Siemens siprotec 7SA6, Manual

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Functions
6-183
7SA6 Manual
C53000-G1176-C156-2
In meshed or ring networks the measuring points at the ends of the faulted cable also
see a maximum of earth fault (capacitive or ohmic) current. Only in this cable will the
direction “forwards” be indicated on both line ends (Figure 6-99). The remaining direc-
tional indications in the network can aid location of the earth fault. But under certain
circumstances one or more indications may not be given due to insufficient earth cur-
rent. Further advice can be found in the leaflet “Earth-fault detection in isolated neutral
or arc-suppression coil earthed high voltage systems”.
Figure 6-99 Faulted line location in meshed networks using directional indications
6.13.2 Applying the Function Parameter Settings
This section applies only to relay models with earth fault detection module and only
when these are used in networks with isolated or compensated starpoint. In other cas-
es, this section can be passed over.
Earth fault detection is only possible if address
Sens. Earth Flt
(Section 5.1) was
set to
enabled
during the configuration (Section 5.1). If the device is equipped with
earth fault detector but supposed to operate in an earthed network, address
130
Sens. Earth Flt
must be set to
disabled
!
In address
3001 Sens. Earth Flt
the options can be set for the earth fault detec-
tion function:
ON
,
OFF
and
Alarm only.
In the latter case (presetting) the device
announces detected earth faults, identifies the faulty phases and the earth fault direc-
tion according to the other settings.
If the earth fault detection is switched
ON,
it also issues a trip command. In this case
no earth fault protocol is generated, but a trip log that registers all information about
the earth fault and the earth fault tripping. The tripping can be delayed via address
3007 T 3U0>
.