IS 14956 : Part 1 : 2025/IEC 61472 : 2013 Live Working - Minimum Approach Distances - Part 1 a.c. Systems in the Voltage Range 72.5 kV to 800 kV - A Method of Calculation

ICS 13.260; 29.240.20; 29.260.99

ETD 36

NATIONAL FOREWORD

This Indian Standard (Part 1) (Second Revision) which is identical to IEC 61472 : 2013 'Live working - Minimum approach distances for a.c. systems in the voltage range 72,5 kV to 800 kV - A method of calculation' issued by the International Electrotechnical Commission (IEC) was adopted by the Bureau of Indian Standards on the recommendation of the Tools and Equipment For Live Working Sectional Committee and approval of the Electrotechnical Division Council.

This standard was first published in year 2001 and subsequently revised in 2014 to align it with the IEC 61472 : 2004. This revision has been undertaken to align it with the latest version of IEC 61472.

This edition includes the following significant technical changes with respect to the previous edition:

a) clarification of the scope;

b) review of the definitions;

c) clarification of the methodology of determining whether live working is permissible and the calculation of the minimum approach distances;

d) modification of the basic equation for calculation of the minimum approach distance;

e) introduction of Table 1 for altitude correction factor simplification ka;

f) introduction of criteria in presence of composite insulator and clarification on the use of insulator factor ki

g) review of the informative Annex F on the influence of floating conductive objects on the dielectric strength; and

h) review of the informative Annex G on live working near contaminated, damaged or moist insulation.

This standard is published in two parts. The other part in the series is: Part 2 Method of determination of the electrical component distance for a.c. systems from 1.0 kV to 72.5 kV

The text of the 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' appears referring to this standard, they should be read as 'Indian Standard'; and

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.