When determining the setting value, please keep in mind the measurement method and the measuring
connection that you have selected. If you work with the positive-sequence voltage, remember that the
maximum voltage is equal to the phase-to-ground voltage. The default setting is referred to this value.
Parameter: Dropout differential
•
Recommended setting value (_:2311:109) Dropout differential = 20 mHz
Due to the high-precision frequency measurement, the recommended setting value for the Dropout
differential can remain at 20 mHz. If in your application you wish a subsequent dropout of the tripping
stage, then increase the setting value of the dropout differential. For instance, if the pickup value (parameter
Threshold ) of the tripping stage is set to 50.20 Hz and the Dropout differential to 100 mHz, the
stage will drop out at 50.10 Hz.
Application example of the overfrequency protection
Overfrequency protection can be used for monitoring the frequency range. If the frequency deviates from the
rated frequency by for example, 0.2 Hz, a fault indication is generated. The trip command is delayed to avoid
overfunction due to disturbing influences (for example, switching operations). A delay of a few seconds (for
example, 10 s) is deemed to be a good value. You can leave the Dropout differential at the default
value of 20 mHz. The following table shows a setting recommendation.
For this application, 1 stage of the overfrequency protection is used. The following table shows a setting
suggestion.
Stage Caused by Setting Values
At f
rated
= 50 Hz At f
rated
= 60 Hz Delay
f1> Warning 50.20 Hz 60.20 Hz 10.00
f2> Not used (OFF) - - -
NOTE
This table shows one example of a possible frequency protection setting. The setting values can differ
depending on the application.
Settings
Addr.
Parameter C Setting Options Default Setting
General
_:2311:101 General:Minimum voltage 3.000 V to 175.000 V 37.500 V
_:2311:109 General:Dropout differential 20 mHz to 2000 mHz 20 mHz
Stage 1
_:31:1 Stage 1:Mode
•
off
•
on
•
test
off
_:31:2 Stage 1:Operate & flt.rec.
blocked
•
no
•
yes
no
_:31:3 Stage 1:Threshold 40.00 Hz to 70.00 Hz 51.50 Hz
_:31:6 Stage 1:Operate delay 0.00 s to 600.00 s 10.00 s
Stage 2
_:32:1 Stage 2:Mode
•
off
•
on
•
test
off
_:32:2 Stage 2:Operate & flt.rec.
blocked
•
no
•
yes
no
_:32:3 Stage 2:Threshold 40.00 Hz to 70.00 Hz 54.00 Hz
6.32.5
Protection and Automation Functions
6.32 Overfrequency Protection
766 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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