanical rotation (d) Solar photovoltaic conversion - Wind power generation converts:
(a) Kinetic energy of wind into electrical energy via a turbine-generator (b) Chemical energy directly into electrical energy with no mechanical stage (c) Nuclear energy into electrical energy (d) Only thermal energy into electrical energy with no mechanical stage - Solar photovoltaic (PV) systems convert:
(a) Solar radiation directly into DC electrical energy via the photovoltaic effect (b) Wind energy into electrical energy (c) Nuclear energy into electrical energy (d) Mechanical rotational energy into electrical energy - A grid-connected solar PV system typically requires an inverter primarily to:
(a) Convert the panel's DC output into grid-compatible AC (b) Convert AC into DC for the panels (c) Increase the sunlight intensity received by the panels (d) Serve only a decorative display function - "Net metering" for a grid-connected rooftop solar system allows a consumer to:
(a) Receive credit for excess solar power exported back to the grid (b) Only pay a fixed fee with no relation to actual generation/consumption (c) Never export any power to the grid under any condition (d) Disconnect entirely from the grid permanently - A "microgrid" refers to:
(a) A localised group of generation/loads that can operate connected to or independent of the main grid (b) Only a single household's internal wiring (c) A concept unrelated to electricity distribution (d) Only the main national interconnected grid itself - "Islanding" of a distributed generation system refers to a condition where:
(a) The system continues supplying a local load after disconnection from the main grid (b) The system permanently shuts down with no local supply capability ever (c) The system only operates in the middle of a physical island location (d) The system automatically increases its output to match the entire national grid's demand - Unintentional islanding of distributed generation is generally considered a safety concern primarily because:
(a) Line workers may not expect the "de-energised" line to still be live from local generation (b) It always immediately damages the generation equipment with certainty (c) It has no safety implication whatsoever (d) It is required by all grid codes as the preferred, encouraged mode of operation - Anti-islanding protection in grid-connected inverters is designed to:
(a) Detect loss of grid connection and disconnect the inverter output (b) Increase output power upon grid disconnection (c) Serve only a decorative function with no protective role (d) Ignore any grid disconnection event entirely - A "busbar" in a substation is:
(a) A conductor system that serves as a common connection point for multiple circuits (b) Only a decorative structural beam with no electrical function (c) Only a mechanical support with no current-carrying function (d) Only a protective relay - "Bus coupler" circuit breakers in a substation allow:
(a) Connection/isolation between two busbar sections (b) Only permanent, irreversible connection between busbars with no isolation option (c) No practical switching function at all (d) Only voltage transformation - "Isolators" (disconnectors) in a substation are primarily used to:
(a) Provide visible physical isolation of equipment for safe maintenance, generally not for interrupting load current (b) Interrupt fault currents directly, replacing circuit breakers entirely (c) Serve only a decorative function (d) Generate additional reactive power - Isolators are generally operated:
(a) Only after the associated circuit breaker has already opened the circuit (b) Before opening the associated circuit breaker, while current is still flowing (c) Simultaneously with load switching under full current, as their primary intended function (d) Only during a fault condition, never during planned maintenance - A "current-limiting reactor" in a power system is used to:
(a) Limit fault current magnitude by adding series reactance (b) Increase fault current magnitude deliberately (c) Convert AC to DC (d) Serve only a decorative function - Reliability indices such as SAIDI/SAIFI in distribution system performance monitoring relate to:
(a) Average outage duration/frequency experienced by consumers (b) Only the physical size of transformers (c) Only the colour of distribution poles (d) Only billing accuracy with no relation to outages - Distribution automation technologies (e.g., automated switches, remote monitoring) primarily aim to:
(a) Improve fault detection/isolation speed and overall reliability (b) Increase outage duration deliberately (c) Serve only a decorative monitoring display with no operational benefit (d) Eliminate the need for any protection scheme - Overall, power system reliability and modernisation topics are relevant to RRB JE Electrical preparation because:
(a) They reflect real, ongoing improvements in the systems JEs may help operate/maintain (b) They have no relevance to any electrical engineering role (c) Only senior utility executives need this understanding (d) This knowledge is tested only in interviews, never the written exam
Section D: Measurements, Electronics, Control, and Power Electronics (20 Questions)
- A "shunt" used with an ammeter allows measurement of currents:
(a) Larger than the meter's basic full-scale range, by diverting most current around the meter movement (b) Only smaller currents than the meter's basic range (c) Only AC currents, never DC (d) Only currents at exactly zero magnitude - A "multiplier" resistor used with a voltmeter allows measurement of voltages:
