Difference between Core type and Shell type Transformer

Core type Transformer

In core type transformers, winding is positioned on two limbs of the core and there is ONLY one flux path and windings are circumventing the core.

 

core type transformer

 

These transformers are quite favorite in High voltage practical applications like Distribution, Power, and Auto-Transformers.

Shell Type Transformer

In shell type transformers, winding is positioned on the middle limb of the core while other limbs are utilized as the mechanical support.

shell type transformer

These transformers are quite favorite in Low voltage practical applications such as transformers employed in electronic circuitry as well as in power converters.

This article is intended to cover the key differences between Core type and Shell type Transformers on the basis of many practical factors such as Windings, Limbs, Copper Requirement, Lamination, Flux Distribution, Windings Position, Cooling, Repair, Out, Design, Efficiency, Mechanical Strength, Leakage Reactance, Heat Dissipation, and Application. The following table keys out the main differences between Core and Shell type Transformers.

Difference between Core type and Shell type Transformer

CharacteristicsCore type transformerShell type transformer
WindingIn this type, winding surrounds the coreIn this type, core surrounds the winding
LimbsIt has two limbsIt has three limbs
Copper requirementRequires lessRequires more
LaminationLaminations are usually in the form of alphabet letter LLaminations are usually in the form of alphabet letter E and L
Flux distributionFlux is equally distributed on the side limbsSide limbs carry the half of the flux while the central one carries the whole flux
Windings positionPrimary and secondary both windings are wound on the side limbs Both windings are wound on the central limb
Magnetic circuitOnly one magnetic circuitThere are two magnetic circuits
TypesCylindricalMultilayer and Sandwich type
CoolingBetter cooling because more surface is exposed to external atmosphereNatural cooling is not very effective so fans are used
RepairEasy to repair because assembly can be dismantled easilyDifficult to repair because both windings are on the same limb
OutputOutput is less because of more losses so less efficiencyOutput is high because of less losses so efficiency is high in this type
DesignEasy in design and constructionComparatively complex
Mechanical strengthLow because of non-bracingPossesses high mechanical strength
Leakage reactanceLeakage reactance is not easily possibleIn this type, leakage reactance is highly possible
Heat dissipationBetter heat dissipation from windingsWindings are surrounded by core so heat dissipation is not easy
ApplicationUsed for high voltage application like power transformers, autotransformersUsed for low voltage application like transformers in an electronic circuits