en99000044_ansi.vsd
Strong
source
LINE 1
LINE 2
A:1
A:2
B:1
B:2
A
B
Weak
source
CLOSED
CLOSED
OPEN
CLOSED
FAULT
ANSI99000044 V1 EN-US
Figure 392:
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.
16.6.2.2
Weak-end infeed logic
M15285-6 v5
Figure
shows a typical system condition that can result in a missing operation.
Note that 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.
en99000054_ansi.vsd
LINE 1
A
B
Strong
source
Weak
source
CLOSED
CLOSED
FAULT
ANSI99000054 V1 EN-US
Figure 393:
Initial condition for weak-end infeed
16.6.3
Setting guidelines
IP15042-1 v1
M13933-4 v5
The parameters for the current reversal and weak-end infeed logic for residual
overcurrent protection function are set via the local HMI or PCM600.
1MRK 504 163-UUS A
Section 16
Scheme communication
Transformer protection RET670 2.2 ANSI
835
Application manual
Содержание RELION RET670
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