Schweitzer Engineering Laboratories SEL-311B, Instruction Manual

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Date Code 20011205 Setting SEL
OGIC
Control Equations G-7
SEL-311B Instruction Manual
If the rising edge operators / were not applied and setting ER was:
ER = 51P + 51G + OUT103
the ER setting would not see the assertion of OUT103, because 51G and 51P would continue to
be asserted at logical 1, as shown in Figure G.1.
SEL
OGIC
Control Equation Falling Edge Operator \
The falling edge operator \ is applied to individual Relay Word bits only—not to groups of
elements within parentheses. The falling edge operator \ operates similarly to the rising edge
operator, but looks for Relay Word bit deassertion (element going from logical 1 to logical 0).
The falling edge operator \ in front of a Relay Word bit sees this logical 1 to logical 0 transition
as a “falling edge” and asserts to logical 1 for one processing interval.
For example, suppose the SEL
OGIC
control equation event report generation setting is set with
the detection of the falling edge of an overcurrent element:
ER = ... + \50G1
This allows recovery from an overcurrent condition to be observed. Figure G.2 demonstrates the
action of the falling edge operator \ on the overcurrent element 50G1 in setting ER.
Figure G.2: Result of Falling Edge Operator on a Deasserting Out-of-Step Blocking
Element
All SEL
OGIC
Control Equations Must Be Set
All SEL
OGIC
control equations must be set one of the following ways (they cannot be “blank”):
·
single Relay Word bit (e.g., 52A = IN101)
·
combination of Relay Word bits (e.g., TR = 51PT+51GT+50P1 * SH0)
·
directly to logical 1 (e.g., 67P1TC = 1)
·
directly to logical 0 (e.g., DTT = 0)
Set SEL
OGIC
Control Equations Directly to 1 or 0
SEL
OGIC
control equations can be set directly to:
1 (logical 1) or 0 (logical 0)