Functions
2.3 Directional Overcurrent Protection 67, 67N
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
100
2.3.3 Definite Time, Directional Overcurrent Elements 67-1, 67N-1
For each element an individual pickup value 67-1 PICKUP or 67N-1 PICKUP is set, which can be measured
as Fundamental or True RMS. Phase and ground currents are compared separately with the common setting
value 67-1 PICKUP or 67N-1 PICKUP. Currents above the setting values are signaled separately when fault
direction is equal to the configured direction. If the inrush restraint feature is used, either the normal pickup
signals or the corresponding inrush signals are issued as long as inrush current is detected. When, after pickup
without inrush recognition, the relevant delay times 67-1 DELAY, 67N-1 DELAY have expired, a tripping
command is issued. 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 signals upon expiry of the time delay are available separately for each element. The dropout
value is approxmiately 95% of the pickup value for currents > 0.3 I
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 function
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 ex-
ceeded again during the dropout delay time, the time is cancelled. 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 configurable
dropout times if an inrush pickup occurs, because the occurrence of an inrush does not constitute an intermit-
tent fault.
These elements can be blocked by the automatic reclosure feature (AR).
The following figure shows by way of an example the logic diagram for the directional overcurrent element 67-1.
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