Utility frequency
The utility frequency is the frequency at which alternating current is transmitted from a power plant to the end user.
In the Western Hemisphere, this is typically 60 Hz, with the exceptions of Argentina, Barbados, Bolivia, Chile, Colombia, French Guiana, Jamaica, Netherland Antilles, and Uruguay, where it is 50 Hz.
In the Eastern Hemisphere, it is typically 50 Hz, with the exceptions of Lesotho, Liberia, the Philippines, South Korea, Taiwan, and some portions of Bahrain, India, and Japan.
Places that use the 50 Hz frequency tend to use 220/230 voltage, and those that use 60 Hz tend to use 110/120.
For traction current in the Traction power network single phase AC with 16.7 Hertz is used in Germany, Austria, Switzerland, Norway and Sweden (no Traction power network in Sweden and Norway) and single phase AC with 25 hertz for the Mariazeller Bahn and some railway systems in New York and Pennsylvania (Amtrak) in the USA.
History
Early alternating-current generating schemes did not need to standardize the frequency, since most of the load was incandescent lighting which worked well at any frequency. It was not until the advantages of interconnecting all generating stations into a distribution grid became apparent, that a standard frequency was found to be useful. Electrical generators can only be interconnected to operate in parallel if they are of the same frequency and wave-shape.