Siemens SIPROTEC 4 7UT6 Series Manual page 100

Functions
2.2 Differential Protection
[ausloeselogik-differentialschutzes, 1, en_GB]
Figure 2-25
A dropout is detected when, during 2 cycles, pick-up is no longer recognised in the differential value, i.e. the
differential current has fallen below 70 % of the set value, and the other pickup conditions are no longer
fulfilled either.
If a trip command has not been initiated, the fault is considered ended on dropout.
If a trip command had been initiated, it is maintained for the minimum command duration set in the general
device data for all protection functions (see also
reset until all other dropout conditions mentioned above are fulfilled as well.
100
Tripping logic of the differential protection (simplified)
2.1.4 Power System Data 1). The trip command will not be
C53000-G1176-C230-5, Edition 09.2016
SIPROTEC 4, 7UT6x, Manual