(a) Larger than the meter's basic full-scale range, by dropping excess voltage across the added resistor (b) Only smaller voltages than the meter's basic range (c) Only AC voltages, never DC (d) Only voltages at exactly zero magnitude - An "induction-type" energy meter's rotating disc speed is proportional to:
(a) The power being consumed (b) Only the ambient temperature (c) Only the meter's physical weight (d) Only the meter's colour - A "clamp meter" (clamp-on ammeter) measures current without:
(a) Direct series connection/breaking of the circuit, using a clamp around the conductor (b) Any electrical measurement capability whatsoever (c) Any practical application in fieldwork (d) Any relation to magnetic principles - An "LVDT" (Linear Variable Differential Transformer) is a sensor used to measure:
(a) Linear displacement (b) Only temperature (c) Only sound intensity (d) Only chemical concentration - A "strain gauge" is a sensor used to measure:
(a) Mechanical strain/deformation, via a resulting change in electrical resistance (b) Only ambient light intensity (c) Only magnetic flux directly (d) Only sound frequency - A "thermocouple" is a temperature sensor that operates based on:
(a) The Seebeck effect, generating a voltage related to temperature difference between two junctions (b) Only mechanical expansion with no electrical output (c) Only chemical colour change (d) Only magnetic flux variation - An "RTD" (Resistance Temperature Detector) measures temperature based on:
(a) A predictable change in electrical resistance with temperature (b) Only mechanical expansion with no electrical relation (c) Only chemical colour change (d) Only sound frequency change - A "photodiode" is a semiconductor device that:
(a) Generates/modulates current in response to incident light (b) Only generates sound in response to light (c) Only measures temperature with no light response (d) Only measures magnetic flux with no light response - An "LED" (Light Emitting Diode), in reverse operation compared to a photodiode, primarily:
(a) Emits light when forward biased (b) Absorbs light to generate current, identical to a photodiode's primary function (c) Only measures temperature (d) Only measures sound - A "relay" (electromechanical) uses a small control current to:
(a) Energise a coil that operates a mechanical switch contact for a separate circuit (b) Directly carry all load current through the control circuit with no switching action (c) Serve only as a decorative indicator lamp (d) Generate additional electrical power - A "contactor" is essentially a:
(a) Heavy-duty relay designed for switching higher power loads such as motors (b) A type of measuring instrument with no switching function (c) A type of protective fuse exclusively (d) A type of lighting fixture - A "solid-state relay" (SSR), compared to an electromechanical relay, generally offers:
(a) No moving parts and typically faster, quieter switching (b) Significantly more mechanical wear from moving parts (c) Complete inability to switch any load (d) Use exclusively in decorative lighting with no industrial application - "Feedback control" in an automated system relies fundamentally on:
(a) Measuring the actual output and comparing it to the desired reference (b) Ignoring the actual output entirely (c) Only a fixed, unchanging control signal regardless of output (d) Only manual human intervention at every single instant - A control system's "steady-state error" refers to the difference between desired and actual output:
(a) After transient effects have settled (b) Only during the very first instant after a step input is applied (c) Only when the system is completely disconnected from any input (d) Only in systems with no feedback whatsoever - Increasing "proportional gain" excessively in a feedback control loop can lead to:
(a) Instability or excessive oscillation (b) Guaranteed improved stability with no downside whatsoever (c) No change in system behaviour at all (d) Complete elimination of any error at all times - A "buck converter" in power electronics is a type of:
(a) DC-DC converter that steps down voltage (b) DC-DC converter that only steps up voltage, never down (c) AC-AC converter exclusively (d) A purely mechanical, non-electronic device - A "boost converter" in power electronics is a type of:
(a) DC-DC converter that steps up voltage (b) DC-DC converter that only steps down voltage, never up (c) AC-AC converter exclusively (d) A purely mechanical, non-electronic device - Power electronic converters are increasingly used in renewable energy systems (solar/wind) primarily to:
(a) Interface variable DC/AC output with the grid in a controlled, compatible manner (b) Increase the raw energy content of sunlight/wind itself (c) Serve only a decorative function with no interfacing role (d) Eliminate the need for any generation equipment - Overall, understanding measurement/sensor/control/power-electronics fundamentals equips an RRB JE Electrical candidate to:
(a) Engage with modern instrumentation, automation, and power conversion systems in practice (b) Only pursue a purely theoretical, non-practical career path (c) Perform tasks entirely unrelated to electrical engineering (d) Avoid any further technical learning throughout their career
Section E: General Awareness, Computer Applications, and Current Affairs (20 Questions)
- Which of the following best describes India's "National Electricity Policy"?
