Setting guidelines for weak-end infeed logic
The WEI function returns the received carrier signal with the ECHO output when
it receives the carrier signal (CR) if no fault has been detected by forward- and
reverselooking zones and the signal duration is longer than the
Wei Crd time
coordination time delay setting. Set the
Wei Crd time
= "0.010" s to avoid the
spurious carrier received signals that activate the WEI logic and cause unwanted
communication.
Set the voltage criteria
PPV level for Wei
and
PhV level for Wei
for the weak-end
trip to 70 percent of the system's base voltage. The setting should be below the
minimum operate voltage of the system but above the voltage that occurs for a
fault on the protected feeder. The phase-to-phase elements must be verified not to
operate for the phase-to-earth faults.
5.12.7 Signals
5.12.7.1 CRWPSCH Input signals
Table 1199: CRWPSCH Input signals
Name Type Default Description
U3P SIGNAL - Three-phase voltages
BLOCK BOOLEAN 0=False Block signal for acti-
vating the blocking
mode
BLK_IRV BOOLEAN 0=False Block of current rever-
sal function
BLK_WEI1 BOOLEAN 0=False Block of WEI Logic
BLK_WEI2 BOOLEAN 0=False Block of WEI logic due
to operation of other
protections
IRV BOOLEAN 0=False Activation of current
reversal logic
FF BOOLEAN 0=False Block of trip from
WEI logic through
fuse-failure function
CB_OPEN BOOLEAN 0=False Block of trip from
WEI logic by an open
breaker
CR BOOLEAN 0=False POR Carrier receive
for WEI logic
CR BOOLEAN 0=False POR Carrier signal re-
ceived from remote
end
1MRS759142 F Protection related functions
REX640
Technical Manual
1271
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