SEL-787L
Line Current Differential Relay
- The SEL-787L is a compact line current differential relay designed for overhead and underground lines or industrial power networks. It provides an economical and reliable protection solution for short cables, critical feeders, and distributed generation tie-lines. The relay integrates proven protection algorithms with next-generation hardware to deliver fast, secure, and dependable performance.
Key Features
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Line Current Differential Protection (87L)
Provides primary protection for two-terminal lines using advanced hardware and field-proven algorithms. -
Directional Overcurrent Protection
Combines line current differential with directional and non-directional overcurrent elements for comprehensive feeder protection. -
External Fault Detection (EFD)
Utilizes EFD and disturbance detection logic to enhance the operational security of the 87L element. -
Optical Communication Interface
Supports a direct serial fiber interface compliant with IEEE C37.94, offering a point-to-point range of up to 25 km. -
Arc-Flash Protection
Increases personnel safety by supporting arc-flash protection via an optional Slot E card. -
Channel Monitoring
Continuously monitors communication quality to prevent unintended operations caused by channel failure. -
Comprehensive Protection Suite
Includes earth fault protection along with voltage- and frequency-based protection for holistic system monitoring.
Convenience features
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Compact Design and Intuitive HMI
Housed in a compact industrial package with a simplified interface for straightforward operation and configuration. -
Extensive Protocol Support
Compatible with multiple standard protocols, including SEL, Modbus TCP/RTU, DNP3, FTP, Telnet, IEC 61850 Edition 2.1, and IEEE C37.118 (synchrophasors). -
Real-Time Monitoring
Enables local, real-time access to metering data, communication status, and device health through the front-panel bay screen. -
Flexible Power Supply
Accommodates a broad range of AC and DC input voltages (e.g., 110–250 Vdc or 110–240 Vac) to fit various installation environments.
