Modern practices and field experience with MC-based relays

When the advantages of microcomputer (MC) technology in protective relaying are added to the communication facilities given by local and wide area networks (LANs and WANs), there are almost unlimited possibilities for the future development of protective and network management. It is expected that the bulk of protective equipment delivered in the future will go into conventionally designed plants and must, therefore, fit into the existing equipment in terms of constructive set-up, interfacing, environmental conditions and operating and testing policies. Power supply utilities which are faced with a new situation of low rate of energy demand growth must apply policies which concentrate investment more on that which is essential than that which is possible or desirable. Protection concepts with MC-based relays which correspond to the above outlined policy are discussed. The concepts are based on actual installations and on the recommendations of the Association of German Power Supply Authorities