GE P24DM - Selective Logic; Selective Logic Implementation; Selective Logic Diagram; Figure 65: Selective Logic

10 SELECTIVE LOGIC
With Selective Logic you can use the Start signals to control the time delays of upstream IEDs, as an alternative to
simply block
ing them. This provides an alternative approach to achieving non-cascading types of overcurrent
scheme.
10.1 SELECTIVE LOGIC IMPLEMENTATION
Selective Logic is set in the SELEC
TIVE LOGIC column of the relevant settings group.
The Selective Logic function works by temporarily increasing the time delay settings of the chosen overcurrent
elements. This logic is initiated by issuing signals to an upstream IED.
This function acts on the following protection functions:
● Non-Directional/Directional phase overcurrent (3rd, 4th and 6th stages)
● Non-Directional/Directional earth fault – 1 (3rd and 4th stages)
● Non-Directional/Directional earth fault – 2 (3rd and 4th stages)
● Non-Directional/Directional sensitive earth fault (3rd and 4th stages)
Note:
In the event of a conflict between Selective Logic and CLP, Selective Logic takes precedence.
10.2 SELECTIVE LOGIC DIAGRAM
Selective LogicSelective Logic
EnabledEnabled
V04006
I>3 Timer BlockI>3 Timer Block
I>3 Start AI>3 Start A
&
SELE CTIVE LOGI C
timer settings
Applied Time r Se ttings
Note: Selective logic only applies to DT-only stages.
This diagram only shows stage 3
Note: Selective logic only applies to DT-only stages.
This diagram only shows stage 3
Figure 65: Selective Logic
The logic diagram is shown for overcurrent phase A, but is valid for all three phases for each of the stages. The
principle of operation is also identical for earth fault protection.
When the selective logic function is enabled, the action of the blocking input is as follows:
No block applied
In the event of a fault condition that continuously asserts the start output, the function will assert a trip signal after
the normal time delay has elapsed.
Logic input block applied
In the event of a fault condition that continuously asserts the start output, the function will assert a trip signal after
the selective logic time delay has elapsed.
P24xM Chapter 6 - Current Protection Functions
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