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



Arc Flash Calculations

Working in the vicinity of electrical equipment poses an hazard. In addition to electric shock hazard, fault currents passing through air causes Arc Flash...

What are you reading!

Reading is a bit of a hobby of mine and I"ve done a few off-topic posts in the past on this. Rather than continue doing the occasional post I thought ...

Post Editing Tips

If you at all familiar with programs like office and outlook, then adding and editing posts is pretty straightforward and intuitive.  However, there are...

Wiki Depreciation

We have had the Wiki with us for a long time now, but at last I have decided to say bye bye – more details on why below.

Understanding electric motor insulation & temperature

Anyone specifying or using electric motors should have a basic understanding how the insulation is related to temperature. Three classes of insulation...

Capacitors - Energy Storage Application

Capacitors have numerous applications in electrical and electronic applications.  This note examines the use of capacitors to store electrical energy....

Voltage Levels to IEC 60038

The standard aims to consolidate AC and traction voltages within the industry and defines the following bands: band 1 - A.C. systems 100 V to 1...

Fault Calculation - Symmetrical Components

For unbalance conditions the calculation of fault currents is more complex. One method of dealing with this is symmetrical components. Using symmetrical...

How to Check a Circuit is Dead

If you want to check a circuit is dead (not live), you should always use the three point method. First check a known live circuit, then check the dead...

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...

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