Siemens 7SJ85 - Settings

System Type/
Neutral-Point Treat-
ment
Description
Resistance-
Grounded
In the resistance-grounded system, the ohmic-inductive ground-fault current is decisive
for the direction determination.
To evaluate this short-circuit current, set the parameters as follows:
•
Dir. measuring method = cos φ
•
φ correction = -45.0°
Set the Min.polar.3I0> for dir.det. and 3I0> threshold value parame-
ters to a value below the minimum ground-fault current to be expected.
Parameter: α1 reduction dir. area, α2 reduction dir. area
•
Recommended setting value (_:12601:105) α1 reduction dir. area = 2°
•
Recommended setting value (_:12601:106) α2 reduction dir. area = 2°
With the α1 reduction dir. area and α2 reduction dir. area parameters, you specify the angle
for the limitation of the direction range. Siemens recommends using the default setting of 2°.
In an arc-suppression-coil-ground system in feeders with a very large reactive current, it can be practical to set
a somewhat larger angle α1 to avoid a false pickup based on transformer and algorithm tolerances.
Parameter: V0> threshold value
•
Default setting (_:12601:103) V0> threshold value = 30.000 V
The V0> threshold value parameter allows you to set the zero-sequence voltage sensitivity of the stage.
Set the threshold value smaller than the minimum absolute value of the zero-sequence voltage V0 that must
still be detected.
Parameter: Dir. determination delay
•
Default setting (_:12601:104) Dir. determination delay = 0.00 s
The start of the ground fault normally shows a significant transient behavior. This can lead to an incorrect
direction decision. The direction determination can be delayed from the occurrence of the zero-sequence
voltage with the Dir. determination delay parameter to achieve steady-state measurands. The dura-
tion of the transient cycle is determined from the system conditions and the respective fault characteristics. If
you have no knowledge of a suitable time delay, Siemens recommends keeping the default setting.
Parameter: Operate delay
•
Default setting (_:12601:6) Operate delay = 2.0 s
The Operate delay parameter determines the time during which the pickup conditions must be met to
issue the operate indication. The operate indication is issued when this time expires.
Settings
Addr.
Parameter C Setting Options Default Setting
3I0> cos/sinφ1
_:12601:1 3I0> cos/sinφ1:Mode
•
off
•
on
•
test
off
_:12601:2 3I0> cos/sinφ1:Operate
& flt.rec. blocked
•
no
•
yes
no
_:12601:10 3I0> cos/sinφ1:Blk. by
meas.-volt. failure
•
no
•
yes
yes
_:12601:27 3I0> cos/sinφ1:Blk. w.
inrush curr. detect.
•
no
•
yes
no
6.15.4.3
Protection and Automation Functions
6.15 Sensitive Ground-Fault Detection
576 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017