Fire Protection for Transformers

NONE

Hi

Wet or dry type transformers ?

A sufficient controlsystem, that identify failures and disconnect the transformer in time to decrease the risk of fire.

Or is it fire-figthing solutions to transformers already on fire you are asking about ?

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Without failures, no fire accidents !

This is for protecting from possible externel fire for Wet type transformers at design stage.

Does it change drastically for dry type?

Since transformers are built from metal, fire hazard is minimal. (the greator hazard would be an electrical short due to water ingress) so an overload protection is recommended.

They can produce heat. so proper ventolation and distance from flamables may be required.

The fire rating of whatever liquid is used as a dielectric should be checked. If it is highly flamable or reactive, you should either change the dielectric or engineer some protection such as insulation in the case, over-pressure release, protect or restrict materials around the transformer.

For Oil filled transformers, (Rarely installed indoors except in dedicated vaults):
All must be protected from weather or of proper type if outdoors.
If indoors most codes require a means of containing the coolant which may
escape if the transformer is damaged.

Fire rating / venting of the room is dependant on whether the coolant is of a
flammable type.
Because of the fire rated room, fire from external source is not considered a factor.

Consult local Codes.

I suggest to use a dry chemical powder automatic system with a rate of rise temperature detection.Or a carbone dioxyde system with the same detection.

Normand Audet /special hazard consultant

I can't quite get a handle on the question - maybe I shouldn't be answering it!

Are talking about power transmission transformers?

In the UK, our open air compound, oil filled, exposed insulator type connection transformers have no particular fire fighting protection.

Transformers which are in accessible indoor locations, with sealed chamber terminating boxes are protected by Emulsifier (sprinkler systems). Such locations would normally have large ventilation grills as part of the building and the sprinkler system would be of the Dry type (i.e. the sensor pipes and glass bulb detectors are filled with air pressure which holds the flap valve closed against the water pressure. If a bulb is burst, the air leaks out and the water valve flips open)

"All wet" systems would be liable to freezing when exposed to the cooling air coming from the outside. Oil filled transformers would be contained within a bunded area to stop oil escaping in the event of a leak or fire, allowing the sprinkler system to extinguish the burning oil.

Some of you are now going to say that you don't fight oil fires with water, but an emulsifier system produces a heavy wet mist blanket as opposed to direct jets of water.

Traditionally CO2 discharge was used in controlled access areas which was subsequently superseded by Halon, but this is also prohibited as it is a CFC gas.