Some general remarks on the dielectric loss mechanisms in mineral oils

The mechanisms of conduction and dielectric loss pertaining to electrical insulating oils, are examined with specific reference to the conduction and dielectric loss processes involving ionic and macroscopic particle charge carriers. Specific examples are presented; one of the most serious types of conduction by particles is that due to semiconductive copper sulfide particles, which are formed in a reaction between copper conductors or copper particles and the corrosive sulfur components contained in the oils.