Mandatory SF6 Reporting

[saladhawks]

The California Air Resources Board (CARB) is in the process of finalizing the requirements for the mandatory reporting of SF6 beginning 1/1/2008.

In the infinite wisdom of the Management at the unnamed utility I work for, future ordering of SF6 products (switches, breakers, etc.) has been put-on-hold indefinitely. Engineering has been tasked to locate and specify non-SF6 products for future orders.

Has anyone heard of similar decisions at other U.S. utilities?

What is especially concerning is that this utility includes the following voltages:

4.16 KV
13.8 KV
34.5 KV
69 KV
138 KV
220 KV

I know that solid-dielectric products exist for the distribution class voltages (4.16 KV, 13.8 KV, & 34.5 KV), but do not know of any non-SF6 products at the transmission class voltages. Is this correct?

 

[ScottyUK]

SF₆ usage is reportable under UK legislation (probably EU legislation adopted by the UK). We don't have any restriction on purchasing the gas to maintain existing equipment, although its environmental impact is a consideration when specifying new equipment. The technical advantages outweigh the environmental negatives so far.


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I don't have an attitude problem. You have a perception problem...

 

[TurbineGen]

There are a few vacuum breakers that work for the distribution class voltages. I do not recall any 3 phase units, all single phase routed through one control to make a 3-phase set. Joslyn Hi-Voltage makes the VBM up to 69 kv I believe. The VBU goes up to 230kv. They are both series vacuum interrupter breakers.

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If it is broken, fix it. If it isn't broken, I'll soon fix that.

 

[sslobodan]

Try Siemens I think they have all listed voltages, most probably also ABB, Schneider, Moler.... has it
And yup the time of SF6 is a past today vacuum switches are more reliable, less costly, easy for maintenance, require less space and children can play in there I was in both SF6 and vacuum facilities and there is significantly more reasons to purchase vacuum equipment and two biggest are: cost and space.

 

[Gianoli]

The transmission class is totally dominated by SF6 switchgear. I won't go so far as to say no other options exist but they are few are far between.

Years ago SF6 interrupter technology replaced all other interrupter technologies in the transmission class. I was somewhat surprised to see this because other viable technologies certainly did and still do exist but have not been developed for many years.

SF6 is clearly a potent green house gas. Manufactures have successfully marketed SF6 products by claiming that the gas is totally sealed with the switchgear and that leaks are rare. This claim is valid. However, during servicing of equipment leaks can occur if precautions are not taken. I know of some horrendous SF6 leaks in GIS during installation and commissioning.

Environmental pressure may force manufactures to revisit older interrupting technologies some day but for now it is a SF6 ball game in the transmission class

 

[dpc]

There are plenty of vacuum breakers available at distribution voltages, but at transmission voltage, there is no real alternative to SF6 breakers.

 

[ScottyUK]

Leaks might be rare from switchgear but from CGIT (SF₆ bus duct) it is more common. We have several thousand linear metres of 275kV CGIT made by ABB Westboro where the gas has breached the inner seal of the double O-ring joint and is holding on the outer seal. One or two outer seals are not particularly healthy too. Dismantling and joint splitting to replace the rings looks to be a tricky task due to the environmental conditions at site where we have significant levels of airborne contamination from chemical and steel industry neighbours. Maintaining clean conditions will be interesting! If anyone has any experience on solving this kind of problem I'll start a new thread and transfer discussion there.


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I don't have an attitude problem. You have a perception problem...

 

[sslobodan]

I cant say people do not produce green house gases (we do it by every breath --> CO2 ) but I must go in a line of people that have been taken the serious research on that matter in hands and I must ask everyone here that do they think that that puny 0.45 % of total green house gases emission in nature that come from humanity will do anything, The oceans produce 100 times more CO2 when they heat up a bit than entire human population. And if you take seriously thinking that is not poisoned by Green market... ooops I believe they would like to be called Green movements, you would make question your self who is the biggest producer of heat in our neighborhood?

http://www.btmon.com/Video/Unsorted...ming_Swindle.avi953861185729.187.torrent.html

Is the link to a film you might wanna take look if you are interested in this subject that gives simple explanation to this problem, so that even someone that has not went deeper in that subject can understand it. And Scotty if leakage is really happening you can schedule general maintenance with filming the leaking spots making general plan how to close leaking and react. Take line out of power, pump out gas, repair sealings and put it back on power. That should not take more than few days to complete.

 

[ScottyUK]

Hi sslobodan,

The leaks are on a 400m long CGIT which uses a plug & socket arrangement to joint the inner bars. To replace a defective O-ring the CGIT must be dismantled up to that point. The sections are about 6m - 10m long and the interior must be kept clinically clean. We optimistically predict an outage of 2 weeks assuming we have no problems with contaminants entering the duct! We are looking at resin or wax injection techniques to shore up the leaking ring but are nervous about material penetration onto the duct.


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I don't have an attitude problem. You have a perception problem...

 

[sslobodan]

Scotty I am going on a vacation in few days and I will see that I speak with my godchild father that is doing electrical maintenance for over 30 years on electrical equipment for 2 million people city and had all kinds of problems with all types of gears. I will see with him how did they finished the maintenance of one substation that was first SF6 facility in my home city. And I will try to get the answer for you. BTW As I know pressure is a bit high (few atmospheres) in such gear so the wax would not be such a good solution on a long term. Can you give me more data on that problem?

 

[Gianoli]

ScottyUK,

I have seen this style of buss duct before but I have no direct experience. I have some experience with a similar product manufactured by Siemens. I believe the joints on the ABB Westboro units can be welded or bolted; yours must be bolted with flanges.

One possible solution I have seen applied to similar equipment is to machine out of aluminum a big clamp that splits in half. The ID of the clamp is the same as the OD of the ABB Westboro buss duct with provisions to completely encompass the flanges. The two half’s of the clamp have rubber seals that when clamped together completely seal the original flange assembly. A tapped hole with a valve in the clamp provides a means check the integrity of the original o-ring joint as time goes by.

Might be a little bit of work but may be an option worth exploring further.