Source google image: http://horta.ulb.ac.be/gvg/tractions/docs_tractions/Electricit%C3%A9/schema_electrique_m.jpg
Schema electrique traction
Source google image: http://horta.ulb.ac.be/gvg/tractions/docs_tractions/Electricit%C3%A9/schema_electrique_m.jpg