ABB RELION REX640 Technical Manual page 1274

Protection related functions
5.13 Current reversal and weak-end infeed logic for
residual overcurrent RCRWPSCH (ANSI 85 67G/N
CREV,WEI)
5.13.1 Identification
Function description
Current reversal and weak-end in-
feed logic for residual overcurrent
5.13.2 Function block
Figure 721: Function block
5.13.3 Functionality
The current reversal and weak-end infeed logic for residual overcurrent function
RCRWPSCH can be used when the communication logic for residual overcurrent
RESCPSCH requires additional logics to operate correctly in all power system
conditions.
In parallel feeder applications, the direction of the fault current on the healthy
feeder can change when the circuit breaker on the faulty feeder opens to clear the
fault. This can lead to an unwanted operation of the residual overcurrent protection
on the healthy parallel feeder when RESCPSCH with the permissive overreach
scheme is used. The main purpose of the current reversal logic is to prevent such
unwanted operations.
The permissive communication schemes can operate only when the protection
in the remote terminal can detect the fault. This detection requires sufficient
minimum fault current. If such current is not available due to too weak a remote
end source, the WEI logic can be used to overcome the situation and trip the remote
end breaker.
5.13.4 Analog channel configuration
RCRWPSCH has one analog group input which must be properly configured.
1274
IEC 61850 IEC 60617
identification identification
RCRWPSCH CLCRWN
1MRS759142 F
ANSI/IEEE C37.2
device number
85 67G/N
CREV,WEI
REX640
Technical Manual