Fire Protection systems for transformers

[prc]

Power Transformers are provided with various types of fire protection systems like deluge (water sprinkler), water mist with high pressure water, nitrogen injection system, water curtain etc. The water mist system came in to use during last 20 years. What is the service experience of it? Any where this is extensively used? Whether the nitrogen injection system(originally by French) is widely used in US &UK? Any account of success rate?

 

[ScottyUK]

In the UK most of the systems I have seen are sprinkler deluge systems triggered by frangible bulbs. Fire protection is quite a conservative industry, probably driven (or held back) by the insurers. I've thankfully only seen one of these systems operate for real and although the fire was very intense and caused a lot of damage it would likely have been much worse if the deluge wasn't present.

 

[itsmoked]

When I was working at the Helms Reservoir power plant the transformers were all in vaults with about 40 CO₂ nozzles surrounding them and about 50 large CO₂ cylinders lined up outside each vault. We had to disable the system when we entered as it would be fatal to be caught in that snow storm. I had the distinct feeling that one of those fires would actually be put out in the -100F blizzard.

It looked a lot like this:

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

Keith,

Similar, albeit smaller, systems are commonly in use in older British substations where the switchgear is legacy oil-filled equipment. The CO₂ suppression is provided in case of a fire in the switch house. The system is manually disabled before entry into the protected zone. I haven't see anything similar used to protect against an oil-filled transformer fire, but most of our transformer are located outdoors where the gas flood would quickly disperse. Vault-type installations are unusual.

 

[itsmoked]

Hi Scotty,

These transformers were in hewed out-of-rock rooms buried deep in the rock structure. As I was marveling at how they even got them into place a guy told me they were the only power plant transformers that were inside a dam in the USA. I'm not sure if it was true but it was definitely not something I'd seen before.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

You have me wondering what protects the massive pumped hydro installation at Dinorwig, Wales with 6x 330MVA generator transformers inside the mountain. I am not sure - maybe us Brits do have such a CO₂ system after all.

 

[itsmoked]

When I was googling for a picture it seemed like a great many of the systems were actually Brit, so I'm guessing you guys do.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[prc]

Nearly 45 years back, I had to supply generator transformers first time, to an underground power station- transformers were under a mountain, in separate rock caverns as mentioned by itsmoked. After putting the transformer in to cavern, a brick wall with a door, was made in the front,completely isolating the transformers from the generator hall. Water sprinkler system was used for fire protection . I doubt CO2 will ever be used for such situations as it may choke the entire substation and air conditioning system. There is a CIGRE brochure on the subject- No.537-2013 "Guide for Transformer Fire Protection Practice"