Apply the SEL-T400L Time-Domain Line Protection for ultra-high-speed protection of transmission lines. With breakthrough time-domain technologies, the SEL-T400L trips securely in as fast as 1 ms, records events with a 1 MHz sampling rate, and locates faults to the nearest tower. Adding the SEL-T400L to your line protection system can dramatically reduce your fault-clearing time and let you achieve the many benefits associated with speed.
Ultra-High-Speed Tripping With Security—The SEL-T400L features a traveling-wave differential scheme (TW87) over a dedicated point-to-point fiber channel; an incremental-quantity distance element (TD21) that does not require communications; 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 line length and system conditions.
Simplicity—Requiring only a few protection settings, the SEL-T400L is easy to learn, easy to apply, and easy to set. The relay settings require only very basic short-circuit studies, and the relay settings are greatly resilient to power system evolution and changing short-circuit levels.
High-Fidelity Recording—The SEL-T400L 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 SEL-T400L also streams time-stamped Fast Time-Domain Values (FTDV). Contact SEL to obtain a detailed format description as well as tools (such as the preliminary SEL-5611 synchroWAVe MegaScope client software) to experiment with this advanced SEL-T400L functionality.
Accurate and Economical Fault Locating—The SEL-T400L includes traveling-wave fault-locating methods that work with or without communications. The SEL-T400L routinely locates faults within one tower span. The double-ended fault location result is available within a few tens of milliseconds, allowing the SEL-T400L to control autoreclosing depending on the location of the fault (such as in applications on lines with underground cable sections).
Testing Made Easy—Requiring only a few protection settings, the SEL-T400L is easy to commission. You can apply any standard relay test set for testing the TD21 distance and TD32 directional elements or use the SEL-T4287 Traveling-Wave Test System for end-to-end testing of the TW87 scheme, the TW32 element, and the traveling-wave fault locator. You can also test the protection and fault-locating functions without a relay test set by using the built-in event playback function and events recorded in the field or simulated using electromagnetic transient programs. With the event playback function, you can trigger a playback test in multiple relays based on time for end-to-end testing of the SEL-T400L protection schemes and multi-ended fault locators.
Apply the SEL-T400L to a variety of line and system configurations, including:
Use the SEL-T400L with standard control cables and wiring to connect to conventional current and voltage transformers, including coupling capacitor voltage transformers (CCVTs), and directly to breaker trip-coil circuits. The relay uses current traveling waves, and these waves are adequately measured with standard CTs and cabling. The relay uses the very first voltage traveling wave in the TW32 directional element, and this wave is reproduced correctly by many CCVTs or not reproduced at all, guaranteeing security of the TW32 element. You can employ Mirrored Bits communications to signal local devices for breaker failure protection and autoreclose control applications and to signal remote SEL-T400L Relays in POTT and DTT applications.
Relay Configuration and Settings
Designed with simplicity in mind, the SEL-T400L uses simple multiple-choice user preferences to accommodate a wide array of applications without the need to write custom logic equations. The protection elements and schemes have very few or no settings at all in addition to the customary enable and overcurrent supervision settings. The majority of protection settings involve nameplate data, such as current and voltage transformer ratios, line parameters, nominal voltage, or system frequency and phase rotation. These settings are easy to set and do not need to be reevaluated as the power system evolves and the short-circuit levels change.
Trigger fault locating for line faults from the SEL-T400L protection or from external relays in redundant protection applications or in standalone fault-locating applications. SEL-T400L fault-locating highlights include:
Digital Fault-Recording Applications
SEL-T400L recording highlights include:
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