IS 7421 : 1988 Porcelain bushings for alternating voltage up to and including 1000 V

1 Scope

1.1 This standard covers the requirements, characteristics andmethods of tests for porcelain bushings for indoor and outdoor use,suitable for electrical equipment of nominal system voltages up toand including 1000 V and frequency between 15 and 60 Hz.

1.2 This standard also applies to bushings supplied separatelyfor use in the construction of electrical apparatus, transformers,electrical installations and to bushings supplied as an integralpart of equipment when required by the relevant equipmentspecifications.

1.3 This standard does not apply to bushings for use withrectifiers, rotating machines, testing transformers, dc convertertransformers or to terminals for power cables (pot heads). Suchbushings, if not covered by relevant Indian Standard, shall besubjected to special agreement between the purchaser and thesupplier.

2 References

IS 2 :1960Rules for rounding off numerical values

IS 2071 : Part 1 :1974Methods of high voltage testing : Part 1General definitions and testrequirements

IS 1885 : Part 54 :1980Electrotechnical vocabulary : Part 54Insulators

IS 2099 :1986Specification for bushings foralternating voltages above 1 000 volts

IS 3347 : Part 1 : Sec 1 :1979 Dimensions for porcelain transformerbushings for use in normal and lightly pollutedatmospheres : Part 1 Up to andincluding 1 kV, Section 1 Porcelainparts

IS 3347 : Part 1 : Sec 2 :1979 Dimensions for porcelain transformerbushings for use in normal and lightlypolluted atmospheres : Part 1 Up to andincluding 1 kV, Section 2 Metal parts

IS 5621 :1980Specification for hollow insulators foruse in electrical equipment

IS 6697 :1972Specification for hot dip aluminium coating on ferrousparts (other thansheet, strip and wire) for generalpurposes

IS 10314 :1982Dimensions for ceramic bushings forterminals