Introduction of Electrical Steel -

When a steel core is magnetized and then demagnetized, it absorbs energy (and heats up). Then a loss of power is happened. Electrical steels are designed to reduce this power loss. Electrical steels are also designed to have a high permeability. This means that the electrical current needed to produce the magnetism should be as low as possible.

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Electrical steel, also called lamination steel, silicon electrical steel, silicon steel, relay steel or transformer steel, is specialty steel tailored to produce certain magnetic properties, such as a small hysteresis area and high permeability.Electrical steel is an iron alloy which may have from zero to 6.5% silicon (Si: 5Fe). Commercial alloys usually have silicon content up to 3.2% (higher concentrations usually provoke brittleness during cold rolling). Manganese and aluminum can be added up to 0.5%

The material is usually manufactured in the form of cold-rolled strips less than 2 mm thick. These strips are called laminations when stacked together to form a core. Electrical Steels are normally supplied in coils. Coils can be ordered slit to a width used most economically by the fabricator.  Many fabricators have their own slitting or shearing equipment where volume warrants. This reduces the amount and variety of stock that must be carried in inventory.

Magnetic cores for the wide range of modern electrical and electronic devices require magnetic materials with many combinations of properties and characteristics. Of all the soft magnetic core materials, the most widely used are known as electrical steels.

The purpose of this manual is to present only practical information that can be helpful in the selection and use of electrical steels. Major attention is focused on those that are used in wound or stacked magnetic cores for transformers, motors and allied apparatus operating primarily at 50 / 60 Hz.

Below Table lists the complete range of electrical steels. 

For uniformity in specifying, producing, and purchasing, electrical Steels are primarily graded by core loss. This is because maximum permissible core loss usually is one of the most important considerations for cores of power frequency apparatus and for some electronic devices. Each electrical steel producer has an identifying trade name for each grade. This resulted in confusion for many years until the American Iron and Steel Institute (AISI) assigned a type number to each grade according to its core loss.

ASTM and International Standardizing Groups have other systems of identification. Core loss is the electrical power expended in the form of heat within the core of electrical equipment when those cores are subjected to alternating magnetizing force. This, of course, is incidental to the production of the desired magnetic flux. According to classic magnetic theory, core loss is considered to be composed of several types of loss. These are hysteresis loss, eddy current loss within individual laminations, and inter laminar losses that may arise if laminations are not sufficiently insulated from one another. Core loss and each of its elements are discussed more completely in subsequent sections.

Energy turnaround: electrical steel as a core component

In the energy sector, particular attention is currently being paid to a material that has been established for a long time, but whose potential is only really coming to fruition against the backdrop of the energy turnaround: high-alloyed electrical steel. The high-tech material, which is manufactured in a complex production process, shows its strengths, among other things, in areas where rotational movements are efficiently converted into electrical energy or energy has to be transformed from one voltage to another with low losses.

"Without electrical steel, a transformation of the energy infrastructure is not feasible. It is the key material for core components of the energy transition such as wind turbines generators and transformers. Electric mobility will not work without electrical steel either, because it is needed for every electric vehicle and in every charging station," agree Angelo di Martino, CEO of thyssenkrupp Electrical Steel, and Georgios Giovanakis, Head of Sales. At thyssenkrupp Steel, they are responsible for the two electrical steel divisions: grain-oriented and non-grain-oriented.

thyssenkrupp Electrical Steel, as an international premium manufacturer of grain-oriented powercore® electrical steel products and one of the leading suppliers in Europe, mainly serves the transformer sector. The Sales Automotive unit, on the other hand, with its non-grain-oriented powercore® brand gets wind turbine generators moving, for example, and brings electric mobility up to speed with its powercore® Traction products. Di Martino continues: "With our high-tech powercore® electrical steels, we are helping to meet the increasing ecological demands in transformer construction. The material enables high efficiencies that help our customers meet the demanding efficiency targets of the EU Ecodesign Directive, helping to reduce global energy demand and associated CO2 emissions."

With our high-tech powercore® electrical steels, we are helping to meet the increasing ecological demands in transformer construction.

