devices connected are only shown schematically wherein the respective electrical or electronic devices may be associated to respective drilling hole or christmas tree equipments fig2 shows the respective first and second modules 31 32 for at least one system in more detail wherein to simplify matters the respective connection to and representation of subsea anodes 27 was dispensed with to further simplify matters the control means 26 is not shown in fig2 but only a divider unit 20 which may be part of the central control means or which is at least associated thereto in fig2 the first and second modules 31 32 according to fig1 are characterized as data transfer voltage conversion units 3 and power supply modules 6 wherein each module is composed of sub modules such a first module 31 or data transfer voltage conversion unit 3 is connected on the input side for voltage supply with a universal power supply in the form e g of a three phase electric power supply with connection 36 this supplies three phase electric power or voltage and also a connection to ground 29 the supply is implemented via a power bus 12 which may be arranged in the form of a power bus rail 16 this power bus 12 is connected to power supply 8 and 23 respectively of the data transfer voltage conversion units 3 or the power supply modules 6 voltage converters 7 in the form of an ac dc converter and respective voltage.