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What happens when a transformer blows?

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  • 4 min read

Electricity is a rather important part of our lives. Without it, daily life as we know it would cease to exist. There’s quite a process involved in generating electricity and delivering it to your house, and transformers play an important role. 

In this article, we’re taking a look at what happens when a transformer blows, why it might happen and what comes after.

Also read: Electric vehicle buying guide: All you need to know

How do transformers work?

Before we can get to how transformers blow, we need to understand how transformers work. In order to minimise losses during transmission, electricity companies usually send a high voltage current using overhead or underground wires. 

This high voltage current (around 440v here in India) is too much for regular households and businesses to handle, so transformers are installed at all distribution points to step this voltage down to 220v which is then distributed using thinner electric lines. 

A standard step down station equipped with a transformer.

A transformer itself is rather simple in construction. It’s just two sets of coiled wires wrapped around a ferromagnetic core. The incoming side with the higher voltage has more coils as compared to the outgoing side which is supposed to carry less voltage. When power comes into the transformer it creates a magnetic field and transfers the electricity to the smaller coil at a lesser voltage. 

Generally, these wires are covered in plastic insulation and the entire assembly is cooled using special coolants such as mineral oil. This is what keeps the transformer from causing sparks or overheating and keeps it from exploding. 

Why do transformers explode?

There are a number of reasons why transformers explode, but one of the most popular causes is a voltage overload usually caused by lightning striking a transformer. This causes the incoming voltage to become much higher than the coils in the transformer are supposed to tolerate, resulting in overheating of the coils which eventually leads to an explosion. 

Transformers do have protective circuitry built into them to avoid such situations, but these circuits can sometimes take as much as 60 milliseconds to kick in and sometimes that’s not quick enough. 

Overhead transformers are often at risk of exploding.

Other than this, regular wear and tear over continued regular usage can also often lead to malfunctions such as weakening of the wire insulation or other transformer components which in turn lead to explosions. Such explosions often set fire to the internal mineral oil coolant in the transformer which can be a fire hazard. 

Other common reasons include:

  • Wiring issues.
  • Power surges.
  • Moisture.
  • Insects, rodents or other foreign objects. 

What happens after the explosion?

The simple answer is that the transformer stops working, which in turns stops electricity delivery to all connected endpoints. As a general consumer, this means that you’ll have no electricity until the transformer and its supporting infrastructure are repaired by the concerned authorities. 

Once a transformer blows, the aftermath and repair are for the electricity company owning the transformer to handle. Generally, a blown transformer is beyond repair and is simply replaced with a new one. However, because of the damages these explosions cause, it can also mean that the power lines around the transformer and other related infrastructure might well be in need of repair as well.

Also read: What is HVAC?

Yadullah Abidi

Yadullah is a Computer Science graduate who writes/edits/shoots/codes all things cybersecurity, gaming, and tech hardware. When he's not, he streams himself racing virtual cars. He's been writing and reporting on tech and cybersecurity with websites like Candid.Technology and MakeUseOf since 2018. You can contact him here:

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