Why does a transformer exploded

A failure doesn't always equate to a fire or explosion either; in fact, in the steadily decreasing number of failures per year, such an explosion is rare. It will take time to analyze just what went wrong. Older transformers can explode when their insulating materials begin to fail. This happens as cellulose and oil absorb water over time and degrade cellulose's ability to insulate, triggering an explosion.

The U. This story was originally published on February 11th, and has been updated. Power failed from 39th Street all the way to the southern tip of Manhattan, and the affected area likely will not regain power for up to a week. Popular Mechanics explains :. When flooded with too much electricity, the sudden surge can cause a transformer explosion. Electrical energy is a necessity for all aspects of civilisation. Increasing electrical energy consumption and demand have made the world highly reliant on electrical power systems.

Solar cell technology has recently attracted significant attention due to the excellent photovoltaic performance of current solar cell technology 3 , 4 , 5. However, in many countries, electricity is currently produced by fossil fuel combustion in thermal power plants 6.

As these plants are typically located outside citylimits, the electrical energy needed for households and other activities is transported through powerlines to substations or transformers.

Transformers are electrical devices used to convert an alternating current AC at a certain voltage to another AC voltage using the principles of electromagnetism and electromagnetic induction 7.

The voltage conversion process generates heat due to electrical resistance; insulating fluids are used to absorb this heat. Three types of transformers are commonly used: i less-flammable-liquid-filled transformers, ii flammable-liquid-filled transformers, and iii non-liquid dry type transformers 8. Dry-type transformers sometimes called cast resin transformers use gases or dry compounds as the insulation material, and are generally considered safer than liquid-type transformers 8.

However, they are costly and bulky. The liquid inside transformers is referred to as the insulant, insulating liquid, or dielectric liquid 9. Petroleum-based mineral oils have been used as transformer insulating liquids since 10 , and most modern electrical power transformers use mineral oils derived from petroleum crude oil for cooling and insulation. These oils comprise various classes of hydrocarbon compounds, including naphthalenes, paraffins, iso-paraffins, and aromatics 11 , According to the United States Environmental Protection Agency, the main component of most commercially available mineral-oil-based transformer fluids is hydrotreated light naphthenic petroleum distillate Mineral oil is a highly refined hydrocarbon-based oil and has been the most widely used insulation liquid in electrical applications for more than years The most important fire safety parameters of fluids are their fire point and flash point A fluid will only ignite if it its temperature reaches its fire point and it is exposed to an ignition source.

As a fluid is heated, the concentration of vapour above the fluid increases. At the flash point, the resulting vapour-air mixture can be ignited; when the temperature is further increased to the fire point, combustion will be sustained on the fluid surface. That is, under typical ambient conditions mineral oil may burn, but will it not ignite readily However, due to excessive heating, mineral oil may become combustible or flammable. This type of fault may lead to fire and explosion due to the decomposition and vaporisation of the oil and the subsequent formation of gas bubbles 8.

The exact conditions under which mineral oil will become flammable depend on its composition. The composition of transformer oil can be identified using various analytical methods, such as gas chromatography—mass spectrometry GC—MS and gas chromatography—isotope ratio mass spectrometry GC—IRMS. GC analysis is sufficient to identify the compounds present in a sample and the percentage of each one Outside this range, the oxygen or fuel concentration will be insufficient to sustain combustion.

These flammability limits can be measured using various apparatuses or determined using empirical equations Several methods and databases provide flammability limit information for hydrocarbons 29 , Transformer fires and explosions can occur for a variety of reasons.

Strong rain and high winds can cause trees to fall on transformers, causing explosions. Although transformer fires and explosions are highly unlikely under normal weather conditions, they can potentially occur due to design faults, faulty hardware, or an overload in the system. Sudden damage to transformers can also lead to overcharging, which can create sufficient quantities of heat and sparks to ignite the mineral oil.

The gases generated by boiling mineral oil create a massive overpressure inside the sealed transformer, leading to oil tank rupture, which results in the release of large amounts of energy and strong thermal radiation, scattering flaming oil, gaseous decomposition products, solid insulation, and molten conductor material over the surrounding area 17 , However, transformer tank explosions do not always result in a fire; the possibility of fire depends on how quickly the transformer protection system operates However, even when no fire occurs, the release of oil onto the site can cause major environmental pollution.

Transformer fires are generally of two types: pool fires and spray fires. A pool fire can occur when transformer oil leaks onto the ground via gaskets, holes in the radiator fins or the steel tank, or similar defects. Over time, the oil accumulates on the ground, forming an oil pool that can easily burn if ignited, resulting in a pool fire. Spray fires occur when the mineral oil inside the storage container is heated due to internal insulation failure.

The temperature of the mineral oil inside the transformer tank increases, forming flammable vapour that is suddenly released from an opening in the tank into the surrounding atmosphere.

Although the probability of transformer fires and explosions is relatively low, it is not negligible. Transformer fires are difficult to extinguish and control. Additionally, mineral oil fires can spread to nearby equipment and buildings, presenting a high risk Several notable transformer fire accidents have occurred in the past. Perhaps the worst transformer accident occurred in a coalmine in western Turkey in May when an electrical fault resulted in a transformer explosion and a fire.

More than people were killed in the disaster, and 80 were injured To the best of our knowledge, most previous studies related transformer explosions and fires have focused on investigation of the electrical and mechanical failure of the transformers.

In contrast, this workis aimed at investigating the possibility of fire and explosion due to the formation and release of flammable mixtures from power transformers. Two samples of mineral oil new and used were collected from an electric power substation in Riyadh. The new oil was still in its original container and had never been used. The used oil had been filled into a transformer tank, and the transformer was operated for a maximum period of one year.

In electrical stations, transformer oil is usually replaced with new oil after one year regardless of whether the transformer has been operated. GC-MS analysis was conducted using a procedure based on our previous study Helium purity The end of the column was connected to the ion source of a mass-selective detector operated in electron impact ionisation mode. The components were analysed and identified via computer spectral matching methods by matching their mass spectra with data obtained from the National Institute of Standards and Technology NIST database.

The mass fraction of each compound in the liquid phase was calculated using the ratio of the area of the peak corresponding to that compound to the total area of all compounds Eq. Vaporisation characteristics are important to investigations of flammability.

Some components of mineral oil vaporise at ambient temperature or can produce flammable mixtures if exposed to heat. Therefore, the composition of the vapour phase must be identified.

In the absence of experimental data, flammability limits can be predicted using established theoretical methods. Jones 39 found that in the formation of hydrocarbon vapours, the flammability limits were functions of the stoichiometric concentration of the fuel, C st Eqs. For most organic compounds, the stoichiometric concentration can be determined using the following general combustion reaction:. The stoichiometric concentration, C st , can be determined as a function of z :.

Zabetakis et al. This means that an increase in temperature widens the flammability range. Read their reports on this site, and hear them on public radio stations across Pennsylvania. Climate Solutions , a collaboration of news organizations, educational institutions and a theater company, uses engagement, education and storytelling to help central Pennsylvanians toward climate change literacy, resilience and adaptation.

Our work will amplify how people are finding solutions to the challenges presented by a warming world. How a lab works to seek and destroy the harmful chemicals known as PFAS. In Pa. Central Pa.