Behaviour of low current discharges between water drops

Discharges between water drops present an ageing activity on a polymeric insulator surface. Such discharges can develop into arcs and can propagate to flashover in high pollution conditions. The water drops may be deformed and move during the arcing phenomenon. These mobile drops can directly change the physical length of arcs or discharges, and in turn, affect the arc power and energy. In this paper, experiment work establishes two water electrodes with controllable separation between which low current arcs are established. Arcing voltage and current waveforms are recorded and the trends of breakdown voltage, current peak, duration and arc energy as functions of initial droplet separation are analyzed. It is shown that that arc energy and energy density increase as arc length decreases. This establishes that the physical dimension of an arc is important to its thermal properties, independent of a dielectric surface. The physical arc length on an insulator is thus an important factor in an arcs ability to damage the surface in service conditions. © 2009 IEEE.