A rotary converter plant is a facility at which one form of electricity is converted into another form of electricity by using a combination of an electric motor and an electric generator. The installed combinations of motors and generators at a plant determine the possible type(s) of conversion. Such facilities also allow the setting of voltages and frequencies, if appropriate equipment is installed. Rotary converter plants existed before the invention of mercury arc rectifiers in the 1920s at each facility where DC gained from an AC power grid was fed into an overhead line or a third rail of a railway. In spite of modern semi-conductor technology they are still common for feeding railway systems with AC of another frequency than that of the main electricity grid. Rotary converter plants were also used for coupling power grids of different frequencies and operation modes. For the latter the former Neuhof Substation

Neuhof Substation

Neuhof Substation is a 110 kV substation in Neuhof, an urban part of Bad Sachsa. Neuhof substation went in service in 1985 and was connected with a 110 kV-powerline for three phase alternating current with Wolkramshausen substation in former GDR. It was therefore one of the few substations in...

 was a good example. Also former machinery transmitters, like the Alexanderson alternator

Alexanderson alternator

An Alexanderson alternator is a rotating machine invented by Ernst Alexanderson in 1904 for the generation of high frequency alternating current up to 100 kHz, for use as a radio transmitter...

 were strictly speaking rotary converter plants.

See also

• Traction current converter plant
  Traction current converter plant
  A traction substation or traction current converter plant is an electrical substation that converts electric power from the form provided by the electrical power industry for public utility service to an appropriate voltage, current type and frequency to supply railways, trams and/or trolleybuses...
  
  
• Rotary converter
  Rotary converter
  A rotary converter is a type of electrical machine which acts as a mechanical rectifier or inverter. It was used to convert AC to DC or DC to AC power before the advent of chemical or solid state power rectification...
  
  
• Static inverter plant
  Static inverter plant
  A static inverter station, also known as an HVDC Converter Station, is the terminal equipment for a high-voltage direct-current transmission line, in which direct current is converted to three-phase alternating current, and, usually, the reverse...
  
  
• Lyon-Moutiers DC transmission scheme
  Lyon-Moutiers DC transmission scheme
  The Lyon–Moutiers DC transmission scheme was the most powerful mechanical high voltage direct current electric power transmission scheme ever built...