Schweitzer Engineering SEL-387-0, Instruction Manual

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4.21
Date Code 20170601 Instruction Manual SEL-387-0, -5, -6 Relay
Control Logic
SEL
OGIC
Control Equations
Parentheses Operator ( )
More than one set of parentheses can be used in a SEL
OGIC
control equation.
However, parentheses cannot be “nested,” that is you cannot have parentheses
within parentheses. The following is an example:
S1V1 = (IN105 + RB3) * (87R + 87U)
The expressions within the parentheses are evaluated first. First, is IN105 OR
RB3 asserted; next, is 87R OR 87U asserted. Assuming that at least one bit is
asserted in each parentheses, the equation can now be evaluated:
S1V1 = 1*1 = 1
The equation for S1V1 is thus asserted.
NOT Operator !
The ! operator performs a simple negation or inversion. On logic diagrams, it
is represented by a small circle on an input or output line. Whatever the state
of the logical quantity to which it is applied, it simply reverses that state. For
example, if 87R is a logical 1, then !87R is a logical 0. The ! operator can be
applied to a parentheses containing several elements. The expression within
the parentheses is evaluated first then the result is negated.
Rising-Edge and Falling-Edge Operators / and \
These operators can be applied to individual Relay Word bits only. They
cannot be used on groups in parentheses or on negated elements. They are not
interested in the present value of that bit, as are most operators. Rather, they
are only intended to detect a
change of that value. The rising-edge operator
“ / “ detects a change from a 0 state to a 1 state. The falling-edge operator
“ \ “ detects a change from a 1 state to a 0 state. Typical applications might
include triggering an event report or unlatching internal logic. These two
operators assert a 1 for a single processing interval, when they sense the
change of state.
AND and OR Operators * and +
These operators produce an output state that combines the states of two or
more inputs. The AND operator requires that every one of the inputs is a
logical 1 before it issues a logical 1 output. For example, in the equation
S1V1 = 87R * IN103, S1V1 will only assert if 87R = 1 and IN103 = 1
The OR operator only requires that one of the several inputs be a logical 1 in
order to assert an output state of 1. For example, in this relay there is a Relay
Word bit TRIPL = TRIP1 + TRIP2 + TRIP3 + TRIP4 + TRIP5. All TRIPL
needs to assert is a 1 from any of the five ORed inputs. Thus, it is useful for
indicating that "any trip" has occurred.
Ways of Setting
SEL
OGIC
Control
Equation Relay
Settings
Many of the Group and Global settings are defined as being SEL
OGIC
control
equations. A typical example would be the torque-control variables for the
various overcurrent elements. For example, let us look at the setting 51P1TC
for torque controlling the Winding 1 phase inverse-time overcurrent element.
We could set 51P1TC to a single Relay Word bit. For example, 51P1TC =
IN105. This might be used for torque controlling by a contact input from some
external device like a directional relay.