[loinru10-040912-01.tif, 1, en_US]
Figure 6-82 Logic of the Harmonic Analysis Function (T = 1 Period)
CWA Method (Current Wave Shape Analysis)
The CWA method executes a wave shape analysis of the phase currents IA, IB, and IC. If all 3 phase currents
show flat areas at the same point in time, the inrush-current detection signal will be issued. This signal applies
for all 3 phases simultaneously. The following figure shows a typical inrush-current characteristic, with the
simultaneously occurring flat areas clearly recognizable.
[dwinru03-240211-01.tif, 1, en_US]
Figure 6-83 Inrush-Current Characteristic
The following figure shows the logic diagram of the CWA method.
From the present fundamental-component current (1st harmonic), the threshold value for identification of the
flat areas is derived via an internal factor.
Protection and Automation Functions
6.8 Inrush-Current Detection
488 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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