The Evenson Power Furnace Transformer is a heavy-duty, high-current power transformer engineered for electric arc, ladle, induction, and submerged-arc furnaces.
Furnace transformers are among the most demanding apparatus in any power system. They must supply enormous secondary currents at low voltage, tolerate violent and rapidly fluctuating loads, survive frequent short-circuits inherent to arc melting, and regulate output voltage across a wide range while doing so. The Evenson Power Furnace Transformer is purpose-built for exactly this environment.
Used in steelmaking, foundries, glass and ceramic production, and a range of high-temperature process industries, these transformers are the energy backbone of the modern electric furnace, converting incoming medium-voltage supply into the controllable, high-current power that drives the melting process.
A furnace transformer steps incoming primary voltage down to a low secondary voltage capable of delivering currents ranging from several thousand to tens of thousands of amperes. Unlike a standard power transformer, its design is dominated by the management of very high secondary current, the associated heat, and the strong electromagnetic forces that current produces.
The Evenson Power range covers arc-furnace duty typically in the 20 MVA to 200 MVA range, with primary voltage classes that do not exceed 72.5 kV. Secondary voltage is selectable across many tap steps so operators can match the furnace through the full melt cycle, from initial bore-in to flat-bath refining.
The core, windings, clamping structure, tank, and cover are built from heavy steel and high-strength materials selected to resist continuous mechanical and thermal stress. Tap windings, usually placed on the high-voltage side, provide the many regulation steps the process requires, and coils are arranged so that primary tap positions affect reactance as uniformly as possible.
Secondary low-voltage delivery is achieved through subdivided, staggered busbars routed through the cover. This arrangement controls leakage-flux concentration, prevents localized overheating of structural steel, and balances the current among parallel conductors. In three-phase units a delta secondary, often an external delta with staggered busbars, is used to combine windings while managing the magnetic field.
Reactance is a defining design parameter. For large arc furnaces the transformer’s inherent reactance, generally kept to roughly 10 to 15 percent, is sufficient to stabilize the arc; smaller furnaces may require a separately specified series reactor. Reactance is engineered to vary inversely with the square of the secondary voltage to maintain stable operation across the tap range.
Evenson Power Furnace Transformers are configured to the specific furnace they serve. Arc-furnace units commonly fall in the 20–200 MVA band, while ladle, induction, and resistance applications are scaled to their respective process loads. Primary voltage classes are held at or below 72.5 kV, and secondary voltage is offered across a wide regulated range with very high rated current.
The chosen secondary voltage range strongly influences transformer weight, cost, and reactance behavior, so each unit is optimized for the operating window of its furnace rather than supplied as a generic rating.
High overload capability and short-circuit strength let the transformer ride through the repeated faults that are normal in arc melting without damage. On-load tap changing enables operators to adjust power input dynamically, maximizing furnace productivity and energy efficiency.
Efficient design, with high-quality units typically achieving 95 percent or better, reduces energy cost per ton of product. Robust insulation rated for elevated operating temperatures supports continuous, high-duty operation.
The Evenson Power Furnace Transformer serves AC and DC electric arc furnaces for steel and alloy production, ladle (refining) furnaces, induction furnaces, resistance furnaces, and submerged-arc furnaces used in ferroalloy and similar processes.
Beyond primary metals, the same technology supports glass and ceramic melting and other high-temperature industrial heating where large, controllable electrical power must be delivered at low voltage.
Furnace transformers are designed to recognized international standards for power transformers and furnace-duty apparatus, with particular attention to short-circuit withstand, temperature rise under fluctuating load, and dielectric integrity. Routine factory tests cover ratio, winding resistance, losses, impedance/reactance verification across taps, and dielectric tests.
Special testing such as temperature-rise and impulse testing is available to validate performance to the product class. Supported compliance and certification marks include IEC, UL, CE, KEMA, and TUV.
Large furnace transformers are installed close to the furnace to minimize secondary busbar length and the associated losses and voltage drop. Cooling is selected to suit the site: water cooling is preferred for the largest furnaces for its compactness and economy, with natural cooling offered where water quality or availability is a concern. Sealed designs with properly engineered stuffing boxes keep dust and contaminants out.
Maintenance focuses on regular insulating-fluid quality checks to guard against moisture and impurities, monitoring of core insulation, verification of internal and busbar connections, and confirming that overload protection and neutral-point grounding (for low-voltage systems) function correctly.
Evenson Power Furnace Transformers are engineered specifically around the customer’s furnace, not adapted from generic designs. That focus delivers the precise reactance, regulation range, and short-circuit strength a productive, energy-efficient melt shop demands.
With rigorous quality control, high-temperature-rated materials, and responsive engineering support, Evenson Power supplies furnace transformers built to perform reliably under the most punishing process conditions.
| Type | Oil-immersed furnace / arc-furnace power transformer |
| Typical Rating (arc furnace) | 20 MVA – 200 MVA |
| Primary Voltage | Up to 72.5 kV |
| Secondary Voltage | Low voltage, wide multi-step range |
| Secondary Current | Thousands to tens of thousands of amperes |
| Reactance | Typically 10–15% |
| Voltage Regulation | On-load or no-load tap changer, many steps |
| Phases | Three-phase (delta secondary) / single-phase |
| Frequency | 50 Hz / 60 Hz |
| Cooling | Water-cooled or natural (oil) cooling |
| Core Material | Grain-oriented silicon steel (CRGO) |
| Winding / Busbar | Copper, subdivided & staggered LV busbars |
| Typical Efficiency | 95%+ |
| Tank & Clamping | Heavy steel, sealed with stuffing boxes |
| Standards | IEC / UL / CE / KEMA / TUV |
| Applications | Arc, ladle, induction, resistance, submerged-arc furnaces |
Engineered, certified and delivered under the Evenson Power name.