Angelo di Martino, CEO thyssenkrupp Electrical Steel

Fresh wind: electrical steel provides green electricity

In developing these key materials needed for the energy and mobility revolution, thyssenkrupp Steel relies on intensive customer cooperation. Giovanakis: "We are continuously researching and developing further solutions to accompany the increasing demands of the energy and mobility industry. Cooperations in the field of research and development for innovative products are a matter of course for us. In doing so, we place great value on long-term partnerships."

To see how successful practical projects emerge from such development partnerships, it is worth taking a look at Aurich. Just as Berlin is the political epicenter of Germany and Frankfurt am Main enjoys a reputation as a financial metropolis, the small northern German town, an hour and a half's drive from Bremen, is the unofficial capital of wind energy. Not only because of the stiff breeze that blows here about 30 kilometers away from the Wadden Sea and the East Frisian Islands. But above all because Enercon has its headquarters here. Germany's biggest wind turbine manufacturer has been using non-grain-oriented electrical steel from thyssenkrupp Steel for many years.

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Since our beginnings, we have relied on high-quality non-grain-oriented powercore® electrical steel from thyssenkrupp Steel for our generators.

Ralf Mühlenbrock, Senior Component Head Generator at Enercon Production

For the Enercon engineers, the electrical steel from Bochum is a core component in several respects: they use the material not only to generate electricity, but also across the entire energy value chain thanks to Enercon's versatile product portfolio. Right through to the consumption of energy in electric motors and devices. Depending on the electrical steel grade used, powercore® can achieve high efficiency there. "The performance of the generators and thus the efficiency of the entire wind turbine (WT) depends to a large extent on the material properties," explains Thomas Sube, Key Account Manager for non-grain-oriented electrical steel at thyssenkrupp Steel.

Electrical steel: tailor-made for customer requirements

Enercon, as one of the world's market leaders with over 31,600 wind turbines installed, has individual requirements for the material; for this reason, thyssenkrupp Steel adapted the properties and composition of the electrical steel especially for the wind turbine manufacturer. For example, through a special alloy that ensures better conductivity and good punchability.

These material properties are necessary because Enercon combines important manufacturing steps. For example, the company cooperates with a foundry in the district of Aurich, where rotor hubs, machinery frames and blade adapters are produced. The special feature: just under half of the material used is steel scrap from the company's own generator production. The chads from electrical steel are collected, melted down and recycled – this is only possible thanks to the tailored material from thyssenkrupp Steel.

Ultranet reduces the strain on the supply system

The energy turnaround is also being driven forward in North Rhine-Westphalia. For example, by the grid operator Amprion, which is expanding its extra-high voltage grid for the current transformation of the energy system. Among other things, the company is responsible for transporting the green electricity generated by wind or solar power in northern Germany to the major consumer centers in southern and western Germany. An expansion of the electricity infrastructure is essential for this – after all, the share of renewable energies in gross electricity consumption is to rise to at least 80 percent by . At least, that's what the amendment to German Renewable Energy Act (EEG) envisages. That's why Amprion and its project partner TransnetBW are currently planning and constructing the so-called Ultranet, a 340 kilometer-long electricity highway. It stretches from Osterath in North Rhine-Westphalia to Philippsburg in Baden-Württemberg and, as things stand at present, will come on stream in . According to Amprion, the total cost of the mammoth project is around 1.7 billion euros.

Like a bypass, the new connection is intended to route the wind energy arriving from the north to the south past the grid in the Rhineland, which is already fully exploited today. And in a technically new way for Germany. To understand this, you need to know: Electric current can be transported by two different methods: as alternating current or direct current. Until now, alternating current, in which the polarity changes constantly, has been considered the European standard. Against the backdrop of the energy turnaround, however, high-voltage direct-current (HVDC) transmission lines, which have lower losses for long-distance transport, are gaining in importance. Ultranet will soon enable more powerful use of the existing power line because an AC circuit on the mast can be operated in DC technology in the future.