(a) A policy framework guiding the development of the power sector (b) A policy focused solely on railway ticketing (c) A policy focused solely on banking regulation (d) A policy focused solely on space research - Which of the following best describes "Deen Dayal Upadhyaya Gram Jyoti Yojana" (DDUGJY)?
(a) A scheme focused on rural electrification and feeder separation (b) A scheme focused solely on urban housing (c) A scheme focused solely on banking reform (d) A scheme focused solely on space research - Which of the following best describes the "Integrated Power Development Scheme" (IPDS)?
(a) A scheme strengthening sub-transmission/distribution infrastructure in urban areas (b) A scheme focused solely on rural roads (c) A scheme focused solely on banking reform (d) A scheme focused solely on space research - Which of the following best describes India's approach to grid-scale battery energy storage systems (BESS)?
(a) Increasing deployment to support renewable integration and grid stability (b) Complete rejection of any storage technology (c) Reliance solely on traditional thermal generation with no storage (d) No relevance to the power sector at all - Which of the following best describes the general purpose of "time-of-day" (ToD) electricity tariffs?
(a) Encouraging demand shifting away from peak hours through differential pricing (b) Charging a flat, unvarying rate regardless of time (c) Eliminating the need for any electricity metering (d) Applying only to railway electricity consumption - In computing, "malware" refers to:
(a) Malicious software designed to harm or exploit systems (b) Beneficial productivity software exclusively (c) Hardware components exclusively (d) Network cabling exclusively - Which of the following best describes "phishing" in cybersecurity?
(a) A fraudulent attempt to obtain sensitive information by disguising as a trustworthy entity (b) A legitimate method of secure data backup (c) A type of computer hardware component (d) A type of network cable - Which of the following best describes "encryption" in computing?
(a) Converting data into a coded form to prevent unauthorised access (b) Deleting data permanently (c) Printing data on paper (d) Displaying data with no security function - Which of the following best describes "e-Way Bill" in India's GST system?
(a) An electronic document required for movement of goods above a specified value (b) A type of railway ticket (c) A type of passport application (d) A type of banking cheque - Which of the following best describes India's "UDAN" (Ude Desh ka Aam Naagrik) scheme?
(a) A regional air connectivity scheme (b) A railway electrification scheme (c) A banking reform scheme (d) A power distribution scheme - Which of the following best describes "Ayushman Bharat," a Government of India scheme?
(a) Providing health insurance/coverage to economically vulnerable families (b) Highway construction exclusively (c) Railway electrification exclusively (d) Banking sector reform exclusively - Which of the following best describes India's "Jal Jeevan Mission"?
(a) Providing piped drinking water to rural households (b) Railway electrification (c) Highway construction (d) Space research - Which of the following best describes "Digital India," a Government of India initiative?
(a) A programme to transform India into a digitally empowered society and knowledge economy (b) A programme focused solely on railway electrification (c) A programme focused solely on road construction (d) A programme with no technology component - Which of the following best describes "Skill India Mission"?
(a) Enhancing the employability of India's workforce through skill training (b) Only funding international scholarships with no domestic training component (c) Only supporting agricultural research (d) Only supporting space research - Which of the following best describes "Startup India," a Government of India initiative?
(a) Promoting and supporting entrepreneurship and new businesses (b) Only large public sector enterprises (c) Only foreign multinational corporations (d) Only agricultural cooperatives - Which of the following best describes "FASTag," used on Indian highways?
