Definite Overcurrent Elements 50-1, 50N-1 - Siemens siprotec SJ62 User Manual

2 Functions
2.2.3

Definite Overcurrent Elements 50-1, 50N-1

63
Each phase and ground current is compared separately with the setting values of the
50-1 and 50N-1 relay elements and is signalled separately when exceeded. If the
inrush restraint feature (see below) is applied, either the normal pickup signals or the
corresponding inrush signals are output as long as inrush current is detected. After
user-configured time delays 50-1 DELAY and 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. Tripping signals and signals on the expiration of time
delay are available separately for each element. The dropout value is roughly equal to
95% of the pickup value for currents greater than > 0.3 I
Pickups 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. The function thus does not drop out instantaneously.
The trip 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 violated again.
If the threshold is violated again while the dropout delay time is still running, it will be
cancelled. The trip delay time 50-1 DELAY or 50N-1 DELAY continues in the mean-
time. If the threshold is still exceeded after the time has elapsed, a trip will be initiated
immediately. If the threshold violation then no longer exists, there will be no response.
If the threshold is violated again after the trip command delay time has elapsed and
while the dropout delay time is still running, a trip will be initiated at once.
Pickup stabilization of the overcurrent elements 50-1 or 50N-1 by means of settable
dropout time is deactivated if an inrush pickup is present since an inrush does not rep-
resent an intermittent fault.
These elements can be blocked by the automatic reclosure feature (AR).
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Nom
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015