Low Frequency Magnetic Field Inside a High Speed Train with A.C. Electrification: Field Calculation and Mitigation Techniques

Extremely low frequency (ELF) magnetic fields produced by 50 Hz currents flowing in the conductors of the a.c. electrified railway traction line are calculated inside a train by numerical techniques. Shielding techniques are then analysed in order to reduce the magnetic field inside a railway car. Passive shields and active coils are therefore investigated. An optimization method is also proposed to define the optimum shielding configuration by a hybrid shielding technique, combining passive shields with active coils.