ABB RED650, Техническое руководство

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13.5.2 Functionality
M13928-3 v8
The Current reversal and weak-end infeed logic for residual overcurrent protection
(ECRWPSCH) is a supplement to Scheme communication logic for residual
overcurrent protection ECPSCH.
To achieve fast fault clearing for all earth faults on the line, the directional earth
fault protection function can be supported with logic that uses tele-protection
channels.
This is why the IEDs have available additions to the scheme communication logic.
M13928-6 v2
If parallel lines are connected to common busbars at both terminals, overreaching
permissive communication schemes can trip unselectively due to fault current
reversal. This unwanted tripping affects the healthy line when a fault is cleared on
the other line. This lack of security can result in a total loss of interconnection
between the two buses. To avoid this type of disturbance, a fault current reversal
logic (transient blocking logic) can be used.
M13928-8 v5
Permissive communication schemes for residual overcurrent protection can
basically operate only when the protection in the remote IED can detect the fault.
The detection requires a sufficient minimum residual fault current, out from this
IED. The fault current can be too low due to an opened breaker or high-positive
and/or zero-sequence source impedance behind this IED. To overcome these
conditions, weak-end infeed (WEI) echo logic is used. The weak-end infeed echo is
limited to 200 ms to avoid channel lockup.
13.5.3 Function block
M13930-3 v6
ECRWPSCH
U3P*
BLOCK
IRVBLK
IRV
WEIBLK1
WEIBLK2
VTSZ
CBOPEN
CRL IRVL
TRWEI
ECHO
IEC06000289-3-en.vsd
IEC06000289 V3 EN-US
Figure 210: ECRWPSCH function block
Section 13
1MRK 505 394-UEN A
Scheme communication
424 Line differential protection RED650 2.2 IEC
Technical manual