ABB RELION REX640 Technical Manual page 523

Protection and control

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1MRS759142 F

Figure 301: 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.

Technical Manual

Protection functions