{"id":17549,"date":"2024-01-17T12:45:18","date_gmt":"2024-01-17T17:45:18","guid":{"rendered":"https:\/\/blog.wika.com\/us\/\/?p=17549"},"modified":"2026-01-30T13:31:13","modified_gmt":"2026-01-30T18:31:13","slug":"monitoring-sf6-and-alternative-gases-in-gas-insulated-switchgear","status":"publish","type":"post","link":"https:\/\/blog.wika.com\/us\/knowhow\/monitoring-sf6-and-alternative-gases-in-gas-insulated-switchgear\/","title":{"rendered":"The Importance of Monitoring SF\u2086 and Alternative Gases in Gas-Insulated Switchgear"},"content":{"rendered":"

Insulating gases \u2013 not just pure SF6<\/sub> but also SF6<\/sub> blends, N2, g3, and others \u2013 protect switchgear from failure. WIKA is a leader in remote sensing solutions that help power transmission and distribution companies monitor the quality and quantity of these gases.<\/strong><\/p>\n

Medium- and high-voltage switchgears can be insulated using different medias: oil, dry air, and other gases like sulfur hexafluoride (SF6<\/sub>)<\/a> and new mixtures. The traditional and most effective insulator is SF6<\/sub>, but its use comes with several hazards<\/a>, especially as this synthetic fluorinated compound has a global warming potential (GWP) of around 24,000\u2014the highest of any known gases. (For reference, carbon dioxide has a GWP of 1.)<\/p>\n

For the power transmission and distribution<\/a> (PT&D) businesses that use SF6<\/sub>, they must monitor density to detect leaks, and periodically analyze the gas to detect the presence of contaminants. But even as many companies still rely on this gas to insulate switchgear, they do realize its role in climate change and are looking into SF6<\/sub> alternatives.<\/p>\n

Reasons for Failure in Gas-Insulated Switchgear<\/strong><\/h2>\n

Most power plants and substations use air or a gas to insulate their switchgear. While air is abundant, non-toxic, and has 0 GWP, it is not as effective in quenching arcs. As a result, the compartment in air-insulated switchgear (AIS) has to be about three times as large as those for gas-insulated switchgear (GIS).<\/p>\n

Both AIS and GIS are susceptible to issues that reduce their effectiveness and lead to switchgear failures.<\/p>\n

Air insulation:
\n\u2022 \u00a0Dirt and dust
\n\u2022 \u00a0Contact resistance
\n\u2022 \u00a0Overload<\/p>\n

Gas insulation:
\n\u2022 \u00a0Gas leakage
\n\u2022 \u00a0<\/span>Humidity, a potent impurity<\/a> for SF6<\/sub>-insulated switchgear
\n\u2022 \u00a0Decomposition products<\/a>, many of which are toxic and will corrode GIS<\/p>\n

Monitoring the insulator\u2019s condition is a key step in preventing potentially dangerous situations. AIS operators should monitor the air\u2019s partial discharge status, temperature, and humidity. For GIS, it is important to monitor the gas\u2019s pressure, temperature, density, and humidity.<\/p>\n

Switchgear has a typical life span of 20\u201350 years, with gas-related failures increasing sharply 15\u201325 years after installation. Therefore, monitoring is especially key during the second half of the equipment\u2019s lifetime.<\/p>\n

Reactive vs. Proactive Maintenance of Gas-Insulated Switchgear<\/strong><\/h2>\n

There are two approaches to monitoring the condition of GIS.<\/p>\n\n

<\/a>

Reactive vs. proactive maintenance of GIS (click to enlarge)<\/p><\/div>\n \n

Reactive approach<\/h3>\n

In this approach, a mechanical instrument, such as a switch contact, sets off an alarm when the gas density has dropped to a certain level. In other situations, technicians manually read the gas density monitor on a predetermined schedule.<\/span> Technicians then take corrective actions as necessary, such as:<\/p>\n