Transformers are classified in two general subdivisions according to the winding arrangement. The subdivisions are core type transformer and shell type transformer. Some important differences in between the above said types are discussed as follows.
In core type transformer, each and every limb is occupied with both primary and secondary winding. Half part of the primary winding and half part of the secondary winding are placed successively around each limb. On the other hand in shell type transformer, the main frame is constructed with three limbs. Both the primary and secondary winding are wound around the central limb.
In core type transformer no additional limb is used as flux flow path but in shell type transformer two limbs are used as low-reluctance flux path. The core type transformer is generally more suitable for high voltage whereas the shell-type is generally more suitable for low voltage.