Functions
2.2 Overcurrent Protection 50, 51, 50N, 51N
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
64
The following table gives an overview of the interconnection to other functions of 7SJ62/64.
Table 2-1 Interconnection to other functions
2.2.2 Definite Time, High-set Elements 50-3, 50-2, 50N-3, 50N-2
For each element an individual pickup value 50-3 PICKUP, 50-2 PICKUP or 50N-3 PICKUP, 50N-2
PICKUP is set. For 50-3 PICKUP and 50N-3 PICKUP, apart from Fundamental and True RMS, the
Instantaneous values can also be measured. Each phase and ground current is compared separately per
element with the common pickup values 50-3 PICKUP, 50-2 PICKUP or 50N-3 PICKUP, 50N-2 PICKUP.
If the respective pickup value is exceeded, this is signaled. After the user-defined time delays 50-3 DELAY,
50-2 DELAY or 50N-3 DELAY, 50N-2 DELAY have elapsed, trip signals are issued which are available for
each element. The dropout value is roughly equal to 95% of the pickup value for currents > 0.3 I
Nom
. If the mea-
surement of the instantaneous values has been configured for the 50-3 or 50N-3 element, the dropout ratio
amounts to 90 %.
Pickup can be stabilized by setting dropout times 1215 50 T DROP-OUT or 1315 50N 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 delay time 50-3 DELAY, 50-2 DELAY or 50N-3 DELAY, 50N-2
DELAY continues running 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 50-3 PICKUP, 50-2 PICKUP or 50N-3 PICKUP,
50N-2 PICKUP has been exceeded again. If the threshold is exceeded again during the dropout delay time,
the time is cancelled. The trip delay time 50-3 DELAY, 50-2 DELAY or 50N-3 DELAY, 50N-2 DELAY con-
tinues running in the meantime. If the threshold value is exceeded after its expiry, the trip command is issued
immediately. If the threshold value is not exceeded at this time, there is 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, trip-
ping occurs immediately.
These elements can be blocked by the automatic reclosing feature (79 AR).
The following figures give an example of logic diagrams for the high-set elements 50-2 PICKUP or
50N-2 PICKUP. They also apply analogously to the high-set elements 50-3 PICKUP and 50N-3 PICKUP.
Overcurrent Ele-
ments
Connection to
Automatic Reclosing
Manual
CLOSE
Dynamic
Cold Load Pickup
Inrush Restraint
50-1 ••• •
50-2 •••
50-3 •••
51 ••• •
50N-1 ••• •
50N-2 •••
50N-3 •••
51N ••• •
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