ABB RELION Series, Technical Manual

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Figure 184: Functional module diagram
Harmonics calculation
This module feeds the measured residual current to the high-pass filter, where the
frequency range is limited to start from two times the fundamental frequency of the
network (for example, in a 50 Hz network the cutoff frequency is 100 Hz), that is,
summing the harmonic components of the network from the second harmonic. The
output of the filter, later referred to as the harmonics current, is fed to the Level
detector and Current comparison modules.
The harmonics current I_HARM_RES is available in the monitored data view. The
value is also sent over horizontal communication to the other protection relays on the
parallel feeders configured in the protection scheme.
Nor
maliz
ed output
0.5
0
0
1.0
Frequency
2f f
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Figure 185: High-pass filter
Section 4
1MRS758755 A
Protection functions
354 REC615 and RER615
Technical Manual