UIC 737-4:2003-02

Thyristors are used in converters or rectifiers, which are used in traction vehicles and sub-stations. These converters and rectifiers form important sources of harmonics, which may cause disturbances in light current installations. From A.C. traction vehicles, the disturbance is reduced if the number of sequentially controlled thyristor bridges is increased. Also, filters on the traction vehicle reduce the harmonic content of the traction current. In D.C. or A.C. sub-stations, filters may be used to reduce the disturbing current. In the A.C. contact line, booster-transformers or auto-transformers may be used to limit the disturbances. Light current cables along the railway line should have a metallic sheath. Steel tape armouring around the sheath reduces the disturbances further. Also, the circuits in the cable should be well balanced to earth. In the second half of the leaflet, studies to be conducted during an electrification project are dealt with.