The HV and LV winding is wound around the central limb. The central limb carries the entire flux (Ф ). The flux (Ф ) divides into two equal part and thus each side limbs carries the half (Ф/2 ) of the total flux(Ф ). As a result, cross section area of the central limb is two times of the side limbs area.The arrangement of the winding around the central limb is as given below.
The transformer can be categorized into core type and the shell type.In a core type transformer the winding encircles the core whereas in a shell type transformer the core encircles the winding. The winding encircles the core of a transformer. The Single phase transformer has two limbs and three phase transformer has three limbs.