Q.1 Which component converts mechanical energy from a turbine into electrical energy?
Transformer
Generator
Rectifier
Inverter
Explanation - A generator uses electromagnetic induction to convert the rotating shaft of a turbine (mechanical energy) into AC electricity.
Correct answer is: Generator
Q.2 What is the primary fuel used in a typical coal‑fired power plant?
Natural gas
Uranium
Bituminous coal
Wind
Explanation - Bituminous coal is the most common type of coal used for electricity generation due to its high energy content.
Correct answer is: Bituminous coal
Q.3 In a hydroelectric plant, the potential energy of water is converted into electricity. Which law explains this conversion?
Ohm’s Law
Faraday’s Law of Electromagnetic Induction
Newton’s Second Law
Kirchhoff’s Voltage Law
Explanation - Faraday’s law states that a changing magnetic flux induces an EMF, which occurs when the turbine drives the generator.
Correct answer is: Faraday’s Law of Electromagnetic Induction
Q.4 What is the typical efficiency range of a modern combined‑cycle gas turbine power plant?
30‑40%
45‑55%
55‑65%
60‑70%
Explanation - Combined‑cycle plants recover waste heat from the gas turbine to run a steam turbine, achieving efficiencies of about 60‑70%.
Correct answer is: 60‑70%
Q.5 Which thermodynamic cycle is most commonly used in coal‑fired power plants?
Rankine cycle
Otto cycle
Brayton cycle
Stirling cycle
Explanation - The Rankine cycle uses water/steam as the working fluid and is the standard for thermal power stations.
Correct answer is: Rankine cycle
Q.6 The term ‘capacity factor’ of a power plant is defined as:
Actual output ÷ Maximum possible output over a period
Rated power ÷ Peak demand
Total generated energy ÷ Energy lost in transmission
Installed capacity ÷ Number of units
Explanation - Capacity factor measures how often a plant runs at its full nameplate capacity.
Correct answer is: Actual output ÷ Maximum possible output over a period
Q.7 Which renewable energy source has the highest power density (MW per km²) among the following?
Solar photovoltaic
Onshore wind
Geothermal
Biomass
Explanation - Geothermal plants can generate large amounts of power from relatively small land areas compared with solar or wind.
Correct answer is: Geothermal
Q.8 In a nuclear power plant, which isotope is most commonly used as fuel?
Uranium‑235
Plutonium‑239
Thorium‑232
Uranium‑238
Explanation - U‑235 is fissile and capable of sustaining a chain reaction in light‑water reactors.
Correct answer is: Uranium‑235
Q.9 What is the purpose of a condenser in a steam power plant?
Increase steam temperature
Convert steam back to water
Compress the steam
Generate electricity directly
Explanation - The condenser removes latent heat from exhaust steam, turning it into condensate for reuse in the boiler.
Correct answer is: Convert steam back to water
Q.10 Which of the following best describes ‘peaking power plants’?
Plants that run continuously at base load
Plants that start quickly to meet short‑term demand spikes
Plants that use only renewable fuels
Plants with the highest efficiency
Explanation - Peaking plants, often gas turbines, can be brought online rapidly to satisfy peak demand periods.
Correct answer is: Plants that start quickly to meet short‑term demand spikes
Q.11 What is the typical unit of measurement for the electrical output of a large power plant?
Volt‑ampere (VA)
Kilowatt‑hour (kWh)
Megawatt (MW)
Ampere (A)
Explanation - Large generating stations are rated in megawatts, which denote instantaneous power capacity.
Correct answer is: Megawatt (MW)
Q.12 Which device is used to step up the voltage from a generator before transmission?
Circuit breaker
Transformer
Capacitor bank
Rectifier
Explanation - Transformers increase voltage to reduce I²R losses during long‑distance transmission.
Correct answer is: Transformer
Q.13 The term ‘heat rate’ in power generation refers to:
Amount of heat rejected per hour
Fuel input required to produce one kilowatt‑hour of electricity
Temperature rise across the turbine
Efficiency of the cooling system
Explanation - Heat rate (Btu/kWh) is a measure of plant efficiency; lower heat rate indicates higher efficiency.
Correct answer is: Fuel input required to produce one kilowatt‑hour of electricity
Q.14 Which of the following is NOT a type of renewable power generation?
Solar thermal
Hydroelectric
Biomass
Subcritical coal
Explanation - Subcritical coal plants burn fossil fuel and are not renewable.
Correct answer is: Subcritical coal
Q.15 In wind turbines, what does the term ‘cut‑in speed’ refer to?
Maximum wind speed before turbine shutdown
Minimum wind speed at which the turbine starts generating power
Rated wind speed for maximum output
Speed of the rotor tip at rated power
Explanation - Cut‑in speed is the lowest wind speed at which the turbine’s control system allows the blades to turn and produce electricity.
Correct answer is: Minimum wind speed at which the turbine starts generating power
Q.16 Which parameter is most directly related to the amount of electricity a solar panel can produce?
Panel temperature
Solar irradiance (W/m²)
Wind speed
Ambient humidity
Explanation - The power generated by a photovoltaic cell is proportional to the incident solar irradiance.
Correct answer is: Solar irradiance (W/m²)
Q.17 What is the primary purpose of a ‘synchronous condenser’ in a power system?
Generate electricity
Store mechanical energy
Provide reactive power support
Control frequency
Explanation - A synchronous condenser operates like a motor without a load, supplying or absorbing reactive power to regulate voltage.
Correct answer is: Provide reactive power support
Q.18 In a thermal power plant, the boiler water is typically heated to what phase before entering the turbine?
Supercritical steam
Subcooled liquid
Saturated vapor
Compressed gas
Explanation - The boiler converts water to saturated steam, which then expands in the turbine; supercritical plants go beyond the critical point.
Correct answer is: Saturated vapor
Q.19 Which component protects a generator from over‑current during faults?
Load tap changer
Circuit breaker
Exciter
Stator winding
Explanation - Circuit breakers interrupt fault currents, protecting the generator and downstream equipment.
Correct answer is: Circuit breaker
Q.20 The term ‘baseload power plant’ refers to a plant that:
Operates only during peak demand
Runs continuously to meet the minimum demand
Uses only renewable fuels
Has the fastest start‑up time
Explanation - Baseload plants provide a constant output to satisfy the lowest level of system demand over 24 hours.
Correct answer is: Runs continuously to meet the minimum demand
Q.21 In a gas‑turbine (Brayton) cycle, the component that compresses the incoming air is called:
Combustor
Turbine
Compressor
Heat exchanger
Explanation - The compressor raises the pressure of the air before it enters the combustor.
Correct answer is: Compressor
Q.22 Which of the following gases is primarily responsible for the greenhouse effect from coal‑fired power plants?
Oxygen
Nitrogen
Carbon dioxide
Helium
Explanation - Combustion of coal releases large amounts of CO₂, a major greenhouse gas.
Correct answer is: Carbon dioxide
Q.23 What is the purpose of the ‘exciter’ in a synchronous generator?
Provide the rotating magnetic field
Cool the stator windings
Regulate output voltage
Convert DC to AC
Explanation - The exciter supplies DC current to the rotor windings, creating the magnetic field needed for induction.
Correct answer is: Provide the rotating magnetic field
Q.24 Which of the following best describes ‘dispatchable’ power generation?
Power that can be turned on or off according to demand
Power generated only during daytime
Power that cannot be stored
Power with zero emissions
Explanation - Dispatchable sources, such as gas turbines or hydro, can be controlled to match the load.
Correct answer is: Power that can be turned on or off according to demand
Q.25 The ‘heat sink’ in a power plant is usually:
The boiler
The condenser cooling water
The turbine inlet
The generator
Explanation - The condenser rejects waste heat to a cooling medium (water or air), acting as the plant’s heat sink.
Correct answer is: The condenser cooling water
Q.26 Which technology allows a wind turbine to keep a constant rotational speed despite variable wind speeds?
Variable‑speed drive with power electronics
Fixed‑gear transmission
Hydraulic pitch control
Static blade angle
Explanation - Modern turbines use power electronic converters to decouple rotor speed from grid frequency.
Correct answer is: Variable‑speed drive with power electronics
Q.27 In a photovoltaic (PV) module, the semiconductor material most commonly used is:
Germanium
Silicon
Gallium arsenide
Cadmium telluride
Explanation - Silicon crystals dominate the PV market due to their abundance and mature manufacturing processes.
Correct answer is: Silicon
Q.28 What is the typical voltage level of high‑voltage transmission lines in the United States?
13.8 kV
138 kV
13.8 kV
138 kV
Explanation - Transmission voltages range from 69 kV to 765 kV; 138 kV is a common intermediate level.
Correct answer is: 138 kV
Q.29 Which of the following describes the ‘spinning reserve’ in a power system?
Energy stored in batteries
Unused capacity of generators already online
Backup diesel generators
Hydroelectric water in reservoirs
Explanation - Spinning reserve is the extra capacity that can be quickly called upon from running generators.
Correct answer is: Unused capacity of generators already online
Q.30 In a nuclear reactor, the term ‘moderator’ refers to:
Material that slows down neutrons
Control rod material
Coolant fluid
Shielding material
Explanation - Moderators, such as water or graphite, reduce neutron speed to sustain a controlled chain reaction.
Correct answer is: Material that slows down neutrons
Q.31 Which parameter defines the rate at which a turbine extracts energy from a fluid?
Specific speed
Blade pitch
Head
Torque
Explanation - Specific speed is a dimensionless number characterizing turbine performance for a given head and flow.
Correct answer is: Specific speed
Q.32 A power plant that uses geothermal steam directly to drive a turbine is called:
Dry steam plant
Binary cycle plant
Flash steam plant
Hybrid solar‑geothermal plant
Explanation - Dry steam plants use natural steam from geothermal reservoirs without additional heat exchangers.
Correct answer is: Dry steam plant
Q.33 Which of the following statements about the ‘load factor’ is true?
It is always greater than one.
It equals average load divided by peak load.
It measures the efficiency of a turbine.
It is the same as capacity factor.
Explanation - Load factor = (average load) / (peak load) over a period, indicating utilization of capacity.
Correct answer is: It equals average load divided by peak load.
Q.34 The main disadvantage of a pumped‑storage hydro plant is:
Low efficiency
High water consumption
Limited site availability
Long start‑up time
Explanation - Pumped‑storage requires suitable topography and large reservoirs, making suitable sites scarce.
Correct answer is: Limited site availability
Q.35 In an electrical generator, the term ‘slip’ is associated with:
Synchronous generators
Induction generators
DC generators
Brushless exciters
Explanation - Slip is the difference between synchronous speed and actual rotor speed in induction machines.
Correct answer is: Induction generators
Q.36 Which of the following gases is emitted in large quantities by biomass power plants?
Methane
Carbon monoxide
Sulfur dioxide
Nitrogen oxides
Explanation - Combustion of biomass can produce NOx, though emissions are generally lower than fossil fuels.
Correct answer is: Nitrogen oxides
Q.37 What does the term ‘grid parity’ refer to in renewable energy?
When renewable energy cost equals or is lower than grid electricity cost
When renewable plants are connected directly to the grid
When renewable energy achieves 100% penetration
When renewable power meets all peak demand
Explanation - Grid parity indicates that renewable generation is economically competitive with conventional electricity.
Correct answer is: When renewable energy cost equals or is lower than grid electricity cost
Q.38 In a power plant, the term ‘boiler pressure’ is measured in:
Volts
Pascals (Pa)
Bar
Degrees Celsius
Explanation - Boiler pressure is commonly expressed in bar (or MPa), indicating the pressure of steam generated.
Correct answer is: Bar
Q.39 Which type of turbine is most suitable for low‑head, high‑flow hydro sites?
Francis turbine
Kaplan turbine
Pelton turbine
Cross‑flow turbine
Explanation - Kaplan turbines have adjustable blades and work efficiently at low heads with large flow rates.
Correct answer is: Kaplan turbine
Q.40 The term ‘reactive power’ (measured in VAR) is needed to:
Transfer real energy over distances
Maintain voltage levels in the system
Charge batteries
Increase system frequency
Explanation - Reactive power supports electric and magnetic fields in AC systems, keeping voltage stable.
Correct answer is: Maintain voltage levels in the system
Q.41 A plant that uses a gas turbine followed by a steam turbine to recover waste heat is called:
Combined‑cycle plant
Cogeneration plant
Simple‑cycle plant
Hybrid renewable plant
Explanation - Combined‑cycle plants improve overall efficiency by using both Brayton and Rankine cycles.
Correct answer is: Combined‑cycle plant
Q.42 Which of the following is a primary advantage of using a superconducting generator in a power plant?
Higher operating temperature
Reduced size and weight
Lower cost of construction
Simpler cooling system
Explanation - Superconducting windings allow higher current densities, resulting in smaller and lighter generators.
Correct answer is: Reduced size and weight
Q.43 In a solar thermal power plant, the fluid that transports heat from the collector to the turbine is usually:
Water/steam
Molten salt
Helium
Freon
Explanation - Molten salt can store heat at high temperatures, enabling power generation even when the sun is not shining.
Correct answer is: Molten salt
Q.44 The term ‘black start’ capability refers to:
Starting a plant without external power
Using black coal as fuel
Operating at night only
Starting a plant after a cyber‑attack
Explanation - Black start units can self‑start and help restore the grid after a total blackout.
Correct answer is: Starting a plant without external power
Q.45 Which of the following is the most common cooling method for large thermal power stations?
Air cooling
Dry cooling
Wet (once‑through) cooling
Cryogenic cooling
Explanation - Most large plants use water from rivers, lakes, or seas for cooling due to its high heat‑removal capacity.
Correct answer is: Wet (once‑through) cooling
Q.46 In a generator, the term ‘synchronous speed’ for a 60 Hz system with 4 poles is:
120 rpm
180 rpm
360 rpm
720 rpm
Explanation - Synchronous speed = 120 × frequency / poles = 120 × 60 / 4 = 180 rpm.
Correct answer is: 180 rpm
Q.47 Which of the following statements about a ‘flywheel energy storage system’ is true?
It stores energy chemically.
It can respond in milliseconds to grid demands.
It requires a nuclear reactor to operate.
It cannot be used for frequency regulation.
Explanation - Flywheels have very fast response times, making them suitable for ancillary services like frequency regulation.
Correct answer is: It can respond in milliseconds to grid demands.
Q.48 The term ‘heat‑to‑power conversion efficiency’ for a nuclear plant is typically around:
15‑20%
30‑35%
45‑50%
60‑65%
Explanation - Nuclear plants have efficiencies limited by the temperature of the steam cycle, usually 30‑35%.
Correct answer is: 30‑35%
Q.49 Which device is used to control the pitch of wind turbine blades?
Yaw drive
Pitch actuator
Gearbox
Stator winding
Explanation - Pitch actuators adjust blade angle to regulate power output and protect against overspeed.
Correct answer is: Pitch actuator
Q.50 In the context of power generation, the acronym ‘CCGT’ stands for:
Cold‑Chain Gas Turbine
Combined‑Cycle Gas Turbine
Continuous‑Current Generation Technology
Carbon‑Capture Gas Treatment
Explanation - CCGT plants combine a gas turbine with a steam turbine for higher efficiency.
Correct answer is: Combined‑Cycle Gas Turbine
Q.51 Which factor most directly affects the levelized cost of electricity (LCOE) for a solar PV plant?
Panel tilt angle
Solar irradiance at the site
Distance to the nearest substation
Number of inverters
Explanation - Higher solar resource reduces the cost per kWh produced, lowering LCOE.
Correct answer is: Solar irradiance at the site
Q.52 The primary function of a ‘heat recovery steam generator’ (HRSG) in a combined‑cycle plant is to:
Compress inlet air
Convert exhaust gas heat to steam
Generate electricity directly
Store fuel
Explanation - HRSG captures waste heat from the gas turbine exhaust to produce steam for the steam turbine.
Correct answer is: Convert exhaust gas heat to steam
Q.53 Which of the following is a major limitation of offshore wind farms compared to onshore wind farms?
Lower wind speeds
Higher visual impact
More expensive installation and maintenance
Less reliable power output
Explanation - Offshore locations increase logistical challenges, raising capital and O&M costs.
Correct answer is: More expensive installation and maintenance
Q.54 In a hydroelectric plant, the term ‘head’ refers to:
The distance between turbine blades
The vertical height difference between water source and turbine
The flow rate of water
The power rating of the generator
Explanation - Head determines the potential energy available for conversion to electricity.
Correct answer is: The vertical height difference between water source and turbine
Q.55 Which type of battery is most commonly used for grid‑scale energy storage?
Lead‑acid
Lithium‑ion
Nickel‑cadmium
Alkaline
Explanation - Lithium‑ion batteries offer high energy density, efficiency, and fast response for large storage installations.
Correct answer is: Lithium‑ion
Q.56 The ‘critical point’ of water (used in supercritical power plants) is approximately:
374 °C and 22.1 MPa
100 °C and 0.101 MPa
150 °C and 5 MPa
250 °C and 10 MPa
Explanation - Above this temperature and pressure water becomes a supercritical fluid, allowing higher efficiency cycles.
Correct answer is: 374 °C and 22.1 MPa
Q.57 Which of the following is NOT a typical function of a power plant’s SCADA system?
Remote monitoring of equipment
Automatic generation control
Physical protection of the site
Data logging for performance analysis
Explanation - SCADA focuses on monitoring and control; security systems handle physical protection.
Correct answer is: Physical protection of the site
Q.58 In the context of power generation, the term ‘dispatch interval’ refers to:
The time a generator can stay online without fuel
The time period over which the grid operator schedules generation
The interval between maintenance inspections
The length of a typical turbine blade
Explanation - Dispatch intervals (e.g., 5 min, 15 min) are used for market clearing and unit commitment.
Correct answer is: The time period over which the grid operator schedules generation
Q.59 Which gas turbine inlet temperature is typical for modern high‑performance aero‑derivative units?
800 °C
1100 °C
1500 °C
1800 °C
Explanation - Advanced materials and cooling allow inlet temperatures around 1500 °C, increasing efficiency.
Correct answer is: 1500 °C
Q.60 Which method is used to reduce nitrogen oxide (NOx) emissions in coal‑fired power plants?
Flue‑gas desulfurization
Selective catalytic reduction (SCR)
Electrostatic precipitators
Dry cooling towers
Explanation - SCR injects ammonia into the flue gas over a catalyst, converting NOx to N₂ and H₂O.
Correct answer is: Selective catalytic reduction (SCR)
Q.61 In a wind farm, the ‘capacity factor’ is typically around:
5‑10%
15‑20%
30‑40%
80‑90%
Explanation - Wind turbines generate at full capacity only part of the time; typical capacity factors are 30‑40%.
Correct answer is: 30‑40%
Q.62 Which of the following best defines ‘ancillary services’ in power systems?
Primary electricity generation
Transmission line construction
Support functions like frequency and voltage regulation
Customer billing and metering
Explanation - Ancillary services maintain grid stability and quality beyond simply delivering energy.
Correct answer is: Support functions like frequency and voltage regulation
Q.63 The main advantage of using a ‘binary cycle’ in geothermal power plants is:
Higher temperature steam directly drives the turbine
Use of low‑temperature resources
No need for cooling water
Elimination of corrosion
Explanation - Binary cycles employ a secondary working fluid, allowing electricity generation from lower‑temperature geothermal fluids.
Correct answer is: Use of low‑temperature resources
Q.64 Which component in a power plant is responsible for removing ash from the flue gas of a coal‑fired boiler?
Electrostatic precipitator
Baghouse filter
Scrubber
Cyclone separator
Explanation - Cyclones use centrifugal forces to separate larger ash particles before the gas enters downstream equipment.
Correct answer is: Cyclone separator
Q.65 In an AC generator, the term ‘salient‑pole’ refers to:
A pole that moves relative to the stator
A pole with a large surface area extending from the rotor
A pole that is electrically insulated
A pole made of superconducting material
Explanation - Salient‑pole rotors have protruding poles, common in low‑speed hydro generators.
Correct answer is: A pole with a large surface area extending from the rotor
Q.66 Which of the following is the most common method for synchronizing a generator to the grid?
Manual voltage matching
Phase‑locked loop (PLL)
Frequency‑shifting
Load‑sharing controller
Explanation - PLLs ensure the generator’s voltage, frequency, and phase match the grid before closing the breaker.
Correct answer is: Phase‑locked loop (PLL)
Q.67 A ‘combined heat and power’ (CHP) plant primarily improves overall efficiency by:
Generating electricity at a lower voltage
Utilizing waste heat for useful thermal applications
Operating at supercritical pressure
Using renewable fuel sources
Explanation - CHP captures thermal energy that would otherwise be discarded, achieving efficiencies of 70‑80%.
Correct answer is: Utilizing waste heat for useful thermal applications
Q.68 The standard frequency of electricity in most of the world’s power grids is:
50 Hz
60 Hz
55 Hz
65 Hz
Explanation - Europe, Asia, Africa use 50 Hz; North America uses 60 Hz.
Correct answer is: 50 Hz
Q.69 Which type of renewable energy uses the temperature difference between two fluid streams to generate power?
Wind energy
Geothermal energy
Ocean thermal energy conversion (OTEC)
Solar photovoltaic
Explanation - OTEC exploits the temperature gradient between warm surface water and cold deep water to run a heat engine.
Correct answer is: Ocean thermal energy conversion (OTEC)
Q.70 In a coal‑fired power plant, the device that removes sulfur dioxide (SO₂) from flue gases is called:
Selective catalytic reduction (SCR)
Flue‑gas desulfurization (FGD) scrubber
Electrostatic precipitator
Carbon capture unit
Explanation - FGD scrubbers use a lime or limestone slurry to absorb SO₂ from exhaust gases.
Correct answer is: Flue‑gas desulfurization (FGD) scrubber
Q.71 Which factor most directly influences the cut‑out speed of a wind turbine?
Generator rating
Blade length
Maximum allowable rotor speed
Hub height
Explanation - When wind speed causes the rotor to exceed its design speed, the turbine shuts down (cut‑out).
Correct answer is: Maximum allowable rotor speed
Q.72 The term ‘heat‑pump’ in the context of power generation most closely relates to:
A device that converts electrical energy into heat
A system that moves heat from a low‑temperature source to a high‑temperature sink
A turbine that extracts heat from exhaust gases
A solar collector that stores heat
Explanation - Heat pumps use work input to transfer heat against the temperature gradient, similar to refrigeration cycles.
Correct answer is: A system that moves heat from a low‑temperature source to a high‑temperature sink
Q.73 Which of the following best describes the function of a ‘load‑following’ power plant?
Operates continuously at full capacity
Adjusts output to match variations in demand
Provides only emergency power
Runs only during night hours
Explanation - Load‑following plants can ramp output up or down relatively quickly to follow daily load changes.
Correct answer is: Adjusts output to match variations in demand
Q.74 The primary purpose of a ‘transformer tap changer’ is to:
Alter the frequency of the output voltage
Regulate the output voltage level under varying load conditions
Increase the power factor of the system
Convert AC to DC
Explanation - Tap changers adjust transformer turns ratio, maintaining voltage within desired limits.
Correct answer is: Regulate the output voltage level under varying load conditions
Q.75 In power generation, the term ‘firm capacity’ refers to:
The maximum possible output under ideal conditions
The guaranteed minimum output that can be relied upon
The amount of power stored in batteries
The capacity of a plant after accounting for maintenance outages
Explanation - Firm capacity is the portion of installed capacity that is reliably available to the grid.
Correct answer is: The guaranteed minimum output that can be relied upon
Q.76 Which of the following is NOT a typical advantage of using a supercritical coal plant over a subcritical one?
Higher thermal efficiency
Reduced CO₂ emissions per MWh
Lower capital cost
Higher operating pressure
Explanation - Supercritical plants require more advanced materials and higher pressures, increasing capital costs despite efficiency gains.
Correct answer is: Lower capital cost
Q.77 In a power system, ‘frequency response’ is primarily provided by:
Voltage regulators
Inertia of rotating generators
Transformers
Capacitor banks
Explanation - Rotating masses store kinetic energy; when frequency deviates, they help stabilize it by releasing or absorbing energy.
Correct answer is: Inertia of rotating generators
Q.78 Which of the following is a common method for increasing the efficiency of a steam turbine?
Increasing the number of blades
Using reheat stages
Operating at lower pressure
Reducing inlet steam temperature
Explanation - Reheating steam between turbine stages raises average temperature of heat addition, improving efficiency.
Correct answer is: Using reheat stages
Q.79 What is the typical range of the power factor for most industrial loads?
0.2‑0.4
0.5‑0.6
0.8‑0.95
1.0‑1.2
Explanation - Industrial loads usually have lagging power factors between 0.8 and 0.95, requiring correction in some cases.
Correct answer is: 0.8‑0.95
Q.80 The term ‘dispatchable renewable’ most accurately describes:
Solar PV with battery storage
Wind farms with variable output
Hydroelectric plants that can be scheduled
Geothermal plants with constant output
Explanation - When coupled with storage, solar can be controlled and scheduled, making it dispatchable.
Correct answer is: Solar PV with battery storage
Q.81 In a power plant, the term ‘trip’ generally means:
A scheduled maintenance shutdown
An automatic shutdown due to a fault
A temporary increase in output
A change in fuel type
Explanation - A trip is a protective action that disconnects equipment to prevent damage.
Correct answer is: An automatic shutdown due to a fault
Q.82 Which technology enables a solar thermal plant to generate electricity after sunset?
Photovoltaic cells
Molten‑salt thermal storage
Wind turbines
Hydrogen fuel cells
Explanation - Molten‑salt storage retains heat, allowing the steam cycle to operate even without sunlight.
Correct answer is: Molten‑salt thermal storage
Q.83 The main purpose of a ‘de‑aerator’ in a boiler system is to:
Remove dissolved oxygen from feedwater
Increase water temperature
Add chemicals for corrosion control
Reduce steam pressure
Explanation - De‑aerators strip oxygen to prevent corrosion in the boiler and turbine.
Correct answer is: Remove dissolved oxygen from feedwater
Q.84 Which of the following is the most common configuration for a 3‑phase generator connection to the grid?
Delta‑Delta
Wye‑Wye (Star‑Star)
Delta‑Wye (Delta‑Star)
Open‑Delta
Explanation - Wye‑Wye provides a neutral point and is widely used for high‑voltage transmission connections.
Correct answer is: Wye‑Wye (Star‑Star)
Q.85 In power generation, the term ‘black‑coal’ refers to:
A high‑grade, low‑ash coal
Coal that is used for electricity only
The most carbon‑rich type of coal with high energy content
Coal that has been completely burned
Explanation - Black‑coal, also called anthracite, has high carbon and calorific value.
Correct answer is: The most carbon‑rich type of coal with high energy content
Q.86 Which parameter is most directly affected by the ‘blade pitch’ of a wind turbine?
Generator voltage
Turbine rotational speed
Power output
Tower height
Explanation - Adjusting blade pitch changes the aerodynamic angle of attack, directly influencing power capture.
Correct answer is: Power output
Q.87 The term ‘grid inertia’ is decreasing worldwide because:
More renewable generation lacks rotating mass
Older generators are being retired
Transmission lines are being upgraded
Load demand is decreasing
Explanation - Solar PV and wind turbines (especially converter‑based) contribute little mechanical inertia, reducing overall system inertia.
Correct answer is: More renewable generation lacks rotating mass
Q.88 Which of the following best defines ‘heat sink temperature’ in a power cycle?
Temperature of the fuel before combustion
Temperature of the cooling medium that absorbs waste heat
Temperature of the steam entering the turbine
Temperature of the ambient air around the plant
Explanation - The heat sink is the low‑temperature reservoir where rejected heat is discharged.
Correct answer is: Temperature of the cooling medium that absorbs waste heat
Q.89 In a nuclear power plant, the term ‘shutdown margin’ refers to:
The time required to restart the reactor
The amount of reactivity that can be inserted safely after shutdown
The difference between rated and actual power output
The gap between the reactor vessel and the containment
Explanation - Shutdown margin ensures the reactor remains subcritical under all conditions.
Correct answer is: The amount of reactivity that can be inserted safely after shutdown
Q.90 Which of the following is a primary reason for using a ‘cooling tower’ in a power plant?
To increase steam pressure
To remove latent heat from condenser water
To generate electricity directly
To store fuel
Explanation - Cooling towers dissipate waste heat to the atmosphere, cooling water before it returns to the condenser.
Correct answer is: To remove latent heat from condenser water
Q.91 The ‘heat of vaporization’ of water at 100 °C is approximately:
2260 kJ/kg
100 kJ/kg
4180 kJ/kg
540 kJ/kg
Explanation - At the boiling point, water requires about 2260 kJ per kilogram to change phase to steam.
Correct answer is: 2260 kJ/kg
Q.92 In power generation, ‘wet‑scrubbing’ is mainly used to control:
Particulate matter
Nitrogen oxides (NOx)
Sulfur dioxide (SO₂)
Carbon monoxide (CO)
Explanation - Wet scrubbers use a slurry to absorb SO₂ from flue gases.
