There are two widely used mains power frequencies for alternating current: 50 Hz and 60 Hz. Unless specified by the manufacturer to operate on both 50 and 60 Hz, appliances may not operate efficiently or even safely if used on anything other than the intended frequency.
But there are also other frequencies used for power. But let’s start from the history.
The utility frequency, (power) line frequency (American English) or mains frequency (British English) is the frequency of the oscillations of alternating current (AC) in an electric power grid transmitted from a power plant to the end-user. In large parts of the world this is 50 Hz, although in the Americas and parts of Asia it is typically 60 Hz. Current usage by country or region is given in the list of mains power around the world.
However, as of the turn of the 21st century, places that now use the 50 Hz frequency tend to use 220–240 V, and those that now use 60 Hz tend to use 100–127 V. Both frequencies coexist today (Japan uses both) with no great technical reason to prefer one over the other[1] and no apparent desire for complete worldwide standardization. The primary reason for accurate frequency control is to allow the flow of alternating current power from multiple generators through the network to be controlled.
Other frequencies:
16 Hz:
Germany, Austria, Switzerland, Sweden and Norway use traction power networks for railways, distributing single-phase AC at 16⅔ Hz or 16.7 Hz. 16⅔ Hz power is suitable for heavy commutator-type motors. The 15 kV AC rail networks, used in Germany, Austria, Switzerland, Sweden and Norway, still operate at 16⅔ Hz or 16.7 Hz.
20 Hz
In landline telephones, bells or ringtones are rung by impressing a 60 to 105-volt RMS 20-Hertz sine wave across the tip and ring conductors of the subscriber. The most common frequency used to ring telephones is 20Hz, while 16Hz and 24Hz are also widely used. Ring generators are sine wave output, high voltage inverters for the express purpose of ringing telephone bells. In decades past, the phone company generated ring tones with motor generator sets. The output voltage is typically about 90V with less than 10mA-per-bell output current capability.
25 Hz
The first generators at the Niagara Falls project, built by Westinghouse in 1895, were 25 Hz, because the turbine speed had already been set before alternating current power transmission had been definitively selected. The compromise frequency of 25 Hz, with 12 pole 250 RPM generators, was chosen (machines could have been made to deliver 16⅔ Hz power, Westinghouse company objected that this would be undesirable for lighting and suggested 33⅓ Hz).
A frequency of 25 Hz is used for the Austrian railway Mariazeller Bahn, as well as Amtrak and SEPTA‘s traction power systems in the United States.
400 Hz
Power frequencies as high as 400 Hz are used in aircraft, spacecraft, submarines, server rooms for computer power,[18] military equipment, and hand-held machine tools. Such high frequencies cannot be economically transmitted long distances; the increased frequency greatly increases series impedance due to the inductance of transmission lines, making power transmission difficult. Consequently, 400 Hz power systems are usually confined to a building or vehicle. At 400Hz the skin depth is 3.3 mm, so wires thicker than 8 gauge will have more resistance than expected. Litz wire, which is individual strands of thin insulated wire woven into a cable can be used to avoid the skin effect.
Typical voltage levels for 400 Hz power are 115V AC (nominal)and 200V line to line (three phase wye). In addition to 400 Hz power, airplanes also often use 28V DC.
Transformers, for example, can be made smaller because the magnetic core can be much smaller for the same power level. Induction motors turn at a speed proportional to frequency, so a high frequency power supply allows more power to be obtained for the same motor volume and mass. Transformers and motors for 400 Hz are much smaller and lighter than at 50 or 60 Hz, which is an advantage in aircraft and ships. A United States military standard MIL-STD-704 exists for aircraft use of 400 Hz power.
In some cases that 400 Hz power frequency can vary, and in some standard avionics power plant simulation runs from 360 Hz to about 800 Hz. These modern aircraft like Boeing 787 and Airbus A380 have opted to do without the alternator speed regulator required to keep the frequency stable. Therefore their frequencies extend from about 360 Hz to 800 Hz depending on the speed of the engines.
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Sources:
https://en.wikipedia.org/wiki/Alternating_current
https://en.wikipedia.org/wiki/Utility_frequency
https://www.powerstream.com/400hz-tutorial.htm
https://fcxinc.com/why-the-aviation-industry-operates-on-400-hz-power/
https://monroeaerospace.com/blog/why-airplanes-use-400-hz-power/
https://www.analog.com/en/technical-articles/lt1684-solves-global-ringing-problem.html
https://en.wikipedia.org/wiki/Ringing_(telephony)
Related reading:
Commonly used AC voltage levels
Common DC voltage levels
1 Comment
Tomi Engdahl says:
60Hz/230V is the norm in cruise ships
60hz 220v and quite possibly IT-grounding is pretty much standard.