Full-Length Mock Test 10 — RRB JE CBT 2 Technical Abilities Pattern (100 MCQs)
Free study material · concepts, shortcuts & solved questions
Section A: Circuit Fundamentals and AC/DC Basics (20 Questions)
- The "apparent power" in an AC circuit is the product of RMS voltage and RMS current, measured in:
(a) Volt-amperes (VA) (b) Watts (c) VAR (d) Ohms - The relationship between apparent power (S), active power (P), and reactive power (Q) is given by:
(a) S² = P² + Q² (b) S = P + Q (c) S = P − Q (d) S² = P − Q² - A capacitor stores energy in its:
(a) Electric field (b) Magnetic field (c) Mechanical spring (d) Chemical bonds - An inductor stores energy in its:
(a) Magnetic field (b) Electric field (c) Mechanical spring (d) Chemical bonds - The energy stored in a capacitor of capacitance C charged to voltage V is given by:
(a) ½CV² (b) CV (c) ½LI² (d) V²/C - The energy stored in an inductor of inductance L carrying current I is given by:
(a) ½LI² (b) LI (c) ½CV² (d) I²/L - Two capacitors in series have a combined capacitance that is:
(a) Less than the smallest individual capacitance (b) Equal to the sum of the individual capacitances (c) Always exactly double the largest capacitance (d) Independent of either capacitor's value - Two capacitors in parallel have a combined capacitance that is:
(a) Equal to the sum of the individual capacitances (b) Less than the smallest individual capacitance (c) Always exactly half the smallest capacitance (d) Independent of either capacitor's value - A "phasor" is a mathematical representation used to depict a sinusoidal quantity's:
(a) Magnitude and phase angle (b) Only its frequency, with no magnitude or phase information (c) Only its physical location (d) Only its colour on a diagram - In AC circuit analysis, impedance Z is a complex quantity combining:
(a) Resistance (real part) and reactance (imaginary part) (b) Only resistance, with reactance ignored entirely (c) Only capacitance value directly (d) Only frequency value directly - In an RL series circuit driven by AC, the current:
(a) Lags the voltage (b) Leads the voltage (c) Is exactly in phase with the voltage always (d) Is unrelated to the voltage phase - In an RC series circuit driven by AC, the current:
(a) Leads the voltage (b) Lags the voltage (c) Is exactly in phase with the voltage always (d) Is unrelated to the voltage phase - The "quality factor" (Q-factor) of a series RLC resonant circuit is a measure of its:
(a) Sharpness of resonance (selectivity) (b) Physical size only (c) Manufacturing cost only (d) Colour rating only - A "band-pass filter" circuit is designed to allow signals within a certain frequency range to pass while:
(a) Attenuating frequencies outside that range (b) Attenuating all frequencies equally, including those within the range (c) Amplifying only DC signals, with no AC passband (d) Passing every frequency with no attenuation of any kind - A "low-pass filter" allows low-frequency signals to pass while attenuating:
(a) High-frequency signals (b) Low-frequency signals instead (c) No signals at any frequency (d) Only DC signals - A "high-pass filter" allows high-frequency signals to pass while attenuating:
(a) Low-frequency signals (b) High-frequency signals instead (c) No signals at any frequency (d) Only AC signals of all frequencies equally - The term "harmonics" in AC power systems refers to voltage/current components at frequencies that are:
(a) Integer multiples of the fundamental supply frequency (b) Always exactly equal to the fundamental frequency (c) Completely unrelated to the fundamental frequency (d) Always sub-multiples less than the fundamental - Total Harmonic Distortion (THD) is a measure of the:
(a) Extent of waveform distortion caused by harmonic content (b) Total power consumed by a purely resistive load only (c) Total insulation resistance of a cable (d) Total physical length of a transmission line - A capacitor bank installed for power factor correction primarily supplies:
(a) Leading reactive power to offset the lagging reactive power drawn by inductive loads (b) Active power only, with no reactive power role (c) Only harmonic currents, with no fundamental frequency component (d) DC power only - Improving power factor closer to unity in an industrial installation primarily results in:
(a) Reduced line current for the same active power, lowering losses and improving voltage regulation (b) Increased line current for the same active power (c) No change in current or losses whatsoever (d) Complete elimination of active power consumption
Section B: Electrical Machines (20 Questions)
- The "critical field resistance" of a DC shunt generator is the field circuit resistance value above which the generator:
(a) Fails to build up voltage (self-excite) (b) Builds up voltage more rapidly than at any lower resistance (c) Produces exactly rated voltage regardless of speed (d) Runs at exactly synchronous speed - "Critical speed" of a DC shunt generator, for a given field resistance, is the speed below which the machine:
(a) Fails to self-excite and build up voltage (b) Produces excessive overvoltage (c) Runs perfectly at rated voltage regardless of any other factor (d) Reverses its polarity automatically - The "external characteristic" of a DC generator is the plot of terminal voltage against:
(a) Load current (b) Field current only, with no load current considered (c) Speed only (d) Time only, independent of load - A DC shunt generator's terminal voltage tends to _ as load current increases (within normal range), due to armature reaction and resistance drop.
