Types of Transformer

 

Depending upon the type of construction of transformer are classified into two types:-

1.     Core-type transformer

2.     Shell-type transformer

Core Type transformer:-

In core type transformer, the coils are wound around the two limbs of a rectangular magnetic core. Each limb carries one half of the primary winding and one half of the secondary winding so as to reduce leakage reactance. The LV winding is wound on the inside nearer to the core while HV winding over the LV winding away from the core in order to reduce the amount of insulation material is required

          

                                                                                                                            

NOTE:-

HV winding= High voltage winding

LV winding= Low voltage winding

Shell type transformer:-

In shell type transformer, the coils are wound on the central limb of a three limb core. The entire flux  passes through the central limb consequently, the cross-sectional area of the central limb is twice of that of each of the side limbs.

             .                                                                                                                                                                                                                                                                                                                                                                                                                          HV winding

                                                                                                               
                                                                                                                                                                                                                                                                                                                                                                                                     Fig:- Shell type transformer

Difference between core type and shell type transformer:-

Core type transformer	Shell type transformer
1.     The windings surround the core	1.The core sorrounds the windings.
2.     There are two limbs.	2.There are three limbs.
3.     The flux is equally distributed in both limbs.	3.The central limb carry the whole flux and side limbs carries the half of the flux.
4.     Losses is more.	4.Losses is less.
5.     It is used for power and distribution transformer	5.It is used for small transformer.