html{display:none} APP 421: SEL-421 Protection, Automation, and Control System | Schweitzer Engineering Laboratories

APP 421: SEL-421 Protection, Automation, and Control System


This course is designed for utility and industrial protection engineers and power system consultants.

APP 421 provides comprehensive application instruction for the SEL-421 Protection, Automation, and Control System, an extremely flexible, high-speed relay for dual-breaker control applications used in multiple functions. Students (in groups of two) will gain hands-on experience in communicating, setting, metering, monitoring, reading event reports, retrieving event reports, and performing control functions working directly with the SEL-421 Relay.


Day 1
  • Introduction to the SEL-421
  • Introduction to the Example Protection Scheme
  • Introduction to SEL-421 Relay Communications and acSELerator QuickSet SEL-5030 Software
  • SELogic Control Equations
  • Global Settings
  • Breaker Monitor
  • Line Configuration, Relay Configuration, and Distance Element Settings
Day 2
  • Switch-Onto-Fault, Out-of-Step, and Load-Encroachment Settings
  • Time-Overcurrent Elements
  • Directional Elements
  • Pole-Open Detection
  • Communications-Assisted Tripping Schemes
  • Breaker Failure
  • Synchronism-Check Element
  • Reclosing
Day 3
  • Trip Logic
  • Output Settings
  • Front-Panel Settings
  • Data Capture and Event Reports
  • Communication Protocols
  • Metering
  • Time Synchronization and Synchrophasors

Course Objectives

At the conclusion of this course, students can:

  • Apply the SEL-421 Relay protection, monitoring, metering, and control features, including current and voltage selection logic
  • Use the SELogic control equations with math and comparison variables in the independent protection and automation areas
  • Apply relay settings, program SELogic control equations, and analyze fault records and relay element responses using acSELerator QuickSet SEL-5030 Software
  • Analyze Sequential Events Recorder (SER) reports and use COMTRADE files
  • Implement relay-to-relay logic via Mirrored Bits communications
  • Map and retrieve critical analog and digital information in DNP3 Level 2
  • Select the appropriate Enable Source Selection (ESS) setting for required applications
  • Communicate with the relay via the front panel and HMI interface, including pushbuttons and associated LEDs, display points, targeting LEDs, and front-panel metering
Course Information
Course Base Fees: $USD1,425*

CEUs: 2.1
Available Courses

There are currently no courses available. Request to be notified when this course is added to the schedule.


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Course Requirements


Before you attend this class, you must meet the following requirements:

  • Completion of CBT 101: Introduction to SEL Relays
  • OR
  • Familiarity with protective relaying, SELogic control equations, acSELerator QuickSet Software, front-panel controls, and the SEL-4000 Relay Test System
  • Ability to set up a communications session using HyperTerminal

Course Preparation

Please check the General Course Information page for what you should bring to class. In addition, please make sure that the laptop you bring to class has the following software/features:

  • acSELerator QuickSet SEL-5030 Software with the SEL-421 driver and instruction manual, installed and updated through SEL Compass
  • SEL-5401 Software
  • SEL-C662 USB Driver