Siemens 7SJ85 - Application and Setting Notes

Information Target Processing of Signal Status Changes
Communication interface IEC 61850-8-1 Client/Server
IEC 60870-5-103/104
DNP V3.0
Special buffering mechanism
Protection interface PDI Pass through
IEC 61850-8-1 GOOSE Pass through
CFC Pass through
LEDs Pass through
Binary output Pass through
Fault recorder Pass through
Automatic reclosing function Discard
Circuit-breaker failure protection Discard
Group indications Discard
Application and Setting Notes
No Start of the Automatic Reclosing Function
Automatic reclosing is not an effective measure against intermittent ground faults as the protection function
only operates after repeated detection of a fault or after the integration value reaches the predefined Sum of
extended PU times. Besides this, its basic design is to prevent thermal overload. For these reasons, the
intermittent ground-fault protection function is not intended to start the automatic reclosing function.
Rooting of Pickup Signals
The signal
Pickup is supposed to be routed to LED and relay. The signal Limited pickup (log) is only
reported to the fault log and communication interface before the signal Intermittent gnd.flt. is issued.
This scheme prevents a burst of messages.
i
i
NOTE
To avoid a burst of messages, do not route the signal Pickup to the operational log and fault log.
Parameter: Threshold
•
Default setting (_:11341:3) Threshold = 1.00 A
With the Threshold parameter, you set the threshold value of the ground current 3I0, measured as RMS
value.
A rather sensitive setting is possible to respond also to short ground faults since the pickup time shortens as
the ground-fault current increases.
Parameter: No. pickups till interm.GF
•
Default setting (_:11341:101) No. pickups till interm.GF = 3
With the parameter No. pickups till interm.GF, you set the number of counted Pickup signals after
which the ground fault is considered as intermittent.
Parameter: Pickup extension time
•
Default setting (_:11341:102) Pickup extension time = 0.10 s
You can get a stabilized pickup signal with the Pickup extension time parameter. This stabilization is
especially important for the coordination with existing static or electromechanical overcurrent protections.
6.13.4
Protection and Automation Functions
6.13 Non-Directional Intermittent Ground-Fault Protection
548 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017