Siemens siprotec 7SD5, Руководство пользователя

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2.5 Distance Protection
125
7SD5 Manual
C53000-G1176-C169-1
diff
). Another way of blocking the zone is to set a binary input (No 3610
„>BLOCK
Z1-Trip“
).
Switching onto a
Fault If the circuit breaker is manually closed onto a short circuit, the distance protection can
issue an instantaneous trip command. By setting parameters it may be determined
which zone(s) is/are released following a manual close (refer to Figure 2-39). The line
energization information (input „SOTF“) is derived from the state recognition.
Figure 2-39 Switching onto a fault
Note
When switching onto a three-pole fault with the MHO characteristic, there will be no
voltage in the memory or unfaulted loop voltage available. To ensure fault clearance
when switching onto three-pole close-up faults, please make sure that in conjunction
with the configured MHO characteristic the instantaneous tripping function is always
enabled.
2.5.1.4 Setting Notes
At address
1501 FCT Distance
the distance protection function can be switched
ON
or
OFF
.
Minimum Current The minimum current for fault detection
Minimum Iph>
(address
1502
) in case of
impedance pickup is set somewhat (approx. 10 %) below the minimum short-circuit
current that may occur. For the other pickup modes it is set at address
1911
.
Earth Fault
Detection In systems with earthed starpoint, the setting
3I0> Threshold
(address
1503
) is
set somewhat below the minimum expected earth fault current. 3 I
0
is defined as the
sum of the phase currents | I
L1
+ I
L2
+ I
L3
|, which equals the starpoint current of the set
of current transformers. In non-earthed systems the setting value is recommended to
be below the earth current value for double earth faults.
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