SEL SEL-787L Line Current Differential Relay



SEL-787L

Line Current Differential Relay

The SEL-787L is an economical and dependable line current differential protection solution for lines and feeders, providing conventional/low-energy analog (LEA) current and voltage input support, flexible I/O options, easy mounting, and fast settings.

The SEL-787L also offers directional overcurrent protection, arc-flash mitigation, fault locating, high-impedance fault detection, broken-conductor detection, intermittent ground fault (IGF) detection,

event analysis, and more—making it an effective choice for short lines, critical feeders, and distributed generation tie-ins.You can quickly integrate the relay into serial- or Ethernet-based communications with IEC 61850 Edition 2.1.

IEC 60870-5-103. the IEC 62439 Parallel Redundancy Protocol (PRP), the High-Availability Seamless Redundancy (HSR) protocol, EtherNet/IP, the Rapid Spanning Tree Protocol (RSTP), the IEEE 1588 Precision Time Protocol (PTP), Modbus, DNP3. and other protocols.

Line Current Differential Protection

Apply differential protection in two-terminal applications using a serial fiber-optic communications port.

The differential element operates on percentage-restrained characteristics with settable normal and secure mode slopes.

Disturbance detection logic enables the 87L function to operate with exceptional security against undetected bit errors in communications packets.

External fault detection logic provides security against CT saturation under heavy external fault conditions. Built-in charging current compensation improves the sensitivity of differential protection for long lines.

LEA Sensor Inputs

Apply the SEL-787L in applications that use low-energy current/voltage sensors.

LEA sensors for measurement of primary voltages and currents offer excellent linearity, a wide dynamic range, reduced size and weight, and enhanced personnel safety.

The LEA current/voltage input card supports three current channels that are either Rogowski coil or low-power current inputs; three LEA voltage sensor inputs; and one 200 mA neutral input.

The LEA current and voltage channels accept an RJ45 connector input, and the 200 mA neutral channel accepts a terminal block input.

Arc-Flash Mitigation

Improve safety for personnel with optional arc-flash detection capabilities.

The SEL-787L offers combined light detection and high-speed overcurrent detection for arc-flash events.

This combination provides the ideal solution for speed and security.

High-Impedance Fault Detection

Detect downed conductors, even on poorly conducting surfaces, with Arc Sense technology (AST).

AST algorithms detect arcing produced by some high-impedance faults and will send an alarm or trip the breaker.

This technology provides an added level of protection over conventional feeder protection methods.

Fault Locating

Find faults faster and restore service more quickly with fault-locating algorithms.

Communicate fault location information automatically to a control center by using serial or Ethernet communications and SCADA protocols.

Flexible I/O Options

Order the SEL-787L with the I/O needed to support your application and allow for future expansion.

The back of the relay features field-upgradable I/O cards; many options are available, including a card with 14 digital inputs.

Provide ample I/O for automation and control applications by ordering up to four extended I/O modules with your relay; each module provides 21 programmable inputs or 12 contact outputs.

IGF and Zero-Sequence Phi Elements

Use the IGF detection and zero-sequence phi elements in resonant-grounded and ungrounded systems to identify ground faults and their direction.

Set them to send a trip command if the count of faults exceeds a particular threshold.