3. Interaction between the railway system and its electromagnetic environment

3.1 General principles

Any electrification needs to be carefully considered, particularly in terms of EMC. Indeed, the presence of traction currents on an asymmetrical line will generate electromagnetic fields at low frequencies (50 Hz and its harmonics), but also at higher frequencies due to the power control principles of traction units (see § 3 of [TRP 3 013] , § 1 and § 2). Whether electrifying an existing line, or building a new one, EMC issues should be anticipated...