This Application Guide supports the European Standards EN50526‑1 and EN50526‑2 . Guidance is offered on the following subjects: the selection and installation of surge arresters; the selection and installation of voltage limiting devices as VLD-O and VLD-F; the arrangement of the surge arresters and VLDs. Because of differences in the established, proven methods, electric traction systems of nominal voltage d.c. 600V — d.c. 750V are treated separately from the systems at higher nominal voltages. This Application Guide only applies to d.c. electrified traction systems