Advanced unit rectifier assembly

The X-Pact® AURA as Advanced Unit Rectifier Assembly is designed to achieve efficient and stable power controller to feed DC arc furnaces in all power networks configurations, including weak grids. Based on modern IGBT technology, the new design achieves world class performances in terms of current stability, dynamic performances, efficiency, reliability, redundancy and minimum impact on electric network quality. In most cases, no SVC or Statcom is required to fulfill IEEE 519 standards.

X-Pact® AURA power electronics modules

Customer challenges addressed

  • Reducing the impact on the power grid
  • Avoiding the installation of expensive SVC or STATCOM
  • Having a faster and precise energy input regulation
  • Reducing electrical energy consumption
  • Reducing electrode’s consumption
  • Increase the availability of EAF even in presence of single failures
  • Reducing the spare part’s stock
  • Scale-up productivity
  • Setting an architecture ready to accept connection to renewable power sources

Key features

  • Advanced DC EAF feeding
  • World class efficiency, reliability and redundancy.
  • No SVC or Statcom required to fulfill flicker requirements
  • Active energy real-time control
  • 0.95 minimum power factor, THD fulfills IEEE 519
  • No large reactor to control flicker or for arc stability


  • What is X-Pact AURA technology?

    IGBT technology combined with diode rectifiers and dry-type transformers

    X-Pact AURA is a compact, modular system for feeding Electric Arc Furnaces: installed in cabinets, each cabinet rated approx. 14 MW. Line interface consists of uncontrolled diode rectifiers, which generate a DC bus (high cosϕ, low THD). Strong redundancy is included, with eight parallel IGBTs circuits x module. The cooling and AC systems are integrated in each module. An individual module controller manages the low level, high speed control loops, while a furnace master controller synchronizes the different modules and interfaces with the electrode controller and the furnace automation. All AC and DC power and control interconnections between components are included.

  • Technology for the digital power

    Power scale up is NOW possible

    With X-Pact AURA, the investment can be made in stages. Steps size is flexible, according to available raw material type and power amount. The equipment type remains the same, with identical functionality & controls: increasing power is made by adding parallel modules, with extremely short shut down time. The system operation is flexible, with possibility of running efficiently with less modules also after full size installation and consequent increased efficiency and extended equipment lifetime.


    • Allows large furnace operation also with very weak networks
    • Reduced flicker impact due to very low furnace Kst and high freq. commutation
    • No phase unbalance at MV & HV side
    • Natural high power factor (0,95) due to uncontrolled rectifying bridge (diodes)
    • Extremely low harmonic distortions due to high equivalent pulse (≥ 36)
    • Extended arc stability and improved dynamic performances due to very high (1000÷2000Hz) PWM frequency and up to 30% Voltage margin on the DC bus
    • Reduced OPEX and TCO
    • Increased overall system efficiency, lower losses, lower electrode consumption
    • Compact modular system, installed in cabinets (easy maintenance)
    • No heavy load MV Furnace Circuit Breaker required
    • 1 x dry-type transformer per module (no tap changer, no oil, no oil pit, no fire separation walls), with lower CAPEX and easier to transport and install
    • High redundancy included with increased production availability
    • Low amount of spares required or on-line spares concept
    • Extremely high scalability (just by adding modules increases overall furnace power)
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