Difference between core type and shell type transformer

One of the biggest distinctions between the core type and the shell type transformer is that the winding encircles the more in a core type, whereas the core encircles the winding of the transformer in a shell type transformer. Now let us check some key points for both of the transformers.

Core type transformer :

  • It has one yoke and two limbs
  • Both the limbs are provided with winding and the core is surrounded by windings.
  • Winding is less protected by the core
  • Leakage flux is more than power transfer less capability
  • Series magnetic circuit
  • Both limbs have the same cross-sectional area
  • More amount of copper is required for winding
  • Required less amount of insulating material
  • Used high-voltage power transmission applications
  • High voltage, small KVA rating transformers are suitable
  • Easy to repair
  • Better cooling because more surface is exposed to the atmosphere

Shell type transformer :

  • It has three limbs and two yokes
  • Only the middle limbs are provided with winding and winding ar being surrounded by a core
  • More protected by the core
  • Leakage flux is less
  • Parallel magnetic circuit
  • The different cross-sectional area
  • Amount of chopper required for winding is less
  • Not easy to repair
  • Cooling is not very efficient 

The key difference between core-type and shell-type transformers are given below.

  • The core surrounds the winding in a core-type transformer, whereas the winding surrounds the core of the transformer in a shell-type transformer.
  • The core-type transformer has two limbs, and the shell-type transformer has three limbs.
  • The lamination is cut in the form of L in the core-type transformer while the lamination is cut in the form of E and L in the shell-type transformer.
  • The core-type transformer required less insulation compared to the shell type transformer.
  • The mechanical strength of the core-type transformer is low compared to the shell-type transformer.
  • The output of the core-type transformer is less as compared to the shell-type transformer because it has more losses.
  • There are two magnetic circuits in the core type transformer, whereas one magnetic circuit in the shell type transformer.
  • The losses in a transformer of core type are more compared to the transformer of shell type.
  • In a core-type transformer, less winding is removed for maintenance, in a shell-type transformer number of the winding are required to remove for maintenance.
  • The winding of the shell type transformer is distributed type and hence heat is dissipated naturally, whereas in core type transformer the natural cooling is not possible.
  • In core-type transformers, both the primary and secondary windings are placed on the side limbs whereas the winding is placed on the central limbs of the transformer in shell-type transformers.
  • There are two magnetic circuits in the core type transformer, whereas one magnetic circuit in the shell type transformer.
  • The core type transformer cross-section area is rectangular, whereas the shell type transformer cross-section area is square, cross-sectional two bent, or three bent in shape.