(a) Decrease gradually (b) Increase gradually (c) Remain exactly constant regardless of load (d) Increase sharply to twice the no-load value - A separately excited DC generator obtains its field current from:
(a) An independent external DC source (b) Its own armature output, exactly like a self-excited machine (c) An AC source directly, with no rectification (d) No source at all, as separately excited machines have no field winding - Parallel operation of DC generators requires that, before connecting, the incoming generator's voltage be:
(a) Adjusted to match the bus voltage (b) Set to exactly zero (c) Set to twice the bus voltage (d) Left unregulated, with no matching required - The "hunting" phenomenon in a synchronous machine refers to oscillations of the rotor about its:
(a) Steady-state (synchronous) position, following a disturbance (b) Physical mounting bolts, unrelated to electrical operation (c) Nameplate rating, which is a fixed printed value (d) Manufacturing tolerance, unrelated to any operating condition - Damper windings in a synchronous machine help to:
(a) Suppress hunting oscillations and provide starting torque as an induction motor effect (b) Increase the field excitation permanently (c) Serve only a decorative function (d) Prevent the machine from ever synchronising with the grid - The "voltage regulation" of an alternator is defined based on the rise in terminal voltage when the load is removed, expressed as a percentage of the:
(a) Rated (full-load) terminal voltage (b) No-load current (c) Armature resistance value (d) Field winding's physical length - The EMF method (synchronous impedance method) for determining an alternator's voltage regulation tends to give results that are:
(a) Higher than actual (a pessimistic estimate) (b) Lower than actual (an optimistic estimate) (c) Always exactly equal to the actual value with no error (d) Unrelated to the actual value in any way - Parallel operation of alternators (synchronising) requires matching of voltage magnitude, frequency, and:
(a) Phase sequence and phase angle (b) Only the machines' physical colour (c) Only the machines' manufacturer (d) Only the prime mover type, with no electrical matching needed - A "synchroscope" is an instrument used to indicate:
(a) The phase relationship between an incoming alternator and the bus, for synchronising (b) Only the alternator's field current (c) Only the alternator's physical speed in RPM with no phase information (d) Only the alternator's oil temperature - In a three-phase induction motor, "no-load test" and "blocked-rotor test" are analogous to which transformer tests respectively?
(a) Open-circuit test and short-circuit test (b) Short-circuit test and open-circuit test (c) Only the open-circuit test for both (d) Only the short-circuit test for both - The "circle diagram" of an induction motor, derived from no-load and blocked-rotor test data, is used to predict:
(a) Performance characteristics such as power factor, efficiency, and torque at various loads (b) Only the motor's physical dimensions (c) Only the motor's manufacturing cost (d) Only the motor's paint colour code - A "universal motor" can operate on:
(a) Both AC and DC supply (b) Only DC supply, never AC (c) Only AC supply, never DC (d) Neither AC nor DC, only mechanical input - A "stepper motor" moves in discrete angular steps in response to:
(a) A sequence of digital pulses applied to its windings (b) A single continuous DC voltage with no pulsing (c) A continuously varying analog signal, exactly like a DC motor (d) No electrical input at all - A "servo motor," widely used in precision control applications, typically operates in conjunction with a:
(a) Feedback (position/speed) sensor for closed-loop control (b) No feedback device at all, purely open-loop (c) Only a mechanical gear train with no electrical feedback (d) Only a manual control lever - The "linear induction motor" (LIM) produces:
