Schweitzer Engineering Laboratories SEL-701-1, Instruction Manual

Page: 255 / 452

Date Code 20011009
SEL-701-1 Monitor
SEL
OGIC®
Control Equations and Monitor Logic
SEL
OGIC
Control Equations
B.13
SEL
OGIC
Control Equation AND Operator [*]
Use the asterisk [*] symbol to denote logical AND operations. When you use the
[*] between two Relay Word bits, both must pick up in order for the monitor to perform
the operation in question. For instance, if SV1 is the equation that controls SEL
OGIC
control equation variable 1, you could set SV1 equal to:
Equation B.1
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
SELogic Control Equation Limitations on
page B.15 .
SEL
OGIC
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 monitor 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
SELogic Control Equation Limitations on
page B.15 .
SEL
OGIC
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 monitor 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.
SV1 50P1T * IN4 =
SV1 50P1T 50P2T + =
ER ... \81D1T + =