Minimizing hazard to personnel, damage to equipment, and process outages by optical arc-flash protection

Arc-flash fault is a disastrous electrical accident. It can be characterized as an electrical explosion, and it often leads to injuries to personnel, significant damage to equipment, and long process outage. These negative impacts can efficiently be mitigated by early arc-flash detection and fast protection. This paper presents aspects and practical examples of how to apply very fast protection technology, based on detection of arc light. Along with optical detection, fast detection of overcurrent is normally used in order to avoid nuisance tripping caused by ambient light. Four categories of light-based arc-flash protection are presented: 1. Stand-alone devices, 2. Arc-flash protection integrated into common numerical relays, 3. Dedicated arc-flash protection systems and devices, and 4. Ultra-fast protection by special arc quenching devices in addition to circuit-breakers.