Relay protection, SCADA, Metering, and Cybersecurity for electrical infrastructure.
What IEC 61869-9 actually requires, and where the boundary lies between "still synchronized" and "no longer synchronized". The article unpacks the "2 → 1 → 0" misconception about SAMU/NCIT behavior on PTP loss, the link between clockClass, timeTraceable and SmpSynch, and how a complex protection function should react when one of its source streams loses synchronization.
Most digital substation projects are single-vendor, single-site proofs of concept. RTE — the operator of France's 2,600-substation transmission grid — decided to do something harder: build a fully digital, multi-vendor PACS from scratch, act as its own system integrator, and scale it across the entire network.
CIGRE Study Committee B5 has opened Working Group B5.90, tasked with writing the first dedicated guidelines for commissioning and testing of fully digital protection and automation control systems. The Terms of Reference, published in January 2026, cover FAT, SAT, and operational testing for IEC 61850 process bus architectures.