This European Standard establishes requirements for the compatibility of rolling stock with infrastructure particularly in relation to: – co-ordination of protection principles between power supply and traction units, especially fault discrimination for short-circuits; – co-ordination of installed power on the line and the power demand of trains; – co-ordination of traction unit regenerative braking and power supply receptivity; – co-ordination of harmonic behaviour. This European Standard deals with the definition and quality requirements of the power supply at the interface between traction units and fixed installations. This European Standard specifies the interface between rolling stock and electrical fixed installations for traction, in respect of the power supply system. The interaction between pantograph and overhead contact line is dealt with in EN 50367. The interaction with the “control-command” subsystem (especially signalling) is not dealt with in this standard. Requirements are given for TSI lines (both high speed and conventional) and classical lines. For classical lines, values, where given, are for the existing European networks. Furthermore the maximum values that are specified are applicable to the foreseen developments of the infrastructure of the Trans European rail networks. The following electric traction systems are within scope: – railways; – guided mass transport systems that are integrated with railways; – material transport systems that are integrated with railways. This European Standard does not apply retrospectively to rolling stock already in service. Information is given on electrification parameters such as to enable train operating companies to confirm, after consultation with the rolling stock manufacturers, that there will be no consequential disturbance on the electrification system.