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Oil Filled Transformers Clearence
2

Oil Filled Transformers Clearence

Oil Filled Transformers Clearence

(OP)
Hi,
I have 3 transformers, oil filled, pad-mounted, 2 of them 25kV/480, 2500KVA and one 25kv//4160, 5000KVA. Can anyone help me to find out what will be the minimum clearance distance between them without using a blast wall?

RE: Oil Filled Transformers Clearence

Probably not until you tell us where the transformers will be installed and what codes you are trying to comply with.  

This forum is read by engineers from all over the world.  There are probably a hundred different codes that MIGHT apply.  

 

David Castor
www.cvoes.com

RE: Oil Filled Transformers Clearence

(OP)
Sorry the transformers are installed in US and shall comply with NEC and NFPA codes.

RE: Oil Filled Transformers Clearence

Without knowing the type of facility or occupancy, I don't believe there is any general Code requirement for separation due to fire concerns, assuming these transformers are outside.

There may be some requirement for distance from the building wall depending on the fire rating of the wall.  

The NEC does not worry much about things that are outside.  

As for NFPA, that is going to depend on the type of facility.  If it's a hospital or wastewater treatment plant, you may need separation or a firewall.  If it's a Walmart, probably not.  

Local fire marshall will have the last word (actually, the insurance underwriter may have the last word in some cases).  



 

David Castor
www.cvoes.com

RE: Oil Filled Transformers Clearence

Besides the codes, insurance company requirements may apply. Meeting codes is just an statuary requirement, one should still strive to adhere to best practices in the industry.

There are too many variables involved to be advising here.  

Rafiq Bulsara
http://www.srengineersct.com

RE: Oil Filled Transformers Clearence

(OP)
Thanks everyone for your valuable posts. I will check with the insurance company and fire marshal in the area.

RE: Oil Filled Transformers Clearence

FM Global has a "Loss Prevention Data Sheet" on transformers which includes some recommendations. It's available on their web site.

Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.

RE: Oil Filled Transformers Clearence

The IEEE has a document regarding firewall being install between transformers.  The document contains the distance apart where firewalls are not mecessary.

However, you must also consider the facility as well.  A fire on a transformer often means there is an oil spill which will spread, so you will likely be required to have some sort of containment for the oil.

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

RE: Oil Filled Transformers Clearence

(OP)
Thank you very much. Can you pass me the IEEE document number? Around each mounting pad we have some sort of concrete wall to prevent the oil spill.

RE: Oil Filled Transformers Clearence

A wall won't prevent oil spill if it is outdoors.  The oil will get in the ground fairly quickly and where it ends up from there who knows.  You would need a full containment system to prevent an environmental spill.  The wall will just keep the public from noticing... that is unless it's on fire :)

RE: Oil Filled Transformers Clearence

Oil containment is an environmental issue - it has nothing to do with fire protection.  

Oil containment is generally not actually a legal requirement in the US in most locations.  The owner can choose to not put in oil containment and deal with the consequences of a clean up after a spill.  

 

David Castor
www.cvoes.com

RE: Oil Filled Transformers Clearence

(OP)
I agree with David, Oil containment is an environmental issue that everybody is dealing with in different ways. In a previous project in Europe the utility company specific asked for a containment system underground.  

RE: Oil Filled Transformers Clearence

The purpose of the blast wall is not the oil spill control, but to prevent debris, fire and hot oil from splashing over to the adjacent transformer, should one of the transformers catch fire and explode (blast), which they do at more regular intervals than one would think.

There was such an incident last year in CT, which took out an entire hospital, when one the three transformers caught fire and took down the other two with it. Not sure there were any blast walls between them. I believe they were all in a utility vault.

Rafiq Bulsara
http://www.srengineersct.com

RE: Oil Filled Transformers Clearence

I believe the IEEE standard is IEEE 979 - Guide for substaion Fire Protection, if my memory serves me correctly.  

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

RE: Oil Filled Transformers Clearence

I almost forgot about venting deflagrations.  We installed a venting deflagration system in place of a firewall at one of our plants.  See NFPA 68.  The company that performed the engineering and installation was Transformer Protection Corp in Texas.

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

RE: Oil Filled Transformers Clearence

(OP)
Thank very much Turbinegen, those are very good information.

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