Why Are Laminations Used In Constructing The Field Core

Dc motors are constructed with two major parts.

Why are laminations used in constructing the field core.

The laminations of required size and shape are stamped together to get a pole which is then bolted to the yoke. Adding silicon to steel increases its electrical resistance improves the ability of magnetic fields to penetrate it and reduces the steel s hysteresis loss. Following farady s law when the core is rotated in a magnetic field a voltage or emf is induced in the coils. Laminations and core packages are used for small transformers and chokes from mains frequency to several khz.

These individual laminations are tightly butted together during the transformers construction to reduce the reluctance of the air gap at the joints producing. These lamination stampings when connected together form the required core shape. A magnetic core is a piece of magnetic material with a high magnetic permeability used to confine and guide magnetic fields in electrical electromechanical and magnetic devices such as electromagnets transformers electric motors generators inductors magnetic recording heads and magnetic assemblies it is made of ferromagnetic metal such as iron or ferrimagnetic compounds such as ferrites. If non oriented steel was used we would need a certain amount of magnetizing force to establish flux in the core i e.

Lamination is the technique process of manufacturing a material in multiple layers so that the composite material achieves improved strength stability sound insulation appearance or other properties from the use of the differing materials such as plastic a laminate is a permanently assembled object created using heat pressure welding or gluing. The next layer is laid offsetting each layer like a brick or cinder block wall. For example two e stampings plus two end closing i stampings to give an e i core forming one element of a standard shell type transformer core. The magnetizing force should be sufficient to force the domains whose axes are widely divergent from the applied field axis to come into alignment with i e.

This induced emf causes current to flow known as eddy current. To magnetize the core. The rotor and the stator. The rotor has a ring shaped iron core with slots that hold coils or windings.

Standard laminations are described in din en 61021 in a variety of sizes and grades. Silicon steel also known as electrical steel is steel with silicon added to it. They are stamped from a pre material strip of the respective thickness and finished by a consequent annealing process to optimize the magnetic properties. As it requires a definite shape and size laminated construction is used.

1 3 field winding f1 f2 the field winding is wound on the pole core with a definite direction.