Oil pit sizing of transformer. 2

[SauravWest]

Dear Sirs,

Please let me know how to calculate the size of oil pit and sump pit. Is soak pit also present in transformer oil drainage system?

Regards,

 

[r13]

The link below may provide help.

Link

 

[dauwerda]

In the US, secondary oil containment pits are typically sized to hold the volume of oil that the transformer holds, plus the water volume of a 10 year, 24 hour rain event plus 0-6 inches of freeboard (amount of freeboard is often an owner specified amount). The sump pit is generally provided so that maintenance crews can drop a portable pump in to pump out all of the rain water, or you can permanently install an oil minder pump to avoid the need to pump water manually - the sump pit size is pretty arbitrary and simply needs to be large enough to place a small trash pump in (18"-24" diameter by 24" deep is pretty typical).

 

[dik]

dauwerda, that's the criteria I've often used. Most of the recent containments I've done have used a product called Sorbweb. It allows water to 'pass'. An impervious membrane is installed beneath the transformer with a Sorbweb 'window' for drainage. If there is any leakage of transformer coolant, the Sorbweb quickly gels to an impervious material containing the oil. By letting the water drain out as groundwater a lot of costly concrete containment is eliminated.

Sorbweb is a great product, IMHO, and is very cost effective; I've used it on about a dozen projects. I have no financial interests in the product and recommendation is without personal gain. It is provided by a company in Ontario called Albarrie.

Dik

 

[dauwerda]

dik, at my previous employer with a large utility, we looked into that product (or maybe a competitor). However, it was decided to stick with concrete containment for new installations. The reasoning for this being that if there was a oil leak, the permeable material would have to be dug up and replaced (large cost) while the concrete would not. We once had a new transformer dump all of its oil a week or so after it was put into service (no fire thankfully). The concrete containment worked great and the transformer was replaced under full warranty (I forget what they decided the issue was).

We also had installations where there was essentially just a collection basin around the transformer that was drained into a large underground precast containment vault, this was typically done for space reasons and fire abatement.

 

[dauwerda]

Now that I re-read your post perhaps what you are doing is not quite the same thing as the product we looked into. The product we were presented was used to line the entire containment area, so the whole thing would need to be replaced. It sounds like your product is only installed in a small drainage area so replacement would be localized and easier/cheaper?

 

[dik]

Correct... when I first started using Sorbweb, the entire basin was covered... it evolved to a smaller window.

Dik

 

[SlideRuleEra]

Thanks, dauwerda, I did not know the basis for pit volume. At our generating stations the concrete containments are filled with large stone, so the liquids in the pit are only in the spaces between stones. Actual size of the pit has is based on:

Required pit volume = Empty pit volume - Calculated exact volume of the stone backfill

http://www.SlideRuleEra.net

 

[r13]

SRE,

Stone/rocks...it was dated back to 19?? A pain on the butt for the large area required.

 

[SlideRuleEra]

...it was dated back to 19??

So am I... try to be careful about offering outdated info but some things fall through the cracks

http://www.SlideRuleEra.net

 

[bridgebuster]

SRE - a few years ago I worked at a site where we were building a waster water treatment plant inside of a landfill. The leachate tanks had secondary containment tanks. However, the tanks were built in a giant sump that was backfilled with stone. Belt and suspenders.