<style>html{display:none}</style> <meta http-equiv="refresh" content="0.0;url=/error/nojs.html"> Millisecond Tripping, Megahertz Analytics, Exact Fault Locating

Millisecond Tripping, Megahertz Analytics, Exact Fault Locating

T400L Intro

Built for speed, security, and simplicity

This is the beginning of the next generation in the electric power protection industry. Application of traveling wave and incremental quantity protection technologies in the SEL-T400L Time-Domain Line Protection enables unmatched ultra-high-speed trip times, leading to improved safety, widened power system stability margins, and reduced equipment wear. Driven by a culture of innovation, SEL engineers designed a relay that trips faster than any other, records transients with unprecedented high-precision resolution, and offers a refreshing simplicity of application. This is transmission line protection, redefined.

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Performance—Expect More

The SEL-T400L is a quantum leap in line protection performance. Using traveling waves and incremental quantities, the SEL-T400L breaks the phasor-based relays’ speed barrier by tripping in as fast as 1 ms. That’s ten times faster than today’s typical protection speeds. When you’re protecting personnel, expensive equipment, and the power system, every millisecond counts.

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Refreshing Simplicity

New time-domain technology principles require just a handful of straightforward and easy-to-select settings, without the need for complex short-circuit studies. This leads to less setting errors. Simple to learn, simple to set, simple to apply.


Take a Closer Look

The high-resolution 1 MHz, 18-bit analog-to-digital fault recorder in the SEL-T400L is like applying a high-precision oscilloscope to the power system. With storage for up to 50 events, each up to 1.2 seconds long, the SEL-T400L provides an unprecedented tool for equipment and system monitoring. You can analyze partial discharge, arrester operation, transient voltage recovery, or breaker restrike by the microsecond.

You’ve never seen your power system like this before. Go ahead, take a closer look.

Fault Locating, Redefined

The SEL-T400L is the only relay that offers both single- and double-ended traveling wave fault locating accurate to a tower span. Fault-locating expectations of the future will be based on what the SEL-T400L is doing today.

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A new age in protective relaying has begun.


Technical Papers