Functions
6-397SA522 Manual
C53000-G1176-C119-2
Figure 6-24 circuit breaker closure onto a dead fault
6.2.2.2 Applying the Function Parameter Settings
General Function
Parameters
The distance protection can be switched on or off with the parameter in address
)&7'LVWDQFH 212))
The minimum current for fault detection 0LQLPXP,SK! (address ) is set some-
what (approx. 10 %) below the minimum short-circuit current that may occur.
The setting parameters for the treatment of earth faults ,!7KUHVKROG and
8!7KUHVKROG were already discussed in Sub-section 6.2.1.2.
Correction of
measured values
on Parallel Lines
The mutual coupling between the two lines of a double-circuit configuration is only rel-
evant to the 7SA522 when it is applied on a double-circuit line and when it is intended
to implement parallel line compensation. A prerequisite is that the earth current of the
parallel line is connected to the I
4
measuring input of the 7SA522 and this is entered
in the configuration settings.
In this case, the setting 3DUDO/LQH&RPS = <(6 must be set in address ; oth-
erwise the presetting 12 remains.
The coupling factors were already set as part of the general protection data (Sub-sec-
tion 6.1.3), as was the reach of the parallel line compensation.
Double Earth Faults
in Effectively
Earthed Systems
The loop selection for double earth faults is set in address 3K(IDXOWV
(Phase–Phase–Earth–fault detection). This setting can only be modified with DIGSI
®
4 under “Additional Settings”. In general the %ORFNOHDGLQJ (blocking of the
leading phase, presetting) is favourable, because the leading phase-earth loop tends
to overreach, especially in conjunction with large earth fault resistance. In certain cas-
es (fault resistance phase-phase larger than phase-earth) the setting %ORFNODJ
JLQJ
Ø (blocking of the lagging phase) may be more favourable. The selection of all
affected loops with the setting $OO ORRSV allows a maximum degree of redundancy.
Alternatively, ORRSVRQO\ may be evaluated. This ensures the most accuracy
for two phase to earth faults. Ultimately it is possible to declare the
Ø-E loops only
as
valid.
Line Energization
onto a Dead Fault
To determine the reaction of the distance protection during closure of the circuit break-
er onto a dead fault, the parameter in address 627)]RQH is used. The setting
,QDFWLYH specifies that there is no special reaction, i.e. all distance stages operate
according to their set zone parameters. The setting =RQH=% causes all faults inside
the overreaching zone Z1B to be cleared without delay following closure of the circuit
Z1B instantaneous.
627)]RQH
=RQH=%
,QDFWLYH
3,&.83
„1“
SOTF Op. mode
≥1
&
≥1
&
Z2 instantaneous.
Z3 instantaneous.
Z4 instantaneous.
Z5 instantaneous.
ENABLE Z1B
3611
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