(a) An electronic toll collection system using RFID technology (b) A railway ticket booking system (c) A banking loan application system (d) A construction material testing certification - Which of the following best describes "PM Gati Shakti," a national infrastructure planning initiative?
(a) An integrated approach to plan and coordinate infrastructure connectivity projects across sectors (b) A programme focused solely on space research (c) A programme focused solely on banking regulation (d) A programme focused solely on agricultural subsidies - Which of the following best describes the relevance of the RRB JE General Awareness section's coverage of power-sector/infrastructure current affairs to Electrical candidates?
(a) It tests awareness of developments relevant to their future employer and sector (b) It is entirely unrelated to the recruiting organisation (c) It only tests unrelated general knowledge with no sector relevance ever (d) It replaces the technical section entirely - Which of the following best describes the value of solving previous years' RRB JE question papers during preparation?
(a) Familiarising with actual exam-level difficulty, question style, and commonly tested topics (b) No value at all compared to only reading textbooks (c) Value only for the General Awareness section (d) Value only in the very first week of preparation - As a concluding note for this mock test, which of the following best summarises effective exam-day strategy?
(a) Attempt known/easier questions first, manage time carefully, and apply informed elimination on uncertain questions (b) Attempt questions strictly in serial order regardless of difficulty (c) Spend equal, fixed time on every question regardless of difficulty (d) Skip the technical section entirely to focus only on general awareness
Answer Key with Explanations
1.(a) KVL applies to any closed loop, linear or non-linear.
2.(a) KCL applies at any node/junction.
3.(a) A node is where two or more elements connect.
4.(a) Mesh analysis uses loop currents as unknowns.
5.(a) Nodal analysis uses node voltages as unknowns.
6.(a) Reciprocity: response/excitation ratio is unchanged if source and response positions swap.
7.(a) Millman's theorem finds voltage at a node from multiple parallel branches.
8.(a) A practical voltage source has non-zero internal resistance.
9.(a) A practical current source has finite shunt resistance.
10.(a) Instantaneous power varies with time as v(t)×i(t).
11.(a) Delta windings connect between two line terminals directly.
12.(a) Star windings connect from a line terminal to a common neutral point.
13.(a) PF correction capacitors supply leading reactive power to offset lagging loads.
14.(a) Frequency is measured in hertz.
15.(a) ω = 2πf.
16.(a) A purely resistive circuit has unity power factor.
17.(a) A purely reactive circuit has zero power factor.
18.(a) A balanced three-phase system has equal magnitudes with 120-degree displacement.
19.(a) The neutral carries unbalance current under unbalanced load.
20.(a) Thevenin's theorem simplifies a circuit portion into an equivalent source plus resistance.
21.(a) Self-excited generators derive field excitation from their own armature output.
22.(a) Separately excited generators use an independent external DC source.
23.(a) Starting current is very high since back EMF is zero at standstill.
24.(a) A DC motor starter limits starting current via initial armature resistance.
25.(a) Reversing either armature or field connections (not both) reverses rotation direction.
26.(a) Voltage regulation is based on no-load vs full-load secondary voltage difference.
27.(a) Efficiency peaks when copper losses equal iron losses.
28.(a) Sumpner's test finds full-load performance using two identical transformers without high power supply.
29.(a) Power transformers suit higher-voltage bulk transmission-level use.
30.(a) Induction motor power factor is generally poorer at light load.
31.(a) VFD-based frequency variation controls induction motor speed.
32.(a) Pole-changing alters synchronous speed by changing stator pole count.
33.(a) V-curves relate armature current to field excitation at constant load.
34.(a) SCR relates to field current needs and inherent stability characteristics.
35.(a) Armature winding is typically on the stator in modern large synchronous machines.
36.(a) The field winding is typically on the rotor, DC-excited.
37.(a) A brushless exciter avoids brushes/slip rings for field supply.
38.(a) Three-phase motors are preferred for self-starting and higher efficiency/power density.
39.(a) A linear induction motor produces linear rather than rotary motion.
40.(a) Both DC and AC machines remain relevant across different applications.
