Tdworld 7469 T400l Pr Web

'Fastest' Transmission Line Relay

April 3, 2017
For the first time, incremental quantities and traveling wave protection come together in the SEL-T400L Time-Domain Line Protection

Schweitzer Engineering Laboratories has released the SEL-T400L Time-Domain Line Protection—the world’s first traveling-wave microprocessor-based relay. It detects power system faults and sends a trip signal to breakers four to 10 times faster than present-day phasor-based relays, offering ultra-high-speed and secure protection of critical transmission lines.

“We are protecting energy moving at the speed of light. The T400L is like moving from a car to a jet!” SEL President Dr. Edmund O. Schweitzer, III said. “Time domain-based protection is the future and this is the most important thing SEL has done since releasing the first digital relay in 1984.”

Using a combination of traveling-wave and incremental-quantity protection technologies, the SEL-T400L trips as fast as a single millisecond. Faster tripping times mean improved safety, less damage to equipment, improved system stability, and better power quality.

With this product, utilities are able to extend the life of existing transmission infrastructure, resulting in significant cost savings. Additionally, Fast Time-Domain Values is like having an oscilloscope on the power system, allowing users to analyze high-speed transient events to understand what happened and take corrective actions.

“We designed the SEL-T400L to complement traditional line relays while dramatically reducing trip times of the complete redundant protection system. It’s a quantum leap in line protection performance,” Dr. Bogdan Kasztenny, SEL senior engineering director of research and development said. “Plus, it locates faults to an exact tower, and with 1 MHz recording, it gives you new eyes into your power system.” 

Now available for $12,000, the SEL-T400L is easy to set and ships from stock within two days. Initial orders of two or more relays placed by June 30, 2017 will include a free SEL-T4287 Traveling-Wave Test System, valued at more than $4,000. This standalone device allows for simple and precise testing of the single- and double-ended traveling-wave fault locators and the traveling-wave protection elements in the SEL-T400L.

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