Weak-End Infeed Logic - ABB REL650 series Technical Manual

Section 12
Scheme communication
12.6.6.3
526
Figure 249. The logic is now ready to handle a current reversal without tripping. The
output signal IRVL will be connected to the block input on the permissive overreaching
scheme.
When the fault current is reversed on the healthy line, IRV is deactivated and IRVBLK is
activated. The tDelayRev timer delays the reset of the output signal. The signal blocks
operation of the overreach permissive scheme for residual current and thus prevents
unwanted operation caused by fault current reversal.
BLOCK
IREV
0
tPickUp
Rev
IRWD
CurrRev = On
ANSI09000031 V2 EN
Figure 249: Simplified logic diagram for current reversal

Weak-end infeed logic

The weak-end infeed function can be set to send only an echo signal (WEI=Echo) or an
echo signal and a trip signal (WEI=Echo & Trip). See figure
The weak-end infeed logic uses normally a reverse and a forward direction element,
connected to WEIBLK1 via an OR-gate. See figure 250. If neither the forward nor the
reverse directional measuring element is activated during the last 200 ms, the weak-end
infeed logic echoes back the received permissive signal. See figure 250.
If the forward or the reverse directional measuring element is activated during the last 200
ms, the fault current is sufficient for the IED to detect the fault with the ground-fault
function that is in operation.
BLOCK
WEIBLK1
200 ms
0
CRL
tPickUpWEI
0
WEI = Echo
ANSI09000032 V2 EN
Figure 250: Simplified logic diagram, weak-end infeed - Echo
0
tPickUp
Rev
AND
10ms
0
& 0 200 ms
50 ms
1MRK 506 335-UUS A
IRVL
0
tDelay
Rev
ANSI09000031-2-en.vsd
250 and figure 251.
ECHO
AND
0
ANSI09000032-2-en.vsd
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