GIS vs. Air insulated MV Substation (pro & cons)

[jhonwyn73]

Greeting,

For a new 34.5kV substation 60Hz, we have two proposals, GIS and Air insulated. I would appreciate if you can help to have a comparison that shows the pro & cons of each. At present, I am thinking for the following:
1. The %( d$) of the Initial cost between the two options (we will have about 28 CB's, eight out of them will be for incomers and bus section).
2. Operating cost.

FYI, there is no space restrictions.

Thanks in advance for your help.

 

[jkristinn]

At this voltage level the required air-clearances are so small that I have never even considered GIS. Here in IEC world the 36 kV (Ur = 36, highest voltage of equipment) is the highest voltage level where which comes standard in enclosed cubicles and is therefore quite economical.

Regarding % price difference between AIS and GIS I can't help.

From the top of my head:

Pros of GIS:
minor reduction in space requirements

Pros of AIS:
Price
Faster installation
Easier to maintain
Faster to fix (in case of a failure)
More options (in regards of available equipment and manufacturers).
More environmentally friendly

 

[DTR2011]

If you have an environment where contamination is likely (salt, soot, etc) GIS would be advantageous. Otherwise, I agree with jkristinn's comments. I have seen GIS used extensively in mission critical industries (petrochemical, refinery) for such reasons. You will probably have fewer crispy critters to deal with as well.

Additionally, there are more regulations coming soon (in US) as far as managing SF6 leakage to atmosphere, which may prove to be extremely costly in the long run.