Understanding the DOE 2029 Energy Efficiency Standards for Distribution Transformers

by Dr. David Walker, CTO, MGM Transformers- February 2025

The Department of Energy (DOE) has finalized new energy efficiency standards for distribution transformers, set to take effect in 2029. Here’s what you need to know and how MGM Transformers is preparing for the transition.

Why the Change?

The DOE’s goal is to improve energy efficiency across the board, reducing losses in electrical power systems, cutting down carbon emissions, and saving costs for electricity consumers. The new standards aim to decrease energy losses by 10% to 30%, depending on the transformer type and size.

Key Updates:

• Extended Deadline: Originally proposed for 2027, the DOE extended the compliance deadline to 2029, giving manufacturers and suppliers more time to adapt.
• Core Material Adjustments: Initially, the DOE suggested a full shift to amorphous steel cores. However, after industry feedback, the final rule allows for a mix—about 75% of transformers can still use grain-oriented electrical steel (GOES), while 25% will transition to amorphous steel.
• Efficiency Gains: The new standards will reduce energy losses in liquid-immersed transformers by up to 20% and in low-voltage dry-type transformers by as much as 30%.

Proposed Efficiency Requirements

The DOE has outlined specific efficiency improvements that manufacturers must meet for various transformer types. These include:

• Low-voltage transformers are tested for efficiency at 35% load, and the results are temperature corrected to 75°C.
• Medium-voltage transformers (both dry and liquid-immersed) are tested at 50% load, with efficiency results also temperature corrected to 75°C.

Because of the low percentage loading, the efficiency is primarily driven by core losses. This focus on core material types is crucial since load losses are proportional to the loading percentage squared, while core losses remain constant regardless of loading. For example, at 50% load, the load losses drop to 25% of their full-load value, whereas core losses remain unchanged. As a result, efficiency improvements are generally achieved by reducing core losses.

What This Means for You

At MGM Transformers, we’re committed to keeping your projects running smoothly. We are already integrating these new efficiency requirements into our production planning and working closely with our suppliers to ensure a seamless transition. Whether you’re an engineer, contractor, or facility manager, these updates mean improved efficiency and long-term cost savings for your electrical systems.

We’ll continue to keep you informed as we move closer to the 2029 deadline. Have questions? Reach out to our team—we’re here to help you navigate these industry changes.

Additional Resources:

• 2016 Standards
• 2029 Final Rule
• Energy Improvements
• Standards and test procedures