Small Current Grounding Line Selection Based On The Frequency Characteristics Of The Study

Medium voltage distribution network mostly use the way of non-solidly earthed network in our country. Because the fault current is weak and electric arc is not steady, non-solidly electric current does not have the thorough settlement. The analyses breakdown produces the characteristics of transient zero foreword electric current. According to circuit parameter, extracts its transfer function and analyzes logarithm amplitude-frequency characteristic and the frequency characteristic with the frequency method. When expounding and proving a malfunction, momentary state zero order electric current coming into being in SFB frequency channel amplitude bigger and present to hold nature. Proposes the way of fault selection of the SFB frequency band zero foreword electric current. This method is not effected by Eliminate the arc circle and unstable electric arc. The reliability and sensitivity are high.