Power Transformer Explosion: Why it Happens & What to do?

Transformer explosion cause interruption of the power supply to facilities and buildings connected to the transformer. Therefore, we need to ensure the reliable operation of the power transformer.

A power transformer is an intermediate part between a generator and a distribution system and is very vital equipment for the distribution system. It feeds electrical energy from the generator to its primary distribution system.

The power transformer steps up the voltage of the generator bus for long-distance transmission to reduce transmission losses. At the primary distribution end, the voltage is decreased to the desired utility voltage by a step-down power transformer. The stepping up and stepping down of the voltage is done to improve the efficiency of the electrical power system.

The power transformer is a critical equipment of a power distribution system and its reliable operation is paramount for hassle-free operation of the entire electrical system network.

In an electrical system, moving machines like motors and generators are more prone to fail in comparison to transformers. Although a power transformer is a very reliable piece of equipment and there is very little chance of its failure, the probability of the transformer failure can not be negated. Therefore, we can’t firmly say that the transformer will never explode or burn.

We will discuss the reasons for transformer explosion and transformer blowing so that we can take utmost care of those points that cause the transformer explosion. Let us discuss all those points in detail.

Transformer Explosion

Common Causes of a Transformer Explosion

A transformer explosion is caused by an internal short-circuit in the transformer. The reason for short-circuit is an insulation failure. During short-circuit oil temperature reaches 1200 degrees Celsius, and it gets vapored and evolves into explosive gas. The explosive gases cause an explosion and burn.

The followings are the common causes for transformer failures and faults, leading to explosion and burn. They are-

  1. Electrical Failure
  2. Lightning Strike
  3. Extreme Weather Conditions
  4. Mechanical Failure
  5. Equipment Failure
  6. Faulty Design

Now, we will discuss the above points in detail.

1. Electrical Failure

All electrical equipment is vulnerable to failure in this physical world, and the same is true for the power transformer. The electrical reasons for transformer failures are voltage surges, overvoltage, static charges, poor insulation, and partial discharges.

The transformer is equipped with an essential protection system to trip the incoming circuit breaker in the case of a fault in the transformer to avoid catastrophic damage to the electrical network. Once detection of the fault in the transformer, it should be removed and after necessary repairs, it must be put back into operation.

After tripping the transformer breaker on fault, the transformer must be thoroughly checked, and the transformer should not be energized again before ascertaining the reasons for the fault. If the faulty transformer is energized at fault, it will lead to transformer explosion and blowing.

2. Lightning Strike

A lightning strike causes a quick discharge of electricity between two charged clouds or between a charged cloud and the ground. If a lightning strike happens between the charges cloud and the transmission line, it induces a very high voltage on the conductors of the overhead transmission line. The high voltage may cause insulation failures in the electrical system. The transmission line has a guard wire to protect the line from such incident high voltage. However, in some of cases when lightning intensity is very high, it can induce voltage.

The electrical system is vulnerable to such high voltage and insulation may break down. The transformer, if receive such high voltage, its insulation may fail that causing a transformer explosion.

3. Extreme Weather Conditions

The voltage transients can occur if the tree branches touch the transmission line during strong winds and rains. Flooding or earthquakes may also cause transformer explosions.

4. Mechanical Failure

Various reasons like aging, wear and tear, overloading, vibration, and mechanical impact can cause the failure of the transformer. The magnetic core of the transformer may fail due to vibrations because of the displacement of the core from its original position. The core dislocation causes increased heating and eventually causes transformer failure. Other reasons like the aging of transformer bushing, corroded tank, and excessive stress on winding may also cause transformer failure.

The transmission line faults like Hoop buckling, conductor tipping, and conductor telescoping can also cause transformer failure.

5. Equipment Failure

When other electrical equipment installed in the electrical network fails, they cause voltage disturbance in the power grid, leading to a transformer explosion.

6. Faulty design

Transformer failure may also occur because of poor design, inadequate materials, or improper assembly of the transformer.

What to Do When a Transformer Explodes

The transformer explosion causes a power outage and the electrical system comes to a halt. Notwithstanding the power outage, the transformer explosion is a severe incident that causes injuries, property damage, and deaths. Therefore, it is a must to do preventive maintenance and condition monitoring of the transformer so that such type of damage or transformer explosion can be avoided.

If a transformer explosion happens, the following measures need to follow.

1. Keep away yourself from the power transformer

Transformer explosion creates various hazards and you must keep yourself away from the transformer if you do not have the expertise to handle these incidents. You must report the explosion to the appropriate authorities to prevent further damage and other risks. The emergency services professional can handle this type of incident effectively.

If you know about an electrical system, ensure switching off the incoming circuit breaker.

2. Evacuate the Area

If an explosion took place in a populated area, the area must be evacuated immediately to ensure public safety.

3. Report the Local Utility Company

The power outage caused by a transformer explosion must be immediately reported to the local utility company so that they can switch off the feeder at their end if not tripped during the transformer explosion.

4. Avoid contact with any debris

Transformer explosion leads to damage of the parts of the transformer and debris may scatter around the area. Do not touch the debris as it may be hot or dangerous

5. Take the help of a professional

Take the help of a professional for the replacement of destroyed parts of the transformer. The incoming supply must be shut off first. The replacement/repairs of the damaged parts must be done by a professional electrical engineer.


It is important to know the cause of the transformer explosion so that preventive actions can be initiated. Preventive maintenance and condition monitoring like dissolved gas analysis, tan delta test, BDV tests and other types of tests must be done periodically to ensure trouble-free operation of the transformer.

The transformer explosion is a severe incident and what to do after a transformer explosion is very vital for preventing further damage and injury.

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