Operation: Disabled or Enabled.
SchemeType: This parameter can be set to Off , Intertrip, Permissive UR, Permissive OR
or Blocking.
tCoord: Delay time for trip from ECPSCH (85) function. For Permissive under/
overreaching schemes, this timer shall be set to at least 20 ms plus maximum reset time of
the communication channel as a security margin. For Blocking scheme, the setting should
be > maximum signal transmission time +10 ms.
Unblock: Select Off if unblocking scheme with no alarm for loss of guard is used. Set to
Restart if unblocking scheme with alarm for loss of guard is used.
tSendMin: Time duration, the carrier send signal is prolonged.
tSecurity: The absence of CRG signal for a time duration of tSecurity is considered as CR
signal.
16.7 Current reversal and weak-end infeed logic for residual
overcurrent protection ECRWPSCH (85)
16.7.1 Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Current reversal and weak-end infeed
logic for residual overcurrent protection
ECRWPSCH - 85
16.7.2 Application
16.7.2.1 Fault current reversal logic
Figure 376 and figure 377 show a typical system condition, which can result in a fault
current 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.
1MRK 506 369-UUS - Section 16
Scheme communication
Line distance protection REL670 2.2 ANSI 771
Application manual
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