NATIONAL FOREWORD

This Indian Standard (Part 207) (First Revision) which is identical with IEC 62271-207 : 2012 ‘Highvoltage switchgear and controlgear — Part 207: Seismic qualification for gas-insulated switchgear assemblies for rated voltages above 52 kV’ issued by the International Electrotechnical Commission (IEC) was adopted by the Bureau of Indian Standards on the recommendation of the High-Voltage Switchgear and Controlgear Sectional Committee and approval of the Electrotechnical Division Council.

This standard was first published in 2011 and was identical with IEC 62271-207 : 2007. This IEC Standard has since been revised as IEC 62271-203 : 2012. This revision of this standard (Part 207) has been taken up to incorporate the technical modifications and align it with latest IEC Standard. This revised standard includes the following significant technical changes with respect to the previous version:

- modification of the minimum voltage rating from 72.5 kV to above 52 kV;

- modification of the test procedures;

- addition of criteria of allowed stresses; and

- addition of dynamic analysis CQC.

This standard should be read in conjunction with IS/IEC 62271-1 : 2007, to which it refers and which is applicable unless otherwise specified. In order to simplify the indication of corresponding requirements, the same numbering of clauses and subclauses is used as in IS/IEC 62271-1. Amendments to these clauses and subclauses are given under the same numbering, whilst additional subclauses, are numbered from 101.

The text of IEC Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain conventions are however not identical to those used in Indian Standards. Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appear referring to this standard, they should be read as ‘Indian Standard’.

b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker.