Here are 1000 MCQs on Power System (Chapterwise).
1. Single line diagram of which of the following power system is possible?
a) Power system with LG fault
b) Balanced power system
c) Power system with LL fault
d) Power system with LLG fault
View Answer
Explanation: Only balanced power system can be represented by a single line diagram. Single line diagram is drawn on per phase basis. A power system with LLG, LG and LL faults becomes unbalanced and can not be represented in per phase basis.
2. A power system will have greater flexibility of operation if they have __________
a) Only Base load plants operating in combination
b) Various types of power plants operating in combination
c) Only Peak load plants operating in combination
d) Only thermal power plants operating in combination
View Answer
Explanation: If various types of power plants are operated in combination, the system will become more flexible i.e Steam and Nuclear power plants will supply base loads, Hydroelectric power plants will supply base or peak loads depending upon the availability of water, Gas turbine power plant will meet peak load demand and existing Diesel power plant will operate in emergency only.
3. Single line diagram does not represents:
a) Ratings of machines
b) Neutral wire of transmission lines
c) Delta connection of transformer winding
d) Star connection of transformer winding
View Answer
Explanation: Single line diagram is a representation of balanced power system on per phase basis with neutral eliminated. Neutral wire is not shown in single line diagram. Winding connections (star or neutral) is represented beside the symbol of transformer with its Impidance and rating.
4. In impedance diagram different power system elements are represented by symbols.
a) False
b) True
View Answer
Explanation: In reactance diagram different power system elements are represented by their symmetrical networks.
5. In combined operation of several power plants the reserve capacity requirement is reduced.
a) False
b) True
View Answer
Explanation: In any electric power system the system has to have a certain reserve capacity in order to meet any unforeseen excess power demand. In combined system the effect of all the diversity is may result in still larger benefit from the point of view of Reserve capacity.
6. For a given power system, its zero and maximum regulation will occur at the impedance angle of
a) 45
b) 60
c) 35
d) 50
View Answer
Explanation: At θ=45°, ZVR and maximum VR coincide.
7. A 200 bus power system has 160 PQ bus. For achieving a load flow solution by N-R in polar coordinates, the minimum number of simultaneous equation to be solved is ___________
a) 359
b) 334
c) 357
d) 345
View Answer
Explanation: Total buses = 200
PQ buses = 160
PV buses = 200-160 = 40
Slack bus = 1
Total number of equation = (40-1)*1 + (160*2) = 359.
8. A 50 bus power system Ybus has 80% sparsity. The total number of transmission lines will be ___________
a) 225
b) 563
c) 345
d) 456
View Answer
Explanation: Number of non zero elements = 50*50*20/100 = 500 non zero
Number of TL = (500-50)/2 = 225 transmission lines.
9. The given graph is the depiction of ________ on a large power system network.
a) Three phase motor getting short
b) L-G fault
c) Ratings of machines
d) Any of the mentioned
View Answer
Explanation: A LG fault will create a sudden dip in the voltage profile and it will be recovered.
10. A protection system engineer is planning to provide the complete protection, he can achieve this by ___________
a) a two phase fault relays and three earth fault relays
b) a two phase fault relays and two earth fault relays
c) two phase fault relays and three earth fault relays
d) three phase fault relays and two earth fault relays
View Answer
Explanation: For the complete protection of the power system, one can use 3 phase fault relays and two earth fault relays so that to cover the entire zone of operation.
11. A power system has a maximum load of 15 MW. Annual load factor is 50%. The reserve capacity of plant is _____ if the plant capacity factor is 40%.
a) 3.75 MW
b) 7.75 MW
c) 46.75 MW
d) 8.75 MW
View Answer
Explanation: LF = (Average Demand)/(Maximum Demand)=0.5
Plant capacity factor =(Average Load)/(Plant Capacity)= 0.5/0.4
Plant capacity= (0.5/0.4)*15 = 18.75 MW
Reserve Capacity = 18.75-15 = 3.75 MW.
12. The area under the load curve represents ____________
a) maximum demand
b) load factor
c) the average load on power system
d) number of units generated
View Answer
Explanation: Load curve is obtained by plotting fluctuating load be keeping load on y axis and time in x axis. The area under the load curve represents the total number of units generated in a particular time.
13. If all the sequence voltages at the fault point in a power system are equal, then fault is __________
a) LLG fault
b) Line to Line fault
c) Three phase to ground fault
d) LG fault
View Answer
Explanation: It is LLG fault.
