Behavior of water droplets on polymeric insulation surfaces under hybrid field stress

Abstract

Corona discharges caused by water droplets on the surface of polymeric insulators can affect the long-term reliability of the component by lowering the surface hydrophobicity encouraging surface discharges. It is well-known that droplet-initiated discharges behave differently under AC and DC field stress affecting the hydrophobicity of polymeric outdoor insulation materials. The presented investigations study the effect of hybrid field stress on partial discharges at singular water droplets. The behavior differs depending on the direction of the electric field as also known for uniform AC or DC fields. Tangential oriented field stress is more critical to aging phenomena due to a significantly lower pd inception level. By high speed analysis of the droplet deformation the oscillation frequency is linked to the acting electrostatic forces depending on the AC and DC component of the excitatory electric field. Thus, the mechanical oscillation model is extended for hybrid field stress.

Understanding the performance of corona aged epoxy nano micro composites

“…Under AC voltage, the droplet undergoes characteristic oscillations which depends on the size of the droplet, frequency of the supply voltage and the local electric field at the triple point formed at the interface of water droplet, insulating material and the air medium. Under DC voltages, the water droplet deforms in the direction of electric field but no oscillations are observed [26]. Similar phenomena were observed during experimental studies.…”

Enhancement of Acid Stability of Silicone Elastomers by Using Inert Fillers

“…In order to test the resistance of different silicone rubber compounds against acid, specimens of each compound have been immersed in 1M nitric acid for 168 h. Similar tests have been used by several authors [16][17][18]. To avoid the risk of neutralisation, the specimens were immersed in 100 ml acid.…”

Dynamic formation mechanism of water droplet and induced surface discharges on silicone rubber composites

“…Silicone rubber (SiR) composites have been widely used as outdoor insulation due to the excellent performances such as good hydrophobicity, high contamination flashover resistance, light weight and so on [1, 2]. However, when SiR composites are applied in the coastal power grid, the operating conditions are different from that in the inland grid, with the typical characteristics of higher humidity, lower pollution level, vulnerable to ocean salt fog corrosion etc.…”