Relaiskerne

Relaiskerne are the magnetic cores at the heart of electromagnetic relays. They form the magnetic circuit together with the coil and the armature, concentrating the magnetic flux to produce the attractive force that opens or closes the contacts.

Materials and construction: In many power and industrial relays, the core is made from laminated ferromagnetic steel to minimize energy losses due to eddy currents when the coil is energized. For miniature or high-frequency relays, ferrite cores or powdered iron cores may be used to reduce size, weight, and losses and to tailor permeability.

Geometry and function: Cores may take various shapes such as simple bars, U- or E-shaped laminations, pot cores, or ring cores. The choice of shape and the relative air gap govern the magnetic reluctance, the pull-in force, switching speed, and the contact current rating.

Performance considerations: The core material has a saturation flux density, high permeability, and low coercivity; these properties determine how much current is required to operate the relay and how much the performance varies with temperature. Lamination orientation and insulation reduce eddy currents and heating.

Manufacturing and variants: Cores are typically produced by stamping thin laminations, stacking, and assembling around the coil. Some relays use integrated yokes or flux guides to improve flux distribution and reduce leakage, while others employ ferrite or specialized alloys to optimize actuation for specific applications.