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

Functions
Switching onto a
Fault
6.2.3.2

Applying the Function Parameter Settings

General Function
Parameters
Correction of
Measured Values
on Parallel Lines
6-48
Without parallel line compensation, the earth current on the parallel line will in most
cases cause the reach threshold of the distance protection to be shortened
(underreach of the distance measurement). In some cases — for example when the
two feeders are terminated to different busbars, and the location of the earth fault is
on one of the remote busbars (at B in Figure 6-27) — it is possible that an overreach
may occur.
The parallel line compensation only applies to faults on the protected line. For faults
on the parallel line, the compensation may not be carried out, as this would cause
severe overreach. The relay located in position II in Figure 6-27 may therefore not be
compensated.
An earth current balance is therefore additionally provided in the device, which carries
out a cross comparison of the earth currents in the two lines. The compensation is only
applied to the line end where the earth current of the parallel line is not substantially
larger than the earth current in the line itself. In example Figure 6-27, the current I
larger than I : compensation is applied at I in that Z
EP
evaluation; at II compensation is not applied.
When the circuit breaker is switched onto a fault with a manual close command, fast
tripping by the distance protection is possible. By setting parameters it may be
determined which zone(s) is/are released following a manual close (refer to Figure 6-
28). The line energization information (input "SOTF") are derived from the state
recognition, refer also to Sub-section 6.20.1.
ENABLE Z1B
3611
!"! TPUAÓ‚r
Dhp‡v‰r
a‚rÃa 7
„1"
QD8FVQ
SOTF Op. mode
Figure 6-28 Circuit breaker closure onto a fault
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
somewhat (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.
The mutual coupling between the two lines of a double-circuit configuration is only
relevant to the 7SA6 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
≥1
≥1
&
&
· I is included in the
M EP
Z1B instantaneous.
Z2 instantaneous.
Z3 instantaneous.
Z4 instantaneous.
Z5 instantaneous.
7SA6 Manual
C53000-G1176-C133-1
is
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