The area under the load curve represents

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Examoogle · Accepted Answer

Number of units generated

Explanation: The load curve represents the variation of load on a power station with respect to time. The area under this curve corresponds to the integral of the load (power) over a specific time interval, which yields the total energy produced, measured in kilowatt-hours (kWh) or units generated.

Working Principle: In a power system, load $P$ varies over time $t$. The instantaneous power $P(t)$ integrated over a time duration $T$ gives the energy $E$ delivered: $E = \int_{0}^{T} P(t) dt$. Graphically, this integration is equivalent to the area under the load-time curve, representing the total electrical energy consumption or generation.

Key Formulas: $E = \int_{0}^{T} P(t) dt$ — Integration of load over time gives total energy; $	ext{Load Factor} = \frac{	ext{Average Load}}{	ext{Maximum Demand}}$ — Ratio used for system efficiency analysis

Key Points: The ordinate represents the load in kW or MW.; The abscissa represents time in hours.; Area under the curve = (Average load in kW) × (Time in hours).; It is essential for calculating the cost of generation and planning plant capacity.

Advantages: Helps in determining the total energy requirement.; Facilitates the selection of the most economical number and size of generating units.

Disadvantages: Cannot be used to directly determine the peak capacity required without historical data.; Does not account for transmission losses unless specified.

Applications: Economic load dispatching.; Determining the capacity of power plants and distribution systems.

Additional Info: Maximum demand is the highest point on the load curve, not the area.. Load factor is a dimensionless ratio derived from the area (Total Energy) divided by (Max Demand × Time).. Average load is the constant load that would consume the same total energy as the actual variable load over the same period.

Answer: C is correct — The area under the load curve represents the total electrical energy (in kWh) generated by the station over the given period.

Exam Tip: Remember: Area = Energy, Peak point = Maximum Demand, and Ratio (Avg/Peak) = Load Factor. These three concepts are frequently tested together in power systems.

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