The iron core of transformer
Iron core is the main part of magnetic circuit in transformer. It usually made of hot-rolled or cold rolled silicon steel sheets with high silicon and insulating paint on the surface. The iron core is made of silicon steel what is a kind of magnetic substance with strong magnetic conductivity that produce great magnetic induction … Continue reading The iron core of transformer
Iron core is the main part of magnetic circuit in transformer. It usually made of hot-rolled or cold rolled silicon steel sheets with high silicon and insulating paint on the surface. The iron core is made of silicon steel what is a kind of magnetic substance with strong magnetic conductivity that produce great magnetic induction intensity to shrink the size of transformer in the electric coil. The iron core and coils form into a complete electromagnetic induction system. The power transmitted depends on the material and cross-sectional area of the core.
The part of the winding in the core is called core column,and the part without the winding that only plays the role of magnetic circuit is called iron yoke. What the core surrounds with winding is called shell type. What the winding surround with core column is called core type.Shell type and core type have their own characteristics. The transformer manufacturing process determined by the different iron core.
The actual transformer always works in the ac state, and the power loss is not only in the resistance of the coil, but also in the core magnetized by the alternating current.The power loss in the core is usually called “iron loss” which is caused by two reasons. “Hysteresis loss” and “eddy current loss”.Hysteresis loss is the iron loss caused by hysteresis during the magnetization of iron core.The hysteresis loss of the core of silicon steel is small because of its narrow hysteresis loop.This is because the sheet core reduces another type of iron loss, called eddy current loss.When a transformer works, there is an alternating current in the coil, which produces an alternating flux of course.This changing flux creates an induced current in the core.The induced current in the core circulates in a plane perpendicular to the direction of flux, so it is called eddy current. Eddy current loss also heats the core. In order to reduce eddy current loss, the core of transformer is made of silicon steel pieces insulated from each other, so that the eddy current passes through a small section in a narrow and long circuit to increase the resistance in the eddy current path. At the same time, the silicon in the silicon steel increases the resistivity of the material and also reduces the eddy current.