Transformer failures can wreak havoc on industrial operations, leading to costly downtime and repairs.
From overloading and insulation degradation to environmental factors and improper maintenance, transformers face a myriad of potential issues.
In this blog post, we’ll explore the top causes of transformer failure to help keep your machinery running smoothly.
Overloading and Overheating
Transformers are designed to operate within specific load and temperature ranges. When a transformer is subjected to loads that exceed its rated capacity for an extended period, it can lead to overheating. Overheating causes the insulation materials to deteriorate rapidly, reducing the transformer’s lifespan and increasing the risk of failure. The excessive heat can also cause the transformer’s internal components to expand, potentially leading to mechanical damage and short circuits.
Insulation Degradation
Over time, the insulation materials can degrade due to various factors such as heat, moisture, and electrical stress. As the insulation deteriorates, it loses its dielectric strength, making it more susceptible to electrical breakdowns. This can result in short circuits between the transformer’s windings, leading to catastrophic failure.
Moisture Ingress
When moisture enters the transformer, it can cause several problems. Firstly, it can reduce the dielectric strength of the insulation, increasing the risk of electrical breakdowns. Secondly, moisture can lead to the formation of bubbles in the transformer oil, which can cause partial discharges and accelerate insulation degradation. Additionally, moisture can promote the growth of microorganisms that can further contaminate the transformer oil and damage the insulation.
Lightning Strikes
When lightning strikes a transformer or nearby power lines, it can induce high-voltage surges that exceed the transformer’s insulation capability. These surges can cause insulation breakdowns, leading to short circuits and internal arcing. Lightning strikes can also cause mechanical damage to the transformer’s windings and core, rendering it inoperable.
Loose Connections
When electrical connections become loose due to vibration, thermal cycling, or poor installation, they create high resistance points. These high resistance points generate excessive heat, which can damage the insulation and cause localized overheating. Over time, loose connections can also lead to arcing and sparking, further damaging the transformer and increasing the risk of fire.
Faulty Bushings
Bushings are the insulating components that allow electrical connections to pass through the transformer tank while maintaining proper insulation. Cracks, contamination, or deterioration of the bushing insulation can lead to electrical discharges and flashovers. These discharges can damage the transformer’s internal components and cause a complete failure.
Tap Changer Issues
Tap changers are mechanisms used to regulate the voltage output of a transformer. They allow the transformer to adjust its turns ratio to maintain the desired voltage level. However, tap changers are mechanical devices that can experience wear and tear over time. Faulty tap changers can cause voltage fluctuations, overheating, and arcing. Improper maintenance or lack of lubrication can also lead to tap changer malfunction, resulting in transformer failure.
Improper Maintenance
Transformers require regular maintenance to ensure their reliable operation and longevity. Improper maintenance practices can contribute to transformer failure. Neglecting to monitor and maintain the transformer oil, failing to perform regular inspections, and not addressing identified issues promptly can all lead to accelerated deterioration and eventual failure.
Environmental Factors
- Extreme temperatures: Transformers exposed to extremely high or low temperatures can experience accelerated aging and insulation degradation. High temperatures can cause the transformer oil to lose its dielectric properties and accelerate the breakdown of insulation materials. Low temperatures can cause the oil to thicken, reducing its ability to circulate and dissipate heat effectively.
- High humidity: High humidity environments can lead to moisture ingress into the transformer, as discussed earlier. Moisture can enter through breathers, seals, or even directly through the tank walls if proper moisture control measures are not in place.
- Corrosive environments: Transformers located in industrial areas or near coastal regions can be exposed to corrosive atmospheres containing chemicals, salt, or other pollutants. These corrosive agents can attack the transformer’s external surfaces, leading to rust, deterioration of gaskets and seals, and eventual moisture ingress.
- Contamination: Transformers can be contaminated by various substances such as dust, dirt, and industrial pollutants. These contaminants can enter the transformer through inadequate sealing or during maintenance activities. Contamination can clog cooling ducts, reduce the effectiveness of insulation, and promote the formation of conductive paths, increasing the risk of failure.
Aging
Transformers have a finite lifespan, and as they age, their components and materials naturally deteriorate. The aging process is accelerated by factors such as heat, moisture, and electrical stress. As transformers age, their insulation becomes brittle and loses its dielectric strength, making them more susceptible to failure.
