In order to overcome the contradictory of setting the arc-suppression coil and symmetry of three-phase voltage in 35 kV mountainous area grid can not both take into account.it’s necessary to make judgement on single-phase-to-ground fault type.In this paper

via building of equivalent circuit and simulation & analysis of 35 kV grids in mountainous area

voltage features of phase respectively in the aforesaid faults have been obtained as well as the differences between them

and judgement method for fault types and corresponding circuit are proposed with the discussion of influence of grounding resistance and arc re-burn time.Simulation result indicates that this judgement method and circuit gives a good performance for the judgement of fault types

and besides

there is basically no threat to its judging result from earthing resistance and re-burn time of arc.The proposal of this judgement method and circuit is of great significance in decreasing trip-out rate & improving operation level of 35 kV grids in mountainous area.