Date Code 20001006 Setting SELOGIC
®
Control Equations G-11
SEL-351 Instruction Manual
Table G.2: SELOGIC Control Equation Settings Limitations
for Different SEL-351 Relay Models
Firmware Series SELOGIC Control Equation Settings Limitations per Setting Group
R2xx
Average of 3 Relay Word bits per equation. Average of 1 rising edge or
falling edge operator per three equations. 46 edges maximum.
R1xx
207 total Relay Word bits. 31 total rising edge or falling edge operators.
SELOGIC Control Equation settings that are set directly to 1 (logical 1) or 0 (logical 0) also have to
be included in these limitations – each such setting counted as one Relay Word bit.
After SELOGIC Control Equation settings changes have been made and the settings are saved, the
SEL-351 responds with the following message:
xxx Elements and yy Edges remain available
indicating that “xxx” Relay Word bits can still be used and “yy” rising or falling edge operators
can still be applied in the SELOGIC Control Equations for the particular settings group.
PROCESSING ORDER AND PROCESSING INTERVAL
The relay elements and logic (and corresponding SELOGIC Control Equation settings and resultant
Relay Word bits) are processed in the order shown in Table G.3 (top to bottom). They are
processed every quarter-cycle (1/4-cycle), and the Relay Word bit states (logical 1 or logical 0) are
updated with each quarter-cycle pass. Thus, the relay processing interval is 1/4-cycle. Once a
Relay Word bit is asserted, it retains the state (logical 1 or logical 0) until it is updated again in the
next processing interval.
Courtesy of NationalSwitchgear.com
To Next Page
