Project Description

Arc Sense Technology


Arc Sense


Arc Sense technology (AST) from SEL is an innovative solution that detects high-impedance faults (HIF) on a distribution system. A high-impedance fault occurs when a conductor contacts a ground surface but does not produce a large fault current. SEL’s patented AST detects and clears faults that might not be detected by conventional overcurrent elements. AST algorithms provide improved fault detection over traditional methods as well as enhanced security when compared to existing technologies. Dedicated event reports provide information on high-impedance fault activity for event analysis.

  • Minimize Outages
  • Detect High-Impedance Faults
  • Improve Reliability in Systems

Possible Causes of HIF:

  • Conductors falling on poor conductive surfaces
  • Tree branches leaning against power lines
  • Dirty insulators

These events commonly occur in a distribution system, emphasizing the need for the integration of the AST solution into SEL’s distribution relays and the SEL-651R Advanced Recloser Control.

An algorithm has been designed to improve the accuracy of the devices’ detection capabilities. To ensure the accuracy and reliability of the HIF detection, the algorithm gathers different data to make the best possible decision. Our patented Sum of Difference Current (SDI) method uses the current rate of change to detect arcing results from events such as downed conductors. The necessary elements used for the algorithm are implemented in the block diagram below, with five easy steps.

Understanding High-Impedance Fault Detection

Arc Sense Technology Algorithm Diagram


Arc Sense Transfer Diagram

Automatically transfer AST event files to long-term storage, and never miss a high-impedance event.

Related Products

SEL-651R Advanced Recloser Control


Apply the easy-to-use SEL-651R Advanced Recloser Control for Automatic Network Reconfiguration, three-phase and single-phase tripping, and all your distribution automation needs.

SEL-451 Protection, Automation, and Bay Control System


The new SEL-451 is a complete stand-alone protection, automation, and control system. The SEL-451 has speed, power, and flexibility to combine complete substation bay control with high-speed breaker protection in one economical system.

SEL-751/SEL-751A Feeder Protection Relay

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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.