Electric Transformers Faults ( A Complete Guide)

Electric transformers play a crucial role in the efficient and safe distribution of electrical power. These devices, which transfer electrical energy between circuits through electromagnetic induction, are integral components of power grids worldwide.

However, like any complex machinery, transformers are susceptible to various faults that can impact their performance and, in some cases, lead to failures.

In this comprehensive guide, we will explore the common faults that electric transformers may experience, their causes, and methods of detection and prevention.

Overview of Electric Transformers

Before delving into transformer faults, it’s essential to understand the basic components and operation of these devices.

Transformers consist of primary and secondary coils wound around a magnetic core. They work on the principle of electromagnetic induction, facilitating the transfer of electrical energy from one coil to another.

Common Transformer Faults

a. Overheating:

Overheating is a prevalent issue in transformers and can result from factors such as overloading, poor cooling, or insulation failure. Excessive temperatures can degrade insulation materials and lead to accelerated aging.

b. Short Circuits:

Short circuits can occur due to insulation breakdown, leading to the direct flow of current between the primary and secondary windings. This fault can cause severe damage to the transformer and disrupt the power supply.

c. Winding Failures:

Winding failures can result from mechanical stress, manufacturing defects, or insulation deterioration. These faults can lead to short circuits or open circuits within the transformer windings.

d. Insulation Breakdown:

Insulation breakdown can occur due to various factors, including aging, moisture ingress, and electrical stresses. It can compromise the isolation between the windings and lead to other faults.

e. Tap Changer Issues:

Tap changers are components that adjust the transformer’s turns ratio. Faults in tap changers, such as poor contact or mechanical issues, can impact voltage regulation and overall transformer performance.

f. Corrosion and Contamination:

External factors like corrosive environments or contamination of transformer oil can contribute to degradation and faults. Regular maintenance is crucial to prevent these issues.

Detection Methods

a. Dissolved Gas Analysis (DGA):

DGA involves analyzing the gases dissolved in transformer oil to identify specific fault types. Different gases are produced depending on the nature of the fault.

b. Thermal Imaging:

Thermal imaging helps identify overheating issues by capturing infrared images of the transformer. Hot spots indicate potential problems.

c. Partial Discharge Monitoring:

Partial discharges generate localized heat and can be indicative of insulation breakdown. Monitoring equipment detects these discharges and helps prevent catastrophic failures.

Prevention and Maintenance

a. Regular Inspections:

Routine inspections, including visual checks and oil analysis, can identify early signs of faults before they escalate.

b. Proper Loading:

Avoiding overloading and ensuring transformers operate within their specified limits helps prevent overheating and extends their lifespan.

c. Moisture Control:

Implementing measures to control moisture ingress, such as using moisture-resistant materials and regular drying processes, can prevent insulation breakdown.

d. Periodic Testing:

Conducting diagnostic tests, such as insulation resistance and power factor tests, aids in assessing the overall health of the transformer.


Understanding the common faults associated with electric transformers is crucial for ensuring the reliability and longevity of power distribution systems.

Regular monitoring, preventive maintenance, and the use of advanced diagnostic tools are essential components of an effective strategy to identify and address transformer faults before they lead to major failures.

By implementing these practices, the power industry can enhance the resilience and efficiency of electric transformers, contributing to a more reliable and stable electrical grid.