Line Current Differential Protection—Apply subcycle single- or three-pole line current differential protection with backup distance protection for critical transmission lines. Patented generalized Alpha Plane technology combined with overcurrent supervision, external fault detection, and disturbance detection logic enables the 87L function to operate with exceptional security and sensitivity. Connect to serial or Ethernet networks for differential communications.
Series-Compensated and Long Lines—Prevent Zone 1 overreach on series-compensated lines with optional logic in the SEL-411L-1 Advanced Line Differential Protection, Automation, and Control System. Built-in charging compensation improves the sensitivity and speed of differential protection for long lines.
In-Line Transformers—Simplify protection schemes and reduce equipment costs by providing complete protection for the combined line and transformer. The 87L function of the relay allows in-line transformer applications that compensate for vector group, ratio, and zero sequence of the in-zone transformer. Use harmonic blocking, restraint, or both for stabilization under magnetizing inrush conditions.
Out-of-Step Blocking and Tripping—During power swings, the relay automatically selects either out-of-step blocking or out-of-step tripping. Out-of-step blocking enhances your security by blocking distance elements during stable swing conditions. During unstable power swing conditions, the SEL-411L implements out-of-step tripping to maintain generation load balance.
Multiterminal Transmission Lines—Protect lines with up to four terminals. Apply the SEL-411L on breaker-and-a-half bus configurations or other two-breaker schemes with the relay’s dual CT and PT inputs. Efficiently dispatch line crews to quickly isolate line problems and restore service faster. The multiterminal fault location system quickly locates faults even on lateral transmission lines.
Traveling Wave Fault Locator—Accurately pinpoint faults with time-synchronized traveling wave fault location. Save time and money by sending maintenance crews to the tower nearest the fault.
Bay Control, Reclosing, and Breaker Failure Detection—Apply complete bay control, reclosing, and breaker failure protection for two breakers. Monitor circuit breaker performance, including average and last tripping time, motor run time, and contact-interrupting duty.
Reliable Distance Protection—Provide reliable backup protection with five zones of phase and ground distance elements that include directional overcurrent elements for subcycle operation and security.
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. Communicate using either serial or Ethernet channels.
Multiterminal Protection With Fault Location
The line current differential protection provides high-speed protection for multiterminal lines, even with two breakers per terminal. Protect up to three terminals using serial communications or up to four terminals using Ethernet. In addition, the unique fault location algorithm uses information from all terminals to identify the faulted branch.
Reliable Distance Protection
Complete distance and directional elements provide standalone protection or backup protection in differential schemes in the event communications are 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.
An Ethernet card option provides two copper or fiber ports for communication with failover redundancy. Simplify Ethernet network topology and reduce external equipment with dual Ethernet ports that offer a switched mode for looped Ethernet networks. Available Ethernet communications protocols include FTP, Telnet, DNP3 LAN/WAN, the IEEE 1588 Precision Time Protocol Version 2 (PTPv2), IEC 61850, IEEE C37.118 synchrophasors, and the Parallel Redundancy Protocol (PRP).
* Connect to an SEL-2600 RTD Module using a fiber-optic transceiver.