Applying The Function Parameter Settings - Siemens siprotec 7SA6 User Manual

Functions
Figure 6-91 Faulted line location in meshed networks using directional indications

6.11.2 Applying the Function Parameter Settings

6-162
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 6-91). The remaining
directional 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 current. Further advice can be found in the leaflet "Earth-fault detection in
isolated neutral or arc-suppression coil earthed high voltage systems".
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
cases, this section can be passed over.
Earth fault detection is only possible if address 6HQV (DUWK )OW (Section 5.1) was
set to HQDEOHG during the configuration (Section 5.1). If the device is equipped with
earth fault detector but supposed to operate in an earthed network, address 
6HQV (DUWK )OW must be set to GLVDEOHG!
In address  6HQV (DUWK )OW the options can be set for the earth fault
detection function: 21, 2)) and $ODUP RQO\ In the latter case (presetting) the
device announces detected earth faults, identifies the faulty phases and the earth fault
direction according to the other settings.
If the earth fault detection is switched 21 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
 7 8!.
7SA6 Manual
C53000-G1176-C133-1