Fire detection for oil filled transformers

[Rajavarman N]

Dear friends,
Hope you all doing well.
Can anyone please clarify ,how to calculate the probe heat detector qty for a transformer..I have a detector which can cover 15.2*15.2m area..but here while designing fas for transformers whether we need to provide separate detector for conservative tank and transformer body? Please refer the reference clause as in nfpa
Thanks

 

[chicopee]

I am not sure about the reason for a heat/ smoke detector to cover an oil filled transformer. The oil is normally a non combustible (under definition of NFPA) product and transformers under many circumstances blow up at which point smoke detectors would be meaningless. I have never seen a transformer fire but I have seen them blow up. The oil is in sealed containers and while the oil will get warm the transformer casings have cooling fins to dissipate heat. It is unlikely you'll see smoke or fire from a transformer.

 

[Rajavarman N]

Thanks for your reply Chicopee as you said transformers fires are very explosive and providing detectors cannot detect the fire during incipient stage but here why we need to provide detectors is to alert the professionals and inorder to make necessary suppression arrangements to avoid the fire spread to other areas.
Here in my case UAE fire code specifies to provide probe heat detectors but I have a confusion in arriving the required quantity, whether I have to provide separate detector for conservative tank and TR body or a single detector is enough...because if i give fike make probe heat detector (coverage 15.2*15.2m) it can cover the entire transformer (size L-8m,w-13.2,H-4m)but conservative tank also to be considered means I need to consider the extra quantity..since I have a total of 25 transformers in one of my project I would like to offer the correct design quantity...

Thanks

 

[cdafd]

Are these inside or outside a building/ enclosure???


Have you considered protectowire?

Only listed to 120 F/ 49C

http://www.protectowire.com/product-pages/digital-linear-heat-detector/

Or, not sure how big of area you have to cover, but UV/IR detection???


""""" but conservative tank also to be considered means I need to consider the extra quantity..since I have a total of 25 transformers in one of my project I would like to offer the correct design quantity... """"""""""

 

[Rajavarman N]

Five transformers are in a enclosure by a concrete structure whereas remaining located in outdoor area and as per the UAE fire code i'm proposing Fike make Probe type heat detectors which is enclosed herewith and not providing linear heat sensing cables.

Please advice is there any clause referring to provide separate detectors for conservative tank and TR body

 

[chicopee]

Since Fique thermal detector is of interest, I would contact the manufacturer for quantity and spacing between units. You may already have such information in the product literature.

 

[DavidCR]

Transfomers do get fire, explosions are less frecuent. An overcharge or lightning stryke will cause an overpresure leak and sprayed oil droplets will easily lit fire with lots of heat.

Remember that fire protection on a transformer is not related only to the risk of falure, it is mainly related to amount of oil stored.

Use linear (like protector wire) or thermal compensated (like Fike or Fenwall Detec-a-fire series).

For outdoor units.
For punctual detectors, the temp setting and location is not addressed, wind, weather affect, one or two over main oil tank, and one over conservative tank. Consider radiators as external elements of the tank that may also leak and make fire surface bigger, so additional detectors on them will be required depending on specific geometry of transformer. Ground conduit properly.

With linear around the unit as close as possible no big complications. More expensive but better coverage.

Flame consider sun, weld sparks, etc. can be an issue to false alarms to select the appropiate flame detector (UV/IR). Cost is high.

For indoor use NFPA 72 rules.

If supervising personnel present (oil temp detectors and security devices), fire detection may not be needed. If not supervised fire detection may be needed.


Following FM or NFPA850/851, Reclamation guidelines, distances, to own or neighboring building distances, oil volume, oil type, water protection NFPA15 required. So detection is needed to activate deluge system.