Power Systems Questions and Answers Part-1

1. Which of the following is the correct equation for the electrical power generated by the hydroelectric power plant?
a) 75×0.736 wQHη Watt
b) (7.5/0.736) × wQHη Watt
c) 0.845 ×wQHη Watt
d) 9.81 ×wQHη

Answer: c
Explanation: Rating of any power plant is expressed by its maximum output power. These are large quantities so rating is given in mega watts.The electrical power generated by this plant is proportional to specific weight of water(w), water head(H), generation efficiency(η), flow rate of water(Q) and acceleration due to gravity.

2. Which of the following is not a requirement for site selection of hydroelectric power plant?
a) Availability of water
b) Large catchment area
c) Rocky land
d) Sedimentation

Answer: d
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.

3. The amount of electrical energy that can be generated by a hydroelectric power plant depends upon ___________
a) Head of water
b) Quantity of water
c) Specific weight of water
d) Efficiency of Alternator

Answer: b
Explanation: Potential energy of large quantity of stored water is used by hydroelectric power plant to generate electrical energy. Head of water is important to get kinetic energy from that potential energy. Efficiency of alternator represents that what percentage of input mechanical power it can convert into electrical power.

4. Potential energy of water is used to drive the turbine.
a) True
b) False

Answer: b
Explanation: When water falls, potential energy of water is converted into kinetic energy. This kinetic energy is used to drive the turbine.

5. Hydroelectric power plant is __________
a) Non-renewable source of energy
b) Conventional source of energy
c) Non-conventional source of energy
d) Continuous source of energy

Answer: b
Explanation: Hydroelectric power plants are conventional source of energy. About 16.6% of total electricity and about 70% of total renewable energy of world is provided by hydroelectric power plants. They are not Non-renewable because water is inexhaustible. It is not continuous source of energy because its output fluctuates with change in flow rate of water with season.

6. Hydroelectric power plant is generally located near load centre.
a) True
b) False

Answer: b
Explanation: Hydroelectric power plants are generally constructed in hilly areas. These power plants are quite away from the load centre.

7. Hydroelectric power plant is mainly located in ____________
a) Flat areas
b) Deserts
c) Hilly areas
d) Deltas

Answer: c
Explanation: In order to get sufficient head, hydroelectric power plants are constructed in hilly areas. In desert and flat areas sufficient water head cannot be obtained. Deltas are not suitable for this because of high sedimentation.

8. Which statement about hydroelectric power plant is wrong?
a) Efficiency of hydroelectric power plant does not reduce with age
b) Its construction coast is very high and takes a long time for erection.
c) It is very neat and clean plant because no smoke or ash is produced.
d) Meeting rapidly changing load demands is not possible in hydroelectric power plant.

Answer: d
Explanation: Fluctuating load demands can be met just by controlling the flow of water using valves and gates. Due to its robust construction, its efficiency does not fall with time. Statement ‘b’ is correct because construction of dam, installation of alternator and turbines are very costly.

9. Which of the following is not an advantage of hydroelectric power plant?
a) no fuel requirement
b) low running cost
c) continuous power source
d) no standby losses

Answer: c
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.

10. Which of the following statement is true about hydroelectric power plant?
a) Hydroelectric power plants are multipurpose.
b) Due to non-uniform flow of water frequency control in such plants is very difficult.
c) Hydroelectric power plant has high running cost
d) Water is used as fuel in hydroelectric power plant

Answer: a
Explanation: It is because in addition to generation of electricity they are also used for irrigation, flood control etc. Frequency control in such plants is done easily just by controlling flow of water to the turbine through valves and gates. Due to low maintenance cost and no fuel requirement running cost of a plant is very low. Water is not fuel.