ABB Relion 670 Series Applications Manual page 400

Section 14
Scheme communication
14.5.2 Application
14.5.2.1 Fault current reversal logic
Figure 189
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.
Strong
source
ANSI99000043 V1 EN-US
Figure 189: Current distribution for a fault close to B side when all breakers are closed
Strong
source
ANSI99000044 V1 EN-US
Figure 190: 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 191
is no fault current from node B. This causes that the IED at B cannot detect the fault and trip the
394
and Figure 190 show a typical system condition, which can result in a fault current
CLOSED
LINE 1
A:1
A
CLOSED
LINE 2
A:2
CLOSED
LINE 1
A:1
A
CLOSED
LINE 2
A:2
shows a typical system condition that can result in a missing operation. Note that there
CLOSED
FAULT
Weak
source
B:1
B
CLOSED
B:2
en99000043_ansi.vsd
FAULT OPEN
Weak
source
B:1
B
CLOSED
B:2
en99000044_ansi.vsd
1MRK 511 358-UUS A
IP15041-1 v1
M15285-3 v6
M15285-6 v5
Application manual