Siemens SIPROTEC 4 7SJ61 Manual page 50

Functions
2.2 Overcurrent Protection 50, 51, 50N, 51N
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 following figures show the logic diagrams for the current elements 50-1 and 50N-1.
[7sj6x-ueberstromst-i-fuer-ph-20061212, 1, en_US]
Figure 2-7
If parameter MANUAL CLOSE is set to 50 -1 instant. and manual close detection is used, a pickup causes
instantaneous tripping, even if blocking of the element via binary input is present.
The same applies to 79 AR 50-1 inst.
The dropout delay only operates if no inrush was detected. An incoming inrush will reset a running dropout
delay time.
50
Logic diagram for the 50-1 overcurrent element for phases
SIPROTEC 4, 7SJ61, Manual
C53000-G1140-C210-6, Edition 05.2016