(a) Linear (straight-line) thrust/motion rather than rotary motion (b) Only rotary motion, exactly like a standard induction motor (c) No motion at all, being purely a sensing device (d) Only oscillatory motion with a fixed, non-adjustable frequency - Transformer "vector group" (e.g., Dyn11) notation indicates:
(a) The winding connections (star/delta) and phase displacement between primary and secondary (b) Only the transformer's physical weight (c) Only the transformer's cooling type (d) Only the transformer's manufacturer code - A transformer's "all-day efficiency" is a measure that accounts for:
(a) Energy losses over a full day considering varying load conditions, including no-load periods (b) Only the losses at full-rated load, ignoring all other load conditions (c) Only the losses at exactly zero load for the full day (d) Only the transformer's nameplate rating, with no actual measurement involved
Section C: Power Systems and Protection (20 Questions)
- The "load factor" of a power system is defined as the ratio of:
(a) Average load to maximum (peak) load over a given period (b) Maximum load to installed capacity (c) Installed capacity to average load (d) Peak load to minimum load - The "diversity factor" in power system load analysis is defined as the ratio of:
(a) Sum of individual maximum demands to the system's coincident maximum demand (b) System's coincident maximum demand to the sum of individual maximum demands (c) Average load to peak load (d) Installed capacity to peak load - A higher diversity factor in a distribution system generally indicates:
(a) Individual maximum demands occur at different times, allowing more economical equipment sizing (b) All consumers draw their peak demand simultaneously at all times (c) No variation in load timing whatsoever (d) A system with no consumers connected - The "plant capacity factor" of a generating station is the ratio of:
(a) Average load on the plant to its installed capacity (b) Installed capacity to average load (c) Peak load to installed capacity only (d) Installed capacity to peak load only - "Spinning reserve" in power system operation refers to:
(a) Generation capacity kept online and synchronized, ready to meet sudden load increases (b) Capacity that is completely offline and disconnected (c) Only the reserve fuel stock at a thermal plant (d) Only the transmission line's mechanical spare capacity - A "black start" capability of a generating unit refers to its ability to:
(a) Start up without relying on the external grid supply, following a total system blackout (b) Only start when the grid is fully energized and stable (c) Operate only at night, with no daytime capability (d) Operate only on renewable energy sources - The concept of "grid code" compliance for generators connected to the power system primarily governs:
(a) Technical standards for safe, reliable, and coordinated grid interconnection (b) Only the colour scheme of generating station buildings (c) Only the recruitment policy of the utility (d) Only the billing software used by the utility - Automatic Generation Control (AGC) in power system operation helps to maintain:
(a) System frequency and scheduled tie-line power interchange (b) Only the physical temperature of the generating hall (c) Only the fuel price at the generating station (d) Only the colour-coding of control panels - A "power system stabilizer" (PSS) is used with an alternator's excitation system to:
(a) Damp out low-frequency power system oscillations (b) Increase field current permanently regardless of system conditions (c) Serve only a cosmetic panel indicator function (d) Replace the need for any protective relay - HVDC (High Voltage Direct Current) transmission is particularly advantageous for:
(a) Very long-distance bulk power transfer and interconnecting asynchronous grids (b) Only very short local distribution runs of a few metres (c) Only lighting circuits in homes (d) Only battery charging applications - A converter station in an HVDC system uses which key power-electronic devices to convert AC to DC and back?
