The need of creating a new nominal creepage distance in accordance with heaviest pollution 500Â kV overhead line insulators

The exceptional level of pollution measured on those insulators, especially for the bottom surface for the non-soluble salt deposit density (NSDD) component, where the values are outside of the standard limit given in the currently IEC standard. The results provide important reference for the insulators design, maintenance of operational transmission line insulators and flashover warnings. It should be highlighted that results fall out of the limit of the IEC standard and that in order to plot those values in the graph the limits for the highest NSDD values have been increased from 4 to 20 g/cm2. This clearly shows the unusually high values of the NSDD components measured on those insulators. The case study has been realized on 837,000 insulators for 9000 towers in 500 kV powers lines. This clearly shows the unusual characteristics of the coast and desert environment of the 500 kV overhead lines, and the needs of update in the IEC standards has been researched.