Function Description
Logic of the Stage
[lounbala-090812-03.tif, 1, en_US]
Figure 6-176
Logic Diagram of the Unbalanced-Load Protection Function
Method of Measurement
The stage uses the negative-sequence current I
2
as a measurand. The negative-sequence current is calculated
from the measured 3-phase currents according to the defining equation of symmetrical components.
Warning Stage
If the negative-sequence current I
2
continuously exceeds the parameter Max. continuously perm. I2,
the
Warning
indication is given after expiry of a set time Warning delay.
Thermal Characteristic Stage
The machine manufacturers indicate the permissible unbalanced load using the following formula:
6.22.3
Protection and Automation Functions
6.22 Unbalanced-Load Protection
SIPROTEC 5, Overcurrent Protection, Manual 687
C53000-G5040-C017-8, Edition 07.2017
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