An electrical grid is an interconnected network for delivering electricity from suppliers to consumers.

Components of power grid

It consists of generating stations that produce electrical power, high-voltage transmission lines that carry power from distant sources to demand centers, and distribution lines that connect individual customers.

The Power Plant

Electrical power starts at the power plant.

In almost all cases, the power plant consists of a spinning electrical generator.

Something has to spin that generator -- it might be a water wheel in a hydroelectric dam, a large diesel engine or a gas turbine.

But in most cases, the thing spinning the generator is a steam turbine.

The Power Plant: Alternating Current

Generally household electrical service is come as single-phase, 120-volt AC service.

AC has at least three advantages over DC in a power distribution grid:

Large electrical generators happen to generate AC naturally, so conversion to DC would involve an extra step.

It is easy to convert AC to DC but expensive to convert DC to AC.

The power plant produces AC.

The Distribution Grid

It has transformers that step transmission voltages (in the tens or hundreds of thousands of volts range) down to distribution voltages (typically less than 10,000 volts).

It has a "bus" that can split the distribution power off in multiple directions.

It has circuit breakers and switches so that the substation can be disconnected from the transmission grid or separate distribution lines can be disconnected from the substation when necessary.