Various Failure Modes in Power Transformers

By Rugged monitoring | 19/05/23

Is the most valuable electrical asset of your substation monitored well? 


Power transformers are the central part of substations and play a very important role in the power system. They are predominantly unfailing electrical systems. Though they are one of the most reliable components of the electrical grid they are also prone to failure due to many internal and external factors.


As the population of transformers in utility is increasing, much attention must be directed towards transformers reliability and availability. Also, the condition and risk assessment of the transformers are becoming more and more important to improve the transformers performance, extend their useful life, to decrease costs and to take the best technical and economic decisions, concerning their life cycle management.

Different types of transformer failure modes

Failure mode is the way a failure is occurred, observed, which impacts on the equipment operation. The most common failure in transformers is insulation degradation due to overloading conditions, switching surges, lightening etc. The heating of transformer can increase the temperature of insulation system and eventually can decrease the effectiveness of insulation.

The modes of failures can be divided into the following categories:



Electrical Failure Modes

The Electrically induced factors result in damage to a transformer insulation system. Turn to turn insulation breakdown is the common cause for electrical failure in transformers. Degradation of insulation occurs due to sudden high voltage or current. This breakdown of insulation gives rise to flashover of winding turns and causes short circuits.


Electrical failures can be categorized into the following three main types:

These failures may occur independently or in combination. Therefore, it is important to evaluate all the factors for developing an accurate failure scenario to analyze the failure occurred in the transformer. Transformer insulation should be checked with at most care as the internal electrical failure can result in a catastrophic failure and effect the operations.