This European Standard describes the primary purpose of the EMS, which is to meter energy consumption for billing. The EMS may also be used for other functions such as energy management. This part of EN 50463: gives requirements for the complete Energy Measurement System and also requirements for all devices implementing one or more functions of the Energy Measurement System; applies to newly manufactured Energy Measurement Systems for use on board railway traction units, powered by a.c. and/or d.c. supply voltages as listed in the EN 50163; does not apply to portable Energy Measurement Systems.