The Impact of Temperature Rise on Transformer Life Expectancy

Temperature is one of the most critical factors affecting the lifespan of a transformer. Many in the industry are familiar with the well-established rule:

For every 10°C reduction in operating temperature, a transformer’s life expectancy doubles.

Equally, for every 10°C hotter a transformer runs, the life expectancy is halved.

This simple yet powerful principle underpins the way we design our LV dry-type transformers at SES Transformers—always prioritizing longevity, reliability, and efficiency.

Understanding Transformer Temperature Rise and AS Standards

Transformers generate heat due to electrical losses in the windings and core. To ensure safe operation, Australian Standards (AS 60076.11) set limits on temperature rise—the allowable increase above ambient conditions.

Most LV transformers use either Class F or Class H insulation, which dictates their maximum operating temperatures:

• Class F (155°C max): Temperature rise + ambient temp + 10°C hotspot allowance ≤ 155°CAt an ambient 40°C, the maximum allowable temperature rise is 105°C.
• Class H (180°C max): Temperature rise + ambient temp + 10°C hotspot allowance ≤ 180°CAt an ambient 40°C, the maximum allowable temperature rise is 125°C.

However, SES Transformers takes a more conservative approach. Instead of designing to the upper limit, we prioritize longevity by targeting lower operating temperatures:

• Class F: Designed for an 85–90°C max temperature rise.
• Class H: Designed for a 100–110°C max temperature rise.

This significantly reduces insulation stress, extending transformer life well beyond 25 years. It’s why SES offers an industry-leading 5-year warranty—our transformers are built for long-term reliability, not just compliance.

Why Temperature Control Matters

Excessive heat degrades insulation materials over time, leading to premature failure. The insulation system of a transformer determines its thermal endurance. However, operating near these upper limits significantly shortens a transformer’s life.

By designing our transformers to run cooler, we:
✅ Reduce thermal stress on insulation, slowing degradation.
✅ Improve energy efficiency, as lower resistance in conductors reduces copper losses.
✅ Enhance reliability, reducing the likelihood of unexpected failures.
✅ Double service life for every 10°C reduction in operating temperature.

SES Transformers: Built for Long-Term Performance

At SES Transformers, we don’t push our designs to the thermal edge. Instead, we build with:

• Optimized winding configurations – reducing I²R losses and improving heat dissipation.
• Premium insulation materials – withstanding temperature variations over decades.
• Enhanced cooling design – ensuring efficient air circulation in dry-type transformers.
• Precision engineering & testing – ensuring each transformer operates below standard temperature rise limits.

By running conservatively, our transformers provide longer service life, lower maintenance costs, and greater reliability, making them the preferred choice for industrial and commercial applications across Australia.

Conclusion: Invest in Longevity

Transformer performance is more than just meeting AS standards—it’s about exceeding them. With SES Transformers, you’re not just buying a product; you’re investing in a solution designed to run cooler, last longer, and perform better.

For expert advice on LV dry-type transformers, isolation transformers, or custom solutions, contact SES Transformers today.