Dynamic Behavior of Electric Arc in Low-Voltage Series Arc Faults on the Basis of Load Power Factor Characteristics

This study investigates the effect of the load power factor (PF) on the electrical arc characteristics of low-voltage series arcs. The arc voltage and current waveforms are measured under high- and low-power-factor load conditions, with 100 sweeps averaged to derive the conductance G(t) and its time derivative dG(t)/dt. Based on these data, key parameters of the Cassie–Mayr hybrid model—including the Cassie voltage (Uc), Mayr power (Pm), arc time constant (θh), and transition conductance (Gt)—are estimated using nonlinear least squares optimization. The analysis reveals that in the arc generation phase, low-power-factor loads are associated with higher values of Pm and Gt, indicating more explosive arc initiation with more rapid energy release when compared to those observed under stable and gradual heat accumulation and high-power-factor conditions. Conversely, during the arc extinction phase, high-power-factor loads are associated with a better Pm and longer θh, reflecting stronger resistance to arc extinction and a tendency to sustain heat over time. Overall, these results provide essential data for the quantitative assessment of electrical arc risks, and they serve as a foundation for the development of arc fault detection and interruption technologies.