19 July 2019

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.
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