Correct answer is: Sulfur dioxide (SO₂)
Q.93 Which of the following best describes a ‘grid‑connected inverter’ in a solar PV system?
A device that stores solar energy as heat
A converter that changes DC from panels to AC synchronized with the grid
A transformer that steps up voltage
A battery charger
Explanation - Inverters produce grid‑compatible AC power from the DC output of PV modules.
Correct answer is: A converter that changes DC from panels to AC synchronized with the grid
Q.94 The term ‘thermal rating’ of a transmission line refers to:
Maximum current the line can carry without overheating
Maximum voltage the line can withstand
Length of the line
Number of conductors
Explanation - Thermal rating is limited by conductor temperature rise and ambient conditions.
Correct answer is: Maximum current the line can carry without overheating
Q.95 Which of the following is a characteristic of a ‘run‑of‑river’ hydro plant?
Large storage reservoir
Dependence on natural river flow without major dams
Ability to provide base load power
Use of pumped‑storage
Explanation - Run‑of‑river plants generate power directly from river flow, with minimal storage.
Correct answer is: Dependence on natural river flow without major dams
Q.96 In a power system, ‘N‑1’ contingency criteria means:
The system can tolerate loss of any one component without losing stability
One unit must operate at 100% load
Only one line is used for transmission
One generator provides all the power
Explanation - N‑1 ensures reliability by planning for the failure of any single element.
Correct answer is: The system can tolerate loss of any one component without losing stability
Q.97 Which of the following fuels has the highest energy density (MJ/kg)?
Coal
Natural gas
Uranium‑235
Hydrogen
Explanation - U‑235 releases about 80,000,000 MJ/kg through fission, far exceeding chemical fuels.
Correct answer is: Uranium‑235
Q.98 The purpose of a ‘static VAR compensator’ (SVC) in a power system is to:
Store energy for later use
Provide fast‑acting reactive power compensation
Convert AC to DC
Increase transmission line capacity
Explanation - SVCs use thyristors to inject or absorb reactive power, helping regulate voltage.
Correct answer is: Provide fast‑acting reactive power compensation
Q.99 In a combined‑cycle plant, the overall thermal efficiency can reach up to:
35‑40%
45‑50%
55‑60%
60‑65%
Explanation - By utilizing waste heat from the gas turbine, combined‑cycle plants can achieve efficiencies above 60%.
Correct answer is: 60‑65%
Q.100 Which of the following statements about ‘distributed generation’ (DG) is correct?
DG always reduces transmission losses.
DG is typically located close to the point of consumption.
DG cannot be renewable.
DG requires large-scale power plants.
Explanation - Distributed generation is small‑scale, often on‑site, reducing the need for long transmission lines.
Correct answer is: DG is typically located close to the point of consumption.
Q.101 The term ‘heat‑pump coefficient of performance’ (COP) is defined as:
Output heat divided by input electrical energy
Input electrical energy divided by output heat
Output electricity divided by input fuel
Ratio of turbine speed to generator speed
Explanation - COP > 1 indicates that more heat is moved than the electrical work supplied.
Correct answer is: Output heat divided by input electrical energy
Q.102 Which of the following is a typical feature of a ‘binary cycle’ geothermal plant?
Direct use of steam to drive a turbine
Use of a secondary working fluid with a lower boiling point
Requirement of high‑temperature (>300 °C) resources
Integration with solar PV
Explanation - Binary cycles employ fluids like isobutane to extract energy from lower‑temperature geothermal fluids.
Correct answer is: Use of a secondary working fluid with a lower boiling point
Q.103 In a power system, the term ‘load shedding’ is used to describe:
Increasing generation to meet demand
Intentionally disconnecting some loads to prevent system collapse
Upgrading transmission lines
Installing new generators
Explanation - Load shedding is a last‑resort measure to balance supply and demand and avoid blackouts.
Correct answer is: Intentionally disconnecting some loads to prevent system collapse
Q.104 Which type of turbine is best suited for very high head (over 300 m) hydro sites?
Kaplan turbine
Francis turbine
Pelton turbine
Cross‑flow turbine
Explanation - Pelton turbines use impulse jets and are efficient for high‑head, low‑flow conditions.
Correct answer is: Pelton turbine
Q.105 The term ‘capacity credit’ of a renewable generator refers to:
Its maximum instantaneous power output
The portion of its capacity counted as reliable for planning purposes
The total energy it produces annually
The amount of storage attached to it
Explanation - Capacity credit accounts for the statistical availability of renewables when assessing system reliability.
Correct answer is: The portion of its capacity counted as reliable for planning purposes
Q.106 In a power plant’s balance‑of‑plant (BOP), which component is primarily responsible for fuel handling and preparation?
Condenser
Boiler feedwater system
Fuel handling system
Control room
Explanation - The BOP includes systems for receiving, storing, and feeding fuel to the boiler or reactor.
Correct answer is: Fuel handling system
Q.107 Which of the following is the most common method for measuring the output power of a generator?
Voltmeter only
Wattmeter
Ammeter only
Thermocouple
Explanation - A wattmeter measures real power (P = V × I × cos φ) directly.
Correct answer is: Wattmeter
Q.108 What does the abbreviation ‘MW‑e’ stand for in power generation?
Megawatt‑electric
Megawatt‑thermal
Megawatt‑energy
Megawatt‑efficiency
Explanation - MW‑e denotes the electric power output, as opposed to MW‑th which denotes thermal input.
Correct answer is: Megawatt‑electric
Q.109 Which of the following is a key advantage of using a ‘heat‑integrated’ design in a combined‑cycle plant?
Reduced water consumption
Higher steam pressure only
Elimination of the gas turbine
Simplified control system
Explanation - Heat integration recovers waste heat for multiple purposes, lowering overall water use and improving efficiency.