(a) Thyristor valves (or modern IGBT-based converters) (b) Simple mechanical switches only, with no semiconductor devices (c) Only incandescent lamps as converters (d) Only transformers, with no switching devices at all - FACTS (Flexible AC Transmission System) devices are used in power systems to:
(a) Enhance controllability and power transfer capability of AC transmission (b) Convert the entire grid to DC operation (c) Eliminate the need for any transmission lines (d) Serve only a decorative substation function - A "static VAR compensator" (SVC), a type of FACTS device, is used to:
(a) Provide fast, controllable reactive power compensation (b) Provide only active power generation, with no reactive power role (c) Physically replace all transmission conductors (d) Serve only as a mechanical circuit breaker - The term "islanding" in the context of distributed generation refers to a situation where:
(a) A portion of the grid continues to be energized by local generation after disconnection from the main grid (b) The entire national grid shuts down simultaneously (c) Only offshore wind farms are considered, with no onshore relevance (d) A generator is permanently removed from service with no possibility of reconnection - Anti-islanding protection in grid-connected renewable energy systems is required to:
(a) Disconnect the local generation when the main grid supply is lost, for safety (b) Keep the local generation connected indefinitely regardless of grid status (c) Increase the local generation's output during a grid outage (d) Serve only a metering function with no protective role - A "protection coordination study" in power system engineering is conducted to ensure that:
(a) Protective devices operate in the correct sequence, isolating only the faulted section (b) All protective devices operate simultaneously regardless of fault location (c) No protective device ever operates under any fault condition (d) Only the largest breaker in the system ever operates - "Selectivity" (discrimination) in protection system design means that only the:
(a) Protective device nearest to the fault should operate, minimizing the disconnected area (b) Protective device farthest from the fault should always operate first (c) Entire system should always be de-energized for any fault, however minor (d) No protective device should ever operate under any circumstances - A "restricted earth fault" (REF) protection scheme is commonly applied to:
(a) Transformers and generators, to detect earth faults within a clearly defined zone (b) Only overhead transmission lines many kilometres long (c) Only low-voltage domestic wiring circuits (d) Only battery banks with no transformer involved - The term "arc flash" refers to a hazardous release of energy caused by:
(a) An electric arc fault, posing serious burn/injury risk to nearby personnel (b) A purely mechanical vibration with no electrical origin (c) A planned, controlled lighting effect with no hazard (d) A software error in a digital relay with no physical energy release - Personal protective equipment (PPE) and safe work practices for electrical work are primarily governed, in the Indian context, by standards and regulations issued under:
(a) The Central Electricity Authority (Measures relating to Safety and Electric Supply) Regulations and related IS codes (b) Only informal, unwritten workplace custom (c) Only international standards with no Indian equivalent (d) Only manufacturer-specific guidelines with no regulatory backing
Section D: Measurements, Electronics, Control, and Power Electronics (20 Questions)
- The "loading effect" of a voltmeter on a circuit under test arises because the voltmeter:
(a) Draws some current from the circuit, altering the voltage being measured (b) Draws zero current under all conditions, causing no effect (c) Only affects circuits carrying DC, never AC (d) Only affects circuits with no resistance at all - An ideal ammeter is assumed to have:
(a) Zero internal resistance (b) Infinite internal resistance (c) A resistance exactly equal to the circuit's load resistance (d) A resistance that varies randomly with current - An ideal voltmeter is assumed to have:
(a) Infinite internal resistance (b) Zero internal resistance (c) A resistance exactly equal to the circuit's load resistance (d) A resistance that varies randomly with voltage - A "shunt" used with a moving-coil ammeter is connected:
(a) In parallel with the meter movement, to extend its current range (b) In series with the meter movement, to extend its voltage range (c) Nowhere in the circuit, serving no function (d) Only across the power supply terminals, unrelated to the meter - A "multiplier" resistor used with a moving-coil voltmeter is connected:
(a) In series with the meter movement, to extend its voltage range (b) In parallel with the meter movement, to extend its current range (c) Nowhere in the circuit, serving no function (d) Only across the shunt resistor - In digital electronics, the binary number system uses only the digits:
(a) 0 and 1 (b) 0 through 9 (c) 0 through 7 (d) 0 through 15 - The decimal number 10 is represented in binary as:
(a) 1010 (b) 1000 (c) 1100 (d) 0110 - An "analog-to-digital converter" (ADC) converts a continuously varying analog signal into:
(a) A discrete digital representation (b) A different continuously varying analog signal, unrelated to the original (c) A purely mechanical output with no electrical signal (d) An unmodulated carrier wave only - A "digital-to-analog converter" (DAC) performs the reverse function of converting digital data into:
