Iec 61869 2 Portable May 2026

The new standard asks: "What is your error when a decaying DC component—the ghost of a short-circuit—slams into your core, trying to saturate it? What is your phase displacement when the system frequency dances by 2 Hz? What is your transient response ?"

A merging unit (the device that samples the CT's analog signal and converts it to a digital Ethernet stream) expects a perfect analog input. If the CT's phase error is 1 degree at 10% burden, the merging unit will digitize that error, and the protection relay will calculate the wrong impedance. A fault 10 km away will appear to be 9.8 km away. The zone-1 protection might not trip. iec 61869 2

Imagine a 220 kV line falling onto a tree. The fault current is not a clean sine wave. It is a lopsided, asymmetrical monster: a 50 kVA sinusoidal AC wave riding on a 50 kVA DC sled that decays over 100 milliseconds. This DC component is the ghost. The new standard asks: "What is your error