Project Description

SEL-387L Line Current Differential Relay

SEL-387L Line Current Differential Relay
Use SEL-387L Line Current Differential Relays for economical, easy-to-apply line protection.

Functional Overview

SEL-387L Functional Overview
87L Current Differential


Front- and Rear-Panel Diagrams

SEL387L- Front Panel SEL387L- Rear Panel
Front Rear


Easy Application

Protect two-terminal transmission lines and subtransmission lines with the same ratio CTs on each end. Apply a 64 kb digital communications channel for complete phase and ground fault protection with no settings.

Simple Installation

Connect single-mode optical fiber, 1300 and 1550 nm, for distances up to 120 km without a repeater. No additional transceivers are required.

Flexible Communications

Apply the SEL-387L with a multiplexed communications system using the built-in IEEE C37.94 compliant connection. Connect to EIA-422 and G.703 multiplexers using the SEL-3094 Interface Converter.

Low-Cost Replacement of Obsolete Systems

Use the SEL-387L for complete protection of two terminal lines. Save money with low equipment costs and no settings costs. Replace error-prone pilot-wire relays with a sensitive and secure fiber-optic line current differential relay. Use the built-in communications monitoring and alarm system to improve protection quality


411L 421 311C 311L 387L
Distance Protection
Line Current Differential
Breaker Failure Protection f f
Undervoltage Load Shedding f f f f
Series-Compensated Lines + +
21G Mho Ground Distance
21XG Quad Ground Distance
21P Mho Phase Distance
25 Synchronism Check
27/59 Under-/Overvoltage f
49 Thermal f f
50 (N,G) Overcurrent (Neutral, Ground)
50P Phase Overcurrent
50Q Negative-Sequence Overcurrent
51 (N,G) Time-Overcurrent (Neutral, Ground)
51P Phase Time-Overcurrent
51Q Negative-Sequence Time-Overcurrent
67 (N,G) Directional Overcurrent (Neutral, Ground)
67P Phase Directional Overcurrent
67Q Negative-Sequence Directional Overcurrent
81 Under-/Overfrequency
87L Line Current Differential
Programmable Analog Math
Out-of-Step Block and Trip
Load-Encroachment Supervision
Single-Pole Trip + +
Zone/Level Timers
Pilot Protection Logic
79 Automatic Reclosing
Number of Controlled Breakers 2 2 1 1 1
Fault Locating
Traveling Wave Fault Location +
Subcycle Distance Elements + + +
SELogic Control Equations
Nonvolatile Latch Control Switches
SELogic Remote Control Switches
SELogic Local Control Switches +
Display Points +
Mirrored Bits Communications
Substation Battery Monitor
Breaker Wear Monitor
Trip Coil Monitor f f f f
Event Report (Multicycle Data)
Sequential Events Recorder
Instantaneous Meter
DNP3 Level 2 Outstation + +
IEC 61850 Communications + + + +
Synchrophasors (SEL Format)
Synchrophasors (IEEE C37.118 Format)
Accepts Delta Voltage Transformers +
Connectorized (Quick Disconnect) Available + + +
Configurable Labels +
Standard Feature
+ Model Option
f This function may be created using settings

Product Literature