Siemens 7SJ82 Manual page 392

Protection and Automation Functions
6.5 Overcurrent Protection, Ground
dropout according to characteristic curve (disk emulation) is the same as turning back a rotor disk. The
weighted reduction of the time is initiated from 0.9 of the set threshold value.
The characteristic curve and associated formulas are shown in the Technical Data.
Minimum Time of the Curve (Advanced Stage)
With the parameter Min. time of the curve, you define the minimum operate delay time. The operate
delay time of inverse-time characteristic curve never falls below the minimum operate delay time.
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Figure 6-39
Additional Time Delay (Advanced Stage)
With the parameter Additional time delay, you define a definite-time delay in addition to the inverse-
time delay. With this setting, the whole curve is shifted on the time axis by this additional definite time.
Method of Measurement (Basic and Advanced Stage)
You use the Method of measurement parameter to define whether the stage uses the fundamental
comp. or the calculated RMS value.
•
Measurement of the fundamental component:
This method of measurement processes the sampled current values and filters out the fundamental
component numerically.
•
Measurement of the RMS value:
This method of measurement determines the current amplitude from the sampled values according to
the defining equation of the RMS value. Harmonics are included in the analysis.
Blocking of the Stage (Basic and Advanced Stage)
The following blockings reset the picked up stage completely:
•
Via the binary input signal >Block stage from an external or internal source
•
Via the functionality of the dynamic settings (see subtitle Influence of other functions via dynamic
settings and chapter
Blocking of the Time Delay (Basic and Advanced Stage)
You can use the binary input signal >Block delay & op. to prevent the start of the time delay and thus
also the operate signal. A running time delay is reset. The pickup is indicated and the fault logging and
recording takes place.
392
Minimum Operating Time of the Curve
6.5.8.1 Description ).
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017