Abstract: This invention concerns a railway vehicle (10), including: a power supply device (20), an electrical traction engine (15), first electrical auxiliary equipment (16, 17), and a connector (22) for connecting to an electrical power source external to the vehicle. The power supply device comprises: an electrical converter (26) suited to supply the electrical traction engine with high-voltage current, wherein the electrical converter is connected to the connector; a first medium-voltage electricity network (34) to which the first auxiliary electrical equipment is connected, and a first electrical storage element (30) connected to the first medium-voltage electricity network so as to supply electricity to or draw electricity from the first network. The electrical converter is connected to the first medium-voltage electricity network so as to supply the first network with electricity.