Insulation Co-Ordination and System Engineering of High Voltage Electrical Power Installations Above 1,0 kV AC and 1,5 kV DC

IEC 60071-5:2014 provides guidance on the procedures for insulation co-ordination of high-voltage direct current (HVDC) converter stations, without prescribing standardized insulation levels. This standard applies only for HVDC applications in high-voltage a.c. power systems and not for industrial conversion equipment. Principles and guidance given are for insulation co-ordination purposes only. The requirements for human safety are not covered by this standard. This International Standard cancels and replaces IEC TS 60071-5 published in 2002. On the basis of technical experience gained since the Technical Specification was published, sufficient consensus has emerged for transformation of the Technical Specification into an International Standard. The technical content is essentially the same as that contained in the Technical Specification with amendments mainly for user convenience. The structure of the document has been changed to allow division and subdivision into complete integral parts to facilitate comprehension and ease of referencing. In addition to the high level revisions above, the following main technical changes have been made with respect to the previous edition:
- arresters have been added to several locations to reflect some recent 800 kV HVDC scheme practice, along with their justifications, expected voltages, overvoltages and arrester stresses in service;
- significant changes have been made in Clause 8 - all subclauses on the characteristics, schemes, stresses and specification of arresters have been consolidated into a single entity, Clause 8;
- the implications of a smoothing reactor and of a neutral blocking filter located on the neutral bus (as on some recent 800 kV schemes), on coordination of arresters connected to the neutral end have been added;
- possible use of sacrificial arresters on the neutral bus is introduced to cater for excessive arrester energy in the rather unlikely event of a particular rare fault;
- all subclauses dealing with study tools and modelling details have been consolidated into Clause 10;
- creepage distances and clearances have been consolidated into Clauses 11 and 12, respectively, with more details added.

IEC 60071-1:2019 RLV contains both the official IEC International Standard and its Redline version. The Redline version is available in English only and provides you with a quick and easy way to compare all the changes between the official IEC Standard and its previous edition.

IEC 60071-1:2019 applies to three-phase AC systems having a highest voltage for equipment above 1 kV. It specifies the procedure for the selection of the rated withstand voltages for the phase-to-earth, phase-to-phase and longitudinal insulation of the equipment and the installations of these systems. It also gives the lists of the standard withstand voltages from which the rated withstand voltages are selected. This document describes that the selected withstand voltages are associated with the highest voltage for equipment. This association is for insulation co-ordination purposes only. The requirements for human safety are not covered by this document. Although the principles of this document also apply to transmission line insulation, the values of their withstand voltages can be different from the standard rated withstand voltages. The apparatus committees are responsible for specifying the rated withstand voltages and the test procedures suitable for the relevant equipment taking into consideration the recommendations of this document.
NOTE In IEC 60071-2, all rules for insulation co‑ordination given in this document are justified in detail, in particular the association of the standard rated withstand voltages with the highest voltage for equipment. When more than one set of standard rated withstand voltages is associated with the same highest voltage for equipment, guidance is provided for the selection of the most suitable set.
The main changes from the previous edition are as follows:
- all references are updated to current IEC standards, and the bibliography is deleted;
- some definitions are clarified in order to avoid overlapping and ensure clear understanding;
- letter symbols are changed and corrected in order to keep the consistency with relevant IEC standards;
- some titles are changed to clarify understanding (see Clauses A.2, A.3 and Annex B).
It has the status of a horizontal standard in accordance with IEC Guide 108.