SEL SEL-T400L Time-Domain Line Protection

SEL-T400L Time-Domain Line Protection

Ultra-High-Speed Transmission Line Relay

Traveling-Wave Fault Locator

High-Resolution Event Recorder

Major Features and Benefits

The SEL-T400L is a state-of-the-art time-domain line protective relay operating within a few milliseconds for a wide

range of fault and system conditions. Available in both 5 A and 1 A models, the SEL-T400L incorporates fault locating

with accuracy typically within one tower span. With only a handful of settings and preconfigured protection logic, the

SEL-T400L is simple to apply, yet it supports a variety of applications and protection philosophies.

➤ Ultra-High-Speed Line Protection. Apply a traveling-wave line current differential scheme with a point-to-point

fiber-optic channel to trip faults in 1–5 ms depending on the line length. Apply an incremental-quantity Zone 1

element with a 2–5 ms operating time without communication. Apply a permissive overreaching transfer trip

scheme with any standard teleprotection channel using traveling-wave and incremental-quantity directional

elements operating in 0.1–3 ms.

➤ Versatile Applications. Apply the SEL-T400L to two-terminal overhead transmission lines, including series

compensation, single- and dual-breaker terminations, and three-pole and single-pole tripping.

➤ Simple Configuration. Use preconfigured relay logic and set only a few protection settings without the need for

extensive short-circuit studies.

➤ Accurate Fault Locating. Locate faults to the nearest tower.

➤ Line Monitoring. Monitor the line for incipient faults, recurring faults, or incipient cable faults.

➤ High-Resolution Oscillography. Record line currents and voltages with a 1 MHz sampling rate, storage for as

many as 50 events, and a duration of 1.2 seconds per event

Traveling-Wave Differential

Protection Scheme

The traveling-wave differential (TW87) protection

scheme uses current traveling waves (TWs) and a point

to-point fiber-optic channel to detect in-zone faults with

operating times in the range of 1–5ms depending on the

line length. The TW87 scheme is independent from

external time sources and provides internal synchroniza

tion of data over the communications channel. The

TW87 scheme is suitable for series-compensated lines

and can be used for single-pole tripping applications.

The TW87 scheme uses traditional CTs and wiring. It

uses voltage signals and works well with capacitively

coupled voltage transformers (CCVTs). The TW87

scheme can be applied on two-terminal tapped lines

owing to its first-ever location-dependent supervision.

Protection Element

The incremental-quantity distance (TD21) protection

element uses incremental voltages and currents to pro

vide underreaching distance protection. The element can

be set as high as 80 percent of the line length, has a tran

sient overreach below 10 percent, and operates between

2–5ms depending on the fault location, system short

circuit level, fault resistance, and point on wave. The

TD21 element is suitable for series-compensated lines

and can be set using the line impedance, neglecting the

in-line capacitors. The element is suitable for single-pole

tripping applications