In electric arc furnace (EAF) steelmaking, the “power level” refers to the rated transformer capacity allocated per ton of steel. Essentially, it indicates how much electrical energy (in kVA) is provided for melting each ton of steel. This metric is a key indicator of the furnace’s technical capability and has a direct impact on the melting cycle and overall efficiency.
Importantly, power level is a dynamic value that changes based on the amount of scrap or charge loaded. To optimize production, operators must adjust the furnace charge according to the transformer’s capacity—avoiding situations where equipment is either underutilized or overloaded.
For example, at Xinjiang Bayi Steel Plant, a 70-ton DC EAF equipped with a 6.3 MVA transformer was once loaded with 100 tons of scrap during a later stage of its campaign. This resulted in an extended melting cycle by 5–15 minutes, and performance indicators such as metal yield and oxygen consumption fell short of design targets.
How Are EAF Power Levels Classified? What Is a UHP Furnace?
Power levels in electric arc furnaces are typically categorized based on transformer capacity per ton of steel. There are three main classifications:
- Regular Power (RP): < 400 kVA per ton of steel
- High Power (HP): 400–700 kVA per ton
- Ultra-High Power (UHP): > 700 kVA per ton
The concept of Ultra-High Power (UHP) EAFs was first introduced in 1964 by W. E. Schwabe of Union Carbide and C. G. Robinson of Northwestern Steel & Wire. Their approach involved increasing transformer capacity and enlarging conductor cross-sections to deliver more power efficiently.
The U.S. led the way by upgrading 135 furnaces to UHP standards, and soon after, countries like Germany, the UK, Italy, and Sweden followed suit. These nations gradually phased out regular-power furnaces in favor of UHP technology, marking a major leap in furnace design and steelmaking performance.
