Study on the extension process of AC local arc on wet contaminated insulating surface

In order to research the extension processes of local arc on wet contaminated insulating surface under AC voltages, high speed camera was used to track the extension process, while, the voltage and leakage current waveforms were recorded by the measurement system. measurement systemObservationally, the extension process can be divided into two categories - The arc foot moving forward along the wet contaminated surface and the arc floating through air. In the case of applied voltage was low, the arc foot extension process was suppressed as the electric field ahead was limited. Arc length went on increasing as it was floating more seriously. When the applied voltage approach or reach flashover voltage, the fast extension of arc foot result in flashover rapidly, and the partial arc didn´t had much time to float up. This also indicated that the extension of arc foot was only the result of arc propagation like arc floating instead of surface electric breakdown due to electric field concentration.