This International Standard specifies the characteristics and tests for insulated bushings. This standard is applicable to bushings, as defined in Clause 3, intended for use in electrical apparatus, machinery, transformers, switchgear and installations for three-phase alternating current systems, having highest voltage for equipment above 1 000 V and power frequencies of 15 Hz up to and including 60 Hz. Subject to special agreement between purchaser and supplier, this standard may be applied, in part or as a whole, to the following: - bushings used in other than three-phase systems; - bushings for high-voltage, direct current systems; - bushings for testing transformers; - bushings for capacitors. Special requirements and tests for transformer bushings in this standard apply also to reactor bushings. This standard is applicable to bushings made and sold separately. Bushings which are a part of an apparatus and which cannot be tested according to this standard should be tested with the apparatus of which they form part.