14. If the power system network is at Vs∠δ and receiving end voltage is Vr∠0 consisting of the impedance of TL as (R+j5)Ω. For maximum power transfer to the load, the most appropriate value of resistance R should be __________
a) 1.732
b) 3.45
c) 5.2
d) 0.33
View Answer
Explanation: For maximum power transfer, X=√3 R
3=√3 R
R=√3.
15. Voltage regulation in the power system is __________
a) dip in voltage at sending end
b) rise in voltage at sending end
c) rise in voltage at receiving end
d) dip in voltage at receiving end
View Answer
Explanation: VR is rise in voltage at receiving end for a transmission line.
16. Which of the following is not neglected during formation of reactance diagram from impedance diagram?
a) Shunt component of Transformers
b) Static loads
c) Resistance of various power system components
d) Reactance of alternators
View Answer
Explanation: Reactance diagram is drawn by the help of symmetrical network of various power system components by neglecting resistance of various components, static loads like induction motors and shunt component of Transformers.
17. Which of the following is not a requirement for site selection of hydroelectric power plant?
a) Large catchment area
b) Rocky land
c) Sedimentation
d) Availability of water
View Answer
Explanation: Sedimentation may reduce the water storage capacity of reservoir and may also cause damage to the turbine blades. Availability of water, large catchment area and rocky land are primary requirements for site selection of hydroelectric power plant.
18. Which of the following is not an advantage of hydroelectric power plant?
a) no fuel requirement
b) continuous power source
c) low running cost
d) no standby losses
View Answer
Explanation: Output of such plants is never constant. This is because of their dependency over flow rate of water in river which is seasonal. No fuel requirement low running cost and no standby losses are advantages of hydroelectric power plants.
19. Which of the following element of hydroelectric power plant prevents the penstock from water hammer phenomenon?
a) Surge Tank
b) Draft tubes
c) Spillway
d) Valves and Gates
View Answer
Explanation: Sudden increase in water pressure in penstock due to closing of gates is called water hammer. Surge tank is a tank at sufficient height , connected to penstock through riser pipe. It takes the rejected water and relives the penstock from excessive water hammer pressure.
20. Which of the following part of thermal power plant causes maximum energy losses?
a) Alternator
b) Ash and unburnt carbon
c) Boiler
d) Condenser
View Answer
Explanation: About 54% of energy losses occurs in condenser. Losses in boiler and alternator are about 1% and 16% because of such high losses overall efficiency of thermal power plant reduces to 29% for normal old thermal power plant and 50% for modern super critical pressure steam power plant which employs many heat saving devices.
21. Which of the following are the most widely used condensers in modern thermal power plants?
a) Low level counter flow type jet condenser
b) Parallel flow type jet condenser
c) High level counter flow type jet condenser
d) Surface condensers
View Answer
Explanation: Power plants mostly use surface condensers because from these condensers condensate can be used as feed water requiring less pumping power. In case of jet condensers exhaust steam mixes with the cooling water hence condenses and cooling water are mixed so condensing cannot be recovered for the use of feed water.
22. Which of the following is most suitable fuel for thermal power plant?
a) Bituminous coal
b) Lignite coal
c) Anthracite coal
d) Peat coal
View Answer
Explanation: Peat and lignite coals have low calorific value and high ash content. Anthracite coals are found in small quantities and are therefore costlier for power generation. Bituminous coals have enough calorific value, low moisture and ash content so most suitable for power generation.
23. Which of the following is most advantageous and most widely method of solid fuel firing?
a) Spreader stoker firing
b) Pulverised fuel firing
c) Underfeed firing
d) Stoker firing
View Answer
Explanation: The advantages of using pulverised fuel outweigh the disadvantages and all the modern power plants uses pulverised fuel firing method. In pulverised fuel firing better combustion is achieved. Pulverization is a means of exposing a large surface area to the action of oxygen and consequently helping the combustion.
24. Which of the following method is used in large modern thermal power plants to heat feed water?
a) Open type heatre is used
b) Surface type heater is used
c) Close type heater is used
d) Steam is directly taken from main turbine and used to heat it feed water
View Answer
Explanation: Open and contact type haters are in small power plants. Such heaters recives steam from back pressure turbine. In large modern power plants heaters bleed steam from the main turbine and use it for heating of feed water.