Only top grades from thyssenkrupp Electrical Steel are used for the Ultranet transformers

Mike König, Siemens Energy

In order for green offshore electricity to be used by consumers in Baden-Württemberg, it must first be made ready for transport in a converter station in Meerbusch near Düsseldorf before it travels via the HVDC line. Here, at the starting point of the Ultranet, in addition to the work of switchgear and converter modules, the most important thing is the performance of the transformers. During the necessary conversion from alternating to direct current and back again, they ensure the efficient transformation to the higher or lower voltage level that is required in each case – and make it usable again at the end point for the 380-kilovolt alternating current grid of the end consumers.

Transformers need top grades

Twelve high-tech transformers are doing their job in each of the three converter stations required for the Ultranet and its extension called A-North in Meerbusch, Philippsburg and Emden. Each is the size of a normal semi-detached house with three floors: twelve meters high, ten meters long, weighing 280 metric tons. The giant apparatuses are manufactured by Siemens Energy, a world leader in energy technology and one of only three global suppliers of direct current technology. Grain-oriented electrical steel plays a key role in the design process, according to commodity manager Mike König. For the central component of the machine, the transformer core, a material is needed that reduces energy losses to a minimum.

"Only top grades from thyssenkrupp Electrical Steel are used for the Ultranet transformers," says König. These are hair-thin iron-silicon alloy electrical steel strips, often no thicker than 0.23 millimeters. They are already partly made of bluemint® powercore®, a reduced-CO2 and thus more climate-friendly material that helps to noticeably reduce the ecological footprint of transformer production at Siemens Energy. Thanks to the innovative high-tech plates, the transformers used for the Ultranet achieve an efficiency of around 99 percent under full load. König: "This means that our systems not only meet the highest standards of energy efficiency, but also fulfill the recently further tightened requirements of the EU Ecodesign Directive." Marcel Hilgers, Sales Manager at thyssenkrupp Electrical Steel, knows the savings potential that can be realized through the successive modernization of transformers in Europe with the help of electrical steel: "The EU hopes the stricter requirements for transformers will save about 16 terawatt hours annually by . This is roughly equivalent to half the electricity consumption of Denmark.

Electric mobility is the future

The advancing energy turnaround is not only changing the energy system itself, but also the use and application fields of energy in general. A serious change can already be observed in the area of mobility: Among other things, the EU Commission is demanding that only zero-emission vehicles be sold from onwards. It fits into the picture that Germany has joined the Zero-Emission Vehicle Alliance (ZEV) as part of its adapted climate policy. This international alliance, which includes the United Kingdom and the Netherlands, among others, aims to accelerate the global switch to zero-emission vehicles. By , there should only be zero-emission passenger cars. Consequently, the automotive industry is also working at full speed on new vehicles and technologies, the operation of which should no longer be dependent on fossil fuels. Instead, manufacturers are focusing on the direct use of electricity through battery-electric drives – and are increasingly striking a chord with customers. Germany already represents the largest market for electric cars in Europe.

Steel from thyssenkrupp Steel is an indispensable part of this development. Numerous renowned brand manufacturers rely on this versatile material in every respect for the development and design of contemporary automotive solutions. For example, there are already CO2-neutral vehicle models on the market, the steel content of which, including doors and hood, is well over 90 percent.However, steel plays a very important role not only in the body, but also in the heart of the electric vehicle – the electric motor. And again, it is electrical steel products that pave the way to the future.

Non-grain oriented electrical steel powercore® and powercore® Traction are our contribution to greater energy efficiency, renewable energy generation and sustainable mobility on rail and road.

Georgios Giovanakis, Head of Sales, thyssenkrupp Steel

This would not be possible without constant research and development work. Frank Bosch: "We operate our own motor test bench in our Application Technology department, where we test our powercore® Traction grades in the various motor types. This enables us to provide our customers with the best possible advice on selecting the right grade depending on the specific requirements." How well this functions is shown not least by the success with end customers. In the past year, the number of new registrations of battery-powered electric cars in the EU increased significantly compared with the previous year: from 539,000 to 878,000 vehicles. A trend that is continuing: As reported by the Association of European Automobile Manufacturers (ACEA), registered all-electric vehicles accounted for just under 10 percent of total registrations in the second quarter of . This is a significant jump compared with the same period of the previous year. And who knows: perhaps some models will soon be charged with green offshore electricity from the Ultranet?