AC fault arcs, especially series fault arcs, are an important cause of fire in AC power supply systems. Their causes are complex, the production process is hidden, and the characteristic phenomena are not obvious. If not detected and dealt with in a timely manner, it may lead to catastrophic fires, posing a serious threat to personal safety and property. It first analyzes the mechanism and typical fault characteristics of AC fault arc hazards；secondly, the methods for detecting and locating fault arcs in AC power supply systems are systematically elaborated; finally, from the perspective of practical applications, the current urgent problems that need to be solved for AC power supply systems are pointed out, and future application scenarios and research directions for AC fault arc detection and fault arc localization are prospected.