Built for speed, security, and simplicity.

  •  1 ms traveling wave elements: TW87 and TW32.
  •  4 ms time-domain elements: TD21 and TD32.
  •  Easy to set and less dependent on short-circuit studies.
  • Nearest-tower fault location, with and without communications.
  • time-synchronized, high-resolution data recorder with 1 MHz
  • 18-bit sampling rate captures transient events.
  • Complements your traditional protection and gives you speed.

Key Features 

Ultra-High-Speed Fault-Clearing Times With Security Protect critical lines using the SEL-T400L with time-domain principles. The relay operates at ultra-high speeds without compromising security. The incremental quantity- based TD21 distance element can be set as far as 80 percent of the line length and operates in the order of 4 ms without communications. The POTT scheme with an incremental quantity-based TD32 directional element operates as fast as 2 ms, and the TW32 directional element operates as fast as 1 ms. The TW87 traveling-wave differential element operates in 1 to 4 ms, depending on the line length and fault location. The relay includes solid-state, trip-rated outputs. When used with a low-latency communications channel, the SEL-T400L trips breakers in

the order of 4 to 6 ms for the vast majority of line faults.

Easy Settings and Deployment Use the SEL-T400L with existing control cables and wiring to connect to conventional current and voltage transformers, including CCVTs. The traveling wave differential (TW87) element uses current inputs for differential protection. The traveling wave directional (TW32) element can be used with CCVTs because it relies on stray capacitances for measuring the polarity of the first voltage wave. The incremental quantity elements (TD21 and TD32) use a lower-frequency spectrum and work well with any voltage or current transformer.

fast Mirrored Bits communications over direct fiber or a multiplexer for communications-assisted schemes. The TW87 differential element uses a dedicated 1 Gbps direct fiber channel for both communications and data alignment. None of the SEL-T400L protection elements require absolute time input, such as IRIG-B. Setting the SEL-T400L is simple and does not require complex short-circuit studies. It uses nameplate data that do not need to be reevaluated as the system evolves.

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These include current and voltage transformer ratios, line impedances and length, TD21 reach, and port configuration settings.