Research On Detecting Low-Voltage Arc Fault

In low-voltage power system, arc fault can arise from insulation fault, which even bring fire accident. In order to avoid fire accident, it is necessary to detect arc fault.The properties of voltage and current created by normal working conditions of electrical appliance are closely resemble or mimic the abnormal properties created by the low-voltage arc fault, such as switch power supply, fluorescent lamp and light-change lamp and so on. So it is difficulty to distinguish from normal working loads and abnormal cases, and a powerful detecting principle is needed. This paper is intended to find a rational detecting principle for distinguishing from normal working loads and low-voltage series arc faults.Firstly this paper analyzes the line voltage-current phase property of low-voltage series arc fault based on resistance, and finds a rule: when low-voltage series arc fault occurs, in the Power fundamental-harmonic frequency, among some seriate half a cycles of the Power, the phase diversity between line-voltage and line-current changes, and the change of phase diversity isn't monotone. In the following step, this paper analyzes the line voltage-current phase properties of switch power supply, fluorescent lamp and light-change lamp, and finds a rule: when low-voltage wiring system is normal, in the Power fundamental-harmonic frequency, among some seriate half a cycles of the Power, the phase diversity between line-voltage and line-current is same, or the change of phase diversity is monotone. During the study of the project, some experimentation had been tried, including low-voltage arc fault experimentation and normal working experimentation of electrical appliance. The majority of experimentation data validates the above rules.The above Theory and experimentation makes clear: in the Power fundamental-harmonic frequency, among some seriate half a cycles of the Power, it can judge that the low-voltage series arc fault has occurred when the phase diversity between line-voltage and line-current changes and the change of phase diversity isn't monotone.