(a) A continuously varying analog signal (b) Discrete binary pulses only, with no analog output (c) A purely mechanical output (d) An unmodulated carrier wave only - In control system terminology, "steady-state error" refers to the difference between the desired and actual output:
(a) After all transients have died out, as time approaches infinity (b) Only during the initial transient period, never afterward (c) Only at the exact instant the input is first applied (d) Only when the system is completely disconnected from its input - A "first-order system" in control theory is characterized by a transfer function with a highest-order term in the denominator of:
(a) One (b) Two (c) Zero (d) Infinity - A "second-order system" in control theory is characterized by a transfer function with a highest-order term in the denominator of:
(a) Two (b) One (c) Zero (d) Infinity - The "damping ratio" of a second-order control system determines whether the system's response is:
(a) Underdamped, critically damped, or overdamped (b) Always exactly critically damped regardless of any parameter (c) Always unstable regardless of any parameter (d) Always undamped with sustained oscillation regardless of any parameter - "Critically damped" response in a second-order system reaches steady state:
(a) As fast as possible without oscillating (b) With the maximum possible number of oscillations (c) Only after an infinite time, never actually settling (d) Only if the system is first-order, not second-order - An "underdamped" second-order system's response is characterized by:
(a) Oscillations that decay over time before settling (b) No oscillation whatsoever, with the slowest possible settling (c) Sustained oscillations that never decay under any condition (d) An immediate, instantaneous settling with zero time delay - A buck converter (a type of DC-DC converter) produces an output voltage that is:
(a) Lower than the input voltage (step-down) (b) Higher than the input voltage (step-up) (c) Always exactly equal to the input voltage (d) Always negative regardless of input polarity - A boost converter (a type of DC-DC converter) produces an output voltage that is:
(a) Higher than the input voltage (step-up) (b) Lower than the input voltage (step-down) (c) Always exactly equal to the input voltage (d) Always zero regardless of input - A buck-boost converter can produce an output voltage that is:
(a) Either higher or lower than the input voltage, depending on duty cycle (b) Always exactly equal to the input voltage only (c) Always exactly zero (d) Only ever higher than the input, never lower - In a three-phase full bridge (six-pulse) rectifier, the number of thyristors/diodes typically used is:
(a) Six (b) Two (c) Four (d) Three - The "firing angle" (or delay angle) of a controlled rectifier using SCRs determines the:
(a) Average DC output voltage obtained from a given AC input (b) Physical temperature rating of the SCR only (c) Number of SCRs required in the circuit (d) Colour of the output waveform on an oscilloscope
Section E: General Awareness, Computer Applications, and Current Affairs (20 Questions)
- The Central Power Research Institute (CPRI), headquartered in Bengaluru, is primarily involved in:
(a) Research, testing, and certification in the power sector (b) Railway signal manufacturing (c) Currency printing (d) Postal service operations - Damodar Valley Corporation (DVC) is a multi-purpose project primarily associated with:
(a) Power generation and flood control in the Damodar river basin (b) Airport construction in southern India (c) Postal network expansion (d) Coastal shipping regulation - The Rural Electrification Corporation (REC) primarily provides financing for:
(a) Power sector projects, especially in rural electrification (b) Only urban real estate development (c) Only agricultural crop insurance (d) Only textile sector loans - In computing, "IoT" stands for:
(a) Internet of Things (b) Input Output Terminal (c) Integrated Optical Transmission (d) Internal Operations Team - In computing, "AI" commonly stands for:
(a) Artificial Intelligence (b) Automated Interface (c) Analog Input (d) Applied Instrumentation - A "spreadsheet" software application, such as MS Excel, is primarily used for:
(a) Organizing, calculating, and analysing data in rows and columns (b) Only playing audio/video files (c) Only sending emails (d) Only browsing the internet - In MS Word, the function of "spell check" is to:
(a) Identify and suggest corrections for spelling errors in a document (b) Automatically translate the document into another language (c) Print the document directly with no on-screen review (d) Compress the document file size only - A "database management system" (DBMS) is software used to:
(a) Store, organize, and retrieve structured data efficiently (b) Only display static images with no data storage (c) Only play music files (d) Only manage printer queues - The full form of "USB" (a common computer peripheral interface) is:
(a) Universal Serial Bus (b) United System Board (c) Unified Signal Bridge (d) Universal Storage Backup - "Malware" is a general term referring to:
(a) Malicious software designed to damage, disrupt, or gain unauthorised access to systems (b) Authorised system utility software only (c) Hardware components only, with no software involved (d) A type of antivirus protection program exclusively - The Central Electricity Regulatory Commission (CERC) and State Electricity Regulatory Commissions (SERCs) were constituted under which Act?
