Power supply device (SV1; SV2; SV3; SV3'; SV4; SV5; SV6; SV7) for supplying direct current to a plurality of loads (FE, FE1,..., FEn) for use in railway control- and safety systems, wherein the power supply device comprises a first energy bus (B1, B2) having a 2-pole bus line (L1, L3) and a first feed, and the loads (FE; FE1,..., FEn) are connected to the first feed via the 2-pole bus line (L1; L3) of the first energy bus (B1, B2) in parallel with the first feed, wherein the bus line (L1; L3) is divided into bus segments by load-bus coupling elements (VBA; VBA1,... VBAn), wherein each load-bus coupling element (VBA; VBA1... VBAn), both at the negative and at the positive potential side of the bus line, in each case comprises a first switching element for electrically disconnecting the bus line (L1; L3) and a second switching element for connecting the load to the energy bus, wherein the first switching elements are part of the bus line and the second switching elements (S2, S3) are part of a supply line leading from the bus line to the load, so that the bus coupling elements (VBA; VBA1... VBAn) can each be brought into a basic state, in which the bus line (L1; L3) is electrically interrupted by the corresponding load-bus coupling element (VBA; VBA1... VBAn) and the load is disconnected from the bus, into a first operating state, in which the bus line (L1; L3) is electrically interrupted by the corresponding load-bus coupling element (VBA; VBA1,... VBAn) and the load is switched on, and into a second operating state, in which the bus segments are electrically connected by the corresponding load-bus coupling element (VBA; VBA1... VBAn), and wherein at least one of the loads (FE; FE1..FEn) is connected to one of the load-bus coupling elements (VBA; VBA1... VBAn), wherein each load-bus coupling element further comprises: electronics for line diagnosis, filters, and protective devices, a small processor for monitoring and joining the feed to the load, and diodes which are intended for joining the small processor and the load to the bus line L, wherein the small processor is fed in the basic state via the diodes on one or two sides of the bus line L, and wherein each load-bus coupling element is configured to throughconnect the bus line to the first switching elements S1 after a time delay after reaching the first operating state. wherein the bus line (L1; L3) is divided into bus segments by load-bus coupling elements (VBA; VBA1,... VBAn), wherein each load-bus coupling element (VBA; VBA1... VBAn), both at the negative and at the positive potential side of the bus line, in each case comprises a first switching element for electrically disconnecting the bus line (L1; L3) and a second switching element for connecting the load to the energy bus, wherein the first switching elements are part of the bus line and the second switching elements (S2, S3) are part of a supply line leading from the bus line to the load, so that the bus coupling elements (VBA; VBA1... VBAn) can each be brought into a basic state, in which the bus line (L1; L3) is electrically interrupted by the corresponding load-bus coupling element (VBA; VBA1... VBAn) and the load is disconnected from the bus, into a first operating state, in which the bus line (L1; L3) is electrically interrupted by the corresponding load-bus coupling element (VBA; VBA1,... VBAn) and the load is switched on, and into a second operating state, in which the bus segments are electrically connected by the corresponding load-bus coupling element (VBA; VBA1... VBAn), and wherein at least one of the loads (FE; FE1..FEn) is connected to one of the load-bus coupling elements (VBA; VBA1... VBAn), wherein each load-bus coupling element further comprises: electronics for line diagnosis, filters, and protective devices, a small processor for monitoring and joining the feed to the load, and diodes which are intended for joining the small processor and the load to the bus line L, wherein the small processor is fed in the basic state via the diodes on one or two sides of the bus line L, and wherein each load-bus coupling element is configured to throughconnect the bus line to the first switching elements S1 after a time delay after reaching the first operating state.