R.3.3
Date Code 20111215 Reference Manual SEL-421 Relay
SELOGIC Control Equation Programming
Separation of Protection and Automation Areas
programming. The relay combines the results in the output settings that drive
relay outputs to control substation equipment. Separation of protection and
automation storage areas is illustrated in Figure 3.1.
Figure 3.1 Protection and Automation Separation
Figure 3.1 illustrates how the SEL-421 keeps protection and automation
programming separate while still exchanging information. The arrows
indicate data flow between components. The Relay Word Bits and Analog
Quantities are visible to protection, automation, and output programming.
Protection programming uses the Relay Word Bits, Analog Quantities,
Protection Variables, and Automation Variables as inputs, but only writes and
stores information to the Protection Variables. Similarly, automation
programming uses data from all parts of the relay, but only stores data in the
Automation Variables.
The Output SEL
OGIC control equation settings use the Relay Word Bits,
Analog Quantities, Protection Variables, and Automation Variables to control
outputs and other information leaving the relay. Use the output settings to
create a custom combination of the results of protection and automation
operations. For example, an OR operation will activate an output when
protection or automation programming results necessitate activating the
output. You can use more complicated logic to supervise control of the output
with other external and internal information. For example, use a command
from the SCADA master to supervise automated control of a motor-operated
disconnect in the substation.
Protection
SEL
OGIC
Control Equation
Programming
Relay Word
Bits/
Analog
Quantities
Protection
Boolean/
Math
Variables
Output
SEL
OGIC
Control Equation
Settings
Automation
SEL
OGIC
Control Equation
Programming
Automation
Boolean/
Math
Variables
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