Difference Between Core Type and Shell Type Transformer

Hello, friends, I hope you all are doing great. In today’s tutorial, we will discuss the Difference Between Core Type and Shell Type Transformer. The basic difference core and shell-type transformer are that in core type transformer winding is wounded on the core and in shell type transformer core cover the windings mean core encircles the winding.

In today’s post, we will have a detailed look at both core and shell types of transformer do comparison between them to find their differences. So let’s get started with Difference Between Core Type and Shell Type Transformer.

Difference Between Core Type and Shell Type Transformer

Core Type Transformer

• In this type of transformer windings are covered on the core of transformer.
• The lamination used in this transformer is cut in the shape of the letter L.

• The cross-section of this transformer is square, cruciform and three stepped.
• In this transformer for winding large copper is needed than the shell type transformer.
• The winding used in this transformer is concentric or Cylindrical.
• There are 2 limbs exits in this transformer.
• This transformer needed more insulation than the shell type transformer.
• The quantity of flux is equal at both limbs of transformer.
• There are 2 magnetic circuit exits in this transformer.
• There are more power losses in this transformer than the shell type.
• Its maintenance is easy than the shell type transformer.
• The mechanical strength of this transformer is less than the shell type transformer.
• Its output is less than the shell type transformer.
• In this transformer, there is no existence of a natural colling process.

Shell Type Transformer

• In this transformer is core is at the outer side and the windings is at the inner side.
• The E and L shape lamination is used in this transformer.
• The rectangular cross-sectional area is used in this transformer.
• It needed less copper than the core type transformer.
• The winding used in this transformer also called a sandwich or Disc Winding.
• There are 3 limbs exits in this transformer.
• It required less insulation than the core type of transformer.
• There is an unequal distribution of flux in this transformer the hole flux passes in the central limb and half flux carried by the side limbs.
• The primary and secondary windings are inserted at the central limb of the transformer.
• There are one magnetic circuit exits in this transformer.
• There are less power losses occurs in this transformer than the core type transformer.
• Its maintenance is difficult as compared to the core transformer.
• The mechanical strength of this transformer is larger than the core transformer.
• Its generated output is larger than the core transformer.
• In this transformer natural colling exits.

What is Core Type Transformer

• For the construction of a rectangular frame for transformer magnetic core is created with the laminations. The physical structure of laminations is L-shaped as shown below figure.
• To minimize the large value of reluctance at connections where laminations are connected with each other the alternate layers are placed at different positions for the reduction of continuous joints.
• For reduction of leakage flux primary and secondary windings are interleaved.

• Half part of the winding is positioned concentrically on the limbs of core you can see it in the below figure.
• To make a simple structure primary and secondary windings are placed at different limbs.
• The layer of insulation material is placed among the core and lower winding and among the primary and secondary winding.
• To reduce the insulation the lower windings is located close to the core. The structure of winding is cylindrical and lamination is placed after it.

What is Shell Type Transformer

• The laminations used in this transformer are cut in the shape of letter E and I you can see in the below figure.
• To decrease the large value of reluctance at points where laminations have common points the alternate layers are positioned to minimize the regular joints.
• There are 3 limbs exits in this transformer. Through mid limb complete flux flows and through other limbs half flux passes.
• For this purpose, the width of a mid limb is two times the widths of the other 2 limbs.
• Both primary and secondary windings are positioned at the mid limb. For reduction the insulation cost less voltage winding is positioned at the close to the core and high voltage windings is positioned at over the less voltage winding.
• The shape of windings are cylindrical and laminations are placed on it.

Comparison between Core and Shell Type Transformer

• The core transformer has assembly winding such that core is the outer side of windings and in shell type transformer windings is at outside of the core.
• The physical structure of lamination for core transformer is L shaped and for shell type is E and L.
• The cross-sectional area of core type transformer is like a rectangle and the shell-type transformer has a cross-sectional area like the square, cruciform 2 slipped, or 3 stepped.
• The conductor needed for the core type transformer is larger than the shell type transformer since winding is inserted at the different legs.

• Due to concentric windings arrangments, the core type transformer is also called cylindrical. While in shell transformer less voltage and high voltage windings are arranged like a sandwich so it called sandwich transformer.
• There are 2 limbs exits in the core transformer and 3 in the shell transformer.
• The mechanical strength of the shell-type transformer is larger than the core type transformer since shell uses bracings.
• Due to 3 limbs, more insulation is needed in the shell type transformer than the core.
• In core transformer flux is equal at both limbs and shell-type transformer net flux is exited across the mid limb and half at outer limbs.
• At side legs, primary and secondary windings are located in core transformer while in shell type transformer windings are located at the mid limb.
• In shell-type transformer single magnetic circuit exits while in core transformer 2 exits.
• Due to 2 magnetic circuits power losses in the core, the transformer is larger than the shell.

So, friends, it is a detailed post about the difference between core type and shell-type transformer. If you have any query ask in comments. thanks for reading. have a good day.