Correct answer is: Reduced water consumption
Q.110 In power system protection, the device that measures current and trips a breaker when it exceeds a set value is called:
Voltage regulator
Current transformer
Over‑current relay
Power factor controller
Explanation - Over‑current relays detect excessive currents and initiate breaker operation to isolate faults.
Correct answer is: Over‑current relay
Q.111 Which of the following is a primary environmental concern associated with large hydroelectric dams?
Radioactive waste
Air pollution
Displacement of communities and ecosystem impacts
Acid rain
Explanation - Dams flood large areas, affecting habitats and often requiring relocation of people.
Correct answer is: Displacement of communities and ecosystem impacts
Q.112 The term ‘heat rate’ of a power plant is expressed in:
kW/MW
Btu/kWh
kg/MW
V·A
Explanation - Heat rate quantifies the amount of fuel energy needed to produce one kilowatt‑hour of electricity.
Correct answer is: Btu/kWh
Q.113 Which of the following best describes the function of a ‘load bank’ used in power plant testing?
Store excess energy
Simulate electrical loads for performance testing
Regulate voltage
Convert AC to DC
Explanation - Load banks provide a controllable, resistive load to test generators under realistic conditions.
Correct answer is: Simulate electrical loads for performance testing
Q.114 In a power plant, the term ‘trip zone’ for a protective relay refers to:
The range of temperatures for safe operation
The time‑current characteristic where the relay will trip
The physical location of the relay
The voltage level at which the relay operates
Explanation - Trip zones define the relationship between fault magnitude and the time before the relay operates.
Correct answer is: The time‑current characteristic where the relay will trip
Q.115 Which of the following is the most common fuel for modern natural‑gas combined‑cycle plants?
Liquefied natural gas (LNG)
Compressed natural gas (CNG)
Methane (CH₄)
Propane (C₃H₈)
Explanation - Methane is the primary component of natural gas used in CCGT plants.
Correct answer is: Methane (CH₄)
Q.116 The primary purpose of a ‘draft tube’ in a hydro turbine is to:
Increase water pressure before the runner
Recover kinetic energy from the water exiting the runner
Regulate turbine speed
Provide a path for steam
Explanation - Draft tubes convert kinetic energy to pressure, improving turbine efficiency.
Correct answer is: Recover kinetic energy from the water exiting the runner
Q.117 Which of the following devices is used to control the voltage on a high‑voltage transmission line?
Phase shifter
Series capacitor
Shunt reactor
Transformer tap changer
Explanation - Shunt reactors absorb reactive power, helping to maintain voltage levels on long lines.
Correct answer is: Shunt reactor
Q.118 In the context of power generation, the abbreviation ‘IPPU’ stands for:
Industrial Power Production Unit
International Power Plant Union
Industry, Process and Product Use
Integrated Power Plant Utility
Explanation - IPPU refers to energy consumption in industrial processes, not directly to electricity generation, but is a key sector in overall energy analysis.
Correct answer is: Industry, Process and Product Use
Q.119 Which of the following is the main advantage of using a ‘direct‑drive’ wind turbine over a gearbox‑driven one?
Higher rotational speed
Reduced mechanical losses and maintenance
Lower initial cost
Ability to operate in lower wind speeds
Explanation - Direct‑drive eliminates the gearbox, decreasing wear and increasing reliability.
Correct answer is: Reduced mechanical losses and maintenance
Q.120 The term ‘energy return on investment’ (EROI) for a power source is defined as:
Total energy output divided by total energy input over the system’s lifetime
Cost of the plant divided by its capacity
Capacity factor multiplied by efficiency
Peak power output divided by average demand
Explanation - EROI assesses how much usable energy a system provides compared to the energy invested to build and operate it.
Correct answer is: Total energy output divided by total energy input over the system’s lifetime
Q.121 Which of the following is a typical characteristic of a ‘solid‑oxide fuel cell’ (SOFC) used for power generation?
Operates at low temperature (below 200 °C)
Uses molten salt as electrolyte
Requires a high operating temperature (800‑1000 °C)
Produces only DC power without conversion
Explanation - SOFCs operate at high temperatures, enabling internal reforming and high efficiency.
Correct answer is: Requires a high operating temperature (800‑1000 °C)
Q.122 In a nuclear plant, the component that slows down neutrons is called a:
Control rod
Moderator
Coolant
Reflector
Explanation - The moderator reduces neutron kinetic energy, increasing the probability of fission.
Correct answer is: Moderator
Q.123 Which of the following is the primary reason for using a ‘cooling tower’ with a wet‑type system instead of a dry‑type system?
Lower water consumption
Higher heat rejection efficiency
Smaller footprint
Reduced visual impact
Explanation - Wet cooling towers use evaporation, achieving higher heat removal rates than dry (air‑cooled) systems.
Correct answer is: Higher heat rejection efficiency
Q.124 In a power plant, the term ‘auxiliary power’ refers to:
Power supplied to the grid
Power used by the plant’s own equipment
Power purchased from external sources
Power generated by renewable sources only
Explanation - Auxiliary power supports pumps, fans, controls, etc., and is typically a small fraction of gross output.
Correct answer is: Power used by the plant’s own equipment
Q.125 The typical range of the steam temperature at the inlet of a modern supercritical boiler is:
250‑300 °C
350‑380 °C
540‑600 °C
650‑700 °C
Explanation - Supercritical boilers operate at temperatures above 540 °C to achieve higher efficiencies.
Correct answer is: 540‑600 °C
Q.126 Which of the following is the most common method for controlling the output frequency of a power system?
Adjusting transformer tap settings
Changing the speed of synchronous generators via governor control
Modifying transmission line length
Altering the capacitance of shunt reactors
Explanation - Governor systems adjust turbine valve positions, altering generator speed and thus system frequency.
