This British Standard specifies requirements for unused and reclaimed oxidation inhibited and uninhibited mineral insulating oils, as delivered, for use in transformers, switchgear and similar electrical equipment in which oil is required as an insulant or for heat transfer. These oils are obtained by the distillation and refining of petroleum. Oils with and without additives are within the scope of this standard.
This standard does not apply to mineral insulating oils used as impregnates in cables or capacitors nor to hydrocarbon insulating liquids obtained by synthesis.
NOTE. Oils conforming to the requirements of this standard, of the same class and containing no additives, are considered to be compatible with one another and can be mixed in any proportion. This does not necessarily apply to oils containing additives and where the user wishes to mix such oils a check should be made to ensure that the mixture complies with the requirements of this standard.
BS 148:1998 history
2020BS 148:2020 Recycled mineral insulating oil for transformers and switchgear. Specification
2009BS 148:2009 Reclaimed mineral insulating oil for transformers and switchgear – Specification
1998BS 148:1998 Specification for unused and reclaimed mineral insulating oils for transformers and switchgear