Date Code 990430 Setting SEL
OGIC
®
Control Equations G-3
SEL-351P Manual Técnico
Other Relay Word Bits
The preceding example was for a phase time-overcurrent element, demonstrating Relay Word bit
operation for pickup, time-out, and reset conditions. Other Relay Word bits (e.g., those for
definite-time overcurrent elements, voltage elements, frequency elements) behave similarly in
their assertion or deassertion to logical 1 or logical 0, respectively. The time-overcurrent
elements (like the preceding phase time-overcurrent element example) are rather unique because
they have a Relay Word bit (e.g., 51P1R) that asserts for the reset state of the element.
Relay Word bits are used in SEL
OGIC Control Equations, which are explained in the following
subsection.
SEL
OGIC
C
ONTROL
E
QUATIONS
Many of the protection and control element logic inputs shown in the various figures in
Section 3: Overcurrent, Voltage, Synchronism Check, and Frequency Elements
through
Section 8: Breaker/Recloser Monitor, Battery System Monitor, Metering, and Load Profile
Functions
are SELOGIC Control Equations (labeled “SELOGIC Settings” in most of the figures).
SEL
OGIC Control Equations are set with combinations of Relay Word bits to accomplish such
functions as:
• tripping reclosers
• assigning functions to optoisolated inputs
• operating output contacts
• torque-controlling overcurrent elements
• switching active setting groups
• enabling/disabling reclosing
Traditional or advanced custom schemes can be created with SEL
OGIC Control Equations.
SEL
OGIC
Control Equation Operators
SELOGIC Control Equation settings use logic similar to Boolean algebra logic, combining Relay
Word bits together using one or more of the six SEL
OGIC Control Equation operators listed in
Table APPENDIX G: .1.
Table APPENDIX G: .1: SEL
OGIC
Control Equation Operators (listed in processing
order)
Operator Logic Function
/ rising edge detect
\ falling edge detect
() parentheses
! NOT
* AND
+ OR
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