In rainy weather

water drops existing on the surface of a transmission line conductor will distort the electric field around the conductor

thus the corona characteristics of the conductor will be changed.In this study

based on a laboratory corona cage

the self-developed corona loss measurement system was utilized to measure the corona loss of conductor under different water drop level（water film

a drop of water

moderate water drops

and saturated water drops）.Thus

the influence law of the surface water drop on corona inception characteristic was obtained.Moreover

the effect of water conductivity on corona discharge characteristics was investigated considering the diff

erence in conductivity of different rain water.The results show that: 1)Water drops on conductor significantly affect the corona loss of the conductor

e.g.

under same voltage

the corona loss of a conductor with water drops on its surface is much greater than that of a clean conductor; 2)The conductor’s corona inception voltage decreases with the level of water drop on its surface increasing

and the minimum can reach 34.02% of original value; and 3)In the conductivity range of30

6

80 μS/cm

water drop conductivity has little impact on corona discharge of AC conductor.