There are many avenues for achieving new feats in sustainability. One foundational method of pursuing sustainability is efficient furnace design. In this Control’s Corner installment of Technical Tuesday, Stanley Rutkowski III, senior applications engineer, RoMan Manufacturing, Inc., explores ways to design furnace electrical power systems for efficiency.
This informative piece was first released in Heat Treat Today’s June 2025 Buyers Guide print edition.
In the world of industrial heat treating, sustainability isn’t just a buzzword; it’s a measurable outcome of engineering decisions. While discussions around energy usage often focus on renewable sources or carbon offsets, the path to sustainability begins much earlier — with the design of the furnace’s electrical power system.
From transformers and load configurations to modern control technologies, every part of the furnace power pathway affects how efficiently energy is used — and how much of it is wasted. A well-designed system doesn’t just heat effectively; it does so with less resistance, fewer losses, and minimal disruption to the power grid.
The Power Triangle: Real, Reactive, and Apparent
Understanding sustainability starts with understanding how energy is consumed. Utility companies bill based on more than just energy (kWh). They measure and potentially build via:
- Real power (kW): the usable energy
- Reactive power (kVAR): the energy lost due to inductance and system inefficiencies
- Apparent power (kVA): the total power delivered, including losses
- Power factor: the ratio of real power to apparent power, indicating system efficiency
- Peak demand: the highest level of power drawn during a billing period
Furnace systems with poor power factor or high reactive power incur more cost, even if their real energy usage is low. That’s why electrical design is so critical.
Control Systems: The Shift to Digital
Legacy systems, such as tubes or saturable reactor-based VRTs, have largely given way to more efficient SCR- (silicon controlled rectifier) and IGBT- (insulated-gate bipolar transistor) based controls. IGBT technology, in particular, offers high-frequency switching, reduced losses, and excellent power factor performance. These systems also provide communication protocols — giving real-time insight into power draw, voltage stability, control temperatures, and even predictive maintenance alerts.
Digital communication allows users to evaluate trends over time. For example, changes in DC bus voltage or output current may signal a degrading heating element, enabling early intervention. Smart controls also help avoid peak demand charges by shifting high-load operations to off-peak hours or adjusting recipes to consume less total power.
Load Configurations and Layout
Load configuration is equally as important: single-phase, Scott-T two-phase, or balanced three-phase arrangements. Poorly balanced systems place stress on utility infrastructure and reduce power factor. Balanced loads, especially when combined with IGBT control, lower disturbances to the grid and increase efficiency.
Physical layout also plays a key role. Long conductor runs increase resistance and inductive reactance, which raises energy consumption and heat loss. “Close coupling” the transformer and conductors near the furnace feedthrough reduces losses and improves power delivery, which is important for sustainability and cost savings.
AC vs. Rectified DC Power
Finally, consider how power is delivered. While AC remains common and easy to install, rectified DC systems eliminate voltage zero-crossings, resulting in more stable heating and reduced thermal stress on elements. For high-precision applications like carburizing or annealing, DC systems can extend equipment life and improve thermal uniformity.
Conclusion
Energy sustainability in heat treating isn’t just about switching to greener sources — it starts with how power is delivered, controlled, and consumed. Getting a power conversion expert involved early in the planning and system design process ensures that every component is optimized for efficiency, reliability, and long-term performance. This early collaboration helps manufacturers reduce energy costs, extend equipment life, and achieve more sustainable operations without compromising results.
About The Author:
Senior Applications Engineer
RoMan Manufacturing, Inc.
Stanley F. Rutkowski III is the senior applications engineer at RoMan Manufacturing, Inc., working on electrical energy savings in resistance heating applications. Stanley has experience in welding, glass and furnace industries from R&D, design, and application standpoints. For more than 15 years, his focus has been on energy savings applications in industrial heating applications.
For more information: Contact Stanley at srutkowski@romanmfg.com.