Correct answer is: Changing the speed of synchronous generators via governor control
Q.127 In power generation, the term ‘heat exchanger effectiveness’ is defined as:
Actual heat transfer divided by the maximum possible heat transfer
Temperature difference between hot and cold streams
Ratio of inlet to outlet temperatures
Heat capacity rate of the hot fluid
Explanation - Effectiveness quantifies how closely a heat exchanger approaches its ideal performance.
Correct answer is: Actual heat transfer divided by the maximum possible heat transfer
Q.128 Which of the following is a typical operating pressure for a subcritical coal‑fired boiler?
5 MPa
10 MPa
15 MPa
25 MPa
Explanation - Subcritical boilers operate below the critical point (≈22 MPa), commonly around 5‑10 MPa.
Correct answer is: 5 MPa
Q.129 What is the main purpose of a ‘boiler feedwater pump’ in a thermal power plant?
To increase steam pressure
To circulate water through the condenser
To supply high‑pressure water to the boiler
To cool the turbine
Explanation - Feedwater pumps raise the pressure of condensate so it can enter the boiler for steam generation.
Correct answer is: To supply high‑pressure water to the boiler
Q.130 The term ‘distributed generation’ (DG) includes which of the following technologies?
Large coal‑fired power stations
Utility‑scale nuclear reactors
On‑site rooftop solar PV systems
Intercontinental HVDC links
Explanation - DG refers to small, often renewable generators located close to the load, like rooftop solar.
Correct answer is: On‑site rooftop solar PV systems
Q.131 Which of the following best explains why wind turbines are equipped with a yaw system?
To adjust blade pitch
To rotate the nacelle so the rotor faces the wind direction
To increase generator voltage
To control turbine speed
Explanation - Yaw systems turn the turbine to align with prevailing wind direction for optimal energy capture.
Correct answer is: To rotate the nacelle so the rotor faces the wind direction
Q.132 In a power plant, the ‘dead‑leg’ of a pipe refers to:
A pipe segment with no flow
A pipe that connects directly to the turbine
A pipe used for fuel supply
A pipe that carries exhaust gases
Explanation - A dead‑leg is a section of piping that is isolated from flow, often used for maintenance or instrumentation.
Correct answer is: A pipe segment with no flow
Q.133 Which of the following is a key benefit of using a ‘high‑temperature superconductor’ (HTS) in generator windings?
Operation at room temperature
Higher current density, reducing size and weight
Elimination of the need for a cooling system
Increased magnetic hysteresis losses
Explanation - HTS windings can carry much higher currents, allowing more compact generator designs.
Correct answer is: Higher current density, reducing size and weight
Q.134 The primary function of a ‘gas‑oil separator’ in a power plant is to:
Separate oil from steam in the turbine
Remove dissolved gases from boiler feedwater
Extract oil droplets from exhaust gases
Separate natural gas from liquid fuels
Explanation - Gas‑oil separators (deaerators) remove dissolved gases (especially oxygen) to protect boiler equipment.
Correct answer is: Remove dissolved gases from boiler feedwater
Q.135 Which of the following devices is typically used to limit the inrush current when a transformer is energized?
Surge arrester
Inrush current limiter (ICL)
Capacitor bank
Load tap changer
Explanation - ICLs (often resistors or reactors) reduce the initial surge current during transformer energization.
Correct answer is: Inrush current limiter (ICL)
Q.136 In a power system, the term ‘harmonic distortion’ refers to:
Variations in voltage magnitude
Presence of frequency components that are integer multiples of the fundamental frequency
Fluctuations in load demand
Changes in line impedance
Explanation - Harmonics are undesired frequencies (2nd, 3rd, etc.) that can affect equipment performance.
Correct answer is: Presence of frequency components that are integer multiples of the fundamental frequency
Q.137 Which of the following is the most common method for de‑aerating boiler feedwater?
Mechanical filtration
Thermal distillation
Vacuum deaeration using a deaerator
Electrolysis
Explanation - Deaerators remove dissolved gases by heating water and reducing pressure.
Correct answer is: Vacuum deaeration using a deaerator
Q.138 In a power plant, the term ‘gross output’ refers to:
Electricity sold to the grid
Total electricity generated before subtracting auxiliary consumption
Power generated by renewable sources only
Maximum possible generation under ideal conditions
Explanation - Gross output includes all electricity produced; net output is after accounting for plant’s own use.
Correct answer is: Total electricity generated before subtracting auxiliary consumption
Q.139 Which of the following is a typical use for excess heat from a combined‑heat‑and‑power (CHP) plant?
Space heating for residential districts
Powering electric vehicles directly
Cooling data centers
Generating hydrogen via electrolysis
Explanation - CHP captures waste heat for district heating, improving overall energy utilization.
Correct answer is: Space heating for residential districts
Q.140 The abbreviation ‘MW‑th’ in power plant specifications stands for:
Megawatt‑thermal
Megawatt‑hydro
Megawatt‑high temperature
Megawatt‑total
Explanation - MW‑th denotes the thermal input power (heat) supplied to the plant, as opposed to electrical output.
Correct answer is: Megawatt‑thermal
Q.141 Which of the following is the primary function of a ‘filter press’ in a coal‑fired power plant’s water treatment system?
Remove suspended solids from boiler feedwater
Compress steam for turbine inlet
Increase water temperature
Control pH of cooling water
Explanation - Filter presses dewater sludge and help produce clean feedwater for the boiler.
Correct answer is: Remove suspended solids from boiler feedwater
Q.142 In a wind turbine, the ‘cut‑in wind speed’ is typically around:
1‑2 m/s
3‑5 m/s
8‑10 m/s
15‑20 m/s
Explanation - Below this speed the turbine cannot generate enough power to overcome its own losses.
Correct answer is: 3‑5 m/s
Q.143 Which of the following is a key advantage of using a ‘thermal energy storage’ system in a solar‑thermal plant?
Higher solar panel efficiency
Ability to generate electricity after sunset
Reduced need for mirrors
Elimination of water cooling
Explanation - Thermal storage retains heat, enabling power generation when sunlight is unavailable.
Correct answer is: Ability to generate electricity after sunset