This European Standard covers the requirements applicable to the Energy Measurement Function (EMF) of an Energy Measurement System (EMS) for use on board traction units for measurement of energy supplied directly from/to the Contact Line system. This European Standard also gives requirements for the Current Measurement Function (e.g. current sensor), the Voltage Measurement Function (e.g. voltage sensor) and the Energy Calculation Function (e.g. energy meter). The Conformity Assessment arrangements for the Voltage Measurement Function, Current Measurement Function, the Energy Calculation Function and a complete Energy Measurement Function are also specified in this document. The standard has been developed taking into account that in some applications the EMF can be subjected to legal metrological control. All relevant metrological aspects are covered in this part. Figure 2 shows the flow between the functional blocks of the EMF. Only connections between the functional blocks required by this standard are displayed. (...)