The relationship between the physical, chemical, and functional properties
Electrical insulating liquids are one part of the insulating system for transformers and other electrical apparatuses. Through decades of experience, insulating liquids, especially mineral insulating oil, have been found to meet the requirements for the whole spectrum of transformers, from small distribution to large power— even though the technical requirements for each apparatus are different. The chemical composition of the insulating liquid will determine its physical and chemical properties which will, in turn, determine its functionality in an electrical apparatus. Standard specifications, e.g., IEC 60296 or ASTM D3487, list the physical/chemical/dielectric requirements that an insulating liquid must meet to be marketed as conforming to those specifications. These requirements are the mutually agreed upon minimum specifications. OEMs and utilities are free to add or subtract from those specifications.