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SEL-421 Relay
Instruction Manual
Date Code 20171021
Table of Contents
Load-Encroachment Logic .................................................................................................................................5.49
Out-of-Step Logic (Conventional) ......................................................................................................................5.50
Out-of-Step Logic (Zero Settings) ......................................................................................................................5.56
Mho Ground-Distance Elements ........................................................................................................................5.72
Quadrilateral Ground-Distance Elements ...........................................................................................................5.76
Mho Phase-Distance Elements ...........................................................................................................................5.80
Quadrilateral Phase-Distance Elements..............................................................................................................5.85
Zone Time Delay ................................................................................................................................................5.91
Instantaneous Line Overcurrent Elements ..........................................................................................................5.93
Inverse-Time Overcurrent Elements ...................................................................................................................5.99
Over- and Undervoltage Elements ....................................................................................................................5.113
Switch-Onto-Fault Logic ..................................................................................................................................5.117
Communications-Assisted Tripping Logic .......................................................................................................5.120
Directional Comparison Blocking Scheme.......................................................................................................5.121
Permissive Overreaching Transfer Tripping Scheme .......................................................................................5.124
Directional Comparison Unblocking Scheme Logic ........................................................................................5.133
Trip Logic .........................................................................................................................................................5.137
Circuit Breaker Failure Protection ....................................................................................................................5.146
Synchronism Check ..........................................................................................................................................5.158
Section 6: Protection Applications Examples
230 kV Overhead Distribution Line Example ......................................................................................................6.1
500 kV Parallel Transmission Lines With Mutual Coupling Example...............................................................6.18
345 kV Tapped Overhead Transmission Line Example .....................................................................................6.53
EHV Parallel 230 kV Underground Cables Example .........................................................................................6.87
Out-of-Step Logic Application Examples ........................................................................................................6.119
Autoreclose Example ........................................................................................................................................6.137
Autoreclose and Synchronism-Check Example ...............................................................................................6.141
Circuit Breaker Failure Application Examples.................................................................................................6.151
230 kV Tapped Transmission Line Application Example ................................................................................6.170
Section 7: Metering, Monitoring, and Reporting
Metering................................................................................................................................................................7.1
Circuit Breaker Monitor........................................................................................................................................7.7
Station DC Battery System Monitor .....................................................................................................................7.7
Reporting ..............................................................................................................................................................7.7
Alias Settings ........................................................................................................................................................8.1
Global Settings......................................................................................................................................................8.2
Breaker Monitor Settings ......................................................................................................................................8.9
Group Settings ....................................................................................................................................................8.12
Protection Freeform SEL
Notes Settings .....................................................................................................................................................8.34
Output Settings ...................................................................................................................................................8.35
Front-Panel Settings............................................................................................................................................8.35
Report Settings....................................................................................................................................................8.38
Port Settings ........................................................................................................................................................8.38
DNP3 Settings—Custom Maps ..........................................................................................................................8.39
Bay Settings ........................................................................................................................................................8.39
Summary of Contents for SEL-421-4
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