Detail of GB/T 21421.1-2021

Introduction of GB/T 21421.1-2021

1 Scope This document specifies the prescribed values for the mechanical characteristics of composite insulator string elements and the main dimensions of the couplings used on composite insulator string elements to enable the assembly and interchangeability of insulators and end fittings supplied by different manufacturers. This document also specifies the standard coupling symbols for composite insulator string elements. Note 1: The general provisions and methods of testing are described in the relevant product standards. Note 2: This document only deals with the dimensions necessary for the assembly of the coupling and does not specify the material properties and working loads. This document applies to composite insulator string elements for AC overhead lines with a nominal voltage above 1 000 V and a frequency not exceeding 100 Hz, and to composite insulator string elements for DC overhead lines with a nominal voltage above 1 500 V. This document also applies to insulators of similar design for use in substations or power traction lines. 2 Normative references The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, note the date of the reference document, only the date of the corresponding version applies to this document; do not note the date of the reference document, its latest version (including all the revision of the list) applies to this document. GB/T 2900.8-2009 Electrical terminology for insulators (IEC 60050-471:2007, IDT) GB/T 4056-2019 Dimensions of ball and socket coupling of insulator string elements (IEC 60120:1984,MOD) GB/T 19519-2014 Definition, test methods and acceptance criteria for overhanging and tension-resistant composite insulators for a.c. systems with a nominal voltage above 1 000 V(IEC 61109:2008,MOD) GB/T 22079-2019 General definitions, test methods and acceptance criteria for high-voltage polymer insulators for indoor and outdoor use (IEC 62217:2012, MOD) GB/T 25317-2010 Dimensions of slotted connections for insulator string elements (IEC 60471;1977,IDT) 3 Terms and definitions The terms and definitions defined in GB/T 2900,8-2009, GB/T 22079-2019 and GB/T 19519-2014 apply to this document. 4 Mechanical and dimensional characteristics 5 Standard programme This document includes 11 SML grade specifications and 5 coupling series. The SML grade specifications (in kN) are: 40, 70, 100, 120, 160, 210, 300, 420, 550, 840, 1 000. 5 coupling series are: A standard series of foot ball joints, according to GB/T 4056-2019 A standard series of cap-and-socket couplings, according to GB/T 4056-2019 A standard series of L-shaped flat foot couplings, according to GB/T 25317-2010; A standard series of L-shaped groove couplings, according to GB/T 25317-2010 A standard series of ear ring coupling, should comply with the provisions of Appendix C. 6 insulator coupling symbols meaning The arrangement and meaning of the insulator coupling symbols are as follows. 7 Marking Each insulator shall be clearly and permanently marked with the name or trademark of the manufacturer, the year of manufacture, the specified mechanical load (SML) and each component shall be allowed to be marked in one way. 8 Composite insulator string elements The specified mechanical loads (SML) of the composite insulator string elements and their corresponding coupling marks are shown in Table 1. the coupling letters given in Figure 1 can be combined in any combination to indicate different designs. Appendix A (informative) List of chapter numbers of this document compared to IEC 61466-1;2016 Appendix B (informative) List of technical differences between this document and IEC 61466-1:2016 and their causes Appendix C (normative) Dimensional requirements for ear ring couplings Bibliography

Contents of GB/T 21421.1-2021

1 Scope 2 Normative references 3 Terms and definitions 4 Mechanical and dimensional characteristics 5 Standard programme 6 insulator coupling symbols meaning 7 Marking 8 Composite insulator string elements Appendix A (informative) List of chapter numbers of this document compared to IEC 61466-1;2016 Appendix B (informative) List of technical differences between this document and IEC 61466-1:2016 and their causes Appendix C (normative) Dimensional requirements for ear ring couplings Bibliography