ASTM
ASTM D3487 is a specification published by ASTM International for mineral insulating oil used in electrical apparatus. Rather than describing one laboratory procedure, it sets out the property requirements that new, unused oil must meet, referring to separate test methods for each property, and it distinguishes oil types by their intended service.
Editions cited: ASTM D3487
The specification addresses petroleum-based oil that serves as both insulation and coolant in transformers, reactors, switches and similar equipment. Its requirements cover physical, electrical and chemical characteristics, including viscosity, flash point, pour point, interfacial tension, moisture, acidity, dielectric strength, gassing behavior and oxidation stability. Oil suppliers use it to qualify products, equipment manufacturers cite it when they specify the oil for a unit, and owners and testing firms use it to judge a delivered shipment or a newly filled apparatus against the agreed requirements. It concerns new oil at delivery, not oil that has aged in service, which is evaluated through separate guidance. The pages in this encyclopedia that cite ASTM D3487 explain sampling and quality testing of insulating liquid in general terms and point the reader to the specification and the referenced methods for the governing values.