Impact of Operating Temperature on Transformers

The operating temperature of a transformer plays a critical role in determining its service life and performance. The longevity of a transformer is primarily influenced by the aging rate of its winding insulation, which in turn is dependent on the temperature at the hottest point of the winding.

Aging of Transformer Insulation

The winding conductor and core of a transformer can generally endure higher temperature rises without sustaining damage. However, prolonged exposure to elevated temperatures significantly affects the insulation material of the winding. The key effects of high temperatures on insulation include:

• Elasticity Loss: The insulation’s elasticity diminishes over time when exposed to high temperatures.
• Mechanical Strength Reduction: Prolonged heating weakens the mechanical strength of the insulation.
• Aging Phenomenon: The insulation undergoes an aging process where it becomes increasingly brittle, leading to potential cracks and peeling.

As insulation ages, it loses its ability to effectively protect the winding, increasing the risk of electrical faults and reducing the transformer’s reliability.

Temperature and Service Life Correlation

The relationship between the operating temperature of the winding’s hottest point and the transformer’s service life is stark. Under specified ambient temperature conditions:

• At 95°C: If the hottest point temperature of the transformer winding is maintained at 95°C, the transformer can continuously operate for up to 20 years.
• At 120°C: If the winding temperature rises to 120°C, the operational lifespan of the transformer drastically reduces to approximately 2.2 years.

This correlation highlights the exponential impact of temperature on the insulation’s aging rate and, consequently, on the transformer’s overall lifespan.

Conclusion

Maintaining an optimal operating temperature is crucial for the longevity and reliability of transformers. Excessive temperatures accelerate the aging process of the winding insulation, leading to a significant reduction in service life. Ensuring that the hottest point temperature remains within safe limits can help in maximizing the operational lifespan of transformers and maintaining their performance. For long-term efficiency and reliability, it is essential to monitor and control the operating temperature of transformers.