Application; Fault Current Reversal Logic; Weak-End Infeed Logic - ABB Relion REC670 Applications Manual

1MRK 511 358-UEN A
14.5.2

Application

14.5.2.1

Fault current reversal logic

Figure 176
reversal.
Assume that fault is near the B1 breaker. B1 Relay sees the fault in Zone1 and A1 relay identifies
the fault in Zone2.
Note that the fault current is reversed in line L2 after the breaker B1 opening.
It can cause an unselective trip on line L2 if the current reversal logic does not block the
permissive overreaching scheme in the IED at B2.
IEC99000043 V3 EN-US
Figure 176: Current distribution for a fault close to B side when all breakers are closed
IEC99000044 V3 EN-US
Figure 177: Current distribution for a fault close to B side when breaker at B1 is opened
When the breaker on the parallel line operates, the fault current on the healthy line is reversed.
The IED at B2 recognizes the fault in forward direction from reverse direction before breaker
operates. As IED at B2 already received permissive signal from A2 and IED at B2 is now
detecting the fault as forward fault, it will immediately trip breaker at B2. To ensure that
tripping at B2 should not occur, the permissive overreaching function at B2 needs to be
blocked by IRVL till the received permissive signal from A2 is reset.
The IED at A2, where the forward direction element was initially activated, must reset before
the send signal is initiated from B2. The delayed reset of output signal IRVL also ensures the
send signal from IED B2 is held back till the forward direction element is reset in IED A2.
14.5.2.2

Weak-end infeed logic

Figure 178
there is no fault current from node B. This causes that the IED at B cannot detect the fault and
trip the breaker in B. To cope with this situation, a selectable weak-end infeed logic is provided
for the permissive overreaching scheme.
Application manual
and Figure 177 show a typical system condition, which can result in a fault current
L1
A1
L2
A2
L1
A1
L2
A2
shows a typical system condition that can result in a missing operation. Note that
B1
B2
IEC9900043-2.vsd
B1
B2
IEC99000044-2.vsd
Section 14
Scheme communication
IP15041-1 v1
M15285-3 v6
M15285-6 v5
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