There’s no way around it: transformer fires are highly dangerous, and they can be very expensive. And although they don’t occur frequently, it only takes one catastrophic event to put lives, property, and businesses at great risk. That’s why effective fire suppression systems are so important. With that in mind, how do you protect a transformer from fire? We will briefly explore the essentials of transformer fire protection—including key causes and best practices for preventing transformer fires.
The three most common transformer fire causes are severe weather conditions, mechanical failure, and electrical issues.
Fortunately, transformer fires are rare, with T&D determining “the average probability of a serious transformer fire” to be ”on the order of 0.06% to 0.1% per service year” (which equates to roughly “one fire per 1,000 to 1,500 transformer service years”). Additionally, throughout an average transformer’s lifespan of around 40 service years, “2.4% to 4% of all transformers can be expected to cause a fire”.
Transformers can become a fire hazard any time they’re introduced to the primary causes of transformer fires—inclement weather, mechanical failures, and electrical issues. Without appropriate transformer fire safety practices in place, an organization’s equipment and people are subjected to unnecessary risk. The National Fire Protection Association (NFPA) notes that the most dangerous element of a transformer is the oil used “for insulation, to prevent electrical arcing, and to serve as a coolant” since it “is similar to mineral oil and very flammable.”
Generally speaking, dry-type transformers pose less risk of fire or explosion. This transformer type, ideal for medium- and low-voltage indoor applications, does not contain any flammable liquid (i.e., oil), eliminating that particular risk.
When a transformer catches fire, a dangerous chain reaction begins. Let’s use the example of a transformer fire caused by electrical issues, like poorly-insulated wire or a lightning strike. Initially, heat (and a spark) is created, sufficient to ignite the mineral oil meant to serve as a coolant. All three elements of the fire triangle are present: oxygen, heat, and fuel. As the oil burns, it generates enough pressure to cause an explosion.
As we’ve mentioned, the best fire protection is prevention. Transformer fires can be catastrophic, so it’s not wise to simply “hope it doesn’t happen to me.” Instead, a comprehensive transformer fire protection system is the best course of action.
If you’re looking for more information about preventive measures to protect transformers from fire, the NFPA is a great place to start. This organization publishes transformer fire protection standards, including:
If a transformer fire does occur, there are a few main methods for suppressing or extinguishing it. These include: