What ePRTC and TDG are: why a digital substation needs a new precise-time architecture
Precise time is a mandatory part of a modern substation: it is needed for event recording and oscillography, for Sampled Values, for phasor measurements and for other applications. But relying on a local receiver alone is becoming increasingly dangerous: jamming, interference and spoofing turn a single satellite source into a systemic risk. An architecture built around an ePRTC (enhanced Primary Reference Time Clock) in the telecom network and a TDG (Time Distribution Gateway) on site offers a heterogeneous approach: one precise time comes «from the sky», another «via the ground». The article — what ePRTC and TDG are, how they fit IEC 61850-9-3 PTP, and why a single redundant GNSS receiver is not enough.