Functions
2.12 Breaker Failure Protection 50BF
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
200
the set threshold or thresholds (enabled w/ 3I0>) are detected, the breaker failure protection trips even if
the auxiliary criterion indicates „Breaker Open“.
Monitoring of the Current Flow
Address 170 50BF can be set in such a way that either the current criterion can already be met by a single
phase current (setting Enabled) or that another current is taken into consideration in order to check the plau-
sibility (setting enabled w/ 3I0>), see Figure 2-73.
The currents are filtered through numerical filters to evaluate the fundamental harmonic. They are monitored
and compared to the set limit value. Besides the three phase currents, two further current thresholds are pro-
vided in order to allow a plausibility check. For purposes of the plausibility check, a configuration of a separate
threshold value can be applied accordingly. (see Figure 2-73).
The ground current I
N
(3·I
0
) is preferably used as plausibility current. Via the parameters 613 you decide
whether the measured (Ignd (measured)) or the calculated (3I0 (calcul.)) values are to be used. In
case of system faults not involving ground currents, no increased ground currents/residual currents are flowing,
and therefore the calculated triple negative sequence current 3·I
2
or a second phase current is used as plau-
sibility current.
Figure 2-73 Monitoring of the current flow
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