This test method describes the procedures for determining the oxidation induction time (OIT) of natural ester insulating liquids using a DSC testing cell. The method utilizes a conventional DSC cell with flowing oxygen and a choice of isothermal temperatures to obtain oxidation induction times between 10 and 120 minutes. Typical temperatures range from 120C to 160C. This test method is applicable to natural ester liquids used as dielectric coolants in electrical equipment, such as transformers and switchgear. This test method is applicable for the evaluation of the oxidation stability of natural ester liquids for quality control, quality assurance or research and development purposes.
Fluid and equipment manufacturers, specifiers, end-users, and testing labs have no standard method for measuring the oxidation stability of natural ester dielectric liquids for use in electrical equipment. Only one method has been standardized based on a 48 hour modified IEC 61125 method C, but this method is very time consuming and cumbersome. Laboratory time can be cut from 2 weeks to 2 hours.
KeywordsDifferential Scanning Calorimeter; natural ester; electrical insulating liquid; oxidation induction time; OIT; DSC; thermal analysis
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top