Schweitzer Engineering Laboratories SEL-321 - Equation Programming

2-22 Specifications Date Code 20011026
SEL-321/321-1 Instruction Manual
5. If you want the same logic and relay element settings in more than one group, you do not
need to re-type the equations and settings. Instead copy them using the COPY command. To
copy Group 1 settings to Group 2, use the command COPY 1 2.
Equation Programming
Program intermediate logic points (elements listed in Table 2.10) and the output contacts with
SEL
OGIC control equations. This permits you to combine any element in Table 2.7, Table 2.9, or
Table 2.10, use nondedicated timers for special applications, and assign these combinations to
output contacts. Inputs can be assigned labels listed in Table 2.4.
Programming SEL
OGIC control equations consists of combining relay elements with logical
AND (*), OR (+), and inversion (!) variables in a single string for each output contact. The
following list defines the use of these variables. The simplest string consists of directly entering
a single element.
* AND Requires elements on both sides of the * symbol be asserted before the logic
condition is true. For example, to supervise the M1P element with the 27L
element, program the SELogic control equation as: M1P * 27L.
+ OR Requires one element on either side of the + symbol be asserted before the logical
condition is true. The following setting closes the OUT9 output contact when either
the M1P or 27L element asserts: OUT9 = M1P + 27L.
! Invert Inverts the value of the element immediately following the ! symbol. For example,
to block the 50H element if the voltages of all three phases are below the 27L
threshold, program the SEL
OGIC control equations as: 50H * !3P27.
\ Insert a \ symbol at the end of the first line of a SEL
OGIC control equation (just
before pressing [RETURN]), to continue the same equation to the second line.
Otherwise, the equation may only be one line. There is a two-line (80 characters
per line – 160 characters max) limit for a single equation and a 100-term (element
names and operators) limit per equation.
The total number of overall SEL
OGIC control equation terms is limited to 160. If the overall
number of SEL
OGIC control equation terms is exceeded, the relay will issue an error message at
the end of the SEL
OGIC control equation setting procedure (SET L command). You can
determine the total number of SEL
OGIC control equation terms by counting each AND (*)
operator, OR (+) operator, and relay element used in the SEL
OGIC control equation
programming. Note that the Invert (!) operator is not counted.
For example, the SEL
OGIC control equation string M1P + 27L contains three terms. The string
50H * !3P27 also contains three terms. The string TPA * SOTFE + TPB * SOTFE + TPC *
SOTFE contains eleven terms.