BS 148:1998 was the specification for unused and reclaimed mineral insulating oil for transformers and switchgear. The specification for unused mineral insulating oil is now covered in BS EN 60296. Due to the continued market requirement for reclaimed oil to an agreed specification, BS 148 is now dedicated to reclaimed mineral insulating oil only.
BS 148 specifies requirements for 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. Oils with and without additives are within the scope of this standard.
BS 148 does not differentiate between the methods used to reclaim used mineral insulating oil; thus it is also applicable to oils having undergone a re‑refining process.
BS 148 gives guidance on:
- Identification and delivery
- Sampling
- Properties of the oils
- Test methods.
This standard does not apply to mineral insulating oils used as impregnates in cables or capacitors, or to hydrocarbon insulating liquids obtained by synthesis.
BS 148:2009 supersedes BS 148:1998, which is withdrawn.
