User:Ted7234889
I have just done a search for information on the G59 relay. This is a specialised device connected to a consumers installation when the consumer has the ability to generate electricity and to sell it back to the grid. Examples include standby diesel generators, wind turbines and solar panels to name a few.
The device detects any out of frequency situations and also disconnects the source from the grid in the event of a failure of the grid.
An example of such a device can be found here.
There appears to be no wikipedia page for this at the moment, but i am not sure I have the time or qualification to creat one.