Fault det
is blocked for the fault log and the system interface. This method accounts for the fact that the
ΙΙE element may also pick up for a normal short-circuit. In this case the pickup does not launch the alarm
Intermitt.EF
.
Intermittent ground faults may cause other overcurrent elements to pick up (e.g. 50-1, 50N-1, 50Ns-1), which
may result in a burst of messages. In order to avoid an overflow of the fault log, its messages are no longer
entered in the fault log after detection of intermittent ground faults (indication
Intermitt.EF
), unless they
cause a trip command. If an intermittent ground fault has been detected, the following pickup messages of
the time overcurrent protection will still be reported without restraint (see
Intermitt.EF
):
Table 2-8 Unrestricted Messages
FNo. Message Description
1800
50-2 picked up
50-2 picked up
7551
50-1 InRushPU
50-1 InRush picked up
7552
50N-1 InRushPU
50N-1 InRush picked up
7553
51 InRushPU
51 InRush picked up
7554
51N InRushPU
51N InRush picked up
7565
Ia InRush PU
Phase A InRush picked up
7566
Ib InRush PU
Phase B InRush picked up
7567
Ic InRush PU
Phase C InRush picked up
7564
Gnd InRush PU
ground InRush picked up
Table 2-9 shows all messages subject to a restraint mechanism avoiding a message burst during an intermit-
tent ground fault:
Table 2-9
Buffered Messages
FNo. Message Description
1761
50(N)/51(N) PU
50(N)/51(N) picked up
1762
50/51 Ph A PU
50/51 Phase A picked up
1763
50/51 Ph B PU
50/51 Phase B picked up
1764
50/51 Ph C PU
50/51 Phase C picked up
1767
50-3 picked up
50-3 element picked up
1810
50-1 picked up
50-1 element picked up
1820
51 picked up
51 element picked up
1765
50N/51NPickedup
50N element picked up
1768
50N-3 picked up
50N-3 element picked up
1831
50N-2 picked up
50N-2 element picked up
1834
50N-1 picked up
50N-1 element picked up
1837
51N picked up
51N element picked up
5159
46-2 picked up
46-2 picked up
5165
46-1 picked up
46-1 picked up
5166
46-TOC pickedup
46-TOC picked up
1221
50Ns-2 Pickup
50Ns-2 elementpicked up
1224
50Ns-1 Pickup
50Ns-1 elementpicked up
1227
51Ns Pickup
51Ns elementpicked up
6823
48 pickup
48 Startup supervision Pickup
Before they are entered in the fault log (event buffer) and transmitted to the system interface or CFC, the indi-
cations of Table 2-9 are buffered (starting with the incoming indication
Intermitt.EF
). The buffering does
not apply to signaling to relays and LEDs as it is required by time-graded protection systems for reverse inter-
locking. The buffer can store a maximum of two status changes (the most recent ones) for each indication.
Functions
2.10 Intermittent Ground Fault Protection
SIPROTEC 4, 7SJ61, Manual 143
C53000-G1140-C210-6, Edition 05.2016
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