Schweitzer Engineering Laboratories SEL-701 - Figure B.2 Result of Falling-Edge Operator on a Deasserting Underfrequency Element

701 Motor Protection Relay Date Code 20010719
SEL
OGIC
®
Control Equations & Relay Logic
SEL
OGIC Control Equations
B.10
With this setting, SV1 is true, or logical 1, when both 50P1T and IN4 are true. Any
number of Relay Word bits may be ANDed together within an equation, subject to the
overall limitations described in SEL
OGIC Control Equation Limitations on page B.12.
SELOGIC Control Equation OR Operator [+]
Use the plus [+] symbol to denote logical OR operations. When you use the [+]
between two Relay Word bits, either can pick up to cause the relay to perform the
operation in question. For instance, if SV1 is the equation controlling SEL
OGIC control
equation variable 1, you could set SV1 equal to:
Equation B.2
With this setting, SV1 is true, or logical 1, when either 50P1T or 50P2T are picked up.
Any number of Relay Word bits may be ORed together within an equation, subject to
the overall limitations described in SEL
OGIC Control Equation Limitations on
page B.12.
SELOGIC Control Equation Falling-Edge Operator [\]
Use the falling-edge operator [\] with individual Relay Word bits to cause a single
processing-cycle assertion when the Relay Word bit changes state from logical 1 to
logical 0. The falling-edge operator [\] 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. Do not apply the [\] operator to groups of
elements within parentheses.
For example, suppose the SEL
OGIC control equation event report generation
setting is set with the detection of the falling-edge of an underfrequency element:
Equation B.3
When frequency goes above the corresponding pickup level 81D1P, Relay Word bit
81D1T deasserts and an event report is generated (if the relay is not already generating
a report that encompasses the new transition). This allows a recovery from an
underfrequency condition to be observed. Figure B.2 demonstrates the action of the
falling-edge operator [\] on the underfrequency element in setting ER.
Figure B.2 Result of Falling-Edge
Operator on a Deasserting Underfrequency Element.
SV1 50P1T 50P2T+=
ER ... \81D1T+=
81D1T
\81D1T
one processing interval