Metals producers are under pressure to improve efficiency and cut emissions, making electrification their top priority. However, designing a power supply that satisfies local grid requirements and delivers a strong, consistent current – as required by DC electric arc furnaces (EAFs) used in steel production and aluminium smelting lines – takes electrical domain experience, full life cycle system support and a high-power rectifier (HPR).  

These requirements also extend to the broader value chain when manufacturers are considering the production of green hydrogen for processing of iron ore into iron, and graphitization of carbon electrodes for use in electric arc furnaces. 

Rectifiers use semiconductor devices to convert alternating current (AC) from the grid into stable, direct current (DC) needed to operate sensitive and/or continuously operating equipment. High-current environments must also meet stringent requirements to ensure mechanical integrity as well as the subsequent design production circuits and appropriate cooling.  

Broadly speaking, rectifiers use one of two technologies. Diode rectifiers deliver dependable high-current DC power when process conditions are stable, while thyristor technologies unlock more dynamic control of voltage and current.  

Thyristor rectifiers allow instant reaction to load variations making them indispensable for consistent high-quality steel production in DC EAFs. ABB’s reliable thyristor control has also set a standard for thyristor rectifiers in aluminium production, ensuring maximum performance even in case of dynamic load changes or grid fluctuations. Precise voltage and current control helps reduce energy losses and mechanical equipment failures, supporting cost-efficient and consistent steel and aluminium production. 

“ABB provides complete electrification systems to enable metals manufacturers to operate and optimally utilize their process equipment in both greenfield and brownfield projects,” says Ralph Burgener, Business Unit Manager for High-Power Rectifiers at ABB. 

The word “systems” is key, because the rectifier, by definition, doesn't stand alone but forms the bridge between locally available grids or power plants and the customers’ production processes. It must be scaled in its capacity to suit different facilities, and integrated to meet specific needs.

Greenfields for steel and aluminium 

As an industry partner in future proofing metals through advanced power conversion, ABB’s contribution to greenfield projects that will run on electricity, begins at the design stage.

Burgener, who has applied his passion for electrical engineering and innovation in HPR system design for the past 25 years at ABB, says, “One of our strengths is to deliver complete turnkey projects to the global market”. 

The ABB HPR business boasts 200 employees, distributed worldwide in production facilities and Local Engineering Centers, in Europe, China, the Americas, South Africa, Australia and India, to support customers in each region.

An aluminium customer in Iceland might contact Burgener with the intention to build a new “pot line”, which is a series of electrolytic cells in which electricity is used to draw pure aluminium out of an aluminium-oxide solution. The customer’s questions might be around the electrical equipment design: whether to run five or six rectifier units in parallel to feed the pot line; what safety measures they need to consider; and how much redundancy they should include at both system and device level, to compensate for outages.  

“We design the complete system, specifying all the equipment including the critical transformers; do the manufacturing; carry out testing, including FAT (Factory Acceptance Test) of the rectifiers; and ship all components and materials to site, where we carry out installation and commissioning,” says Burgener. Part of the service, he adds, is that “We work with the customer to ensure they make the best choices in overall system design for their specific use case.”

Where safety and domain expertise couNt the most

For brownfield projects, where operating steel or aluminium plants require control upgrades, incident mitigation, spare parts or the replacement of a high-power rectifier – whether ABB or a competitor’s product – ABB can provide comprehensive support.  

“The skills and safety knowledge required during installation and commissioning of brownfield projects compared to greenfield projects”, Burgener explains, “are next level due to the operational nature of existing plants.”  

A recent upgrade for a steel manufacturer in the Middle East, for example, involved replacement of the static VAR compensator (SVC) – dedicated power electronics equipment, often required to facilitate the connection of very large industrial energy loads to the electricity grid, which is an extremely complex procedure. In this case, the factors successfully overcome by the ABB team included limited workspace, interfaces to old equipment, and extremely hot desert site conditions. 

 “There can be many additional challenges on a brownfield project,” says Burgener, “potentially including ‘live welding’ of busbars when connecting a new rectifier while a plant is running. But this is exactly one of ABB’s biggest strengths – understanding the whole system, not just one product.” 

He adds that asset support often extends well past the warranty period, and even the expected lifecycle of the rectifier. “When customers invest in high‑power rectifier infrastructure, they typically consider a planning horizon of about two decades. With proper maintenance, ABB systems have consistently demonstrated the ability to operate far beyond this, as shown by units from the 1970s still running reliably today.” 

Longevity can depend on climatic conditions, how the rectifier is housed, and the customer’s maintenance regimen. Among the ABB rectifier upgrades available is a digital preventive and ​predictive maintenance solution.

“We strive to differentiate ourselves in terms of technology, in terms of system design, and in terms of plant safety,” emphasizes Burgener.

Working with customers at the frontiers of high-power rectifier application 

ABB’s rectifier systems are bespoke – made to suit each individual use case. The company’s experience in this area has repeatedly made it possible to push the boundaries of existing technology in close partnership with its customers and thereby enable projects that have never before been envisaged. For example, Burgener says, “We recently supported a customer in construction and integration of the highest rated power thyristor rectifier ever built.” 

In the second quarter of 2025, ABB also announced its investment and partnership with Arctial, in assessing the feasibility for electrification and automation of the Arctial low-carbon aluminium smelter proposed for a site on the west coast of Finland. The project team behind the first new primary aluminium plant mooted in continental Europe in 30 years anticipates using low-carbon energy from renewable generators, both new and existing. 

Burgener explains, “This project is set to play a critical role in strengthening Europe’s materials supply chain, at a time when demand for sustainable aluminium is on the rise.” 

From enabling efficient conversion and use of power in steel and aluminium production, to its own greenhouse gas emissions target of net zero throughout its value chain by 2050, ABB is committed to enabling a low-carbon society. 

“If you look at the broader picture,” says Burgener, “our biggest sustainability contribution is that we're engaged in enabling industry to run productively and efficiently on electric energy, which means the source can be renewable. We are fundamentally enabling the renewable energy transition.”