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Functions
2.8 Earth Fault Protection in Earthed Systems (optional)
Inrush restraint
The inrush restraint is only required if the device is applied to transformer feeders or on lines that end on a
transformer; in this case also only for such stages that have a pickup threshold below the inrush current and
have a very short or zero delay. The parameters 3I0>>>InrushBlk (address 3115), 3I0>> InrushBlk
(address 3125), 3I0> InrushBlk (address 3135) and 3I0p InrushBlk (address 3150) can be set to YES
(inrush restraint active) or NO (inrush restraint inactive) for each stage. If the inrush restraint has been disabled
for all stages, the following parameters are of no consequence.
For the recognition of the inrush current, the portion of second harmonic current content referred to the funda-
mental current component can be set in address 3170 2nd InrushRest. Above this threshold the inrush
blocking is effective. The preset value (15 %) should be sufficient in most cases. Lower values imply higher
sensitivity of the inrush blocking (smaller portion of second harmonic current results in blocking).
In applications on transformer feeders or lines that are terminated on transformers it may be assumed that, if
very large currents occur, a short-circuit has occurred before the transformer. In the event of such large cur-
rents, the inrush restraint is inhibited. This threshold value which is set in the address 3171 Imax
InrushRest, should be larger than the maximum expected inrush current (RMS value).
2.8.3
Settings
Addresses which have an appended "A" can only be changed with DIGSI, under Additional Settings.
The table indicates region-specific presettings. Column C (configuration) indicates the corresponding second-
ary nominal current of the current transformer.
Addr.
Parameter
3101
FCT EarthFltO/C
3102
BLOCK for Dist.
3103
BLOCK 1pDeadTim
3104A
Iph-STAB. Slope
3105
3IoMin Teleprot
3105
3IoMin Teleprot
3109
Trip 1pole E/F
3110
Op. mode 3I0>>>
3111
3I0>>>
3112
T 3I0>>>
244
C
Setting Options
ON
OFF
every PICKUP
1phase PICKUP
multiph. PICKUP
NO
YES
NO
0 .. 30 %
1A
0.01 .. 1.00 A
5A
0.05 .. 5.00 A
1A
0.003 .. 1.000 A
5A
0.015 .. 5.000 A
YES
NO
Forward
Reverse
Non-Directional
Inactive
1A
0.05 .. 25.00 A
5A
0.25 .. 125.00 A
0.00 .. 30.00 sec; ∞
Default Setting
ON
Earth Fault overcurrent
function
every PICKUP
Block E/F for Distance pro-
tection
YES
Block E/F for 1pole Dead
time
10 %
Stabilisation Slope with
Iphase
0.50 A
3Io-Min threshold for Tele-
prot. schemes
2.50 A
0.500 A
3Io-Min threshold for Tele-
prot. schemes
2.500 A
YES
Single pole trip with earth
flt.prot.
Inactive
Operating mode
4.00 A
3I0>>> Pickup
20.00 A
0.30 sec
T 3I0>>> Time delay
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
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