MT 9 - TC 99/MT 9

IEC 60071-2:2023 is available as IEC 60071-2:2023 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 60071-2:2023 constitutes application guidelines and deals with the selection of insulation levels of equipment or installations for three-phase AC systems. Its aim is to give 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. This association is for insulation co-ordination purposes only. The requirements for human safety are not covered by this document. This document covers three-phase AC systems with nominal voltages above 1 kV, phase-to-earth, phase-to-phase and longitudinal insulation. It has the status of a horizontal standard in accordance with IEC Guide 108. This edition includes the following significant technical changes with respect to the previous edition:
a) Clause 4 Concepts governing the insulation co-ordination has been added.
b) Subclause 5.3 has been revised, and Subclause 5.4 Detailed simulation has been added because it is widely applied in the recent practices of insulation coordination.
c) Special considerations for cable line and GIL/GIB have been added in Clause 9.
d) Annex K (informative) Application of line shunt reactor to limitation of TOV and SFO in high voltage overhead transmission lines has been added.
e) Annex L (informative) Calculation of lightning stroke rate and lightning outage rate has been added.