A technico-economically oriented maintenance strategy for digital protections

As a consequence of the rapid rise of digital protection relays within the Netherlands, Dutch utilities are having increasing doubts about their existing maintenance strategies for protection relays. The utilities have the impression that modern digital relays offer possibilities for improving the efficiency of protection relay maintenance and that the maintenance costs can be reduced by switching over to a new maintenance strategy. In order to underpin this impression KEMA Transmission and Distribution has started a research program. The program has led to the drawing up of a new maintenance strategy for digital relays. In this paper the new maintenance strategy is presented