Comparison of AC dielectric tests of insulating liquids

This paper presents a study on the AC dielectric strength of insulating liquids. The nature of such information is necessary for the definition of the apparent dielectric strength of the liquid and to any further technical development, claiming the use of standard statistical analysis. The liquid, used in this study was a mineral oil applied as the main insulating media to instrument transformers. Tests are carried out according to several standards regulations and the results of the liquid breakdown voltage, mean value and standard deviation, are verified. The analysis of the data aim at the comparison of the results obtained when using different testing procedures, that apply the same electrode shape, and also to define the factors that influence the issued value of the breakdown voltage of an insulating liquid.