IEC 60071-2:2018

FOREWORD
1 Scope
2 Normative references
3 Terms, definitions, abbreviated terms and symbols
4 Representative voltage stresses in service
5 Co-ordination withstand voltage
6 Required withstand voltage
7 Standard withstand voltage and testing procedures
8 Special considerations for overhead lines
9 Special considerations for substations
Annex A (informative) - Determination of temporary
        overvoltages due to earth faults
Annex B (informative) - Weibull probability distributions
Annex C (informative) - Determination of the representative
        slow-front overvoltage due to line energization and
        re-energization
Annex D (informative) - Transferred overvoltages in
        transformers
Annex E (informative) - Lightning overvoltages
Annex F (informative) - Calculation of air gap breakdown
        strength from experimental data
Annex G (informative) - Examples of insulation co-ordination
        procedure
Annex H (informative) - Atmospheric correction - Altitude
        correction
Annex I (informative) - Evaluation method of non-standard
        lightning overvoltage shape for representative
        voltages and overvoltages
Annex J (informative) - Insulation co-ordination for
        very-fast-front overvoltages in UHV substations
Bibliography

IEC 60071-2:2018 constitutes application guidelines and deals with the selection of insulation levels of equipment or installations for three-phase electrical systems. It gives guidance for the determination of the rated withstand voltages for ranges I and II of IEC 60071-1 and to justify the association of these rated values with the standardized highest voltages for equipment. It covers three-phase systems with nominal voltages above 1 kV. This edition includes the following significant technical changes with respect to the previous edition:

a) the annex on clearance in air to assure a specified impulse withstand voltage installation is deleted because the annex in IEC 60071-1 is overlapped;

b) 4.2 and 4.3 on surge arresters are updated;

c) 4.3.5 on very-fast-front overvoltages is revised. Annex J on insulation co-ordination for very-fast-front overvoltages in UHV substations is added;

d) Annex H on atmospheric correction – altitude correction is added.

e) Annex I on evaluation method of non-standard lightning overvoltage shape is added.

It has the status of a horizontal standard in accordance with IEC Guide 108.