Calculating the surface electric field of conductors
Crown effect on overhead power lines

The most obvious characteristic parameter to which we usually relate the intensity of the corona effect is the electric field at the conductor surface, or surface gradient. Due to the high sensitivity of the corona phenomenon to the value of this field, it is necessary to use a calculation method that provides the field with an accuracy of the order of 1%.

Because most conductors are stranded, the actual surface field fluctuates around a mean value along their circumference. It is customary to calculate the surface field of a smooth conductor with the same outside diameter, even if it means introducing an experimental stranding correction coefficient if necessary.