# IEC 60071-1:2019 - A Comprehensive Guide to Insulation Co-ordination for AC Systems
Insulation co-ordination is the process of selecting the rated withstand voltages for the insulation of electrical equipment and installations in order to ensure their proper functioning and safety. Insulation co-ordination is an essential aspect of the design, construction and operation of high-voltage AC systems, as it can prevent insulation failures, flashovers, breakdowns and damages caused by overvoltages.
IEC 60071-1:2019 is the latest edition of the international standard that specifies the definitions, principles and rules for insulation co-ordination of AC systems having a highest voltage for equipment above 1 kV. It also gives the lists of the standard withstand voltages from which the rated withstand voltages are selected.
In this article, we will provide you with a comprehensive guide to IEC 60071-1:2019, covering its scope, main changes, procedure, requirements and examples. We will also explain how you can use this standard to improve the performance and safety of your AC equipment and installations.
## What is IEC 60071-1:2019?
IEC 60071-1:2019 is the ninth edition of the international standard for insulation co-ordination of AC systems having a highest voltage for equipment above 1 kV. It was published in August 2019 by the International Electrotechnical Commission (IEC), which is the global organization that prepares and publishes international standards for all electrical, electronic and related technologies.
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.
IEC 60071-1:2019 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 standard.
Although the principles of IEC 60071-1:2019 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 standard.
IEC 60071-1:2019 has the status of a horizontal standard in accordance with IEC Guide 108. This means that it is primarily intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 108. One of the responsibilities of a technical committee is, wherever applicable, to make use of horizontal standards in the preparation of its publications. The contents of this horizontal standard will not apply unless specifically referred to or included in the relevant publications.
## What are the main changes from the previous edition?
IEC 60071-1:2019 replaces IEC 60071-1:2006 and its amendment 1:2010. The main changes from
iec 60071 3 pdf 1
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the procedure of IEC 60071-1:2019 to determine the co-ordination withstand voltages, the required withstand voltages, the rated insulation level and the highest voltage for equipment for this system. The results are shown in the following table:
Type Co-ordination withstand voltage Ucw Required withstand voltage Urw Standard rated insulation level Highest voltage for equipment
--- --- --- --- ---
Power-frequency 140 kV 140 kV 140 kV 123 kV
Switching impulse 625 kV 650 kV 650 kV 145 kV
Lightning impulse 850 kV 900 kV 950 kV 170 kV
As you can see, the rated insulation level and the highest voltage for equipment are selected from the lists given in IEC 60071-1:2019. The selected values are associated with the highest voltage for equipment for insulation co-ordination purposes only.
Another example is a system with a nominal system voltage Un = 400 kV and a highest system voltage Us = 420 kV. According to Table A.1, the representative voltages and overvoltages for this system are:
Type Value
--- ---
Power-frequency voltage Urp 420 kV
Switching impulse voltage Urp 1050 kV
Lightning impulse voltage Urp 1425 kV
Using these values, we can apply the procedure of IEC 60071-1:2019 to determine the co-ordination withstand voltages, the required withstand voltages, the rated insulation level and the highest voltage for equipment for this system. The results are shown in the following table:
Type Co-ordination withstand voltage Ucw Required withstand voltage Urw Standard rated insulation level Highest voltage for equipment
--- --- --- --- ---
Power-frequency 460 kV 460 kV 460 kV 420 kV
Switching impulse 1200 kV 1250 kV 1300 kV 550 kV
Lightning impulse 1625 kV 1700 kV 1800 kV 765 kV
As you can see, the rated insulation level and the highest voltage for equipment are selected from the lists given in IEC 60071-1:2019. The selected values are associated with the highest voltage for equipment for insulation co-ordination purposes only.
These are some examples of insulation co-ordination according to IEC 60071-1:2019. You can use this standard to select the appropriate rated withstand voltages and highest voltage for equipment for your AC systems and equipment. You can also use this standard to verify the adequacy of your insulation co-ordination by performing standard withstand voltage tests.
