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Why Is Your Dry Type Transformer Overheating?

Since transformers convert high voltages into consumable power, they generate significant heat. This heat can significantly affect the transformer’s efficiency and will shorten its life span. With energy efficiency becoming a top priority in many of today’s power applications, choosing a dry type unit that can adequately meet the required power needs and subsequent thermal loads for your specific application is crucial.

Dry type transformers rely on circulating air and other internal components like insulation and windings to prevent the transformer from overheating. Overheating occurs when the transformer generates more heat than anticipated — sometimes due to higher loads — dissipates it slower than expected — such as in cases with insufficient airflow — or some combination of the two. Without the proper cooling measures or when used for the wrong application, any transformer design can overheat, become unsafe and eventually combust.

What Causes a Dry Type Transformer to Overheat?

While many dry type transformer designs can last several decades, constant exposure to heat above a unit’s limit will significantly decrease its service life. Low-quality transformers with substandard insulation and windings often generate more heat, leading to an increased temperature rise, also called C-rise.

The average temperature increase of a unit over the ambient temperature when the transformer is fully loaded determines the C-rise. The better a transformer’s performance and efficiency, the lower the C-rise.

Several factors that can cause a transformer to overheat or increase its C-rise include:

  • Improper load rating selection: Selecting a transformer with a rating that can handle the intended application is crucial. The load rating is the maximum power a unit can efficiently and safely handle without causing damage or overheating.
  • Inadequate airflow: Installing a dry type unit in a location with sufficient airflow and ventilation is vital. Even if a transformer is in an enclosure with air vents, it should not be near anything obstructing the airflow.
  • Poor Insulation: Various insulation types transfer or dissipate heat at different rates. ELSCO uses DuPont Nomex® Type 410 insulation because it offers effective protection against temperature failure.
  • Low-quality windings: Prolonged temperatures exceeding the design temperature can break down the windings’ dielectric strength, leading to power surges, hot spots or total system failure. Different winding methods can also help improve a transformer’s C-rise.

Contact ELSCO Transformers Today to Learn More

Contact ELSCO Transformers Today to Learn More

If you want to learn more about how a high-quality dry type transformer can benefit your operation, the professionals at ELSCO Transformers can guide you. We can analyze your application to determine the best stock solution or create a customized transformer design for your unique needs. In addition, we offer a comprehensive range of transformer services, from custom bus work and retrofitting to repairs and emergency replacements.

Complete a quote request form for pricing and to obtain additional information.