Comparison of breakdown voltage of vegetable olive with mineral oil, natural and synthetic ester liquids under DC voltage.

This paper deals with a comparative study of the negative and positive DC breakdown voltages of different insulating liquids namely two natural esters (an extra virgin olive oil (OO) without additive and rapeseed oil), two synthetic ester fluids (a methyleolate obtained by transesterification of olive oil and tetraester), and a naphthenic mineral oil (MO); an oils mixture namely 80% OO + 20% MO is also investigated. Statistical analysis of the experimental data is also performed. The obtained results are also compared with those obtained in our previous work under AC and lightning impulse voltages. It is observed that the negative and positive DC breakdown voltages of natural esters are higher than those of mineral oil. On the other hand, the DC breakdown voltage of (80% OO + 20 % MO) mixture shows comparable behavior to that of mineral oil. The DC negative breakdown voltages are higher than the positive ones in the tested liquids. It is also shown that the DC breakdown voltage values of the investigated liquids generally obey the normal distribution. [ABSTRACT FROM AUTHOR]