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Procedure
The start of a load restoration element is triggered by the tripping of the associated underfrequency element.
Processing will terminate, if the restoration signal for the circuit breaker is issued or the function has been
blocked. If the underfrequency trips again during the output of the restoration signal, the load restoration
element will restart.
The following figure shows the interaction of underfrequency protection and load restoration.
[7rw80-start-20100525, 1, en_US]
Figure 2-7
You can adjust the trip- and dropout time for every load restoration element. Furthermore, you can adjust the
pickup- and dropout time as a difference to the starting frequency, which together form the threshold of the
load restoration. The frequency must reach this threshold value of the set trip time, before the restoration
signal for the circuit breaker is issued. If the frequency drops below the the set pickup threshold value during
the set dropout time, the time for the pickup will be halted. If the frequency drops to a value below the
dropout threshold value, pickup and dropout time will be reset. This takes into account that the frequency is
not restored monotonously, but rather is subject to intermittent fluctuations.
The following figure shows the interaction of thresholds and timers.
SIPROTEC 4, 7RW80, Manual
C53000-G1140-C233-4, Edition 07.2018
Load Restoration - Start
Functions
2.4 Load Restoration
51
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