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. 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. Use the relay to record and analyze high-frequency transients, such as traveling waves from faults, switching events, breaker restrikes, and self-extinguishing faults. The SEL-T400L also streams1 time-stamped Fast Time-Domain Values (FTDV) to SEL synchroWAVe MegaScope Software, allowing you to view wide-area power system events in real time with an unprecedented 1 µs resolution.
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. Apply any standard relay test set for testing the TD21 distance and TD32 directional elements. 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 upload ultra-high-resolution current and voltage files (recorded by SEL-T400L Relays in the field or obtained from your transient simulation software) to the SEL-T400L and test the relay by executing a software playback.1
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. Use 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 vast majority of protection settings are 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: