Effective Documentation of Microprocessor-Based Protective Relay Configurations in Industrial Applications

Abstract

The protective relays used in modern industrial installations are complex microprocessor-based devices. Some of these relays deserve to be called Protection PLCs due to their complexity and flexibility. The impressive abilities of these relays require careful design and documentation of the intended functions and the philosophy underlying them. Inter-relay communications for high speed zone selective interlocking or complex control interlocking and inter-tripping add further complexities, as does the common practice of multiple design entities working on different portions of the same facility. This paper will consider the documentation schemes developed for two recent projects with complex protection equipment. Protection Philosophies, Protection Narratives, communications scheme documentation and programmable logic documentation will be discussed in an effort to illustrate a complete documentation scheme that will be useful both to a specialist and to field personnel in understanding the protection system.