SEL L90 Line Differential Protection Relay Unit

Module Feature

L90TC3HKHF8LH6LL6UN67SXXUXXWXX is Schweitzer SEL-90 series multi-terminal line differential protection relay.

It supports two-terminal or multi-terminal fiber-optic differential protection, high-speed tripping for phase fault and earth fault. Integrated backup distance protection, phase/ground overcurrent protection, power swing detection, out-of-step blocking and fault locator. Supports SEL Mirrored Bits, IEC61850, DNP3, Modbus and SEL-2030 communication. Built-in disturbance recorder for fault waveform capture. Suitable for overhead transmission line and cable line protection, widely used in power plant, substation and industrial power grid.

Working principle

The relay samples CT current signals at each line terminal, exchanges synchronous current data with opposite-end SEL L90 relay via optical fiber.

Differential current is calculated internally. Once differential current exceeds setting threshold, trip command is sent to breaker. Distance and overcurrent protection act as backup protection. Fault event, alarm message and disturbance waveform are uploaded to SCADA or SEL-5030 workstation.

Onboard components

Main CPU board, analog CT/PT sampling module, fiber optical transceiver, binary input/output module, HMI display panel, DC power supply unit, status LED array, rear terminal block.

LED indicators

Front LEDs indicate power normal, protection run, trip action, channel fault and self-diagnosis alarm.

Hardware self‑diagnosis

Built-in supervision detects CT wiring error, fiber channel loss, internal hardware failure, power abnormality and clock sync loss. Fault logs and COMTRADE disturbance files can be downloaded by SEL AcSELerator software.

Programming softwareAcSELerator QuickSet, used for protection setting, channel matching, communication mapping and fault record analysis.

Electrical & Process Parameters

Model:L90TC3HKHF8LH6LL6UN67SXXUXXWXX Brand:SEL (Schweitzer) Device type:Fiber line differential protection relay Function:Main high-speed differential protection and backup protection for transmission lines

Mechanical & Structure

Mounting:Standard 19-inch panel flush mounting Protection class:IP40 front panel Housing:Metal reinforced molded relay case

Environmental

Operating temperature:-40℃ ~ +85℃ Storage temperature:-40℃ ~ +85℃ Ambient humidity:5~95% non‑condensing

Certification:CE, IEC 60255, UL

Status:Original SEL power protection spare

Installation

Install in relay protection cabinet, complete CT wiring, fiber channel and DC control power connection.

Set differential parameters, time synchronization and communication address, perform channel delay test and protection logic test before energization.

Interface

CT/PT analog input terminals, binary DI/DO terminal block, fiber communication port, DC auxiliary power, Ethernet and serial communication port.

Diagnostic

Differential false alarm: CT polarity reversed, channel delay mismatch or sampling data abnormal.

Fiber channel break: Optical fiber broken, optical module damaged or attenuation over limit.

Protection refuse to trip: Blocking signal active, unreasonable setting value or output circuit fault.

Product Brief

SEL L90TC3HKHF8LH6LL6UN67SXXUXXWXX protection relay, SEL-90 fiber line differential relay spare for substation transmission line protection cabinet replacement.