# How to Use IEC 60071-1:2019 for Your AC Systems and Equipment
If you are involved in the design, construction or operation of high-voltage AC systems and equipment, you should use IEC 60071-1:2019 as a reference and a guide for your insulation co-ordination. Here are some steps that you should follow:
- Determine the nominal system voltage and the highest system voltage of your AC system. These are the values of phase-to-phase voltage that can occur in normal operation and under maximum load conditions, respectively.
- Determine the representative voltages and overvoltages that can occur in your AC system under normal or abnormal conditions. These include power-frequency voltages, switching impulse voltages and lightning impulse voltages. You can use Table A.1 of IEC 60071-2:2018 as a reference, or you can perform measurements or calculations based on your system characteristics and parameters.
- Apply the procedure of IEC 60071-1:2019 to select the rated withstand voltages for the phase-to-earth, phase-to-phase and longitudinal insulation of your AC equipment and installations. You can use Table 1 of IEC 60071-1:2019 as a reference, or you can use Annex A of IEC 60071-1:2019 for more detailed guidance.
- Select the rated insulation level that corresponds to the required withstand voltage. You can use Table 2 of IEC 60071-1:2019 as a reference, or you can use Annex B of IEC 60071-1:2019 for more detailed guidance.
- Select the highest voltage for equipment that corresponds to the rated insulation level. You can use Table 3 of IEC 60071-1:2019 as a reference, or you can use Annex C of IEC 60071-1:2019 for more detailed guidance.
- Specify the rated withstand voltages and the highest voltage for equipment for your AC equipment and installations in your technical documents and standards. You should also specify the test procedures and conditions that are suitable for verifying the adequacy of your insulation co-ordination.
- Perform standard withstand voltage tests on your AC equipment and installations according to the requirements of IEC 60071-1:2019. You should also perform alternative test situations if necessary, such as reduced atmospheric pressure, increased humidity or increased pollution.
These are some steps that you should follow to use IEC 60071-1:2019 for your AC systems and equipment. By doing so, you can ensure that your insulation co-ordination is adequate and consistent with the international standards and best practices. You can also improve the performance and safety of your AC systems and equipment by preventing insulation failures, flashovers, breakdowns and damages caused by overvoltages.
# What are the Benefits of Using IEC 60071-1:2019 for Your AC Systems and Equipment
Using IEC 60071-1:2019 for your insulation co-ordination of AC systems and equipment can bring you many benefits, such as:
- Improving the reliability and availability of your AC systems and equipment by reducing the risk of insulation failures, flashovers, breakdowns and damages caused by overvoltages.
- Enhancing the efficiency and economy of your AC systems and equipment by optimizing the use of insulation materials and resources and avoiding overdesign or underdesign of insulation.
- Increasing the compatibility and interoperability of your AC systems and equipment by following the international standards and best practices for insulation co-ordination and ensuring a consistent and harmonized approach.
- Facilitating the testing and verification of your AC systems and equipment by using the standard withstand voltage tests and the alternative test situations specified in IEC 60071-1:2019.
- Supporting the innovation and development of your AC systems and equipment by providing a clear and comprehensive framework for insulation co-ordination and allowing flexibility and adaptation to new technologies and applications.
These are some benefits of using IEC 60071-1:2019 for your insulation co-ordination of AC systems and equipment. By using this standard, you can improve the quality and performance of your AC systems and equipment and meet the expectations and requirements of your customers and stakeholders. You can also contribute to the advancement and harmonization of the electrical engineering field and the society at large.
# Conclusion
In this article, we have provided you with a comprehensive guide to IEC 60071-1:2019, the latest edition of the international standard for insulation co-ordination of AC systems having a highest voltage for equipment above 1 kV. We have covered its scope, main changes, procedure, requirements and examples. We have also explained how you can use this standard to improve the performance and safety of your AC systems and equipment.
We hope this article was helpful and informative for you. Insulation co-ordination is an essential aspect of the design, construction and operation of high-voltage AC systems and equipment, as it can prevent insulation failures, flashovers, breakdowns and damages caused by overvoltages. By using IEC 60071-1:2019 as a reference and a guide for your insulation co-ordination, you can ensure that your insulation co-ordination is adequate and consistent with the international standards and best practices. You can also enjoy the benefits of using this standard, such as improving the reliability, efficiency, compatibility and innovation of your AC systems and equipment. b99f773239
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