IEC 60247:2004

Describes methods for the determination of the dielectric dissipation factor, relative permittivity and d.c. resistivity of any insulating liquid material at the test temperature. The methods are primarily intended for making reference tests on unused liquids. They can also be applied to liquids in service in transformers, cables and other electrical apparatus. However the method is applicable to a single phase liquid only. When it is desired to make routine determinations, simplified procedures, as described in Annex C, may be adopted. With insulating liquids other than hydrocarbons, alternative cleaning procedures may be required. The main changes from the previous edition deal with the preferred measurement method.