Date Code 20171021 Instruction Manual SEL-421 Relay
Instruction Manual
Table of Contents
List of Tables................................................................................................................................................................................v
List of Figures......................................................................................................................................................................... xiii
Preface.........................................................................................................................................................................................xix
Manual Overview .................................................................................................................................................xix
Safety Information .............................................................................................................................................. xxii
General Information.............................................................................................................................................xxv
Section 1: Introduction and Specifications
Features.................................................................................................................................................................1.2
Models and Options ..............................................................................................................................................1.5
Applications ..........................................................................................................................................................1.8
Product Characteristics .......................................................................................................................................1.12
Specifications......................................................................................................................................................1.14
Section 2: Installation
Shared Configuration Attributes ...........................................................................................................................2.1
Plug-In Boards ....................................................................................................................................................2.13
Jumpers ...............................................................................................................................................................2.15
Relay Placement .................................................................................................................................................2.24
Connection..........................................................................................................................................................2.25
AC/DC Connection Diagrams ............................................................................................................................2.50
Section 3: Testing
Low-Level Test Interface ......................................................................................................................................3.1
Relay Test Connections.........................................................................................................................................3.3
Checking Relay Operation....................................................................................................................................3.8
Technical Support ...............................................................................................................................................3.23
Section 4: Front-Panel Operations
Front-Panel LCD Default Displays.......................................................................................................................4.1
Front-Panel Menus and Screens............................................................................................................................4.3
Target LEDs ..........................................................................................................................................................4.9
Front-Panel Operator Control Pushbuttons.........................................................................................................4.13
One-Line Diagrams.............................................................................................................................................4.15
Section 5: Protection Functions
Current and Voltage Source Selection ..................................................................................................................5.2
Polarizing Quantity for Distance Element Calculations .....................................................................................5.14
Frequency Estimation .........................................................................................................................................5.15
Undervoltage Supervision Logic ........................................................................................................................5.17
Over- and Underfrequency Elements..................................................................................................................5.19
Time-Error Calculation.......................................................................................................................................5.21
Fault Location .....................................................................................................................................................5.23
Open-Phase Detection Logic ..............................................................................................................................5.24
Pole-Open Logic .................................................................................................................................................5.25
Loss-of-Potential Logic ......................................................................................................................................5.28
Fault Type Identification Selection Logic...........................................................................................................5.33
Ground Directional Element...............................................................................................................................5.33
Phase and Negative-Sequence Directional Elements..........................................................................................5.45
Directionality ......................................................................................................................................................5.46
CVT Transient Detection....................................................................................................................................5.47
Series-Compensation Line Logic........................................................................................................................5.48
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