The rapid increase of distribution feeder loading and the wider application of cables requires more frequent usage of effective neutral point grounding. High impedance faults (HIFs) often occur in effectively grounded distribution systems. They exhibit limited fault current which can be too small to be identified by conventional overcurrent relays. HIFs data is always beyond reach due to the poor action of existing relays; therefore

artificial fault experiment becomes a main approach to obtain fault data. However

the experiment is costly and limited to several fault surfaces. Modeling study provides an economical and flexible way for HIFs detection and provides better understanding of HIFs. Existing HIF models are mostly associated with arc

and are not always suitable for small current and open air HIFs. Several existing HIF models are analyzed in detail. Based on the solid dielectric electrical breakdown theory

a nonlinear fault model is proposed. The model is verified by artificial experiment data.