Sel SEL-421 - Separation of Protection and Automation Areas

R.3.2
SEL-421 Relay Reference Manual Date Code 20111215
SELOGIC Control Equation Programming
Separation of Protection and Automation Areas
Use SELOGIC control equations in the SEL-421 to customize protection
operation, create custom protection elements, and automate substation
operation. The SEL-421 introduces several advanced programming features,
operators, and methods. Tab le 3. 2 is a summary that compares SEL
OGIC
control equation programming in SEL-351 series relays and SEL-311 series
relays with the SEL-421.
Separation of Protection and Automation Areas
The SEL-421 acts as a protective relay and as a smart node in distributed
substation automation. The relay collects data, coordinates inputs from many
interfaces, and automatically controls substation equipment. The relay
performs protection and automation functions but keeps programming of these
functions separate. For example, someone modifying or testing a capacitor
bank control system or station restoration system created in automation
programming should not be able to corrupt programming for protection tasks.
Similarly, extended protection algorithms must operate at protection speeds
unaffected by the volume of automation programming.
The SEL-421 contains several separate programming areas discussed in
SEL
OGIC Control Equation Setting Structure on page R.3.6. Separate access
levels and passwords control access to each programming area and help
eliminate accidental programming changes. For example, use Access Level P
to modify protection configuration and protection free-form SEL
OGIC control
equation programming and Access Level A to access automation
programming.
NOTE: If you want unlimited access
to both automation and protection
configuration and programming, log in
to Access Level 2.
Protection and automation areas must interact and exchange information.
Protection and automation interact and exchange information through separate
storage areas (variables) for results of automation and protection
Counters Increased sophistication in custom protection and
automation programming
Aliases Custom programming is more readable when you
rename as many as 200 analog or digital quantities
Table 3.2 SEL-421 SEL
OGIC Control Equation Programming Summary
Element
SEL-351 Series/
SEL-311 Series
SEL-421
Protection Free
Form
Automation
Free Form
SELOGIC control equation
variables
16 64 256
SEL
OGIC math variables 0 64 256
Conditioning timers
a
a
Similar to SEL-300 series relay SELOGIC control equation programming.
16 32 0
Sequencing timers 0 32 32
Counters 0 32 32
Latch bits 16 32 32
Table 3.1 Advanced SEL-421 SEL
OGIC Control Equation Features
(Sheet 2 of 2)
Feature Description