The Arc Fault Hazard
DC arcs in PV systems can reach temperatures of 3,000°C, posing severe fire risks. Arc faults may arise from:
- Damaged insulation
- Loose connections
- Moisture ingress
How AFCI Breakers Work
- High-Frequency Sensing: Detects the unique noise signature of an arc (30–100 kHz).
- Current Ripple Analysis: Identifies irregular current patterns caused by arcing.
- Fast Disconnection: Trips within milliseconds to prevent sustained arcing.
Testing Standards
- UL 1699B: North American standard for PV arc fault detectors.
- IEC 63027: International guidelines for DC arc fault protection.
Installation Best Practices
- Place AFCIs at both string and combiner box levels.
- Ensure compatibility with inverters to avoid nuisance tripping.