Functions
2.4 Load Restoration
SIPROTEC, 7RW80, Manual
C53000-G1140-C233-1, Release date 10.2010
62
Figure 2-11 Example for Load Restoration with 3 elements
In the above example the frequency initially drops below the pickup threshold of the underfrequency element
81-1. The element 81-1 trips.
Because of the configured settings (see Table 2-3) load restoration element LR1 is started with the tripping of
81-1. LR1 is at this point the only running/started element and is therefore processed immediately.
Afterwards the network frequency drops below the pickup threshold of the underfrequency element 81-2.
Element 81-2 trips as well and initiates load restoration elements LR2 and LR3.
LR3 has at that point the highest number of all load restoration elements and is processed immediately. The
processing of element LR1 is interrupted.
When the pickup frequency of 49.5 Hz is reached, load restoration element LR3 picks up. Once the frequency
remains above the threshold during the pickup time of LR3, LR3 issues the CB Close command.
The pickup of the next restoration element LR2 will be processed immediately after the LR3 restoration CB
Close signal.
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