SEL-T401L

Ultra-High-Speed Line Relay

The SEL-T401L is a high-performance, easy-to-use 3U line protective relay built on the extensive field experience of the SEL-T400L. It delivers unprecedented operating times by applying time-domain protection technology, utilizing traveling waves and incremental quantities, moving beyond traditional phasor-based methods. This cutting-edge solution maximizes transmission system stability and enhances disturbance analysis efficiency by integrating high-precision traveling-wave fault locating (TWFL) and ultra-high-resolution transient recording.

Key Features

Ultra-High-Speed Operating Times

Realizes trip times within 1–5 ms using time-domain technology. Specifically, the underreaching incremental-quantity distance element (TD21) can clear close-in high-current faults in approximately 2 ms without relying on a communication channel.
Traveling-Wave (TW) and Incremental-Quantity (TD) Based Protection

Employs TW directional elements (TW32) and TD directional elements (TD32) to perform fast and stable Permissive Overreaching Transfer Trip (POTT) logic over standard digital or analog protection channels.
High-Accuracy Fault Locating (TWFL)

Uses traveling-wave-based fault-locating methods to pinpoint disturbances within a single tower span, significantly reducing restoration time. It also includes impedance-based fault locating for redundant reliability.
Ultra-High-Resolution Transient Recording

Captures system transients at a very high sampling rate, allowing for the collection and analysis of detailed data before and after a fault, including subtle traveling-wave signals.
Comprehensive Backup Protection

In addition to ultra-high-speed elements, it is fully equipped with distance protection, directional elements, and other standard protection functions expected in a line protection system.
Weak-Infeed Logic

Includes specialized logic for detecting faults in sections with weak-infeed conditions.

Reduced Complexity and Simplified Settings

Applies a simplified protection philosophy that significantly reduces the setting count, addressing engineering complexity and lowering the potential for errors.
Compact 3U Package

Increases panel space efficiency by providing a compact 3U hardware size while maintaining flexible I/O configurations and SCADA functionality.
Ultra-High-Bandwidth Protection Communication Port

Supports a data rate of 1 Gbps and allows for direct connection up to 200 km via multimode or single-mode fiber-optic cables.
Flexible Programming Logic and I/O

Features user-definable logic and flexible I/O settings to configure functions according to specific site requirements.
Diverse Communication Interfaces

Provides optical communication ports supporting MIRRORED BITS and IEEE C37.94 encoding, along with Ethernet ports supporting 100 Mbps/1 Gbps.
Precision Time Synchronization

Supports demodulated IRIG-B time input to ensure precise time synchronization across the system.

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