T&D World Magazine
SEL 411L

Line Differential Protection

Apply the SEL-411L Relay for complete protection and control of any transmission line. The SEL-411L provides differential protection with both phase- and sequence-based operating elements for sensitivity and high-speed operation. Choose from many popular fiber and multiplexed communications options. Distance protection and logic from a complete SEL-421 protection, automation, and control system are included to provide backup protection and integration. Any transmission line (short, long, or series-compensated) can be well protected with the SEL-411L Relay.

  • High-Speed, Secure Line Current Differential Protection
    Differential elements provide subcycle operating times to improve system stability. Line charging current compensation provides an accurate response for long or short lines. Apply the proven Alpha Plane operating principle for reliable and secure operation. Multiterminal lines and transformers in the differential zone are protected.
  • Reliable Backup Protection
    Complete distance and directional elements provide backup protection in case the differential communications channel is lost. All the features of the SEL-421 Relay are included in addition to the differential protection.
  • Complete Reclosing System With Synchronism Check and High-Speed Breaker Failure Detection for Two Breakers
    Dual CT and VT input logic and settings are included for control of two circuit breakers. Settable voltage inputs provide flexible operation. Open-pole detection in less than 5/8 cycle allows the use of shorter breaker failure margin times. Independent current inputs provide protection for two circuit breakers.
  • Synchrophasor Measurements to Increase Asset Utilization
    Validate system load flow and fault models using instantaneous voltage angles. Use system-state measurements to increase stable system loading through reduced margin requirements. Use IEEE C37.118 format with 1–60 messages per second or SEL Fast Message format for interleaved communications. Apply direct relay-to-relay synchrophasors for wide-area-based control without additional devices.
  • True Digital Fault Recorder (DFR) Functionality
    Use binary COMTRADE event reports sampled at 8 kHz directly from the relay without expensive auxiliary equipment.
  • Traveling Wave Fault Location
    Accurately pinpoint faults with GPS-synchronized traveling wave fault location. Save time and money by sending maintenance crews to the tower nearest the fault.
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