Object models of transmission line protection relays

This paper is an attempt to describe in a practical way the multifunctional intelligent devices, such as microprocessor transmission line protection relay, from the perspective of object-oriented modeling. It discusses the efforts of the industry in the implementation of the basic concepts of object-oriented analysis methodology, virtual devices and considers the protective relays as both protective devices and data sources for other virtual devices in the substation, such as transformers, breakers, etc