Performance and safety requirements for gas-insulated switchgear

Switchgear is essential part of an electric power system used to control, protect and isolate equipment. Should an electrical surge occur, a switchgear will activate and automatically interrupt the flow of electricity and thus protect the system from damage. They can also be used to disconnect equipment from the power supply to allow for the safe testing and maintenance of equipment.

Different technologies exist to interrupt electric current including the use of a gas-insulated switchgear (GIS) which uses a pressurized gas. Advantages of GIS include its relative low maintenance, low operating noise and lack of emissions thus making it suitable for use in confined spaces.

To ensure the performance and safety of gas-insulated switchgear used in high-voltage systems, the IEC has published a new edition of IEC 62271-203, High-voltage switchgear and controlgear – Part 203: AC gas-insulated metal-enclosed switchgear for rated voltages above 52 kV.

This standard specifies the performance and safety requirements for gas-insulated metal-enclosed switchgear in which the insulation is obtained, at least partly, by an insulating gas or gas mixture other than air at atmospheric pressure, for alternating current of rated voltages above 52 kV, for indoor and outdoor installation, and for service frequencies up to and including 60 Hz.

According to Olav Knudsen who help lead the development of the latest edition of IEC 62271-203, “This is a key standard in the industry that not only provides essential safety and performance requirements but also guidance on design, installation and selection of switchgear and controlgear as well as the impact on the environment. With this new edition to IEC 62271-203, we have updated to align with the latest industry practices.”

The new edition of IEC 62271-203 provides several key changes compared to the previous edition. They include:

• alignment with IEC 62271-1:2017, High-voltage switchgear and controlgear - Part 1: Common specifications for alternating current switchgear and controlgear

• in addition to SF₆, alternative gases have been implemented

• the terms and definitions have been improved and updated

• tightness requirements for SF6 and other gasses with high GWP (global warming potential) have been increased.

• updates made to the sections on Gas and vacuum tightness, Corrosion test on earthing connections, and Corrosion tests on sealing systems of enclosures and auxiliary equipment

• Improved, updated guidance for service continuity requirements during maintenance, repair and extension of installed GIS has been added

IEC 62271-203 has been prepared by IEC subcommittee 17C: Assemblies which is part of IEC TC 17 High-voltage switchgear and controlgear.

A commented version (CMV) of the official IEC 62271-203 standard is available to allow for the easy identification of changes made compared to the previous edition. It also includes comments from the experts who developed the standard to explain the reasoning for the changes.