GIS Application

[buddy91082]

anyone have information on when to apply gas insulated switchgear in medium voltage systems for <22kv indoors?

Any links to application guides would be appreciated.

thanks.
b

 

[rbulsara]

All commercial switchgear below 22kV (which is 15kV or below), in the USA, are air insulated switchgear using vacuum circuit breakers or air switches in metal enclosed gear.

Haven't come across GIS switchgear in that category yet. That does not mean that do not exist, just I have not seen them.

Closest that come are, SF6 insulated bottles used as switching chambers in some switches, but the buses are still air insulated.

 

[ScottyUK]

Agree with rbulsara,

Air-insulated gear with SF₆ interrupters aren't unusual in the UK but are less common than vacuum interrupters.

Cost-wise and space-wise there's not much to separate vacuum and SF₆ technologies for MV installations. Vacuum is arguably a little cheaper. You wouldn't seriously consider air breakers or any of the oil technologies for a modern indoor application so vacuum or SF₆ is what you are left with.


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If we learn from our mistakes I'm getting a great education!

 

[PHovnanian]

I recall reading somewhere recently (might have been in this forum) a discussion regarding the need to decontaminate a substation following the failure of SF6 equipment. This could be a significant issue if the indoor installation is not isolated from other occupancies.

This is not an issue with vacuum breakers, as getting vacuum all over everything is not a serious problem.

 

[slavag]

Hi.
We have a few 12kV swg GIS. reason was space.
Size of AIS bay ( SF6 or Vacumm CB usually is a same size) about 650-1000mm, for the GIS 440-500mm.
Best Regards.
Slava

 

[ScottyUK]

Hi slava,


Who is the manufacturer? Might be worth knowing for those jobs where a client decides to install something in a location where there isn't enough room to install it.


PHovnanian,

Have you ever seen a really bad vacuum spillage? It takes ages to clear it up...


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If we learn from our mistakes I'm getting a great education!

 

[slavag]

Hi Scotty.
Mnf...xmmmm.....it's old , very old type of ABB Sace GIS, some OEM was provide it. Im not sure now, but maybe it was 22kV GIS was used for the 12kV.
xmm, difficult say this, but I woudn't recommend to you work with this company, aspecially with this manager :-(.
BVTW, it was five SS's with really small space.
Sorry, Scotty.
Best Regards.
Slava

 

[rbulsara]

May be someone can enlighten, isn't there some environmental concern with SF6?

 

[dpc]

Yes, it is considered an ozone depleting gas. In the US, special equipment and certification is required for filling and purging of SF6.

 

[buddy91082]

I have recently come cross a few project specifications for <22kV GIS equipment. The projects have all been in the Gulf region.

All of the <22kv projects i have seen until recently have all been AIS w/ vacuum breakers for projects in the US.

GIS may be more popular overseas.

 

[rbulsara]

Protection against fine dust may be a factor in Gulf region.