This European Standard applies to emission and immunity aspects of EMC for electrical and electronic apparatus and systems intended for use in railway fixed installations for power supply. This includes the power feed to the apparatus, the apparatus itself with its protective control circuits, trackside items such as switching stations, power autotransformers, booster transformers, substation power switchgear and power switchgear to other longitudinal and local supplies. Filters operating at railway system voltage (for example, for harmonic suppression or power factor correction) are not included in this standard since each site has special requirements. Filters would normally have separate enclosures with separate rules for access. If electromagnetic limits are required, these will appear in the specification for the equipment. The limits in this standard do not apply to intentional communication signals. The frequency range considered is from DC to 400 GHz. No measurements need to be performed at frequencies where no requirement is specified. Emission and immunity limits are given for items of apparatus which are situated: a) within the boundary of a substation which delivers electric power to a railway; b) beside the track for the purpose of controlling or regulating the railway power supply, including power factor correction; c) along the track for the purpose of supplying electrical power to the railway other than by means of the conductors used for contact current collection, and associated return conductors. Included are high voltage feeder systems within the boundary of the railway which supply substations at which the voltage is reduced to the railway system voltage; d) beside the track for controlling or regulating electric power supplies to ancillary railway uses. This category includes power supplies to marshalling yards, maintenance depots and stations; e) various other non-traction power supplies from railway sources which are shared with railway traction. The immunity levels given in this standard apply for vital equipment such as protection devices; equipment having connections to the traction power conductors; apparatus inside the 3 m zone; ports of apparatus inside the 10 m zone with connection inside the 3 m zone; ports of apparatus inside the 10 m zone with cable length > 30 m. Apparatus and systems which are in an environment which can be described as residential, commercial or light industry, even when placed within the physical boundary of the railway substation, shall comply with the relevant generic European EMC standard. Excluded from the immunity requirements of this standard is power supply apparatus which is intrinsically immune to the tests defined in Tables 1 to 6 of this standard. NOTE An example is an 18 MVA 230 kV to 25 kV power supply transformer. - 7 - EN 50121-5:2015 These specific provisions are to be used in conjunction with the general provisions in EN 50121-1. This part of the standard covers requirements for both apparatus and fixed installations. The sections for fixed installations are not relevant for CE marking.