Why Electrical Steel is Essential to Transformer Cores

As the demand for efficient power grids and sustainable energy solutions increases, the need for advanced transformers, generators, and motors continues to grow. Electrical steel is essential to transformer cores, serving as the backbone of modern electromagnetic machinery. This comprehensive guide covers the importance of selecting high-quality electrical steel essential to transformer cores, its various applications, and why it is indispensable for achieving energy-efficient transformer cores.
Understanding Electrical Steel
Electrical steel, typically containing up to 6.5% silicon, is engineered to increase electrical resistivity and minimize eddy currents. Furthermore, the reduced currents of electrical steel improves the efficiency of transformers, generators, and other electromagnetic machinery.
Grain-oriented electrical steel enhances magnetic permeability by aligning the crystal grains in a specific direction. This process allows for a higher magnetic flux with less input current. This increases the overall performance of the device.
Manufacturers produce electrical steel by cutting it into thin sheets or strips, known as laminations. Next, these laminations are coated to prevent inter-laminar eddy currents. They are then stacked to form the transformer core, with grain orientation precisely matched to the direction of the magnetic flux for optimal efficiency.
Composition of Electrical Steels
Electrical steel is an iron-silicon alloy, with silicon being key for electrical resistance, reducing eddy currents and core loss. In fact, manganese and aluminum are also added to enhance properties.
Material purity is critical, as impurities like sulfur, oxides, nitrides, and carbides lower magnetic permeability and diminish core efficiency over time. To address this, transformer core manufacturers use annealing furnaces to remove these contaminants, ensuring optimal performance.
What Are the Types of Electrical Steel?
- Grain-Oriented Electrical Steel
Grain-oriented electrical steel (GOES) is an iron-silicon alloy designed to provide high permeability and low core loss, making it a type of electrical steel essential to transformer cores. During the manufacturing process of GOES, the material is treated to achieve optimal magnetic properties in the direction of its rolling. The magnetic flux density of grain-oriented material raises by 30% in the rolling direction, but its magnetic saturation somewhat decreases. Therefore, GOES is commonly used in high-efficiency generators, transformers, and motors.
- Non-Grain-Oriented Steel
Non-grain-oriented steel, in contrast, does not undergo cold-rolling to control its crystal orientation. Typically containing 2 to 3.5% silicon, it offers consistent magnetic properties in all directions. While less efficient than GOES, its lower production cost makes it ideal for motors and other applications where cost reduction is more important than maximizing efficiency.
Why Choose Electrical Steel?

- High efficiency — Electrical steel minimizes energy losses from eddy currents and hysteresis, leading to improved efficiency in electrical machines. With electrical steel essential to transformer cores, its low core loss ensures that more energy is converted into practical work rather than wasted as heat.
- High performance — It can produce a stronger magnetic field with less input current. This improves the performance of electrical machines, such as the torque and speed of electric motors, the output voltage and power of generators, and the voltage regulation and power transfer of transformers.
- High reliability — Electrical steel’s higher saturation flux density allows it to handle greater currents and voltages without losing magnetic performance. Its thermal stability ensures that magnetic properties remain intact, even in harsh conditions, making it a reliable and durable material for demanding applications.
What are the Applications and Uses of Electrical Steel?
Electrical steel, engineered for specific magnetic properties, is primarily used in the production of electric vehicles, generators, and transformers. Its ability to minimize energy losses and enhance magnetic performance makes it essential for these technologies.
- Electric Vehicles
Electric vehicles rely on electrical steel to convert electrical energy into mechanical energy, powering motors and other components.

The stator (the non-moving part with windings or coils) and the rotor (the moving part with magnets or an armature) are both constructed using electrical steel laminations.
Electrical steel reduces energy losses from eddy currents and increases magnetic flux density, leading to higher torque and speed — key performance factors in electric motors.
- Generators
Devices that transform mechanical energy into electrical energy are known as generators. They employ the opposite way of electric motors as they rotate a coil of wire in a magnetic field using a prime mover like a turbine, an engine, or a windmill. This, in turn, induces an electric current in the coil. Manufacturers use electrical steel laminations to make the coil and the magnets, which enhances the magnetic field and increases the generator’s output voltage.
This use of electrical steel that is essential to transformer cores ensures higher efficiency and improved performance in power generation.
- Transformers
Transformers modify voltage and current in an AC power supply using coils of wire wound around a core of electrical steel laminations. When the primary coil receives AC voltage, it generates a fluctuating magnetic field, inducing voltage in the secondary coil. The turn ratio between the coils determines the input-output voltage relationship.
Corefficient’s Commitment to Excellence
Corefficient is dedicated to advancing the production of electrical steel essential to transformer cores. Utilizing state-of-the-art technology and rigorous testing methods, Corefficient ensures that its metal products meet the highest standards of quality and efficiency. Corefficient operates an on-site quality control laboratory to ensure the integrity of its raw materials. They test core loss, permeability, and dimensions of electrical steel using ASTM methods.
Electrical Steel Material Testing
- Epstein testing: Corefficient routinely tests shipments for core loss and permeability using a Brockhaus MPG 200 system, with standard and custom Epstein frames based on ASTM A717 methods.
- Single sheet testing (SST): Every coil is measured for no-load losses (NLL) and permeability with modern SST equipment.
- Franklin testing: Single strips of flat-rolled electrical steel are tested under specific pressure, voltage, and temperature conditions.
- Dimensional testing: Variations in material thickness and width are assessed using ASTM A971 methods.
Assembled Core Electrical Testing
Using Yokogawa precision power analyzers, Corefficient tests assembled transformer cores to ensure they meet NNL standards. Optional tests for insulation resistance and sound are also available. Detailed reports, curve graphs, and PPAP inspections guarantee products meet exact customer specifications.
With rigorous material testing, Corefficient ensures superior quality in electrical steel and transformer cores. Whether for power grids or EV production, Corefficient provides high-performance, tailored solutions.

About Corefficient
Based in Monterrey, Mexico, Corefficient specializes in designing and producing energy-efficient transformer cores. As a division of Kloeckner Metals and being North America’s leading steel service company with 45 branches across Mexico and the United States, Corefficient focuses on delivering high-quality transformer cores.
With extensive experience in engineering and materials like hot and cold-rolled steel, grain-oriented steel, and electrical steel, Corefficient is recognized for its industry-leading energy-efficient transformer cores and exceptional customer service.
To enhance your energy efficiency, contact Corefficient today. Call their North American sales engineer at 1 (704) 236-2510 or the Monterrey office at (81) 2088-4000, or visit their website to learn more.
Tags
- annealing, astm methods, cold-rolled grain-oriented steel, core loss, dimensional testing, eddy currents, electric motors, electric vehicles, electrical steel, electrical steel laminations, electrical transformer cores, energy-efficient transformer cores, Epstein testing, EV production, franklin testing, generators, grain-oriented electrical steel, magnetic permeability, magnetic properties, NNL standards, non-grain-oriented steel, power grids, PPAP inspections, single sheet testing, SST equipment, transformer core manufacturer, transformer cores, transformers