The current data and binary status information was retrieved over a dedicated fiber-optic LAN using IEEE 802.4 (Token Bus), a level of interoperability being achieved by unifying the data format and the characteristics of the analog filters used by the various vendors.
Introduction of the fault recording function to digital protection relays was made in 1989. Today this function is making a major contribution to the analysis of relay operations and is implemented in IEDs the world over.