Insulating oils: recent ERA/IEC work

The introduction explains the insulating-liquids committee structure of ERA and its relationship with insulating-oil committees of BSI in Britain and JEC and CIGRÉ internationally. The period since 1958 (the date of the last review) is surveyed, starting with changes made to BS 148 in the 1959 edition and subsequent amendments. The IEC oxidation test is discussed and compared with other national insulating-oil aging tests. A modification, reducing test duration from 8 days to 3, is described, and its correlation with the standard test considered. Mention is made of the ERA 10-year field trials on inhibited transformer oil, and particulars are given of the IEC test for electric strength of insulating oil. The possibility of an internationally agreed specification for transformer oil is discussed. The paper concludes with a brief account of research related to insulating oils, which ERA is sponsoring at three British universities.