Abstract：Power safety is a critical issue related to the reliable supply of energy and the safety of people's lives

and property. In recent years，electrical fire incidents have been frequent in China，and low-voltage AC fault arc

diagnosis，especially for series fault arcs，is difficult to apply to the complex domestic power distribution systems，

making its accuracy hard to guarantee. The research progress on low-voltage AC fault arcs both domestically and

internationally was summarized，the studies on AC arc models and the high-frequency characteristics of arcs were

discussed. The applicable conditions，advantages，and disadvantages of current AC fault arc diagnosis methods

were further analyzed and crosstalk recognition techniques，diagnostic methods that utilize the physical

characteristics of arcs，the time-frequency domain characteristics of arc voltage and current signals，and pattern

recognition were covered. Finally，the arc diagnosis capabilities of some domestic and international arc diagnostic

devices were anylyzed，the shortcomings in the research on low-voltage AC fault arc characteristics and the

difficulties in fault diagnosis were pointed out，and the future research directions was prospected.

      Key words：power distribution system；series fault arcs；fault arc characteristic；fault arc diagnosis