4.75
Date Code 20150130 Instruction Manual SEL-787 Relay
Protection and Logic Functions
Logic Settings (SET L Command)
An example of a single Relay Word bit is as follows:
SV01 := NOT RB01
When Remote bit RB01 asserts from logical 0 to logical 1, the Boolean NOT
operator, in turn, changes the logical 1 to a logical 0. In this example, SV01
deasserts when RB01 asserts.
Following is an example of the NOT operator applied to multiple elements
within parentheses.
The Boolean SEL
OGIC control equation OUT101 setting could be set as
follows:
OUT101 := NOT(RB01 OR SV02)
If both RB01 and SV02 are deasserted (= logical 0), output contact OUT101
asserts, i.e., OUT101 := NOT (logical 0 OR logical 0) = NOT
(logical 0) = logical 1.
In a Math SEL
OGIC control equation, use the NOT operator with any Relay
Word bits. This allows a simple if/else type equation, as shown in the example
below.
MV01 := 12 * IN101 + (MV01 + 1) * NOT IN101
The equation above sets MV01 to 12 whenever IN101 asserts, otherwise it
increments MV01 by 1 each time the equation is executed.
Boolean Rising-Edge Operator (R_TRIG)
Apply the rising-edge operator, R_TRIG, to individual Relay Word bits only;
you cannot apply R_TRIG to groups of elements within parentheses. When
any Relay Word bit asserts (going from logical 0 to logical 1), R_TRIG
interprets this logical 0 to logical 1 transition as a “rising edge” and asserts to
logical 1 for one processing interval.
For example, the Boolean SEL
OGIC control equation event report generation
setting uses rising-edge operators:
ER := R_TRIG IN101 OR R_TRIG IN102
The rising-edge operators detect a logical 0 to logical 1 transition each time
one of IN101 or IN102 asserts. Using these settings, the device triggers a new
event report each time IN101 or IN102 asserts anew, if the device is not
already recording an event report. You can use the rising-edge operator with
the NOT operator as long as the NOT operator precedes the R_TRIG operator.
The NOT R_TRIG combination produces a logical 0 for one processing
interval when it detects a rising edge on the specified element.
Boolean Falling-Edge Operator (F_TRIG)
Apply the falling-edge operator, F_TRIG, to individual Relay Word bits only;
you cannot apply F_TRIG to groups of elements within parentheses. The
falling-edge operator, F_TRIG, operates similarly to the rising-edge operator,
but operates on Relay Word bit deassertion (elements going from logical 1 to
logical 0) instead of Relay Word bit assertion. When the Relay Word bit
deasserts, F_TRIG interprets this logical 1 to logical 0 transition as a “falling
edge” and asserts to logical 1 for one processing interval, as shown in
Figure 4.55.
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