Table 6-9 Threshold Setting Range with Different Connection Types
Connection Type of
the Measuring Point
I-3ph
Current Threshold 3I0/IN CT Terminal Type Threshold Setting
Range
(Secondary)
17
3-phase
Calculated 3I0
18
4 x Protection 0.030 A to 35.000 A
3 x Protection, 1 x sensitive 0.030 A to 35.000 A
4 x Measurement 0.001 A to 1.600 A
3-phase + IN
3-phase + IN-separate
Measured IN
19
4 x Protection 0.030 A to 35.000 A
4 x Measurement 0.001 A to 1.600 A
Measured IN and calculated
3I0 when IN > 1.6 A
3 x Protection, 1 x sensitive 0.001 A to 35.000 A
Method of Measurement
The stage calculates the RMS value of 3I0 since this value takes into account the higher-order harmonics
components and the direct component (DC). Both components contribute to the thermal load.
Maximum 3I0 of the Fault
The stage records the maximum RMS value of 3I0 during the intermittent ground fault. The statistic value
3I0
max.
is a percentage value calculated through dividing the primary maximum RMS value by the rated current
value of the protected object. With the coming operate signal, this value is logged via the information
3I0
max.
.
Pickup and Intermittent Ground-Fault Indication
When 3I0 exceeds the threshold value, the pickup signals
Pickup
and
Limited pickup (log)
are issued.
The stage generates the
Stabilized pickup
signal by extending the
Pickup
for a defined time (param-
eter Pickup extension time).
The stage counts the
Pickup
signals. If the counted number reaches the configured No. pickups till
interm.GF, the
Intermittent gnd.flt.
signal is issued. The signal
Limited pickup (log)
is not
issued anymore after the issue of the
Intermittent gnd.flt.
signal.
[DwIntFaD, 2, en_US]
Figure 6-112 Fault Detection of the Intermittent Ground-Fault Protection
17
These values apply for a secondary rated current of 1 A. The values need to be multiplied by 5 when the secondary rated current is 5 A.
18
If the connection type is without IN, such as 3-phase, the current threshold value is a calculated 3I0 value.
19
If the connection type is with IN, such as 3-phase + IN, the current threshold value is a measured IN value.
Protection and Automation Functions
6.13 Non-Directional Intermittent Ground-Fault Protection
SIPROTEC 5, Overcurrent Protection, Manual 545
C53000-G5040-C017-8, Edition 07.2017
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