25. Which of the following pollutant causes acid rain?
a) NO2
b) SO2
c) CO2
d) NO
View Answer
Explanation: The Sulphur Dioxide emitted by thermal power plant gradually oxides to sulphur trioxide under the influence of Sunlight. This in turn interact with atmospheric moisture and forms sulphuric acid. This sulphuric acid later causes acid rain.
26. What of the below mentioned statements are incorrect as compared to the HVDC system?
a) Distance limitation
b) Back to back connection is possible
c) Extra reactive power compensation
d) More corona losses
View Answer
Explanation: Out of all the corona losses are less in HVDC system.
27. When the ozone gas is produced as a by product of corona, that causes _______
a) increase of power factor
b) corrosion of wires
c) improvement of regulation
d) reduction of power factor
View Answer
Explanation: Ozone gas corrodes the metals.
28. Which component of gas turbine power plant is main cause of its low efficiency?
a) Compressor
b) Starting motor
c) Gas turbine
d) Combustion chamber
View Answer
Explanation: The overall efficiency of gas turbine is low, because a greater part of power developed by the turbine (about 65%) is used in driving the compressor.
29. Which of the following power plants can be profitably employed for supplying base loads as well as peak loads?
a) Diesel power plant
b) Hydroelectric power plant
c) Thermal power plant
d) Nuclear power plant
View Answer
Explanation: Seam and Nuclear power plants are only used to supply base load. Diesel power plants are suitable for only peak load. Only hydroelectric power plant can supply both peak load as well as base load because of its flexibility in operation and low operating cost.
30. Which of the following is an essential requirement for a peak load plant?
a) Economical and speedy repair
b) Capability of working continuously
c) Low operating cost
d) Capability of quick start
View Answer
Explanation: The power plants to be employed as peak load plant should only have the capability of quick start, synchronization and taking up of system load and quick response to load variations.
31. Which of the following pollutants emitted by thermal power plant causes irritation in Eyes?
a) Oxides of sulphur
b) Oxides of Nitrogen
c) Oxides of Mercury
d) Oxides of carbon
View Answer
Explanation: At high temperatures existing in the flame core of high power boilers, the nitrogen of fuel and air may partially be oxidised to form nitrogen oxides. These are toxic and produce a sharp irritating effect especially on the mucous membrane of the eye.
Chapterwise Multiple Choice Questions on Power System
- Hydroelectric Power Plants
- Steam Power Plants
- Nuclear Power Plants
- Diesel Electric & Gas Turbine Power Plants
- Non-Conventional Methods of Power Generation
- Mechanical Design of Overhead Lines, Tariffs and Power Factor Improvement
- Economic Operation of Power Plants
- Combined Operation of Power Plants
- Environmental Aspects of Electric Energy Generation, Cogeneration and Energy Conservation
- Interconnected Systems
- Power Plant Economics
- Inductance and Resistance of Transmission Lines
- Capacitance of Transmission Lines
- Representation of Power System Components
- Characteristics and Performance of Power Transmission Lines
- Load Flow Studies, Optimal System Operation, Automatic Generation and Voltage Control
- Symmetrical Fault Analysis
- Symmetrical Components
- Unsymmetrical Fault Analysis
- Power System Stability
- Compensation in Power Systems
- Voltage Stability
- Distribution Systems
- Underground Cables & Insulators
- Switchgear and Protection
1. MCQ on Hydroelectric Power Plants
The section contains Power System multiple choice questions and answers on hydroelectric power plant basics and elements, water turbines and hydroelectric power plant classification.
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2. Steam Power Plants Multiple Choice Questions
The section contains Power System questions and answers on steam power plant efficiency and constituents, steam turbines, fuels, feed water, fuel combustion and combustion equipments.
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3. Nuclear Power Plants MCQ
The section contains Power System MCQs on nuclear power plant basics, nuclear reaction, nuclear reactor main parts and its functions, nuclear reactors, nuclear fuels and power reactors use.
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4. Diesel Electric & Gas Turbine Power Plants Multiple Choice Questions
The section contains Power System multiple choice questions and answers on gas turbine power plants, tariffs types and diesel electric power plants.
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5. Power System MCQ on Non-Conventional Methods of Power Generation
The section contains Power System questions and answers on magneto hydrodynamic and thermoelectric power generation, thermionic converter, photovoltaic cells, fuel cells, solar power generation, wind and tidal power generation, geothermal power generation, ocean thermal energy and biomass.
