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7
7.2 Fault Recorders
71
Digital Fault Recorder, SIMEAS R-PMU, Manual
E50417-H1076-C360-A5, Release 10.2012
Figure 7-9 Channel B can extend (retrigger) the fault record within the retrigger blocking time of channel A; retrigger
blocking is valid for the given channel only
7.2.1.2.1.1 Level Trigger (Min/Max)
Level triggers monitor the measured values for observance of parameterizable min/max limits.
Triggering is started, as soon as the measured value exceeds the parameterized threshold.
These triggers can be parameterized for all analog values and symmetrical components (see
table 7-11 and 7-12). 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 % 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 7-10).
Figure 7-10 Functioning of the hysteresis for min and max level triggers
Trigger 1
Channel A
Recording time
Trigger 2
Channel B
Prefault
time
Retrigger blocking
time (channel A)
Recording time (restart)
Retrigger blocking
time (channel B)
Fault record
t
t
Recording of fault record
t
t
100 %
0 %
Trigger
Max-Trigger
Hysteresis
Trigger