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



Variable Frequency Drive

Variable frequency drives are widely used to control the speed of ac motors.  This note looks at the mechanisms which enable drive units to control the...

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...

Induction Motor Calculator

Just added a page to the tools, which will allow you to calculate the synchronous speed, slip and rated torque for an induction motor. Not a particularly...

Understanding Circuit Breaker Markings

IEC 60947 is the circuit breaker standard and covers the marking of breakers in detail. Any manufacturer following this standard should comply with the...

Voltage Levels – Confused?

I was having a conversation the other day about voltage levels.  While everyone was in agreement that low voltage was 1000 V and less, there was more confusion...

Introduction to Cathodic Protection

If two dissimilar metals are touching and an external conducting path exists, corrosion of one the metals can take place.  Moisture or other materials...

Load Flow Study – how they work

A load flow study is the analysis of an electrical network carried out by an electrical engineer. The purpose is to understand how power flows around...

Frame Leakage Protection

While not as popular as it once was, frame leakage protection does still have some use in some circumstances.  In essence frame leakage is an earth fault...

Multimeter

Multimeters are undoubtedly the most common item of electrical test equipment in use.  Often it is the first piece of equipment people will turn to when...

Capacitors - Energy Storage Application

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

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