A national grid is a country's method of transmitting electrical power to end users. To meet electrical demands from residential and industrial users, a national grid allows consumers power availability when demand exceeds supply.
Electrical power is generated by a source, such as hydroelectric, nuclear, natural gas, wind or coal, to spin turbines. These turbines are the workhorses of electrical generation. Electricity is then captured at the generation station and sent to substations. Substations are used for the collection, distribution and transmission of power, and are referred to as "yards."
On the receiving end of the national grid are commercial, industrial and residential users. Users are grouped together geographically and serviced with electricity by the yard on a grid. Grid areas can service a substantial number of customers for anticipated demand while electrical power is transmitted along power lines. Because power lines have a maximum capacity of electricity they can carry at one time, electrical kilovolt-amps (kVA) are based upon regional and seasonal usage
When Demand Exceeds Supply
Once the demand for electricity exceeds what is available, power companies contact other power providers and schedule for more kVA. The idea behind this is to ensure that consumers have electricity readily available for use at all times. The purpose of a national grid is to ensure that geographic areas have more than one source to draw from for electrical power.
Other National Grids
England and Ireland use a national grid reference system. It is a geographic mapping system used to pinpoint locations on a map. A business that provides electrical service to these countries, as well as the U.S. New England area, is also named National Grid.