SEL-487B

Bus Differential and Breaker Failure Relay

The SEL-487B provides a comprehensive protection solution, including high-speed low-impedance bus differential protection, circuit breaker failure protection, and backup overcurrent protection. A single relay can protect up to seven terminals, and the system is flexibly designed to expand up to 21 terminals when multiple relays are used in parallel. It is a core device optimized for modern digital substations, supporting SEL’s Digital Secondary System (DSS) technologies, such as TiDL (Time-Domain Link) and Sampled Values (SV).

Key Features

High-Speed Differential Protection (87)

Operates in less than one cycle for busbar differential protection, increasing system stability and minimizing equipment damage.
Up to Six Independent Protection Zones

Provides up to six independent and adaptable differential protection zones within a single relay system, covering complex busbar configurations.
Wide Range of Inputs

Features 21 analog current inputs and three analog voltage inputs to accommodate large-scale busbar systems.
CT Ratio Mismatch Compensation

Accommodates CT ratio mismatches as high as 35:1 through internal settings, eliminating the need for auxiliary CTs.
Failed CT Detection

Reliably indicates open or shorted CT conditions for alarming and/or blocking to prevent misoperation.
External Fault Security Logic

Incorporates advanced security algorithms to prevent misoperation caused by CT saturation during external faults.
Integrated Backup and Breaker Failure Protection

Provides instantaneous and time-overcurrent elements as well as independent breaker failure detection for all terminals.
Digital Substation Technology Support

TiDL Technology: Simplifies wiring by transmitting data via fiber-optic cables.
Sampled Values (SV): Supports digital data streams according to IEC 61850-9-2 or IEC 61869-9 standards.

Advanced Metering and Monitoring

Provides voltage, current, phase data, and real-time power metering, including monitoring for station DC battery systems.
Precision Event Analysis

Enables clear analysis of pre- and post-fault conditions through high-resolution event reports and Sequential Events Recorder (SER) functions.
Synchrophasors

Supports wide-area system monitoring by providing phasor measurement data compliant with the IEEE C37.118 standard.
Diverse Communication Protocols

Supports FTP, Telnet, DNP3, PRP, PTPv2, and IEC 61850 Edition 2.1 (optional) for easy integration with supervisory systems.
Flexible Port Configuration

Offers various Ethernet card options, including copper (RJ45) or fiber-optic (SFP), alongside standard EIA-232 serial ports.
Precise Time Synchronization

Supports PTPv2 and IRIG-B inputs for microsecond-level time synchronization.
SEL Grid Configurator Support

Efficiently manages complex busbar settings and logic configurations through intuitive, modern software.

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