An Investigation of the Operating Characteristics of ELCBs and AFCIs under Series and Parallel Tracking Conditions

In this study, we compared and analyzed the operational characteristics of conventional earth-leakage circuit breakers (ELCBs) and recently introduced arc-fault circuit interrupters (AFCIs) under simulated series and parallel tracking conditions. The experimental results for series tracking revealed a significant fire hazard, with temperatures rapidly exceeding 350 °C due to tracking and subsequent flashover. However, all the tested ELCBs and AFCIs exhibited a critical failure to trip, which prevented the circuit from being interrupted. Under parallel tracking conditions, none of the circuit breakers actuated during the arcing phase; they only tripped via their overcurrent protection function after a short circuit was formed by a conductive carbonized track between the electrodes. This demonstrates a reactive rather than preventive mode of protection. These findings suggest that the current safety standard for AFCIs (KS C IEC 62606) does not adequately address fire scenarios that involve progressive electrical faults such as tracking. Consequently, the standard must be supplemented accordingly. It is also imperative to develop reliable, next-generation smart AFCIs to address the limitations identified in this study, including failure to trip in series tracking and inadequate arc-fault detection capabilities in parallel tracking.