(a) The Electricity Act, 2003 (b) The Companies Act, 2013 (c) The Indian Railways Act (d) The Banking Regulation Act - Time-of-Day (ToD) tariff structures for electricity billing are designed to:
(a) Encourage load shifting away from peak demand periods (b) Charge a single flat rate regardless of time of use (c) Eliminate the need for any metering (d) Apply only to street lighting circuits - Net metering, as applied to rooftop solar installations, allows consumers to:
(a) Export surplus solar energy to the grid and receive credit against consumption (b) Only consume grid power with no export capability whatsoever (c) Only operate completely off-grid with no connection at all (d) Only sell power to neighbouring countries directly - The "PM-KUSUM" scheme in India is primarily aimed at promoting:
(a) Solar energy use in the agricultural sector, including solar pumps (b) Urban metro rail expansion (c) National highway toll collection (d) Digital banking infrastructure - Energy Conservation Building Code (ECBC) in India primarily sets standards for:
(a) Energy-efficient design and construction of commercial buildings (b) Railway coach design standards (c) Currency printing standards (d) Postal packaging standards - The "Ease of Doing Business" reforms relevant to the power sector have included measures such as:
(a) Simplifying new electricity connection procedures (b) Eliminating all electricity connections entirely (c) Removing all regulatory oversight of the sector (d) Applying only to the agricultural sector - A "Power Purchase Agreement" (PPA) is a contract typically signed between:
(a) A power generator and a buyer (such as a distribution company), specifying supply terms (b) Two individual domestic consumers only (c) A bank and a depositor, unrelated to electricity (d) A postal department and a courier company - The "Merit Order Dispatch" principle in electricity procurement means that power is procured, among available sources, in order of:
(a) Increasing cost, to minimise overall procurement expense (b) Decreasing cost, to maximise overall procurement expense (c) Random selection with no cost consideration (d) Alphabetical order of the generating company's name - The "Ujala" scheme (Unnat Jyoti by Affordable LEDs for All) promoted widespread adoption of:
(a) LED bulbs, for energy-efficient lighting (b) Compressed natural gas vehicles (c) Solar water heaters exclusively (d) Wind turbines for household use - Digital India, as a broad government initiative, aims to transform India into a digitally empowered society and knowledge economy, with relevance to the power sector through initiatives such as:
(a) Smart metering and digital utility services (b) Elimination of all physical infrastructure (c) Discontinuation of all internet-based services (d) Restriction of digital access to government offices only
Answer Key with Explanations
1.(a) Apparent power (VA) is the product of RMS voltage and current.
2.(a) S² = P² + Q² relates apparent, active, and reactive power.
3.(a) A capacitor stores energy in its electric field.
4.(a) An inductor stores energy in its magnetic field.
5.(a) Capacitor energy = ½CV².
6.(a) Inductor energy = ½LI².
7.(a) Series capacitors give combined capacitance less than the smallest individual value.
8.(a) Parallel capacitors give combined capacitance equal to the sum.
9.(a) A phasor represents magnitude and phase angle of a sinusoid.
10.(a) Impedance combines resistance (real) and reactance (imaginary).
11.(a) In RL series AC circuits, current lags voltage.
12.(a) In RC series AC circuits, current leads voltage.
13.(a) Q-factor measures sharpness/selectivity of resonance.
14.(a) A band-pass filter passes a range and attenuates outside frequencies.
15.(a) A low-pass filter passes low frequencies, attenuating high ones.
16.(a) A high-pass filter passes high frequencies, attenuating low ones.
17.(a) Harmonics are integer multiples of the fundamental frequency.
18.(a) THD measures the extent of harmonic distortion.
19.(a) PF correction capacitor banks supply leading reactive power to offset lagging loads.
20.(a) Improved power factor reduces line current for the same active power, cutting losses.
21.(a) Above critical field resistance, a shunt generator fails to self-excite.
22.(a) Below critical speed, the generator fails to build up voltage.
23.(a) The external characteristic plots terminal voltage against load current.
24.(a) Shunt generator terminal voltage decreases gradually with load due to armature reaction/IR drop.
25.(a) A separately excited generator's field current comes from an independent external source.
26.(a) Before paralleling, the incoming generator's voltage must be matched to the bus.
27.(a) Hunting is rotor oscillation about its steady-state position after a disturbance.
28.(a) Damper windings suppress hunting and aid starting via induction motor action.
29.(a) Voltage regulation is expressed relative to rated (full-load) terminal voltage.
30.(a) The EMF method tends to overestimate voltage regulation (pessimistic).
31.(a) Synchronising requires matching voltage, frequency, phase sequence, and phase angle.
32.(a) A synchroscope indicates phase relationship between incoming machine and bus.
33.(a) No-load and blocked-rotor tests are analogous to OC and SC transformer tests respectively.
34.(a) The circle diagram predicts performance like PF, efficiency, and torque from test data.
35.(a) A universal motor runs on both AC and DC supply.
36.(a) A stepper motor moves in steps per a pulse sequence.
37.(a) A servo motor works with a feedback sensor for closed-loop control.
