250+ TOP MCQs on Merits of Combined Operation of Power Plants and Answers

Power Systems Multiple Choice Questions on “Merits of Combined Operation of Power Plants”.

1. Which of the following power plant are put on load for maximum time?
A. Plant with minimum operating cost
B. Plant with medium operating cost
C. Plant with maximum operating cost
D. Operating cost does not matter
Answer: A
Clarification: The power plants with minimum operating cost are put on load for maximum time. Plants with medium operating cost are only loaded when required by the load demand on the system. Plants with maximum operating cost are kept in reserve and would operate only in emergency.

2. Which of the following power plants can be profitably employed for supplying base loads as well as peak loads?
A. Thermal power plant
B. Nuclear power plant
C. Hydroelectric power plant
D. Diesel power plant
Answer: C
Clarification: 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.

3. Plants with higher operating cost and greater flexibility are suitable for?
A. Only Base load
B. Only Peak load
C. Base and Peak loads
D. Plants with higher operating cost are not used
Answer: B
Clarification: Plants which can meet sudden variation of load demand are said to have higher flexibility. Plants with higher operating cost can’t be used as base load plants. Plants with such capabilities are most suitable for peak load plants as they can respond immediately.

4. Plants with maximum operating costs are put on load for :
A. Maximum time
B. During peak load
C. Emergency conditions
D. During Medium loads
Answer: C
Clarification: Power plants with minimum operating cost are put on load for maximum time. Plants with medium operating cost are only loaded when required by the load demand on the system. Plants with maximum operating cost are kept in reserve and would operate only in emergency.

5. Gas turbine power plants are most suitable for which of the following loads?
A. Only Base load
B. Only Peak load
C. Base and Peak loads
D. Gas turbine power plants are not practical
Answer: B
Clarification: Gas turbine power plants have advantage of low initial cost and low startup time. So, it is ideally suited for supplying peak loads.

6. A power system will have greater flexibility of operation if they have __________
A. Various types of power plants operating in combination
B. Only Base load plants operating in combination
C. Only Peak load plants operating in combination
D. Only thermal power plants operating in combination
Answer: A
Clarification: 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.

7. Which of the following system is more reliable?
A. Hydroelectric power plant
B. Steam power plant
C. Combined operating steam and hydroelectric power plant
D. Diesel power plant
Answer: C
Clarification: The reliability of steam power plant depends upon the coal supply, that of hydroelectric power plant on stream flow. Due to greater diversity a combine operation of various types of power plant would be more reliable than individual steam or hydro power plant.

8. In combined operation of several power plants the reserve capacity requirement is reduced.
A. True
B. False
Answer: A
Clarification: 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.

9. Thermal power plants are not suitable for supplying base peak loads.
A. True
B. False
Answer: A
Clarification: To operate as peak load plant, a power plant must be able to meet sudden variation of load. The major drawback of a steam power plant is that it requires appreciable time to start up, synchronize and take up load. Hence thermal power plant is not suitable to work as peak load plant.

10. Read the following statements:
I. Diesel power plant is generally used as base load plant.
II. Gas turbine power plant is used as peak load plant.
A. Only I is correct
B. Only II is correct
C. I and II are correct
D. I and II are wrong
Answer: B
Clarification: To supply base load the operation cost should be minimum, but Diesel power plant has very high operating cost. Diesel power plants are best suitable to supply peak loads. Gas turbine can be started in less time and so it is suitable to supply peak loads.

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