Arc-Flash Detection Relay From SEL

April 8, 2009
Minimizing Dangerous Arc-Fault Energy
Minimizing Dangerous Arc-Fault EnergyArc-flash detection (AFD) capability in the SEL-751A Feeder Protection Relay, from SEL, provides fully automatic protection against dangerous arc-flash events. Without AFD, the arc flash can cause severe personal injury, extensive equipment damage, and lengthy system outages. The SEL-751A AFD solution uses fiber-optic, arc-flash light sensors to detect the light produced by an arc-flash event. To prevent false tripping, the SEL-751A looks for an overcurrent that coincides with the light flash. When both conditions are met, the SEL-751A sends a trip signal to the circuit breaker in as fast as 2 msec.