Utility frequency facts for kids

This map shows where 50 Hz and 60 Hz electricity are used around the world.

Utility frequency, also called line frequency or mains frequency, is how fast the AC electricity changes direction when it travels from power plants to your home. Think of it like a wave that goes up and down. The frequency tells you how many times that wave completes a full cycle in one second. This is measured in Hz.

Most places in the world use one of two main utility frequencies:

• 50 Hz: This is common in many parts of the Eastern hemisphere, like Europe, Asia, Africa, and Australia.
• 60 Hz: This is mostly used in the Western hemisphere, including North America and parts of South America.

Having different frequencies means that an appliance made for 50 Hz might not work correctly, or even get damaged, if you plug it into a 60 Hz outlet without a special adapter, and vice versa.

Understanding Alternating Current (AC)

Electricity can flow in two main ways: direct current (DC) or alternating current (AC).

• Direct Current (DC): This is like the electricity from a battery. It flows in one constant direction.
• Alternating Current (AC): This is what comes out of your wall sockets. It regularly changes direction, flowing one way and then the other. This constant change is what we measure as frequency.

AC is used for sending electricity over long distances because it's easier to change its voltage using devices called transformers. This makes it more efficient to transmit power from where it's made to where it's used.

Why Are There Different Frequencies?

The reason we have different frequencies (50 Hz and 60 Hz) goes back to the early days of electricity.

• When electricity systems were first being developed in the late 1800s, different companies and inventors chose different frequencies.
• There wasn't one global standard right away.
• Over time, as countries built their power grids, they often stuck with the frequency that was already being used in their region.
• Changing a country's entire electrical system from one frequency to another is very expensive and difficult, so most places have kept their original standard.

Electricity for Trains

While most homes and businesses use 50 Hz or 60 Hz, some electric railways use different frequencies.

• In parts of Europe, some electric trains use a frequency of 16.7 Hz. This is about one-third of 50 Hz.
• Older electric railways sometimes used 25 Hz, which is half of 50 Hz. You can still find some lines in the northeastern United States that use 25 Hz.
• However, most new electric railways today are built to use the standard mains frequency of 50 Hz, making them more compatible with the general power grid.

See also

In Spanish: Frecuencia de red para niños