Non-contact ignition characteristics of cotton fabric under impact of 220 V AC arc faults

• Three distinct ignition patterns: no, slow, and fast ignition. • T ig of cotton fabric exposed to 220 V AC arc faults ranges from 400 °C to 500 °C. • T ig decreases linearly with distance under constant power. • t ig increases exponentially with increasing distance. • The critical ignition distance model demonstrates high reliability at high power. This study experimentally investigates the non-contact ignition of a single-layer cotton fabric exposed to 220 V AC arc faults. Tests were conducted at load power from 1.5 kW to 5.5 kW, with fabric samples placed 6–32 mm from the arc source. For each power, the electrode gap was set to the maximum width capable of sustaining a stable arc to simulate the worst condition. Three ignition patterns were observed: no ignition, slow ignition, and fast ignition. The ignition temperature of cotton fabric ranged from 400 °C to 500 °C, increasing with power at fixed distances and decreasing nearly linearly with distance at constant power. Ignition time decreased with increasing power at a diminishing rate and increased exponentially with increasing distance, exhibiting a sharp rise near the critical ignition distance. The experimentally measured critical distances showed good agreement with predictions from a theoretical model based on radiative heat transfer and solid ignition theory, particularly at higher load power, validating the model’s applicability for predicting ignition hazards under similar conditions. Abbreviations: d Horizontal distance from fabric center to arc center ; w , Gap width ; t ig , The ignition time ; T max , The maximum temperature ; T ig , The ignition temperature ; r , Radius ; τ , the thickness of the fabric ; ε , Emissivity of the fabric ; a , Absorptance of the fabric ; σ , Stefan-Boltzmann constant ; ρ , Density of the fabric ; c , Specific heat capacity of the fabric ; q ̇ ″ , Net heat flux received at the surface ; q ̇ cr ″ , Critical incident heat flux ; E arc , Arc energy ; P ¯ arc , Time-averaged arc power ; F 12 , View factor from a sphere to a coaxial disk ; d cr , Critical ignition distance ; Δ d cr , Relative error in critical distance ; d cr , p , Predicted critical ignition distance.