Applicable to rotating electrical machines with rated voltages (Un) from 5 kV to 24 kV, and with rated output from 5 MW upwards for motors and 5 MVA upwards for generators. This also applies to machines with rated outputs between 1 MVA (1 MW) and 5 MVA (5MW), and with rated voltages of 5 kV or more, if its use has been agreed on previously.