Review of recent changes to mineral insulating oil specifications

In the past few years the major transformer oil specifications used in North America and Europe have undergone a number of changes. These changes have been in response to specific issues such as corrosive sulphur, changes in oil quality levels and the needs of new large transformers to ensure long, trouble free service life for valuable assets. This paper will review what specifications are in use in these markets and what changes have occurred or are likely to occur in the near term. The specifications reviewed will be CSA C50 (Canada), ASTM D3487 (US), Doble TOPS (US), IEEE C57.106 (US) and IEC 60296 (Europe). The implications of these changes on future transformer fluid development will also be reviewed. This paper will assist utilities and transformer OEM´s, that set their own specifications, to bring these up to current status.