This signal is generated automatically, if reclosure is blocked, CB Ready is inactive, the CB is
open, the single-phase discrimination time
t1P Discrim has elapsed or the signal First AR 3P is
active.
Zone extension ZExtension
The setting of the autoreclosure parameter
ZE Prefault determines the pre-fault reach of the
distance protection when the autoreclosure function is inactive (before the first fault), that is,
setting
ZE Prefault to on activates the output signal ZExtension which then switches the
distance function to overreach.
The parameters
ZE 1. AR reach to ZE 4. AR reach provide facility for individually switching the
reach for each reclosure attempt. Setting one of these parameters to on means that the
ZExtension output is at logical 1 and the distance relay is switched to overreach either before
fault occurrence or for the following reclosure attempt, otherwise the distance relay is set to
underreach.
With the exception of its first change of state when setting the
ZEPrefault parameter to ON it
resets together with the signal Trip CB or Trip CB 3P, this signal picks up and resets together
with the Close CB signal.
The distance relay is switched to overreaching for a Manual close.
It is switched to underreaching when the autoreclosure function is blocked.
Note also that the ZExtension signal is connected to the binary input ZEMode AR of the zone
extension logic in the distance protection function.
5.8.7
Timing diagrams
GUID-EB943681-2270-41A7-81AC-C18A80DCAA35 v1
The time relationship between the various signals during operation of the autoreclosure
function can be seen from the following diagrams.
1MRK 505 406-UEN B
Section 5
Bay protection functions
Bay protection functions REB500
147
Technical manual
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