CHAPTER 7: PROTECTION
PROTECTION FLEXLOGIC™
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
403
FlexLogic™ rules
When forming a protection FlexLogic™ equation, the sequence in the linear array of
parameters must follow these general rules.
1.
Logic operands must precede the logic operator that uses the operands as inputs.
2.
Logic operators have only one output. The output of an operator must be used to
create a virtual output if it is to be used as an input to two or more operators.
3.
Assigning the output of a logic operator to a virtual output terminates the equation.
4.
A timer operator (for example
TIMER 1
) or virtual output assignment (for example,
= Virt
Op 1
) may only be used once. If this rule is broken, a syntax error will be declared.
Graphical programming interface
EnerVista Viewpoint Engineer provides the programming interface for protection logic. It is
a robust graphical user interface that complies with the IEC 61131 function block diagram.
The user can build a FlexLogic™ diagram simply by dragging the desired operator from the
top toolbar and dropping it onto the worksheet. The same process is used to add inputs to
operators and make assignments to protection virtual outputs.
Assignments to contact inputs and outputs can also be made with this tool. This tool also
allows sections of logic to be cut, copied, or pasted between sheets. Multiple logic views
can be open and edited simultaneously. The symbols used to create graphical FlexLogic™
can be switched from IEC, ISO, and Viewpoint Engineer standards. Titles, descriptions, and
notes can also be added to the FlexLogic™ diagram. The files generated by EnerVista
Viewpoint Engineer can be scaled and printed on various paper sizes.
Logic
gates
NOT
A logical NOT gate.
Operates on the previous
parameter.
AND(
n
)
An
n
-input AND gate,
n
= 1 to 16.
Operates on the previous
n
parameters.
OR(n)
An
n
-input OR gate,
n
= 1 to 16.
Operates on the previous
n
parameters.
NOR(
n
)
An
n
-input NOR gate,
n
= 1 to 16.
Operates on the previous
n
parameters.
NAND(
n
)
An
n
-input NAND gate,
n
= 1 to 16. Operates on the previous
n
parameters.
XOR(2)
A two-input exclusive OR gate.
Operates on the previous 2
parameters.
LATCH(S,R)
Latch (set, reset), reset-dominant.
Operates on the previous 2
parameters. The parameter
preceding LATCH(S,R) is the reset
input. The parameter preceding the
reset input is the set input.
Timers TIMER
n
Timer set with the settings
programmed for FlexLogic™ timer
n
, where
n
= 1 to 32.
The timer is started by the
preceding parameter. The output of
the timer is TIMER #.
Assign
outputs
VIRT OP
n
Assigns the previous FlexLogic™
parameter to virtual output
n
,
where
n
= 1 to 96.
The virtual output is set by the
preceding parameter
Type
Syntax
Description
Operation
