The SEL-T401L Ultra-High-Speed Line Relay is a high-performance, easy-to-use line protective relay. Built on the field experience of the SEL-T400L Time-Domain Line Protection, the SEL-T401L delivers unprecedented operating times and includes a complete suite of primary and backup protection functions. Suitable for a wide range of applications, the SEL-T401L allows you to reset the complexity of your line protection applications with its simple protection philosophies, reduced settings count, and 3U package.
You can apply the SEL-T401L on its own or as part of a redundant protection system with other SEL relays without concerns for common-mode failures. Traveling-wave and incremental-quantity technologies and an overall design simplification make the SEL-T401L sufficiently diverse from other SEL relays. You’ll gain efficiency by using common SEL configuration and integration tools and also benefit from strong diversity in hardware, software, and protection operating principles.
Ultra-High-Speed Protection—Protect your lines with ultra-high-speed elements and schemes based on the field-proven SEL time-domain technology of traveling waves and incremental quantities. The SEL-T401L features a traveling-wave differential scheme (TW87) over a dedicated point-to-point fiber channel; an incremental-quantity distance element (TD21); and a POTT scheme with traveling-wave (TW32) and incremental-quantity (TD32) directional elements over a digital or an analog protection channel. You can achieve 1–5 ms trip times, depending on the channel, line length, and system conditions.
The SEL-T401L offers a complete suite of protection functions that you expect in a Main 1 and Main 2 line protection system. Its high-performance distance protection with five zones of ground and phase elements, individually selectable as either mho or quadrilateral, provide subcycle operating times. The SEL-T401L also has dependable protection and supervisory functions, including sensitive directional, switch-onto-fault, overcurrent, over- and undervoltage, load encroachment, out-of-step tripping, and power swing blocking elements.
Simplicity—Reset the complexity of your line protection applications with the SEL-T401L relay’s simple and robust protection philosophies and considerably lower settings count. Its convenient 3U chassis makes it a great option when replacing existing relays. You can gain efficiency by using common SEL configuration and integration tools as well as benefit from strong diversity in hardware, software, and protection operating principles.
Unparalled Fault Locating—The SEL-T401L includes single- and double-ended traveling-wave fault-locating methods that are accurate to a single tower span. It also includes single- and double-ended impedance-based backup methods for a reliable and complete solution. Combining the relay’s high-speed double-ended fault-locating technology and built-in adaptive location-dependent autoreclose logic allows selective reclosing on the overhead portion of hybrid lines. You can use the line-monitoring function in the SEL-T401L for condition-based line maintenance.
High-Fidelity Recording—The SEL-T401L provides high-resolution voltage and current recording with a 1 MHz sampling rate and an 18-bit resolution. You can record and analyze high-frequency transients, such as traveling waves from faults, switching events, breaker restrikes, and self-extinguishing faults.
The Firmware IDs for older versions of the firmware can typically be found in Appendix A of the instruction manual.