BS 5992 : Part 1 : 1980 IEC 255-0-20: 1974 UDC 621.318.5.066.6 , Fri Dec 01 15:00:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Electrical relays Part 1. Specification for contact performance of electrical relays Relais électriques Partie 1. Specification des caracteristiques fonctionnelles des contacts Licensed Copy: sheffieldun sheffieldun, na, de relais électriques Elektrische Relais Teil 1. Spezifikation fur die Kontaktleistung von elektrische Relais BS 5992 : Part 1 : 1980 National foreword This Part of this British Standard, which has been prepared under the direction of the General Electrotechnical Engineering Standards Committee, is identical with IEC Publication 255-0-20 'Contact performance of electrical relays'. published in 1974 by the International Electrotechnical Commission (IEC). Those Parts of IEC Publication 255 ‘Electrical relays' which are concerned primarily with protection relays are BSI incorporated where required into BS 142 : 1980 ‘Specification for electrical protection relays'. All other Parts of IEC d Copy, (c) Publication 255 which are implemented as British Standards form, or will form, Parts of this British Standard. In the UK, it has becn found necessary to supplement this standard in the case of electrical protection relays. The additional requirements for the contact performance of electrical protection relays are specified in BS 142. Classification of relay standards. Some Parts of IEC Publication 255 are designated first level documents, ie. they cover the requirements of all relays within the scope of IEC Technical Committee No. 41, Electrical relays. Other Parts of IEC , Uncontrolled Publication 255 are designated lower level documents, i.e. they are concerned with the requirements of a family of relays (second level) and of smaller and more specialized groups of relays within such a family (third and fourth level). According to this system of classification, this is a first level document. Terminology and conventions. The text of the international standard has been approved as suitable for publication, without deviation, as a British Standard. Some terminology and certain conventions are not identical with those used in British Standards;attention is especially drawn to the following. 1 15:00:17 GMT+00:00 2006, Wherever the word 'recommendation' appears, referring to this standard, it should be read as 'British Standard'. Cross-references. Where reference to other Parts of IEC Publication 255 is made, the appropriate Part of this standard or of BS 142 : 1980 should be consulted, as applicable. Although some Parts of IEC Publication 255 have not been implemented as British Standards, the committee responsible for the preparation of this standard is satisfied that any particular technical requirements which may have been invoked from those Parts of the international standard are fully acceptable for the purposes of this British Standard. Currently, the other published Parts of BS 5992 are as follows. International standard Corresponding British Standard IEC 255-1-00 : 1975 BS 5992 Electrical relays (second level document) Part 2 : 1980 Specification for all-or-nothing electrical relays (Identical) , Fri Dec 01 IEC 255-5 : 1977 Part 3 : 1980 Specification for the insulation testing of electrical relays (first level document) (Identical) For other international standards referred to in the text, the corresponding British Standards are as follows. International standard Corresponding British Standard BS 2757 : 1956 Classification of insulating materials for electrical machinery and apparatus on IEC85:1957 Licensed Copy: sheffieldun sheffieldun, na, the basis of thermal stability in service (Technically equivalent) The technical committee has reviewed the provisions of IEC 410, to which reference is made in 5.2.1, and has decided that they are acceptable for use in conjunction with this standard. The related British Standard is BS 6001 “Sampling procedures and tables for inspection by attribu