38.(a) A linear induction motor produces linear thrust rather than rotary motion.
39.(a) Vector group notation indicates winding connections and phase displacement.
40.(a) All-day efficiency accounts for losses over a full day of varying load.
41.(a) Load factor = average load / maximum load.
42.(a) Diversity factor = sum of individual max demands / coincident max demand.
43.(a) A higher diversity factor means individual peaks occur at different times, allowing economical sizing.
44.(a) Plant capacity factor = average load / installed capacity.
45.(a) Spinning reserve is online, synchronized capacity ready for sudden load increases.
46.(a) Black start capability allows startup without relying on external grid supply.
47.(a) Grid code compliance governs technical standards for safe grid interconnection.
48.(a) AGC maintains system frequency and scheduled tie-line interchange.
49.(a) A PSS damps low-frequency power system oscillations.
50.(a) HVDC suits very long-distance bulk transfer and asynchronous grid interconnection.
51.(a) HVDC converter stations use thyristor valves or modern IGBT-based converters.
52.(a) FACTS devices enhance controllability and power transfer capability of AC transmission.
53.(a) An SVC provides fast, controllable reactive power compensation.
54.(a) Islanding is when a grid portion stays energized by local generation after disconnection.
55.(a) Anti-islanding protection disconnects local generation when grid supply is lost.
56.(a) Coordination studies ensure correct operating sequence, isolating only the faulted section.
57.(a) Selectivity means only the nearest protective device to the fault should operate.
58.(a) REF protection is applied to transformers/generators for zone-limited earth fault detection.
59.(a) Arc flash is a hazardous energy release from an arc fault.
60.(a) Indian electrical safety practice is governed by CEA safety regulations and IS codes.
61.(a) A voltmeter's loading effect arises from the current it draws from the circuit.
62.(a) An ideal ammeter has zero internal resistance.
63.(a) An ideal voltmeter has infinite internal resistance.
64.(a) A shunt is connected in parallel with the meter movement to extend current range.
65.(a) A multiplier is connected in series with the meter movement to extend voltage range.
66.(a) Binary uses only digits 0 and 1.
67.(a) Decimal 10 = binary 1010.
68.(a) An ADC converts analog signals into digital representation.
69.(a) A DAC converts digital data into an analog signal.
70.(a) Steady-state error is the output error as time approaches infinity.
71.(a) A first-order system has a first-order (degree one) denominator.
72.(a) A second-order system has a second-order (degree two) denominator.
73.(a) Damping ratio determines underdamped/critically damped/overdamped response.
74.(a) Critically damped response settles fastest without oscillating.
75.(a) Underdamped response shows decaying oscillations before settling.
76.(a) A buck converter steps down voltage.
77.(a) A boost converter steps up voltage.
78.(a) A buck-boost converter can output higher or lower voltage depending on duty cycle.
79.(a) A three-phase full bridge (six-pulse) rectifier uses six devices.
80.(a) Firing angle determines the average DC output voltage of a controlled rectifier.
81.(a) CPRI conducts research, testing, and certification in the power sector.
82.(a) DVC is associated with power generation and flood control in the Damodar basin.
83.(a) REC finances power sector projects, especially rural electrification.
84.(a) IoT stands for Internet of Things.
85.(a) AI commonly stands for Artificial Intelligence.
86.(a) A spreadsheet organizes, calculates, and analyses data in rows/columns.
87.(a) Spell check identifies and suggests corrections for spelling errors.
88.(a) A DBMS stores, organizes, and retrieves structured data efficiently.
89.(a) USB stands for Universal Serial Bus.
90.(a) Malware is malicious software causing damage/disruption/unauthorised access.
91.(a) CERC/SERCs were constituted under the Electricity Act, 2003.
92.(a) ToD tariffs encourage load shifting away from peak periods.
93.(a) Net metering lets consumers export surplus solar energy for billing credit.
94.(a) PM-KUSUM promotes solar energy use in agriculture, including solar pumps.
95.(a) ECBC sets energy-efficient design standards for commercial buildings.
96.(a) Ease of Doing Business reforms include simplifying new connection procedures.
97.(a) A PPA is a contract between a generator and buyer specifying supply terms.
98.(a) Merit order dispatch procures power in increasing order of cost.
99.(a) Ujala promoted widespread LED bulb adoption for efficient lighting.
100.(a) Digital India's power-sector relevance includes smart metering and digital utility services.