The 3-pole plug-in system according to DIN 9680 is used on tractors and agricultural machinery for the electrical connection of permanent consumers, such as mowers, backhoes and sweepers, with a current consumption of max. 25 A. This standard does not apply to electrical connections for the supply of lighting equipment (see ISO 1724). The 3-pole plug-in system without standard is used for the transmission of additional functions between tractor and trailer.