Core Type vs Shell Type Transformer: Difference and Comparison

Core-type transformers are more efficient and are used in high-voltage power transmission applications. Shell-type transformers have a magnetic core that surrounds the windings. The core is made up of thin strips of laminated iron or steel, with the windings placed around the outside of the core.

Key Takeaways

1. Core-type transformers have primary and secondary windings wrapped around the core’s limbs, which makes them easier to maintain and repair.
2. Shell-type transformers encase the core around the windings, providing better mechanical strength and reduced magnetic leakage.
3. Core-type transformers are more suitable for lower voltage applications, while shell-type transformers are better for higher voltage applications due to their increased efficiency and compactness.

What is a Core-Type Transformer?

A core-type transformer is an electrical device that accepts an alternating current (AC) input and outputs an alternating current (AC) of a different voltage level. It is the most popular type of transformer widely used in power transmission and appliances to transform mains voltage to low voltage to power electronic devices. They come in a variety of power ratings ranging from mW to MW. The insulated laminations reduce eddy current losses in the iron core.

It is constructed with a core of high-grade steel laminations and two or more windings of insulated wire wrapped around it. It operates on the electromagnetic induction principle, in which a changing magnetic field formed by the input voltage induces a voltage in the output windings.

Power distribution, voltage regulation, industrial equipment, and audio equipment are among the applications for core-type transformers. They are built to withstand greater voltage levels.

What is Shell-Type Transformer?

Shell-type transformers are power transformers built with a single steel frame or shell that houses all the windings and core. The capacity of this type of transformer to enable efficient cooling of the windings and core is its primary advantage. The windings are insulated copper strands arranged in a concentric pattern around the core.

The winding of a shell-type transformer is distributed type so that heat can be naturally dissipated. Maintaining these transformers is complex, and mechanical strength is high.

Power distribution, control, and conversion are all ideal applications for shell-type transformers. It is used in various industries, including telecommunications, utilities, and manufacturing. It also provides power to electrical devices, such as computers, televisions, and radios.

The shell-type transformer’s key advantage is its ability to deliver efficient power transfer. It is also lightweight, making it easy to carry and install, and a good choice for use in regions with limited space because it can be quickly moved around.

Difference Between Core-Type and Shell-Type Transformers

1. In core-type transformers, Cross-section may be square, cruciform, or three-stepped; on the other hand, in Shell-Type transformers, the cross-section is rectangular.
2. The flux is equally distributed on the side limbs of the core in Core-Type Transformers, while in Shell-Type Transformers central limb carries the whole flux, and the side limbs carry half of the flux.
3. The primary & secondary winding is placed on the side limbs in Core-Type Transformers, while in Shell-Type Transformers, the Primary, and secondary windings are placed on the central limb.
4. In core-type transformers, the lamination is cut in the form of the L strips, whereas lamination is cut in the form of the long strips of E and L in Shell-Type Transformers.
5. There are two magnetic circuits in Core-type transformers, while there is only one in Shell-Type Transformers.

Comparison Between Core-Type and Shell-Type Transformers

Parameters of Comparison	Core-Type Transformers	Shell-Type Transformers
Meaning	The winding surrounds the core in Core-Type Transformers.	The core surrounds the winding in Shell-Type Transformers.
Alternate name	Concentric Winding or Cylindrical Winding.	Sandwich or Disc Winding.
Maintenance	Core-Type Transformers have easy maintenance.	Shell-Type Transformers have complex maintenance.
Mechanical strength	Core-Type Transformers have low mechanical strength.	Shell-Type Transformers have high mechanical strength.
Insulation	Insulation is more in Core-Type Transformers.	Insulation is less in Shell-Type Transformers as compared to Core-Type Transformers.

References

1. Calculation of leakage inductance of core-type transformers for power electronic circuits | IEEE Conference Publication | IEEE Xplore
2. Electromechanical Analysis of Core- and Shell-Type Inductive Superconducting Fault Current Limiters Under General Fault Conditions | IEEE Journals & Magazine | IEEE Xplore