Question

The core of a transformer is laminated to reduce
(A) Flux Leakage
(B) Hysteresis
(C) Copper loss
(D) Eddy current

Answer 1

Hint: In all type of the transformer construction, in which the central iron core is constructed from of a highly permeable material which are made up of thin silicon steel laminations then these thin laminations are assembled together to provide the required magnetic path with the minimum loss of magnetic field.

Complete step by step solution
Based on the Faraday’s law of Electromagnetic induction, whenever a conductor is subjected to an alternating magnetic flux, then an Electromagnetic field (E.M.F) is induced in the conductor. In a transformer, the core is made up of a ferromagnetic material. Actually, the core gets subjected to the alternating magnetic flux produced by the primary windings of the transformer. Due to which E.M.F is induced in the core.

Since the core forms a closed path, current gets induced (Eddy Current). So, the core has some resistance due to which losses are produced which decreases the efficiency of the transformer. So, we have to reduce this eddy current. In order to reduce the eddy current we have to increase the resistance of the material.

As resistance of a material is inversely proportional to area of cross section, the area of cross section can be decreased to increase resistance. So, in the case of a transformer we can decrease the area of the cross section by using the laminated sheets, by which the resistance gets increased, thus eddy currents can be reduced. Thus, the core of a transformer is laminated to reduce the Eddy Current.

Hence the option (D) is correct.

Note: In the transformer core the laminations are usually stacked alternatively to each other to make an overlapping joint with more lamination pairs which are being added to make up a correct core thickness. The alternate stacking of the laminations also gives the advantage to the transformer to reduce flux leakage and iron losses. E-I core laminated transformer construction is used in isolation transformers, auto transformers as well as in step-up and step-down transformers.