Full-time domain deformation characteristics of water drop on sheds edge causing insulation failure of large-diameter composite post insulators under heavy rainfall

Insulation failures caused by water drops deformation on insulator sheds edge greatly threaten the stable operation of power grid. However, only few studies have focused on water drops deformation characteristics on insulator sheds edge. In this paper, full-time domain deformation of water drop was defined. The rain tests were performed to study the deformation of water drops and obtain water drops parameters under DC voltage. The water drops deformation parameter was selected according to the state of water drops when arc is generated. A fluid-electric field coupling method is employed to establish simulation model to study the influence of water drops initial diameter, initial mass flow rate, DC voltage, and conductivity on water drops deformation. It is indicated that water drops maximum deformation length before first break in simulation is in good consistency with that obtained from rain tests. The water drops initial diameter, initial mass flow rate, and DC voltage significantly influence the deformation of water drops on sheds edge. Moreover, the water drops may even bridge adjacent sheds in some cases. In contrast, the effect of water drops conductivity on the water drops deformation is not apparent.