Clearing Series AC Arc Faults and Avoiding False Alarms Using Only Voltage Waveforms

A series ac arc fault detection method based only on the voltage waveform measured at the power source is implemented. A relay de-energizes the arc fault after receiving an arc fault detected signal. Traditional arc fault detection methods use the current waveform, which may have false alarms with loads, such as electric hand drills (which intentionally generate small electric arcs) and dimmer switches because they show similar energy characteristics to an arc fault. However, in the proposed voltage-based method, a symmetric energy profile is observed, unique to the arc fault, which allows improved detection. This symmetry in the voltage waveform is exploited to derive threshold values from the sample energy that are eventually used to detect the ac arc fault. The approach avoids non-stationary signal analysis, machine learning, and advanced filtering techniques. The experimental results validate that the algorithm can successfully detect an arc fault and avoid common unwanted tripping events. Finally, devices, such as surge protectors will be able to integrate this detection algorithm without the addition of current sensors.