CHAPTER 7: PROTECTION
Protection FlexElements
PLUS
D90
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Table 25: Non-volatile latch operation table
Type
Latch operation
Set
Reset-dominant
ON
OFF
ON
OFF
Set-dominant
ON
ON
OFF
OFF
The figure shows the logic diagram for protection non-volatile latches.
A FlexElement is a universal comparator that can be used to monitor any analog actual
value calculated by the relay or a net difference between any two analog actual values of
the same type. The effective operating signal can be treated as a signed number or an
absolute value. The output from a FlexElement can also be used for further logic
processing. The number of FlexElements dedicated is 16.
The element can be programmed to respond either to a signal level or to a rate-of-change
(delta) over a pre-defined period of time. The output operand is asserted when the
operating signal is higher than a threshold or lower than a user-specified threshold.
Select the Settings > Protection > Protection FlexLogic > FlexElements menu to open the
protection FlexElements configuration window.
Reset
OFF
OFF
ON
ON
OFF
ON
OFF
ON
Figure 352: Non-volatile latch logic
PROTECTION FLEXLOGIC
On
Off
ON
OFF
Previous state
Previous state
OFF
ON
OFF
ON
ON
OFF
ON
OFF
Previous state
Previous state
OFF
ON
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