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Discover the World's Fastest Transmission Line Relay

T400L Discover

Introducing The SEL-T400L

Millisecond Tripping
The SEL-T400L Time-Domain Line Protection breaks the speed barrier of phasor-based relays and trips in single milliseconds before the fault current even reaches the first peak. Designed for impeccable security, the relay provides high-speed tripping with novel protection principles based on traveling waves and incremental quantities.

Refreshing Simplicity
Having only a few settings makes the SEL-T400L simple to learn, simple to set, and simple to apply.

Megahertz Recording
The SEL-T400L fault recorder captures voltages and currents every microsecond with 18 bits of resolution. This breakthrough recording performance opens up a whole other world for power system analytics. Now you can capture and analyze breaker restrikes, partial breakdown of insulators, self-extinguishing faults, and more.

Nearest-Tower Fault Locating
The SEL-T400L routinely locates faults to within one tower span. It distinguishes faults on overhead line sections from faults in underground cable sections and controls autoreclosing accordingly. Plus, the relay works with information from one or both ends of the line.

Learn More

When you’re guarding power system stability, protecting expensive equipment, the public and property, every millisecond counts. To learn more about the SEL-T400L, visit the product page or fill out the form below.