Siemens 7SJ82, Manual

Page: 586 / 1638

In the following, certain settings are explained that are necessary for this application (detection of intermittent
ground faults):
•
Parameter:
(_:2311:102) Dropout delay
The function must treat the intermittent process as one ground fault. For this, it is necessary that the
indication
Ground fault
does not drop out between 2 consecutive current peaks. This is ensured via
the
Dropout delay
parameter (FB General). A dropout delay of 1 s is a feasible value.
•
Parameter:
(_:12601:104) Dir. determination delay
You must set the delay of the direction determination to 0 s so that the direction of the current peaks can
be determined.
•
Parameter:
(_:12601:105) α1 reduction dir. area
and
(_:12601:106) α2 reduction
dir. area
The current peaks show a clear ohmic component. With these parameters, you can limit the direction
characteristic and ensure a reliable direction result.
Siemens recommends setting both parameters to 10°.
•
Parameter:
(_:12601:110) Blk. after fault extinction
To make possible a continuous and immediate detection of the current peaks, you must switch off the
blocking after fault suppression.
No further parameters need particular consideration with regard to an intermittent ground fault. You can set
these as for the detection of permanent ground faults.
Directional 3I0 Stage with φ(V0,3I0) Measurement
Description
Logic
[logfppvi-291112-02.vsd, 1, en_US]
Figure 6-133 Logic Diagram of the Stage Control
6.15.7
6.15.7.1
Protection and Automation Functions
6.15 Sensitive Ground-Fault Detection
586 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017