DIN EN 61099:2011-06

This International Standard covers the specification and test methods for unused synthetic organic esters delivered to the agreed point and time of delivery intended, for use in transformers, switchgear and similar related equipment in which these liquids are required as an insulant and for heat transfer. These unused synthetic organic esters are obtained by chemical processing and physical treatments of fatty acids and polyols. Maintenance of synthetic organic esters in equipment is covered in another standard (IEC 61203). Unused synthetic organic esters to which this standard applies are liquids which contain only carbon, hydrogen and oxygen. They are prepared from mono- or polyhydric alcohols and mono- or polybasic aliphatic or aromatic acids. Commercial products may be based on single esters or a mixture of esters and may contain stabilizers or other additives. The unused synthetic organic esters selected for use in transformers have high flash and fire points and are therefore relatively difficult to ignite. They may, however, have slightly higher viscosities than conventional mineral insulating oils. Unused synthetic organic esters are more hygroscopic than mineral oils, and this aspect will need to be considered in their use and maintenance. Such a liquid, by definition, has not been used in, or been in contact with, electrical equipment or other equipment not required for manufacture, storage or transport. The manufacturers and suppliers of unused synthetic organic esters shall take all reasonable precautions to ensure that the liquid is not contaminated with polychlorinated biphenyls or terphenyls (PCB, PCT), used, reclaimed or dechlorinated oils, or other contaminants. The responsible Committee is K 182 "Flüssigkeiten und Gase für elektrotechnische Anwendung" ("Liquids and gases for electrotechnical applications") of the DKE (German Commission for Electrical, Electronic and Informational Technologies) at DIN and VDE.