IEC/TC 99 - IEC_TC_99

IEC 61936-2:2023 provides, in a convenient form, requirements for the design and the erection of DC installations in systems with nominal voltages above 1,5 kV DC, so as to provide safety and proper functioning for the use intended. For the purpose of interpreting this document, a DC installation is considered to be one of the following: a) A converter station or DC switching station; b) one (or more) DC generating or storage unit(s), such as solar farms or battery storage units, located on a single site, the DC installation includes DC equipment and cables with all associated power electronics, controlgear, switchgear and all electrical auxiliary systems. Connections between DC generating or storage units located on different sites are excluded; c) DC installation erected on offshore facilities for the purpose of generation, transmission, distribution and/or storage of electricity; or d) DC transition station (between overhead lines and underground cable or between different sections of underground cables). This International Standard does not apply to the design and erection of any of the following: - overhead and underground lines between separate installations; - electric railways; - mining equipment and installations; i- installations on ships according to IEC 60092 series and offshore units according to IEC 61892 series, which are used in the offshore petroleum industry for drilling, processing and storage purposes; - electrostatic equipment (e.g. electrostatic precipitators, spray-painting units); - test sites; - medical equipment, e.g. medical X-ray equipment; - valve hall or converter hall. This document does not apply to the requirements for carrying out live working on electrical installations. This document does not apply to the design of factory-built, type-tested thyristor valves, VSC valves and switchgear for which separate IEC standards exist. This first edition cancels and replaces the IEC TS 61936-2 published in 2015. This edition constitutes a technical revision. See the foreword of this edition for the list of significant technical changes with respect to the previous edition.

This part of IEC 60071 constitutes application guidelines and deals with the selection of insulation levels of equipment or installations for three-phase a.c. 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 a.c. systems with nominal voltages above 1 kV. The values derived or proposed herein are generally applicable only to such systems. However, the concepts presented are also valid for two-phase or single-phase systems. This document covers phase-to-earth, phase-to-phase and longitudinal insulation. This document is not intended to deal with routine tests. These are to be specified by the relevant product committees. The content of this document strictly follows the flow chart of the insulation co-ordination process presented in Figure 1 of IEC 60071-1:2019. Clauses 5 to 8 correspond to the squares in this flow chart and give detailed information on the concepts governing the insulation coordination process which leads to the establishment of the required withstand levels. This document emphasizes the necessity of considering, at the very beginning, all origins, all classes and all types of voltage stresses in service irrespective of the range of highest voltage for equipment. Only at the end of the process, when the selection of the standard withstand voltages takes place, does the principle of covering a particular service voltage stress by a standard withstand voltage apply. Also, at this final step, this document refers to the correlation made in IEC 60071-1 between the standard insulation levels and the highest voltage for equipment. The annexes contain examples and detailed information which explain or support the concepts described in the main text, and the basic analytical techniques used.

IEC 60071-11:2022 applies to high-voltage direct current (HVDC) systems. It specifies the principles on the procedures for the determination of the specified withstand voltages, creepage distance and air clearances for the equipment and the installations of these systems. This document gives the insulation co-ordination principles related to line commutated converter (LCC) and voltage sourced converters (VSC) HVDC systems. The main principles of this document also apply to other special converter configurations of LCC, such as the capacitor commutated converter (CCC) as well as the controlled series compensated converter (CSCC), etc. This document applies to insulation co-ordination of equipment connected between the converter AC bus (including the AC harmonic filters, the converter transformer, the circuit breakers) and the DC line side. The line and cable terminations in so far as they influence the insulation co-ordination of converter station equipment are also covered. This document applies only for HVDC applications in 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 document. This international standard replaces, in conjunction with IEC 60071-12, IEC 60071-5 published in 2014. This edition includes the following significant technical changes with respect to IEC 60071‑5:2014:
This standard applies to both LCC and VSC HVDC systems whereas IEC 60071-5 only dealt with LCC HVDC system;
Annex C (normative) gives the recommended specified withstand voltage (LI and SI);
Annex C (normative) gives the minimum air clearances;
Annex E shows the correlation of clauses between this standard and IEC 60071-5:2014.

