GE D90 Plus Instruction Manual page 304

Line distance protection system

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CONTROL ELEMENTS

Figure 252: POTT scheme configuration settings

The following settings are available for the permissive over-reaching transfer trip (POTT)

Range: Enabled, Disabled

Default: Disabled

This setting enables and disables the permissive over-reaching transfer trip (POTT)

Permissive Echo

Range: Enabled, Custom, Disabled

Default: Disabled

If this setting is "Enabled", the scheme sends a permissive echo signal to the remote

ends using pre-programmed logic (refer to the following logic diagram). If set to

"Custom", the echo signal is sent if a condition selected via the

satisfied. The echo is sent only once and then the logic locks out for the time specified by

Echo Lockout

setting. The duration of the echo pulse is specified by the Echo

Duration setting. Operation of the overreaching protection elements (distance zone 2 or

Ground Directional OC Forward

Echo Condition

Range: any FlexLogic™ operand

Default: OFF

This setting selects and applies an echo condition and only if the

is "Custom".

RX Pickup Delay

Range: 0.000 to 65.535 seconds in steps of 0.001

Default: 0.000 seconds

This setting enables the relay to cope with spurious receive signals. The delay should be

set longer than the longest spurious TX signal that can be received simultaneously with

the zone 2 pickup. The selected delay will increase the response time of the scheme.

setting) inhibits the echo.

LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL

CHAPTER 7: PROTECTION

Echo Condition

Permissive Echo