SEL-751/SEL-751A 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

SEL-751 SEL-751A

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

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:

1. Point 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.