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Constructionally, the transformers are of two general types, distinguished from each other merely by the manner in which the primary and secondary coils are placed around the laminated core. The two types are:- Core type   Shell type Another recent development is spiral core or wound core type, the trade name being spirakore transformer. Core type transformer:- In the core type transformer, the windings surround a considerable part of the core. In the simplified diagram of the core type transformer, the primary and secondary winding are shown located on the opposite limbs of the core, but in actual construction they are interleaved to reduce leakage flux. As in the figure, half the primary and half the secondary winding have been placed side by side or concentrically on each limb, not primary on one limb and the secondary on the other. The coil used are form-wound and are of the cylindrical type. In small size core type transformers, a simple rectangular c...

The transformer basically consists of two coils having mutual inductance and laminated steel core. The coils are insulated from each other and the steel core. Other necessary parts are: Some suitable container for assembled core and windings. a suitable medium for insulating the core and windings from the container. suitable bushings for insulating and bringing out the terminals of windings from the tank. In all types of transformers the core is constructed of steel sheet laminations assembled to provide a continuous magnetic path with a minimum of air gap included. The steel used is of high silicon content. The eddy current loss is minimized by laminating the core. The thickness of the laminations varies from 0.35mm for a frequency of 50 Hz to 0.5mm for a frequency of 25 Hz. The sheets are imbricated to avoid the narrow gaps through the cross section of the core. Types of Transformers On the basis of construction, transformers are of two types: 1. Core T...