Accelerated life testing of PV arc-fault detectors

As of 2011, the National Electrical Code
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(NEC) has required arc-fault circuit interrupters (AFCIs) to be incorporated into photovoltaic (PV) systems to prevent fires. Some manufacturers are designing AFCIs to consist of arc-fault detectors (AFD) incorporated into inverters or combiner boxes in order to take advantage of the DC switching functionality of the existing hardware. Since AFCIs and AFDs are safety devices, it is critical to ensure the long-term functionality of AFD devices in these harsh environments. Sandia National Laboratories (SNL) has performed accelerated life tests on 10 arc-fault detectors. The devices were tested after being subjected to the thermal damage equivalent of 1.7-year increments in an inverter until 77.6 equivalent years of solder fatigue damage. 30% of the boards experienced component failures but there were no solder failures, indicating solder fatigue is not the primary failure mode. Based on these results, Sandia recommends an appropriate burn-in process be used for production of arc-fault prevention devices.