Project Description

SEL-751/SEL-751A Feeder Protection Relay

SEL-751 Feeder Protection Relay

The SEL-751 Feeder Protection Relay is ideal for directional overcurrent, fault location, arc-flash detection, and high-impedance fault detection applications. Flexible I/O options, easy mounting, and fast settings make the SEL-751 the right solution for industrial and utility feeder protection.

The SEL-751 provides complete feeder protection, with overcurrent, overvoltage, undervoltage, directional power, load encroachment, and frequency elements. Easily upgrade protection without cutting or drilling existing cutouts, with a small form factor and multiple mounting adapters. Quickly integrate into serial- or Ethernet-based communications with IEC 61850, MIRRORED BITS®, DeviceNet™, Modbus®, DNP3, and other protocols.

Functional Overview

25 Synchronism Check
27 Undervoltage
32 Directional Power
50 (P,G,Q) Overcurrent (Phase, Ground, Neg. Seq.)
50N Neutral Overcurrent
50NAF Arc-Flash Neutral Overcurrent
50PAF Arc-Flash Phase Overcurrent
51 (P,G,Q) Time-Overcurrent (Phase, Ground, Neg. Seq.)
51N Neutral Time-Overcurrent
52PB Trip/Close Pushbuttons
55 Power Factor
59 Overvoltage
59 (P,G,Q) Overvoltage (Phase, Ground, Neg. Seq.)
60 Loss-of-Potential (751)
LOP Loss-of-Potential Logic (751A)
67 (P,G,Q) Directional Overcurrent (Phase, Ground, Neg. Seq.)
79 Autoreclosing
81 (O,U,R/R,F) Over-/Underfrequency (Rate, Fast Rate)
85 SEL Mirrored Bits Communications
AFD Arc-Flash Detector
BRM Breaker Wear Monitor
DFR Event Reports
HIZ SEL Arc Sense Technology (AST)
HMI Operator Interface
LDE Load Encroachment
LDP Load Data Profiling
LGC SELogic Control Equations
LOC Fault Locator
PMU Synchrophasors
RTU Remote Terminal Unit
SBM Station Battery Monitor
SER Sequential Events Recorder

* Optional


Front- and Rear-Panel Diagrams

SEL-751 Front Panel SEL-751 Rear Panel
Front Rear


Feeder Protection

Protect radial and looped distribution circuits with comprehensive protection capabilities, including time-overcurrent, directional overcurrent, autoreclosing, over-/undervoltage, frequency, and much more.

Arc-Flash Mitigation

Improve safety for personnel with optional arc-flash detection capabilities. The SEL-751 Feeder Protection Relay offers combined light and high-speed overcurrent detection for arc-flash events. This combination provides the ideal solution for speed and security.

SEL has 2 types of arc-flash sensor:

Arc-Flash Point Sensor

1. Point Sensor

Arc-Flash Bare-Fiber Sensor

2. Bare-Fiber Sensor

High-Impedance Fault Detection

Detect downed conductors, even on poorly conducting surfaces, with Arc Sensetechnology (AST). AST algorithms (optional in the SEL-751) detect arcing produced by some high-impedance faults and will alarm or trip the breaker. This technology provides an added level of protection over conventional feeder protection methods.

Automation and Control

Apply the SEL-751 on feeders to provide protection, automation, and control capabilities, all in one package. SELogic control equations support many automated applications without the need for additional automation controllers. The configurable front-panel buttons can replace conventional panel controls and simplify overall applications and wiring.

Event Analysis

Conduct postevent analysis more efficiently with the detailed event records that are available in the SEL-751. Combine oscillographic and digital information to find root cause. Add a satellite-synchronized time source, like the SEL-2401 or SEL-2407®Satellite-Synchronized Clocks, for convenient alignment of event information from multiple devices.

Situational Awareness

Improve situational awareness and asset utilization with IEEE C37.118 synchrophasor measurement. Aggregate synchrophasor information from across your system to understand system trends, make decisions based on state measurement rather than state estimation, and aid in postevent analysis.

Reliable in Harsh Environments

Rely on the SEL-751 for protection and control applications, even in harsh and hazardous environments. The SEL-751 is designed and tested to meet and exceed utility and industrial requirements. An operating temperature range of –40° to +85°C (–40° to +185°F); Class 1, Zone 2 approval; and optional conformal coating mean this relay will provide years of reliable service.

Fault Location

Find faults faster and restore service more quickly with fault location algorithms. Communicate fault location information automatically to a control center by using serial or Ethernet communications and SCADA protocols.



451 351 351A 751 751A 551/
Distribution Feeder Protection
Breaker Failure Protection f f
Generator Intertie Protection + +
Synchronism Check + +
Underfrequency Load Shedding f
Undervoltage Load Shedding f +
27/59 Under-/Overvoltage +
32 Directional Power Elements f + +
49 Thermal Overload f
50 (P,N,G,Q) Overcurrent Element (Phase, Neutral, Ground, Neg. Seq.)
51 (P,N,G,Q) Time-Overcurrent Element (Phase, Neutral, Ground, Neg. Seq.)
67 (P,N,Q) Directional Overcurrent (Phase, Neutral, Neg. Seq.) +
81 Over-/Underfrequency
Separate Neutral Overcurrent
Load-Encroachment Supervision +
Mirrored Bits Communications +
Sensitive Earth Fault Protection + + +
Directional Sensitive Earth Fault Protection + +
Pilot Protection Logic
Rate-of-Change-of-Frequency (df/dt) f +
Harmonic Blocking +
Arc Sense Technology (AST) High-Impedance Fault Detection + +
Arc-Flash Detection + +
Phantom Phase Voltage
Current/Voltage Channels 6/6 4/4 4/4 4/4 4/4 4/0
Complete Two-Breaker Control
79 Automatic Reclosing + +
Fault Locating
SELogic Control Equations With Remote Control Switches
SELogic Counters
Voltage Check on Closing + +
Operator Control Pushbuttons
SELogic Nonvolatile Latch +
Nonvolatile Local Control Switches +
Display Points +
Multiple Settings Groups
Substation Battery Monitor + +
Breaker/Recloser Wear Monitor
Trip Coil Monitor f f f f f f
Voltage Sag, Swell, and Interruption (VSSI) +
Load/Signal Profile Recorder +
Sequential Events Recorder
Demand Meter +
DNP3 Level 2 Outstation + + +
Modbus Outstation +
IEEE C37.118 Synchrophasors
Bay Control
Ethernet + + +
IEC 61850 + + + + +
Simple Time Network Protocol (SNTP)
Independent Trip/Close Pushbuttons + + +
Harmonic Metering
RMS Metering
Standard Feature
+ Model Option
f This function may be created using settings

Product Literature