24V and 42V supplies are considered "ELV" Extra-Low Voltage. These are typically used for things like hand-held / mining lights. On pleasure craft e.g. inland waterway cruiser boats and countless other applications.
In domestic installations we use those voltages for fans and lights located right above showers. (the 24V system only)
The 100hz to 500hz systems are typically used for aviation power supplies, not necessarily on-board but the sockets could be found airside at airports and maintanence facilities.
Modern aircraft all use 400Hz power on board. The reason for this is that higher frequency power systems are lighter than 50/60hz gear. It makes transformers much smaller. Aircraft have to make equipment as light as possible so it's a trade off.
The reason that 50hz and 60hz are used for normal mains/line power supplies is quite simple. Back in the 1880s/1890s generators were usually built for a single local purpose if they were supplying arc lights, they tended to use high frequencies >100hz to prevent flicker where as if they were supplying mostly induction motors they'd generally use a low frequency <30hz as it's easier to build a low frequency AC motor than a high freq. one. Particularly, if you're using 19th century materials. There were also no major transmission networks, all electrical power was generated locally.
Both 50hz and 60hz provide reasonable flicker-free operation of incandescent light bulbs, are easy to build transformers and motors for so represented a good compromise.
AEG seems to have picked 50Hz in 1891 and thus set the standard for most of Europe.
Westinghouse picked 60Hz
Pre-existing systems continued to operate on other odd frequencies throughout the 20th century, many of which were only phased out when they became uneconomic to maintain / buy equipment for.
E.g. 42Hz was common in the UK and Italy and 60Hz was used in parts of Australia.
In 1911 in London there were 11 different supply frequencies in use in different areas. It was really only when domestic appliances with motors and radios became a big deal that manufactuers forced the standardisation both in the US and Europe as it was uneconomic to make umpteen different versions of the same machine. When national grids became established, it was necessary to standardise and in Europe 50Hz was the frequency normally picked.
Also having a single standard frequency made it possible to interconnect with the grid. So, if you were a small generator in Europe or North America it was absolutely vital to have the possibility of buying / selling power and being interconnected.
In Ireland, because Siemens was selected for the first really major power projects and long-distance transmission systems in the early 1920s we standardised on 220V/380V 50Hz for domestic supply by 1923. I suspect that many smaller European countries would have similar history.
So, that's the story of how we're stuck with 50 and 60Hz !
In domestic installations we use those voltages for fans and lights located right above showers. (the 24V system only)
The 100hz to 500hz systems are typically used for aviation power supplies, not necessarily on-board but the sockets could be found airside at airports and maintanence facilities.
Modern aircraft all use 400Hz power on board. The reason for this is that higher frequency power systems are lighter than 50/60hz gear. It makes transformers much smaller. Aircraft have to make equipment as light as possible so it's a trade off.
The reason that 50hz and 60hz are used for normal mains/line power supplies is quite simple. Back in the 1880s/1890s generators were usually built for a single local purpose if they were supplying arc lights, they tended to use high frequencies >100hz to prevent flicker where as if they were supplying mostly induction motors they'd generally use a low frequency <30hz as it's easier to build a low frequency AC motor than a high freq. one. Particularly, if you're using 19th century materials. There were also no major transmission networks, all electrical power was generated locally.
Both 50hz and 60hz provide reasonable flicker-free operation of incandescent light bulbs, are easy to build transformers and motors for so represented a good compromise.
AEG seems to have picked 50Hz in 1891 and thus set the standard for most of Europe.
Westinghouse picked 60Hz
Pre-existing systems continued to operate on other odd frequencies throughout the 20th century, many of which were only phased out when they became uneconomic to maintain / buy equipment for.
E.g. 42Hz was common in the UK and Italy and 60Hz was used in parts of Australia.
In 1911 in London there were 11 different supply frequencies in use in different areas. It was really only when domestic appliances with motors and radios became a big deal that manufactuers forced the standardisation both in the US and Europe as it was uneconomic to make umpteen different versions of the same machine. When national grids became established, it was necessary to standardise and in Europe 50Hz was the frequency normally picked.
Also having a single standard frequency made it possible to interconnect with the grid. So, if you were a small generator in Europe or North America it was absolutely vital to have the possibility of buying / selling power and being interconnected.
In Ireland, because Siemens was selected for the first really major power projects and long-distance transmission systems in the early 1920s we standardised on 220V/380V 50Hz for domestic supply by 1923. I suspect that many smaller European countries would have similar history.
So, that's the story of how we're stuck with 50 and 60Hz !
