The Duferco Travi e Profilati steel mill in San Zeno Naviglio in northern Italy is the Duferco Group's largest plant. It has an area of about 491,860 m² and a production capacity of about 950,000 tons per year of steel for the steel mill and 700,000 tons for the rolling mill.
The steel mill has an electric furnace, two refining furnaces - including a twin furnace capable of simultaneously processing two steel castings - a degassing plant, two continuous casting lines, and a water treatment facility.
The primary processing occurs in the large electric arc furnace, which heats materials such as scrap metal, cast iron, or graphite to very high temperatures through an electric arc created between electrodes and the material to be melted. This process requires a significant amount of electricity, supplied through a medium-voltage substation, to generate the heat necessary for melting the materials.
The arc is generated several times during the melting process, requiring that the circuit breaker that controls the ignition to perform more than 30,000 operations annually. Therefore, it’s crucial that the medium-voltage circuit breaker can handle a high number of operations reliably. To meet this need, Duferco steel mill selected the VD4-AF1 circuit breaker, designed to ensure safe and reliable operation in arc furnaces.
One of the main advantages of the VD4-AF1 circuit breaker is its significant reduction in operating costs. With its long service life and reduced downtime, operating costs can be substantially lowered. Additionally, the VD4-AF1 features advanced diagnostics functionality that prevents misuse, ensuring safe and reliable operation with performance 5-10 times better than standard solutions, offering enhanced protection and increased efficiency.
The circuit breaker uses vacuum technology to provide a high-quality, reliable solution. For contact closing operation it employs an advanced actuator system based on servomotors controlled by electronics.
The VD4-AF1 circuit breaker is designed for safe and reliable operation in arc furnaces 
The VD4-AF1 is available in a fixed version for applications with voltage rating up to 40 kV, current rating up to 3150 A and breaking capacity up to 31.5 kA 
Several ABB VD4 circuit breakers are also installed for medium-voltage distribution within the steel mill 
The Duferco Travi e Profilati steel mill in San Zeno Naviglio in northern Italy is the Duferco Group's largest plant
This specialized circuit breaker achieves synchronized switching through a dedicated voltage sensor, which reduces inrush currents when switching inductive loads, thereby reducing stress on the transformer, which extends the average life of the transformer by about 10%.
Thanks to its advanced technology, this circuit breaker has an exceptional operational life, capable of up to 150,000 maintenance-free close-open mechanical operations.
Available in a fixed version for applications with voltage rating up to 40 kV, current rating up to 3150 A and breaking capacity up to 31.5 kA, the VD4-AF1 is an efficient and reliable solution for improving productivity and reducing operating costs in arc furnace application.
In addition to this specialized version, several ABB VD4 circuit breakers are also installed for medium- voltage distribution within the steel mill. These circuit breakers are renowned for their reliability, safety, and high performance. With over 2 million units installed globally, they set the market standard.
“For our production we need an efficient electricity distribution network and for this reason we are constantly committed to updating our plants. As regards medium voltage, and in particular for the power supply of the furnaces, we have found a valid partner in ABB. The VD4 AF1 circuit breaker, thanks to the high number of mechanical closing-opening operations, guarantees us greater continuity of service with a consequent reduction in operating costs”, said Walter Romidi, Head of Plant Maintenance at the Duferco Travi e Profilati in San Zeno Naviglio.
The Duferco Group is dedicated to minimizing the environmental impact of its operations. By constantly monitoring environmental performance and continuously improving production efficiency through the adoption of the best available technologies, the company also prioritizes sustainability in its supplier selection process. Duferco’s decision to partner with ABB for key plant components is rooted in the shared commitment to strive for a sustainable future.
