GE D90 Plus Instruction Manual page 276

CONTROL ELEMENTS
268
Figure 210: Directional comparison unblocking scheme configuration settings
The following settings are available for the directional comparison unblocking scheme.
Function
Range: Enabled, Disabled
Default: Disabled
This setting enables and disabled the directional comparison unblocking scheme.
Block
Range: any FlexLogic™ operand
Default: OFF
This setting allows the user to assign any FlexLogic™ operand to block the directional
comparison unblocking scheme. Contact inputs from a pilot cut-out switch are typically
used for this purpose.
Permissive Echo
Range: Disabled, Enabled, Custom
Default: Disabled
Enabling this setting will send a permissive echo signal to the remote ends under certain
conditions (refer to the logic diagram for details). If set to "Custom", the echo signal is
sent if a condition selected with the
only once and then the echo logic locks out for the time specified by the
setting. The duration of the echo pulse is programmable by the
The echo is returned only if no overreaching and reverse protection elements operate.
Echo Condition
Range: any FlexLogic™ operand
Default: OFF
This setting specifies and applies an echo condition when the
"Custom".
setting is satisfied. The echo is sent
Echo Condition
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: PROTECTION
Echo Lockout
Echo Duration setting.
setting is
Permissive Echo