不同热辐射强度下通电导线短路故障特征研究OA

[Objective]To elucidate the evolution patterns and hazard characteristics of overheating-induced short-circuit faults in energized conductors under external thermal radiation,this study systematically investigated critical heat flux,characteristic temperatures,fault initiation time,insulation resistance evolution,short-circuit current-voltage waveform characteristics,and arc energy variation.The objective was to identify key parameters for the early warning of electrical fires during conductor short-circuit failure under varying thermal radiation intensities.The findings aim to provide experimental evidence for risk identification and assessment of electrical circuit failures in high-temperature environments.[Methods]Using an electrical fault simulation apparatus,stable thermal radiation intensities of 23-32 kW·m2 were applied to ZR-RVVB conductors operating under rated current conditions.Parameters including surface and internal temperatures,insulation resistance,pre-and post-short-circuit current and voltage waveforms,and fault occurrence times were recorded simultaneously.Thermal failure stages were defined using temperature-time curves.Short-circuit types were classified through waveform and time-frequency domain analyses,and short-circuit arc energy was calculated based on voltage-current integration.Comparative analyses were conducted to determine parameter variation patterns across different thermal radiation intensities.[Results]Experimental findings indicated that 23 kW·m2 represents the minimum critical thermal radiation intensity that causes short-circuit failures in ZR-RVVB conductors under rated current conditions.With increasing thermal radiation intensity,the conductor temperature rise showed four stages:transient thermal shock,accelerated pyrolysis,critical failure,and thermal steady state.The initial pyrolysis temperature(T1),peak temperature(T2),short-circuit trigger temperature(Tsc),and steady-state temperature(T3)increased approximately linearly with increasing heat flux.Meanwhile,the duration of each stage decreased with increasing heat flux,showing a power-law relationship.This reduction is associated with faster heating and accelerated insulation degradation under higher thermal radiation intensities.Notably,the short-circuit trigger time shortened from～1 053.4 s to 172.4 s.At a heat flux of 32 kW·m-2,the insulation resistance dropped rapidly to～0 GΩ within 180 s.Overall,insulation resistance declined significantly with increasing thermal radiation intensity.A reduction below～1 GΩsignaled imminent insulation failure.Fault mechanisms transitioned from metallic short circuits to carbonization path-type and arc-type faults as the thermal radiation intensity increased.At a heat flux of 25 kW·m-2,metallic short circuits were the dominant failure mode,accounting for～70％of failures.When the heat flux exceeded 26 kW·m-2,the frequency of carbonization path-type faults increased significantly,peaking near 31 kW·m-2.Time-frequency energy analysis indicated that arc-type short circuits exhibited the highest high-frequency energy characteristic parameters,with a high-frequency energy peak(HHF)of 0.860 and a high-frequency energy ratio(RHF)of 0.416,both of which were significantly higher than those of the other two fault types.Energy released after short-circuit increased significantly with increasing thermal radiation intensity;arc-type faults released the highest energy(approximately～9 324.89 J),followed by carbonization path-type faults.Meanwhile,metallic short circuits released the least energy.This indicated that higher thermal radiation intensities lead to greater short-circuit energy release and increased destructive potential.[Conclusions]This study characterized the temperature rise behavior,insulation resistance evolution,fault type transitions,and energy release characteristics of energized conductors under varying thermal radiation intensities.The findings provide a foundation for rapid short-circuit fault classification and the development of early-warning models.