Schweitzer Engineering Laboratories SEL-701 - Page 259

Date Code 20010719 701 Motor Protection Relay
SELOGIC
®
Control Equations & Relay Logic
SEL
OGIC Control Equations
B.11
SELOGIC Control Equation Rising-Edge Operator [/]
Use the rising-edge operator [/] with individual Relay Word bits to cause a single
processing-cycle assertion when the Relay Word bit changes state from logical 0 to
logical 1. Do not apply the [/] operator to groups of elements within parentheses.
SELOGIC Control Equation Parentheses Operator [( )]
Use parentheses to logically combine multiple elements. More than one set of
parentheses [( )] can be used in a SEL
OGIC control equation setting. Parentheses cannot
be “nested” (parentheses within parentheses) in a SELOGIC control equation setting.
For example, the following SEL
OGIC control equation setting has two sets of
parentheses:
Equation B.4
In the above example, the logic within the two sets of parentheses is processed first and
then the two results are ANDed together. The example equation could be used to
provide simple motor breaker failure protection.
SELOGIC Control Equation NOT Operator [!]
Use the NOT operator [!] to invert a single Relay Word bit and also to invert the
result of multiple elements combined within parentheses.
Set SELOGIC Control Equations Directly to Logical 1 or Logical 0
To define a condition always picked up or always dropped out, you can set
SELOGIC control equations directly to:
1 (logical 1) or 0 (logical 0)
If you set a SELOGIC control equation setting directly to 1, it is always
asserted/on/enabled. If you set a SEL
OGIC control equation setting equal to 0, it is
always deasserted/off/disabled.
All SELOGIC Control Equations Must Be Set
If you use SELOGIC control equations, every one needs to be set by making it
equal to one of the following:
 A single Relay Word bit.
 A logical combination of Relay Word bits.
 Directly to logical 1.
 Directly to logical 0.
If you are satisfied with the factory default logic setting, you may leave the
SEL
OGIC control equation setting unedited.
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