Sähköteräs

Sähköteräs, also known as electrical steel or silicon steel, is a ferrous alloy that has been specifically engineered for use in electrical applications, particularly in magnetic cores of transformers, motors, and generators. Its key characteristic is its low core loss, which is achieved by adding silicon to the steel and carefully controlling its grain structure. The addition of silicon increases the electrical resistivity of the steel, thereby reducing eddy currents, a major source of energy loss in AC electrical equipment.

The manufacturing process for sähköteräs involves a series of hot and cold rolling steps, annealing treatments, and often a final passivation process to create a thin insulating oxide layer on the surface of each sheet. This layer, known as a micalex coating or a similar insulating coating, further helps to reduce eddy current losses by preventing current flow between adjacent laminations.

There are two main types of sähköteräs: grain-oriented (GO) and non-grain-oriented (NGO). Grain-oriented steel is processed in a way that aligns the crystal grains in the rolling direction, significantly enhancing its magnetic properties in that specific direction. This makes it ideal for transformer cores where the magnetic flux is primarily in one direction. Non-grain-oriented steel has a more random grain structure, making its magnetic properties more uniform in all directions. It is commonly used in motors and generators. The performance of sähköteräs is typically characterized by its magnetic flux density, core loss values, and permeability.