Load curve helps in deciding:
The load curve is a graphical representation of the variation in electrical load or demand over a specific period of time. It provides valuable information that helps in making decisions related to power plant operations and planning.

a) The total installed capacity of the plant:
The load curve helps in determining the total installed capacity of the power plant. By analyzing the load curve, engineers can identify the peak demand periods and estimate the maximum load that needs to be met. This information is crucial in determining the capacity of the power plant to ensure that it can meet the peak demand without any shortage of power supply.

b) The size of the generating units:
The load curve also assists in deciding the size of the generating units in the power plant. By analyzing the load curve, engineers can determine the range of load variations that occur throughout the day. This information helps in selecting the appropriate size of generating units that can efficiently operate under different load conditions. For example, during off-peak periods, smaller generating units can be used to avoid operating larger units at low loads, which would be inefficient.

c) The operating schedule of the generating units:
The load curve is useful in determining the operating schedule of the generating units. It helps in deciding when to start or shut down specific units based on the load requirements. During periods of high demand, additional generating units can be brought online to meet the load, while during periods of low demand, some units can be temporarily taken offline to reduce fuel consumption and maintenance costs. The load curve provides insights into the daily and seasonal variations in load, enabling efficient scheduling of the generating units.

d) All of the above:
In conclusion, the load curve plays a crucial role in deciding the total installed capacity of the plant, the size of the generating units, and the operating schedule of the generating units. It provides valuable information that helps in optimizing power plant operations, ensuring reliable power supply, and minimizing costs. By analyzing the load curve, engineers can make informed decisions regarding capacity planning, unit sizing, and scheduling to meet the changing load demands efficiently.