GE UR Series Instruction Manual page 291

8 THEORY OF OPERATION
The FlexLogic™ operand 87L BLOCKED is set when the 87L function is enabled and any of the following three conditions
apply:
1. 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
2. PFFL fail or suspended,
3. Channel ID failure detected on at least one channel at either system.
GE Power Management L90 Line Differential Relay
8.1 OVERVIEW
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