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Functions
2.4 Backup Overcurrent
SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011
81
The non-directional and the directional inverse time overcurrent element
51
always uses the same character-
istic curve that is parameterized via
2642
(IEC) or
2643
(ANSI). Different inverse times and additional times
can be parameterized here.
The following figure shows the logic diagram. The setting addresses of the IEC characteristic curves are shown
by way of example. In the setting notes (Section 2.4.4), the different setting addresses are described in detail.
If parameter
51-B Inrush
(address
2637
) is set to
YES
, the element is blocked.
Figure 2-28
Logic diagram of the
51
element (inverse time overcurrent protection) - example for IEC characteristic