Gas Insulated or Air Insulated Switchgear 

By on

Various arguments exist around SF6 Gas Insulated (GIS) and Air Insulated (AIS) switchgear. Recently we had to change a GIS design to AIS due to an instruction from one of  our clients.  His concern is the global warming potential of SF6.   While understanding the clients reasons, I'm not convinced on the argument.

General arguments in favour of GIS include:

  • GIS is more cost effective
  • requires less space (up to 70% less that Air Insulated)
  • is safer in operation
  • has overall lower system loses
  • has higher protection against ambient conditions
  • is more reliable

As far as I can see the main argument against SF6 is that it has a global warming potential.  From an environmental view, the potential of releasing gas which contributes to global warming is obviously bad.  However, to quantify the effect, Capiel (see link below) has carried out some research:

  • GIS switchgear emissions (Europe, 2002) contribute 0.05% to total greenhouse gas emissions
  • measures implemented in switchgear design since 1995 have reduced GIS gas emissions by 40%
  • there is continuing technological progress in further reducing GIS gas emissions

Key Question

I think the key question in all of this is:

  • do the benefits of a safe reliable, cost effective electrical supply networks outweigh the potential SF6 contribution to greenhouse gas emissions ?

My View

The direct contribution of SF6 to greenhouse gas emissions is relatively low and I tend to think the advantages of a reliable electrical system outweigh these negatives.  Lower system loses and less materials required during manufacture reduce the life cycle carbon emissions, potentially offsetting the negative effects of SF6. 

A life cycle analysis of the German distribution system by Capiel (see link below) which considers materials, manufacture, ohmic losses and SF6 emissions shows that overall GIS contributes 30% less to global warming than AIS. Currently the arguments given against GIS don't appear sufficiently thought out and consider only the SF6 emission issue.

Without closing the door on the debate, I don't see enough evidence to force move away from GIS to AIS. 

Related Links



Steven McFadyen's avatar Steven McFadyen

Steven has over twenty five years experience working on some of the largest construction projects. He has a deep technical understanding of electrical engineering and is keen to share this knowledge. About the author

myElectrical Engineering

comments powered by Disqus



UPS Sizing - Rules of Thumb

It wasn't so long ago I was telling someone that I don't use rules of thumb as most things are easily calculated anyhow.   As it turns out I last week...

Copyright Infringement

myElectrical does not support or promote the use of copyrighted material without the copyright owner's consent. If you believe that material for which...

Capacitor Theory

Capacitors are widely used in electrical engineering for functions such as energy storage, power factor correction, voltage compensation and many others...

Robots - Interesting Videos

The robot folding towels post below was interesting enough at the time to post a link.  Recently I’ve come across a couple of other interesting videos...

Closed Doors

"I can live with doubt and uncertainty and not knowing. I think it is much more interesting to live not knowing than to have answers that might be wrong...

Famous Scientists

Here’s list of some famous scientists. Deliberately short, with the aim to provide a quick memory jog or overview. If your looking for more detailed information...

Introduction to Current Transformers

Current transformers (CTs) are used to convert high level currents to a smaller more reasonable level for use as inputs to protection relays and metering...

Cold Fusion (or not?)

Recently I have seen a few interesting articles on viable cold fusion; the combining of atoms at room like temperatures to create boundless energy. Now...

Fault Calculation - Per Unit System

Per unit fault calculations is a method whereby system impedances and quantities are normalised across different voltage levels to a common base.  By removing...

Differential protection, the good old days

This morning I was explaining how differential protection works to a junior engineer. To give him something to read I opened up the NPAG (Network Protection...

Have some knowledge to share

If you have some expert knowledge or experience, why not consider sharing this with our community.  

By writing an electrical note, you will be educating our users and at the same time promoting your expertise within the engineering community.

To get started and understand our policy, you can read our How to Write an Electrical Note