ARC-flash detection prevents catastrophic damage

This paper shows how adding arc-flash detection (AFD) technology to a motor or feeder protective relay dramatically reduces the time it takes for the relay to detect an arc flash and send a trip signal to a circuit breaker. This can result in a significant reduction in arc-flash incident energy levels. The reduced incident energy levels also have the benefit of substantially reducing damage to the switchgear equipment. This paper includes a field report of an actual arc-flash trip event, demonstrating how AFD technology performs in realworld conditions. We will contrast this field report to the outcome described in the ESW paper, “The $125,000 Field Mouse” [1]. In our incident, a rat entered the switchgear outgoing cable compartment, and came in contact with the cable terminals, resulting in an arc fault. The AFD relay's waveform capture (oscillography) report shows that the arcflash detection element in the relay detected the arc flash and performed an immediate trip of the feeder breaker. Instead of the $125,000 damage cited in the previous paper, this switchgear suffered only minor damage and a brief outage. These field reports show that AFD technology performs as expected in reducing arc-flash hazards.