8 THEORY OF OPERATION
The FlexLogic™ operand 87L BLOCKED is set when the 87L function is enabled and any of the following three conditions
Channel fail as indicated below:
•At least one channel failed either at 3 Terminal or 2 Terminal-1 Channel systems.
•Both channels failed at 2 Terminal-2 Channels
PFFL fail or suspended,
Channel ID failure detected on at least one channel at either system.
GE Power Management
L90 Line Differential Relay