Standardization of serial interfaces of digital protection equipment

Having used microprocessor-based technology successfully for years for remote and local control purposes, the introduction of digital power system protection equipment made it possible to use control systems throughout a substation. Following the possibilities of conventional secondary equipment which means to combine devices of different manufacturers, from the beginning the users´ wish was the standardization of the interfaces. The authors point out the results of the coordination process of the standardization of the serial informative interface of digital protection equipment in Germany. The basic structures of substation control systems as well as the standardized interfaces are shown. The authors describe the worked out recommendation for the serial informative interface in detail. Finally, a summary and a short outlook on the present level and the process of international standardization activities is given