Siemens 7SJ82, Manual

Page: 565 / 1638

[logfpnon-261012-01.tif, 4, en_US]
Figure 6-122 Logic Diagram of the Cross-Stage Functionality of the Non-Directional Function
Operational Measured Value φ(I,V)
The function block calculates the angle between IN and V0 and makes the angle available as function meas-
ured value
Phi(I,V)
.
[DwPhINU0, 1, en_US]
Figure 6-123 Sign Definition for the Measured Value
Fault-Extinction Detection
The extinction of the fault is characterized by the fact that the zero-sequence voltage subsides. Depending on
the system conditions and fault characteristics, this process can last several 100 ms. If a continuously falling
zero-sequence voltage is detected during the set time
Decay time V0
, then the fault is considered extin-
guished. The signal
Flt. extinction det.
is issued.
Thus, the possibility exists, for example, to block the 3I0> stage with cos φ or sin φ measurement directly
after the fault extinction, in order to avoid an overfunction during the subsiding process with a very sensitive
setting of the stage.
Angle-Error Compensation
The high reactive power factor in the arc-suppression-coil-ground system and the unavoidable air-gap of the
core balance current transformer often make necessary a compensation of the angle error of the core balance
current transformer. Using the characteristic shown in the following figure, the device approaches the angle
error of the core balance current transformer with sufficient precision.
Protection and Automation Functions
6.15 Sensitive Ground-Fault Detection
SIPROTEC 5, Overcurrent Protection, Manual 565
C53000-G5040-C017-8, Edition 07.2017