Selective Logic; Selective Logic Implementation; Selective Logic Diagram; Figure 53: Selective Logic - GE MiCOM P40 Agile Technical Manual

Chapter 6 - Current Protection Functions
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 blocking 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 SELECTIVE 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 LOGIC

timer settings
Selective Logic
Enabled
I>3 Timer Block
I >3 Start A
AR Blk Main Prot
I> Blocking
AR Blocks I>3

Figure 53: 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.
Auto-reclose input block applied
In the event of a fault condition that continuously asserts the start output, when an auto-reclose block is applied
the function will not trip. The auto-reclose block also overrides the logic input block and will block the selective
logic timer.
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Note: Selective logic only applies to DT -only stages .
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This diagram only shows stage 3
P14D
Applied Timer Settings
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P14D-TM-EN-8