Rectifier Systems for aluminum smelting process

Heavy-duty rectifier systems for the primary aluminum smelting process.

Where aluminum is extracted from aluminum oxide by electrolysis.


The typical DC current in aluminum smelting is in the range of 80kA to 120kA for each rectifier unit. More units are paralleled to supply the potline’s DC current that is typically in the range of 200kA to 600kA.

FRIEM developed a comprehensive line of power rectifiers for aluminum smelters including:

  • Loop rectifiers (typically in the range of 50kA to 100kA) to compensate the magnetic field generated by the potline’s current;
  • booster rectifiers (typically in the range of 30kA to 60kA) to enable pots developments;
  • swing units (typically in the range of 80kA to 120kA) connected between two potlines of which only one is in operation.


Aluminum electrolysis is among the most energy-intensive industrial processes.
To enhance productivity and continuity of supply, FRIEM supplies rectifier units with the highest level of efficiency and reliability, achieved through continuous improvements and technological development.

Highest level of robustness, reliability, efficiency and longest lifespan

Both in indoor and outdoor installation.

FRIEM’s holds a unique experience and know-how in power electronics, which are essential to support Customers in defining the most effective layout and topology of the power supply aiming at optimizing initial investment’s cost and maximizing production:

  • safer operation of the rectifier thanks to the diode-fuse coordination achieved through calculation and tests;
  • proved design with regulating transformer, OLTC, saturable reactors and diode rectifiers or thyristor rectifier units
  • reduced water consumption by means of oil-to-air cooled transformers and demineralized water-to-air cooled rectifiers.



MOBILITY Knowledge into efficiency


Knowledge into efficiency

SERVICE A partner to our Customer


A partner to our Customer

ENERGY Working now for the future


Working now for the future