All About Transformer Failures

Transformers are a critical part of the power system and help in transferring electricity from one place to another.

The basics

An electrical transformer is a static machine that transfers electric power from one electric circuit to another while maintaining a constant frequency. The transformer works on something known as the principle of mutual induction. It has two coils, namely the primary and secondary coil, wound on a core. An alternating magnetic flux is created when an AC source is connected to the transformer’s primary coil. According to Faraday’s law of electromagnetic induction, this change in flux will result in an emf being induced in the secondary coil. The secondary winding will have a current flow if the circuitry is closed.

There are different types of transformers:

  • Power transformers
  • Autotransformers
  • Generator Step-Up Transformers
  • Auxiliary Transformers

The 101 on transformer failures

There are several important aspects related to transformer failures.

Cause and effect of a transformer failure

A transformer failure can occur for numerous reasons. Some of them include the following:

  • Improper insulation type and capacity
  • Poor artistry by the manufacturer
  • Loose connections due to prolonged vibration.
  • Excessive harmonics
  • Inadequate maintenance
  • Deterioration of insulation
  • Unbalance due to load configuration changes
  • Overloading
  • Line surges
  • Lighting surges
  • Cooling issues causing overheating
  • Natural wear and tear
  • Natural disasters like floods and hurricanes
  • Malicious mischief or sabotage

Some of the effects that can occur due to a transformer failure include the following:

  • Shock: when a brief burst of electrical current passes through your body and causes only mild harm.
  • Electrocution: when electricity travels through the body over a relatively long period. Therefore, causing involuntary muscle contractions, severe internal damage, and even death.
  • Arc flash: exothermic reaction caused by an overload or faulty wire. It causes a substantial rise in temperature, producing sparks and causing the transformer to ignite and explode.

Failure sources 

The possible failure sources of transformers include:

  • Bushings
  • On-load tap changer
  • Windings
  • Core
  • Oil

Classification of transformer failures

Transformer failures can be classified as:

Internal failures

These include:

  • Twist and rupture of windings
  • Grounding mistakes
  • Dielectric interruption
  • Insulating oil issues
  • Tap changer connection issues

External failures

These include:

  • Oil leaks in the weld cord, valve, or gasket
  • Defects of Buchholz relay and cooling fan
  • Defects of oil level gauges, thermometers, and breather bushings

In the event of a transformer failure

There are some critical steps to be followed when a transformer fails.

Safety precautions 

  • Avoid approaching a failed transformer. Only a trained technician should handle failed transformers, as they can be quite dangerous. Power lines with high voltages frequently brought down by blown transformers might start fires or cause electrocution.
  • Broken transformers frequently cause power outages. It is ideal to remain inside until electricity is restored to protect your family. Keep flashlights, extra batteries, non-perishable food, and water handy.
  • Power surges may happen during transformer repairs, so disconnect all your devices and appliances.
  • Call your electric company if a transformer blows nearby.

In the event of a transformer failure, call electrical service and maintenance or electrical civil construction services. The professionals specializing in electrical civil construction are trained to handle this degree of repair without adverse incidents. They possess safety equipment and are well-versed in repair and safety procedures.


Failure of transformers is a severe issue that needs to be solved by a skilled technician. Call electrical civil construction services in the case of transformer failures. Need more information, contact Von Power today!