All Loads (light, fan, freeze etc) do not have connected at a time at home. Load changes with time (This time can be a day, a month, a year etc). This change of load showing in a curve is known as load curve. The load curve exhibits the whole character of the load during a period. Analyzing this curve, it can be balanced between consumers demand and power generated on power plant.
Different terms and factors:

Demand Factor: 


Demand factor is the ratio of the maximum demand on a power station to the connected load. Maximum demand is the highest demand of loads during a period. Maximum demand needs to determine the installed capacity of a power plant. Connected load is the sum of the ratings of all equipment’s connected to the power station. Connected load must be greater than the maximum demand. Therefore, demand factor is always less than 1.


Load Factor: 

Load factor is the ratio of the average load to the maximum demand during a period. Average load is the average of loads during a period. Load factor is always less than 1 because the average load is less than maximum demand. The lesser the maximum demand the higher is the load factor. If the load factor is higher on a power station, the cost per unit generated will be lesser.

Diversity factor:

Diversity factor is the ratio of the sum of individual maximum demands of the consumers to the maximum demand on the power station. Diversity factor will be greater than 1. The higher the diversity factor the lesser is the cost of generation of power on a power plant. Hence the capital investment on the plant is reduced.


Plant Capacity Factor:
Plant capacity factor is the ratio of the average demand to the plant capacity.
Annual plant capacity factor =  (annual kWh output)/(plant capacity*8760)
A power plant should have reserve capacity fed to the additional load demand.
Plant capacity = reserve capacity + maximum demand


Plant Use Factor:
Plant use factor is the ratio of kWh generated to the product of plant capacity and the number of hours for which the plant was in operation.
  •        Units generated per annum = average load in kW * hours in a year

Average load = maximum demand * load factor (L.F.)