IEC 60071-12:2022 applies guidelines on the procedures for insulation co-ordination of line commutated converter (LCC) stations for high-voltage direct current (HVDC) project, whose aim is evaluating the overvoltage stresses on the converter station equipment subjected to combined DC, AC power frequency, harmonic and impulse voltages, and determining the specified withstand voltages for equipment. This document deals only with metal-oxide surge arresters, without gaps, which are used in modern HVDC converter stations. The criteria for determining the protective levels of series and/or parallel combinations of surge arresters used to ensure optimal protection are also presented. Typical arrester protection schemes and stresses of arresters are presented. Annex A contains examples of insulation co-ordination for LCC HVDC converters which support the concepts described in the main text, and the basic analytical techniques used.

IEC 60071-1:2019 is available as IEC 60071-1:2019 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the 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).

This part of IEC 61936 provides requirements for the design and the erection of electrical power installations in systems with nominal voltages exceeding 1 kV AC and nominal frequency up to and including 60 Hz, so as to provide safety and proper functioning for the use intended. For the purpose of interpreting this document, an electrical power installation is considered to be one of the following: a) substation, including substation for railway power supply; b) electrical power installations on mast, pole and tower, switchgear and/or transformers located outside a closed electrical operating area; c) one (or more) power station(s) located on a single site, the electrical power installation includes generators and transformers with all associated switchgear and all electrical auxiliary systems. Connections between generating stations located on different sites are excluded; d) the electrical system of a factory, industrial plant or other industrial, agricultural, commercial or public premises; e) electrical power installations on offshore facilities for the purpose of generation, transmission, distribution and/or storage of electricity; f) transition towers/poles (between overhead lines and underground lines). The electrical power installation includes, among others, the following equipment: - rotating electrical machines; - switchgear; - transformers and reactors; - converters; - cables; - wiring systems; - batteries; - capacitors; - earthing systems; - buildings and fences which are part of a closed electrical operating area; - associated protection, control and auxiliary systems; - large air core reactor. NOTE 1 In general, equipment standards take precedence over the requirements of this document. This document does not apply to the design and erection of any of the following: - overhead and underground lines between separate electrical power installations; - electrified railway tracks and rolling stock; - mining equipment and installations; - fluorescent lamp installations; - installations on ships according to IEC 60092 (all parts) and offshore units according to IEC 61892 (all parts), which are used in the offshore petroleum industry for drilling, processing and storage purposes; - electrostatic equipment (e.g. electrostatic precipitators, spray-painting units); - test sites; - medical equipment, e.g. medical X-ray equipment. This document does not apply to the design of prefabricated, type-tested switchgear and high voltage/low voltage prefabricated substation, for which separate IEC standards exist. NOTE 2 The scope of this document does not include the requirements for carrying out live working on electrical power installations. NOTE 3 The scope of this document considers safety requirements for HV installations and the influences of HV installations on LV installations. For electrical installations up to 1 kV, IEC 60364 (all parts) applies.

NEW!IEC 60071-2:2018 is available as IEC 60071-2:2018 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 60071-2:2018 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. 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) 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.

Provides guidance on the procedures for insulation co-ordination of high-voltage direct current (HVDC) converter stations, without prescribing standardized insulation levels. 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.

This European Standard is applicable to specify the requirements for the design and erection of earthing systems of electrical installations, in systems with nominal voltage above 1 kV a.c. and nominal frequency up to and including 60 Hz, so as to provide safety and proper functioning for the use intended. For the purpose of interpreting this standard, an electrical power installation is considered to be one of the following: a) substation, including substation for railway power supply; b) electrical installations on mast, pole and tower; switchgear and/or transformers located outside a closed electrical operating area; c) one (or more) power station(s) located on a single site; the installation includes generators and transformers with all associated switchgear and all electrical auxiliary systems. Connections between generating stations located on different sites are excluded; d) the electrical system of a factory, industrial plant or other industrial, agricultural, commercial or public premises. The electrical power installation includes, among others, the following equipment: – rotating electrical machines; – switchgear; – transformers and reactors; – converters; – cables; – wiring systems; – batteries; – capacitors; – earthing systems; – buildings and fences which are part of a closed electrical operating area; – associated protection, control and auxiliary systems; – large air core reactor. NOTE In general, a standard for an item of equipment takes precedence over this standard. This European Standard does not apply to the design and erection of earthing systems of any of the following: – overhead and underground lines between separate installations; – electric railways; – mining equipment and installations; – fluorescent lamp installations; – installations on ships and off-shore installations; – electrostatic equipment (e.g. electrostatic precipitators, spray-painting units); – test sites; – medical equipment, e.g. medical X-ray equipment. This European Standard does not apply to the requirements for carrying out live working on electrical installations.

