If the DC component I
rest.DC,phsx
falls below the internal dropout threshold, the dropout delay is determined as
follows:
It is assumed that the de- and re-magnetization of the transformer last equally long. The magnetization is at
the highest at the point in time in which the internal dropout threshold is attained. The time is measured from
the start of the DC-component detection until the internal dropout threshold is reached. Added to this time
are 5 periods and from this, the dropout delay is derived. Following this, the characteristic-curve increase is
reset to the original value. Figure 7-53 shows the overall logic.
[dwdcerkn-201112-01.tif, 2, en_US]
Figure 7-52 Increasing the Characteristic Curve after DC Detection
[lodcerkn-170712-01.tif, 2, en_US]
Figure 7-53 Logic DC Detection
Capacitor Bank Protection
7.8 Differential Protection for Capacitor Banks
1052 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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