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6. Power System Multiple Choice Questions on Mechanical Design of Overhead Lines, Tariffs and Power Factor Improvement
The section contains Power System MCQs on conductor materials, sag, tension, vibrations and dampers, power factor improvement, line support, conductor configuration, spacing and clearances.
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7. MCQ on Economic Operation of Power Plants
The section contains Power System multiple choice questions and answers on loads distribution between generating units in power plant, economic load neglecting transmission losses, coordination equations, optimal unit commitment using dynamic programming method and optimum economic operations.
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8. Multiple Choice Questions on Combined Operation of Power Plants
The section contains Power System questions and answers on signal transduction molecular mechanisms, gated ion channels, interconnected hydroelectric stations, hydro plant and steam power plant operations.
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9. Power System MCQ on Environmental Aspects of Electric Energy Generation, Cogeneration and Energy Conservation
The section contains Power System MCQs on air pollution, aquatic impacts, greenhouse effects, global warming, cogeneration technology and energy conservation.
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10. Power System Multiple Choice Questions on Interconnected Systems
The section contains Power System multiple choice questions and answers on alternators parallel operations, synchronous machines on infinite bus bars, interconnected power station, load frequency control, load dispatching, voltage and reactive power control.
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11. Power Plant Economics MCQ
The section contains Power System questions and answers on power plants cost analysis, power generation economics, depreciation determination methods, units generation and load forecasting.
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12. Power System Multiple Choice Questions on Inductance and Resistance of Transmission Lines
The section contains Power System MCQs on isolated current carrying conductor linkages, single phase two wire line inductance, composite conductor lines inductance, parallel circuit three phase lines, bundled conductors, skin and proximity effects.
13. Power System MCQ on Capacitance of Transmission Lines
The section contains Power System multiple choice questions and answers on electric field, straight conductor potential, earth effect on three phase transmission, two wire lines capacitance, geometric mean distance and radius.
14. Power System Multiple Choice Questions on Representation of Power System Components
The section contains Power System questions and answers on synchronous machine excitation effects, one line or reactance diagrams, per unit system, complex power, synchronous machine circuit model and loads equivalent representation in transmission lines.
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15. Power System MCQ on Characteristics and Performance of Power Transmission Lines
The section contains Power System MCQs on short transmission line, medium and long transmission lines, ferranti effects, voltage control methods and transmission lines compensation.
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16. Power System MCQ on Load Flow Studies, Optimal System Operation, Automatic Generation and Voltage Control
The section contains Power System multiple choice questions and answers on ybus formation, gauss seidel method, newton raphson method, voltage control, generators optimal operation, load frequency and economic dispatch control.
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17. Power System Multiple Choice Questions on on Symmetrical Fault Analysis
The section contains Power System questions and answers on synchronous machine short circuit, transmission line transients, circuit breakers selection and z bus formulation.
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18. Power System Multiple Choice Questions on Symmetrical Components
The section contains Power System MCQs on symmetrical component transformation, star delta transformers, sequence impedances of transmission lines, power system network, synchronous machine networks and sequence networks construction.
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19. Power System MCQ on Unsymmetrical Fault Analysis
The section contains Power System multiple choice questions and answers on faults comparision in three phase system, symmetrical component analysis, single line ot ground fault, line to line fault, double line to ground fault, open conductor faults and bus impedance matrix method.
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20. Multiple Choice Questions on Power System Stability
The section contains Power System questions and answers on rotor dynamics, swing and power angle equations, stability equal area criterion, transient and multi machine stability.
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21. MCQ on Compensation in Power Systems
The section contains Power System MCQs on line compensation, loading capability, load and series compensation, shunt compensators, statcom and svc comparison, facts, facts controllers, converters principles and operations.
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22. Power System Multiple Choice Questions on Voltage Stability
The section contains Power System multiple choice questions and answers on angle and voltage stability comparison, reactive power flow, voltage stability problem mathematical formulation, travelling waves and corona.
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23. Power System MCQ on Distribution Systems
The section contains Power System questions and answers on distribution systems.
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24. Power System Multiple Choice Questions on Underground Cables & Insulators
The section contains Power System MCQs on underground cables and overhead lines insulators.
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25. Power System MCQ on Switchgear and Protection
The section contains Power System multiple choice questions and answers on switchgear and protection.
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Wish you the best in your endeavor to learn and master Power Systems!
