In this paper, a superhydrophobic surface is used to increase the flashover voltage when water droplets are present on a silicone rubber surface. The dynamic behavior of a water droplet and the associated flashover characteristics are studied on common and superhydrophobic silicone rubber surfaces under a high DC voltage. On common silicone rubber, the droplet elongates and the flashover voltage decreases with increasing droplet volume and conductivity. In contrast, the droplet slides off the superhydrophobic surface, leading to an increased flashover voltage. This droplet sliding is due to the low adhesion of the superhydrophobic surface and a sufficiently high electrostatic force provided by the DC voltage. Experimental results show that a superhydrophobic surface is effective at inhibiting flashover.

This letter proposes improved time-frequency maps for separating multiple partial discharge (PD) sources in cable terminations. PD signals are acquired through a digital measurement system and a high frequency current transformer. The waveform of each pulse is analyzed by synchrosqueezed wavelet transform, and six representative feature parameters are proposed to form time–frequency maps. The results show that the proposed algorithm is effective for discriminating mixed PD sources in cable terminations and pulses from power electronic devices detected simultaneously by the PD measurement system.

The study on superhydrophobicity is based on the wetting behavior of droplets on the rough surface. The wetting behavior on the red rose petal was observed by optical microscope at micrometer scale. Results showed that the wetting behavior was dynamic and air moved slowly between the droplet and the red rose petal. Many isolated air cushions were also found at the interface. In order to explain the relationship between the wetting behavior and the high adhesive force on the rose petal, a geometric model about solid-liquid-air three phase interface was proposed. The adhesion on the rose petal mainly depended on the sealed air inside the interface which could not connect to the atmosphere and the strong association of the solid/liquid at Wenzel wetting domains in this model.

Superhydrophobic surface has aroused much interest among researchers due to the low adhesion between water and a substrate surface. This study focuses on the influence of the low adhesion of superhydrophobic surface on flashover characteristics under wet conditions. The flashover experiments were conducted under two different wet conditions. One was placing a constant volume droplet on the silicone rubber. The other one was that silicone rubber was wetted by salt fog. It was found that the adhesion between water droplets and a superhydrophobic surface was very low because of the presence of air cushion. Accordingly, water droplets were easy to slide on a superhydrophobic surface under the effect of electric filed. The sliding of droplets could provide a longer insulation path before flashover occurred. Results showed that flashover voltage could be improved greatly on a superhydrophobic silicone rubber surface.