SEL-751- SEL Arc Flash Relay

The SEL-751 SEL Arc Flash Relay is the right solution for industrial and utility feeder protection, with conventional/low-energy analog (LEA) current and voltage input support, flexible I/O options, easy mounting, and fast settings.


The SEL-751 provides complete protection for radial and looped distribution circuits. It offers arc-flash mitigation, fault location, high-impedance fault detection, broken conductor detection, event analysis, and more. You can quickly integrate the relay into serial- or Ethernet-based communications with IEC 61850 Edition 2, IEC 60870-5-103, the IEC 62439 Parallel Redundancy Protocol (PRP), EtherNet/IP, the Rapid Spanning Tree Protocol (RSTP), the IEEE 1588 Precision Time Protocol (PTP), Modbus, DNP3, and other protocols.

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  • Continuous system self-supervision
  • Event logs, disturbance recording and real-time clock
  • Three-phase current, Zero-sequence current
  • Two change-over alarm contacts including IF
  • Complete digital design, simple principle;
  • Strong electrical performance;
  • Comprehensive record of fault information;
  • Double criterion of over-current and arc, high reliability;
  • Optical fiber transmits, strong electromagnetic interference resistance;
  • Programmable logic of trip exit;
  • Fast exit tripping, short total fault clearing time.



  • Reduce the harm of arc light to human body;
  • Reduce damage to equipment caused by arc short-circuit faults;
  • Avoid transformer damage caused by bus failure;
  • Protect the dc system in the station;
  • Ensure the stable operation of power substations;
  • Thermal power plant electrical section switchgear;
  • Wind farm and photovoltaic station switchgear;
  • Large municipal engineering project;



Basic parameters
Rated working voltage DC24V
AC current 5A or 1A (specify when ordering)
Frequency 50HZ
Working power consumption Working normally, ≤ 3W

Protection operates, ≤ 6W

AC current loop consumption < 1VA/phase (IN =5A);

< 0.5VA/phase (IN =1A);

Current working range 0.08In~10In
Time working range 0~99s
Setting accuracy ≤±5%;
Time accuracy <±1%*setting time+20ms
The whole group action time Single criterion ≤ 7ms

Double criterion ≤ 20ms

Arc signal input
Input type Passive optical signal
Input quantity 3
Interface type: Optical fiber
Output contact capacity
A) Export relay: (3 routes)
Contact rated current carrying capacity 250Vac/220Vdc, 5A
Output type Passive (NO/NC)
B) Signal relay: (1 way)
Contact rated current carrying capacity 250Vac/220Vdc, 5A
Output type Passive (NO/NC)
Address 1~99
Communication interface
Electrical characteristics RS485
Transmission method Asynchronous
Communication protocol Modbus RTU
Communication medium Shielded twisted pair
Working temperature -30 ~ 70°C
Storage temperature -40 ~ +85°C
Humidity 5~95%RH
Electromagnetic compatibility
Electrostatic discharge test IEC 60255-22-2:2008. level-4
Fast transient dry resistance test IEC 60255-22-4:2008. level-A
1mhz burst interference test IEC 60255-22-1-2007. level-3
Electrical disturbance test IEC 60255-22-2:2008.level-3
Surge immunity test IEC 60255-22-5:2008