- by Todd Benadum
- May 15, 2023
- Blog, Build Process, Dry Type
Because transformers convert power into higher or lower voltages, they generate heat as a byproduct. This heat causes increased temperatures in the transformer’s internal components, including the primary and secondary windings. A transformer’s temperature rise — or C-rise — is the average temperature of the windings in Celsius over the surrounding temperature when the transformer is loaded at total capacity.
Transformers can have an 80-degree, 115-degree or 150-degree C-rise. The most efficient transformers generally have the lowest C-rises and operate the coolest. Units with low C-rises are essential for applications where optimal performance and efficiency are crucial, including hospitals, schools, alternative energy and manufacturing facilities.
Transformers that operate more efficiently produce less heat as waste, resulting in lower ventilation and cooling requirements. Choosing a transformer with the proper design, correct C-rise temperature and high-performance components will help maximize the unit’s efficiency and life span.
Why Insulation in Dry Type Transformers Is Important
A transformer’s insulation type receives a class rating based on the highest temperature at which it can function. Insulation ratings range from Class 105 to Class 220. Based on standards established by the National Electrical Manufacturers Association (NEMA), this rating equals the unit’s maximum load C-rise plus the maximum allowable ambient temperature.
For example, insulation with a 220 rating would allow for a maximum 150-degree temperature rise in the windings with a 30-degree hot spot allowance, plus a 40-degree maximum ambient temperature.
The insulation rating also dictates the system’s overload capacity. Although overloads are sometimes tolerable in short durations, operating the transformer below the insulation’s maximum temperature rating is vital for safety and long-term reliability.
Types of Insulation We Use at ELSCO Transformers
While some competitors use inexpensive insulation options for low voltage requirements, ELSCO utilizes the highest-rated insulation for all transformer builds, including DuPont Nomex insulation throughout each unit’s coil and SG-200 fiberglass insulation for our barriers and molds.
Using these premium-grade options achieves benefits like:
- Increased safety: Dry type units with Nomex insulation are safer because there are no flammable materials like fluids or other combustible components.
- Lower transmission losses: Our superior insulation allows facilities to install their transformers closer to their loads, helping to shorten low-voltage lines and limit transmission losses.
- Cost-efficiency: Transformers with premium-grade insulation can handle C-rise temperatures up to 150 degrees Celsius, meaning a unit’s core requires less conductor and steel. These reduced material requirements result in lower overall costs and easier installation.
- Improved harmonic loading capabilities: Dry type units with Nomex insulation have increased capacity to handle applications with high hot spot temperatures generated by heavy harmonic loads.
In addition to using superior-grade installation, our dry type transformer designs contain laminated steel cores and 100% copper windings to deliver maximum efficiency. Our manufacturing technicians manually assemble and hand-wind each unit to meet the highest quality control standards.
Contact Us Today to Learn More
If you want to learn more about which C-rise ratings and insulation options are best for your needs, the professionals at ELSCO Transformers can assist you. We aim to help clients choose the most reliable, efficient and cost-effective solution for each unique application. Besides offering a comprehensive catalog of in-stock transformers, we provide many other services, including custom-built units, transformer retrofits, custom bus work, emergency replacements and repairs.
Complete an online quote request for pricing or call 800-232-9002 for additional product information.