2014-04-03: Publication allocated to tnaqvi@cencenelec.eu

IEC 61936-1:2010 provides common rules for the design and the erection of electrical power installations in systems with nominal voltages above 1 kV a.c. and nominal frequency up to and including 60 Hz, so as to provide safety and proper functioning for the use intended. For the purpose of interpreting this standard, an electrical power installation is considered to be one of the following: a) Substation, including substation for railway power supply; b) Electrical installations on mast, pole and tower; Switchgear and/or transformers located outside a closed electrical operating area; c) One (or more) power station(s) located on a single site. The installation includes generators and transformers with all associated switchgear and all electrical auxiliary systems. Connections between generating stations located on different sites are excluded; d) The electrical system of a factory, industrial plant or other industrial, agricultural, commercial or public premises. The electrical power installation includes, among others, the following equipment: rotating electrical machines; switchgear; transformers and reactors; converters; cables; wiring systems; batteries; capacitors; earthing systems; buildings and fences which are part of a closed electrical operating area; associated protection, control and auxiliary systems; large air core reactor. NOTE: In general, a standard for an item of equipment takes precedence over this standard. This standard does not apply to the design and erection of any of the following: - overhead and underground lines between separate installations; - electric railways; - mining equipment and installations; - fluorescent lamp installations; - installations on ships and off-shore installations; - electrostatic equipment (e.g. electrostatic precipitators, spray-painting units); - test sites; - medical equipment, e.g. medical X-ray equipment. This standard does not apply to the design of factory-built, type-tested switchgear for which separate IEC standards exist. This standard does not apply to the requirements for carrying out live working on electrical installations. This second edition cancels and replaces the first edition, published in 2002. It constitutes a technical revision. The main changes with respect to the previous edition are listed below: - new table of references for additional agreements between manufacturer/contractor/planer and user/orderer/owner (4.1.2); - addition of minimum clearances in air not standardized by IEC but based on current practice in some countries (Annex A); - deletion of nominal voltages (Table 1, Table 2, Clause 5); - addition of regulations for fuses (6.2.15); - simplification of regulations for escape routes (7.5.4); - deletion of special regulations for operating aisles (7.5.4); - modification of clearances for fire protection (Table 3); - modification of safety criteria for earthing systems (10.2.1); - modified curves of permissibly touch voltages (Figure 12, Annex B); - deletion of numbering of subclauses without headlines; - change of "should" to "shall" in many cases or change of subclauses with "should" to a note. The contents of the corrigendum of March 2011 have been included in this copy.

2021-08-25 (data): Work of CLC/SR 28 transferred to CLC/TC 99X (D167/C115)

IEC 60071-1:2006 applies to three-phase a.c. 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 should be selected. This standard recommends that the selected withstand voltages should be 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 standard. Although the principles of this standard also apply to transmission line insulation, the values of their withstand voltages may 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 standard. NOTE: In IEC 60071-2, Application Guide, all rules for insulation co ordination given in this standard 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: - in the definitions (3.26, 3.28 and 3.29) and in the environmental conditions (5.9) taken into account clarification of the atmospheric and altitude corrections involved in the insulation co-ordination process; - in the list of standard rated short-duration power frequency withstand voltages reported in 5.6 addition of 115 kV; - in the list of standard rated impulse withstand voltages reported in 5.7, addition of 200 kV and 380 kV; - in the standard insulation levels for range I (1kV < Um 245 kV) (Table 2) addition of the highest voltage for equipment Um = 100 kV; - in the standard insulation levels for range II (Um 245 kV) (Table 3) replacement of 525 kV by 550 kV and of 765 kV by 800 kV; - in order to remove that part in the next revision of IEC 60071-2, addition of Annex A dealing with clearances in air to assure a specified impulse withstand voltage in installation; - in Annex B, limitation at two Um values for the values of rated insulation levels for 1kV < Um 245 kV for highest voltages for equipment Um not standardized by IEC based on current practice in some countries. It has the status of a horizontal standard in accordance with IEC Guide 108.

Corrigendum to HD issued June 2005 * Superseded by EN 61936-1:2010 and EN 50522:2010