41.(a) Coal-based thermal generation has historically dominated India's mix.
42.(a) Combined cycle plants use gas-turbine waste heat for additional steam power.
43.(a) Pumped storage pumps water up at low demand, generates at peak demand.
44.(a) Nuclear plants generate heat via controlled fission.
45.(a) Wind power converts wind's kinetic energy via a turbine-generator.
46.(a) Solar PV converts solar radiation directly into DC via the photovoltaic effect.
47.(a) A grid-tied inverter converts panel DC into grid-compatible AC.
48.(a) Net metering credits consumers for exported excess solar power.
49.(a) A microgrid is a local group of generation/loads that can operate connected or independent.
50.(a) Islanding is continued local supply after disconnection from the main grid.
51.(a) Unintentional islanding risks line workers not expecting a live "de-energised" line.
52.(a) Anti-islanding protection detects grid loss and disconnects the inverter.
53.(a) A busbar is a common connection point conductor system for multiple circuits.
54.(a) Bus couplers connect/isolate busbar sections.
55.(a) Isolators provide visible isolation for safe maintenance, not for load interruption.
56.(a) Isolators are operated only after the breaker has already opened the circuit.
57.(a) Current-limiting reactors limit fault current via added series reactance.
58.(a) SAIDI/SAIFI relate to average outage duration/frequency for consumers.
59.(a) Distribution automation improves fault detection/isolation speed and reliability.
60.(a) Reliability/modernisation topics reflect real systems JEs may operate/maintain.
61.(a) A shunt extends ammeter range by diverting most current around the movement.
62.(a) A multiplier extends voltmeter range by dropping excess voltage across it.
63.(a) An induction meter's disc speed is proportional to power consumed.
64.(a) A clamp meter measures current without breaking the circuit, via a clamp.
65.(a) An LVDT measures linear displacement.
66.(a) A strain gauge measures strain via resistance change.
67.(a) A thermocouple uses the Seebeck effect for temperature measurement.
68.(a) An RTD measures temperature via predictable resistance change.
69.(a) A photodiode generates/modulates current in response to light.
70.(a) An LED emits light when forward biased.
71.(a) A relay uses a small control current to energise a coil operating a switch contact.
72.(a) A contactor is a heavy-duty relay for higher-power loads like motors.
73.(a) SSRs have no moving parts, offering faster, quieter switching.
74.(a) Feedback control measures actual output and compares it to the reference.
75.(a) Steady-state error is the output-reference difference after transients settle.
76.(a) Excessive proportional gain can cause instability/oscillation.
77.(a) A buck converter is a step-down DC-DC converter.
78.(a) A boost converter is a step-up DC-DC converter.
79.(a) Power electronic converters interface variable renewable output with the grid.
80.(a) These fundamentals equip engagement with modern instrumentation/automation/conversion systems.
81.(a) The National Electricity Policy guides power sector development.
82.(a) DDUGJY targets rural electrification/feeder separation.
83.(a) IPDS strengthens urban sub-transmission/distribution infrastructure.
84.(a) India is increasing BESS deployment for renewable integration/grid stability.
85.(a) ToD tariffs encourage demand shifting away from peak hours.
86.(a) Malware is malicious software harming/exploiting systems.
87.(a) Phishing fraudulently seeks sensitive information via disguised trust.
88.(a) Encryption codes data against unauthorised access.
89.(a) An e-Way Bill is required electronically for goods movement above a threshold.
90.(a) UDAN is a regional air connectivity scheme.
91.(a) Ayushman Bharat provides health insurance to vulnerable families.
92.(a) Jal Jeevan Mission provides piped water to rural households.
93.(a) Digital India aims at a digitally empowered society/knowledge economy.
94.(a) Skill India enhances workforce employability through training.
95.(a) Startup India promotes entrepreneurship/new businesses.
96.(a) FASTag is RFID-based electronic toll collection.
97.(a) PM Gati Shakti integrates planning/coordination of infrastructure connectivity.
98.(a) Sector current affairs test awareness relevant to the recruiting organisation.
99.(a) Previous papers build familiarity with difficulty/style/commonly tested topics.
100.(a) Effective strategy attempts easier questions first with careful time management/elimination.