Abstract: Single-phase grounding faults in non-solidly grounding systems are often accompanied by intermittent features. Analysis of the time of arc re-ignition and the electrical quantity when arc re-ignition happens can improve the fault transient theory and the effect of fault detection. Based on the recovery characteristics of voltage and insulation after arc extinction, the possible arc reignition time and the transient characteristics of the fault after arc re-ignition are analyzed under different stable conditions of the fault point in different grounding systems. When the fault point is stable, it is easy to re-ignite in the ungrounded system within half a power frequency period after the arc is extinguished. In the arc suppression coil grounding system, the arc re-ignition occurs mainly before the peak voltage of the fault phase. When the fault point is unstable, the re-ignition time is not obviously regular.Regarding the arc re-ignition process as a single-phase grounding fault in a non-zero initial state, the resonance frequency and damping factor of the high-frequency transient current are independent of the re-ignition time, and the amplitude is approximately proportional to the instantaneous value of the fault phase voltage at the re-ignition time. The damping factor of the attenuating DC component in resonant grounding system is independent of the re-ignition time, and its amplitude is approximately proportional to the derivative of phase voltage with time. The simulation and field data verify the correctness of the analysis conclusion.