unless an inrush has been recognized or inrush restraint is active. If the inrush restraint feature is enabled, and
an inrush condition exists, no tripping takes place, but a message is recorded and displayed indicating when
the overcurrent element time delay elapses. Trip signals and other flags for each element are issued when the
element times out. The dropout value is roughly equal to 95% of the pickup value for currents > 0.3 Ι
Nom
.
Pickup can be stabilized by setting dropout times 1518 67 T DROP-OUT or 1618 67N T DROP-OUT. This
time is started and maintains the pickup condition if the current falls below the threshold. Therefore, the func-
tion does not drop out at high speed. The trip-command delay time 50-1 DELAY or 50N-1 DELAY continues
in the meantime. After the dropout delay time has elapsed, the pickup is reported OFF and the trip delay time
is reset unless the threshold 50-1 PICKUP or 50N-1 PICKUP has been exceeded again. If the threshold is
exceeded again during the dropout delay time, the time is canceled. The trip-command delay time 50-1
DELAY or 50N-1 DELAY continues in the meantime. Should the threshold value be exceeded after its expiry,
the trip command is issued immediately. If the threshold value is not exceeded at this time, there will be no
reaction. If the threshold value is exceeded again after expiry of the trip-command delay time, while the
dropout delay time is still running, tripping occurs immediately.
The inrush restraint of the overcurrent elements 50-1 PICKUP or 50N-1 PICKUP is disabled via configu-
rable dropout times if an inrush pickup occurs, because the occurrence of an inrush does not constitute an
intermittent fault.
Each of these elements can be directional or non-directional (non-directional from V4.81 on).
These elements can be blocked by the automatic reclosure function (AR).
The following figure shows by way of an example the logic diagram for the directional overcurrent element
67-1.
Functions
2.3 Directional Overcurrent Protection 67, 67N
SIPROTEC 4, 7SJ62/64, Manual 89
C53000-G1140-C207-8, Edition 08.2016
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