Definite Time Overcurrent Elements 50-1, 50N-1 - Siemens 7SC80 Manual

Functions
2.2 Overcurrent Protection 50, 51, 50N, 51N
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 func-
tion 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 canceled. The trip delay time 50-3 DELAY, 50-2 DELAY or 50N-3 DELAY, 50N-2
DELAY continues running in the meantime. If the threshold value is exceeded after this time has elapsed, 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, tripping is initiated immediately.
These elements can be blocked by the automatic reclosing function (79 AR).
The pickup values of each 50-2, 50-3 element for phase currents and 50N-2, 50N-3 element for the ground
current and the element-specific time delays can be set individually.
The logic for the 50-2 and 50-3 elements corresponds to the logic for the 50-1 element shown in
The logic for the 50N-2 and 50N-3 elements corresponds to the logic for the 50N-1 element shown in
Figure 2-9.

Definite Time Overcurrent Elements 50-1, 50N-1

2.2.3
For each element an individual pickup value 50-1 PICKUP or 50N-1 PICKUP is set. Apart from Funda-
mental, the True RMS can also be measured. Each phase and ground current is compared separately with
the setting value 50-1 PICKUP or 50N-1 PICKUP for each element. If the respective value is exceeded, this
is signaled. If the inrush restraint feature (see below) is applied, either the normal pickup signals or the corre-
sponding inrush signals are output as long as inrush current is detected. After user-configured time delays
50-1 DELAY or 50N-1 DELAY have elapsed, a trip signal is issued if no inrush current is detected or inrush
restraint is disabled. 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 on the expiration of time delay are available separately for each element. The dropout
value is approximately 95% of the pickup value for currents > 0.3 Ι
Pickup can be stabilized by setting dropout times 1215 50 T DROP-OUT or1315 50N 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
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 50-1 or 50N-1 has been exceeded again. If the threshold is exceeded
again during the dropout delay time, the time is canceled. However, the trip-command delay time 50-1
DELAY or 50N-1 DELAY continues running. 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, tripping occurs immediately.
Pickup stabilization of the overcurrent elements 50-1 or 50N-1 by means of settable dropout time is deacti-
vated if an inrush pickup is present since an inrush does not represent an intermittent fault.
These elements can be blocked by the automatic reclosing function (79 AR).
The pickup values of each 50-1 element for phase currents and 50N-1 element for the ground current and the
element-specific time delays can be set individually.
The following figures show the logic diagrams for the current elements 50-1 and 50N-1.
72
.
Nom
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017
Figure 2-7.