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7
7.2 Fault Recorders
86
Digital Fault Recorder, SIMEAS R-PMU, Manual
E50417-H1076-C360-A5, Release 10.2012
7.2.2.2.1.1 Level Trigger (Min/Max)
Level triggers monitor the measured values for observance of min/max limits. Triggering is
started, as soon as the measured value exceeds the parameterized permissible range. The level
trigger can be parameterized for all analog and calculated values, as well as for symmetrical
components from Table 7-18. The Min. level trigger cannot be selected for negative-sequence
and zero-sequence systems.
Hysteresis
If a measured value reaches exactly the limit value, this may lead to unwanted fault recordings
even with the smallest possible fluctuations. A hysteresis amounting to 2 % (at frequencies
0.2 %) of the parameterized nominal value of the corresponding channel is therefore applicable
for all level trigger values.
If the level trigger value is set smaller than the given hysteresis, it will be set to 25 % of the
parameterized trigger value. After a limit value violation has occurred, the signal must leave the
hysteresis range first before another triggering is possible if the limit value is exceeded again
(see figure 7-17).
Figure 7-17 Functioning of the hysteresis for min and max level triggers
t
100 %
0 %
Trigger
Max-Trigger
Hysteresis
Trigger