Revised Standard from Last Update.

1. Scope

1.1 This standard covers requirement for composite units of air-break switches and rewirable type electric fuses with rated current not exceeding 100A intended for system voltages not exceeding 650 V a.c.

1.2 The switches incorporated in the composite units are intended for utilization category of AC-21A (frequent operation) and AC-21B (infrequent operation),

1.3 The rewirable type fuses, incorporated in composite units, shall conform to the requirements laid down in IS 2086 : 1993.

NOTES

1 It shall however be recognized that this imposes no restriction on rewirable type fuse-combination of other categories of duties or composite units incorporating cartridge type fuses inwhich case reference shall be made to IS/IEC 60947 (Part 3).

2 This standard shall cover only composite units incorporating:

a) Air-break ‘on’ and ‘off ’ switches of category AC-21A and AC-21B and for rated current not exceeding 100A,

b) Rewirable type of fuses only, and

c) Enclosure of metal-clad insulated types

2. References

2.1 The standards given below contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editionsindicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards listed below.

IS No. Title

IS 1885 (Part 17) : 1979 Electrotechnical vocabulary: Part 17 Switchgear and controlgear ( first revision )

IS 2086 : 1993 Carriers and bases used in rewirable type electric fuses for voltages up to 650V - Specification ( third revision )

IS 11353 : 1985 Guide for uniform system of marking and identification of conductors and apparatus terminals

IS/IEC 60529 : 2001 Degrees of protection provided by enclosures (IP Code)

IS/IEC 60947 Low-voltage switchgear and controlgear

Part 1 : 2007 General rules ( first revision )

Part 3 : 2018 Switches, disconnectors, switch-disconnectors and fusecombination units ( second revision )