SELSEL-T401L Ultra-High-Speed Line Relay

SEL-T401L  Ultra-High-Speed Line Relay

Fast, dependable, and simple

• Apply ultra-high-speed protection based on field-proven SEL

time-domain technology with demonstrated trip times on the order

of 1–5 ms.

• Complement and back up the traveling-wave and incremental-quantity

protection elements and schemes with distance elements, directional

elements, and the other protection functions that you expect in a line

protection system.

• Improve fault-locating results to within a single tower span by using

traveling-wave-based fault-locating methods, and ensure dependability

with impedance-based methods.

• Achieve a balance between flexibility and ease of use in a 3U package

with programmable logic, flexible I/O, and SCADA functionality.

ANSI Numbers/Acronyms and Functions

21 Phase and Ground Distance

TD21 Incremental-Quantity Phase and Ground Distance

27 Undervoltage (Phase, Phase to Phase, and

Positive Sequence)

32 Directional (Phase, Zero Seq., and Negative Seq.)

TD32 Incremental-Quantity Directional

TW32 Traveling-Wave Directional

50 Instantaneous Overcurrent (Phase, Zero Sequence,

and Negative Sequence)

51 Inverse-Time Overcurrent (Phase, Zero Sequence,

and Negative Sequence)

59 Overvoltage (Phase, Phase to Phase, Positive

Sequence, Zero Sequence, and Negative Sequence)

67 Instantaneous and Definite-Time Directional

Overcurrent (Phase, Zero Seq., and Negative Seq.)

68 Power-Swing Blocking

78 Out-of-Step Tripping

85 RIO SEL Mirrored Bits® I/O With Selectable SEL MB8 or

IEEE C37.94 Encoding

TW87 Traveling-Wave Differential

94 High-Speed Trip-Rated Outputs

POTT Permissive Overreaching Transfer Trip Logic

CBECHO Open-Breaker Echo Logic

WI Weak-Infeed Logic

DCB Directional Comparison Blocking Logic

SOTF Switch-Onto-Fault Logic

DTT Direct Transfer Trip Logic (Intertripping)

LOP Loss-of-Potential Logic

OP Open-Pole Detection Logic

LE Load Encroachment Logic

DFR Digital Fault Recorder

SER Sequential Events Recorder

FL Fault Locator

LM Line Monitor

LGC seLoGiC® Equations

MET Metering

ARC Adaptive Autoreclose Cancel Logic

HMI Local Operator Interface

DNP3 Distributed Network Protocol 3.0 (Ethernet)

LB Local Control Bits (Operated Through

Front-Panel HMI)

RB Remote Control Bits (Operated Through DNP3

and SEL Fast Operate Protocols)

FTP File Transfer Protocol

FTDV Fast Time-Domain Values

EMI Electromagnetic Interference Monitoring for

Traveling-Wave Functions

TEST Event Playback and Traveling-Wave Test Mode

Key Features

Unparalleled Fault-Locating Technology

Ultra-High-Speed Protection

Using field-proven traveling-wave and incremental-quantity

technologies pioneered in the SEL-T400L Time-Domain

Line Protection, the SEL-T401L delivers industry-leading

operating speed. Sampling line and voltage currents at

1 MHz, processing data every microsecond, using high

speed protection signaling, and tripping with solid-state

trip-rated outputs, the SEL-T401L securely trips in as fast

as 1 ms. Faster fault clearing improves public and utility

personnel safety, widens transient stability margins, limits

equipment wear, improves power quality, and confines

property damage.

The SEL-T401L offers the complete suite of Main 1 and

Main 2 protection functions that you expect in a line

protection system. Its high-performance distance

protection with five zones of phase and ground distance

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. 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.

Reset the complexity of your line protection applications

with the simple and robust protection philosophies and

considerably lower setting count of the SEL-T401L. It is

available in a 3U chassis, making it a great option when

replacing relays. Gain efficiency by using common SEL

configuration and integration tools, and benefit from

strong diversity in hardware, software, and protection

operating principles.

The SEL-T401L provides state-of-the-art fault locating

based on robust traveling-wave technology. The relay

includes single- and double-ended traveling-wave-based

fault-locating methods that are accurate to within a

single tower span. It also includes single- and double

ended impedance-based methods. The combination

of single-ended and double-ended methods, as well as

traveling-wave-based and impedance-based methods,

provides the best accuracy and dependability for any

combination of operating conditions and fault types. Using

the detailed fault location results, you can confidently

dispatch crews directly to the tower nearest to the fault,

reducing the outage time and maintenance expenses.

Combining the SEL-T401L high-speed double-ended

fault-locating technology and built-in adaptive location

dependent autoreclose cancel logic allows selective

reclosing on the overhead portion of hybrid lines and

inhibits reclosing on cable portions, protecting the cable

from additional insulation damage.

You can use the line-monitoring function in the SEL-T401L

for condition-based line maintenance. This feature helps to

prevent faults and to discover weak spots along the line.

High-Fidelity Transient Recording

The SEL-T401L measures and records line currents

and voltages with high-fidelity (1 MHz, 18-bit) sampling,

offering an enhanced understanding of the events on your

power system. This allows you to analyze high-frequency

transients, such as traveling waves from faults, switching

events, breaker restrikes, and self-extinguishing faults.