Question

Which of the following is the best method to reduce eddy currents?

Answer 1

Ans: In order to reduce the eddy current loss, the resistance of the core should be increased.In devices like transformers, the core is made up of thin sheets of steel, each lamination being insulated from others by a thin layer of varnish.As the laminations are thin, they will have relatively high resistance.The planes of these sheets are placed perpendicular to the direction of the current that would be set up by the induced emf. The planes of these sheets are arranged parallel to the magnetic fields so that they can cut across the eddy current paths.Large resistances between the sheets confines the eddy currents to the thin sheets. Each lamination sheet will have an eddy current circulates within it. Tiny eddy currents still exist, but only within each thin sheet, so are greatly reduced.The sum of individual eddy current of all the laminations are very less compared to that of using single solid iron core.

For more: Understanding Eddy Current Loss: How to minimize it?

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OTHER ANSWERS



Srinivas.k, electrical

Answered May 2, 2016

generally,eddy currents flow due to circulating currents in transformer. there is leakage flux induces an emf, so there by an circulating currents flows.

In order to reduce it ,

(1) increase the resistance (of internal parts of t/f where circulating currents flow)with out increasing length .ie.,it can be done by increasing area of cross section of laminations so as resistance increases less circulating current flows &this does not effect on main current

(2) other inefficient method is reducing frequency as eddy current loss is linear to square of freq

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William Stoertz, AP English Literature Teacher at Cheongshim International Academy (2009-present)

Answered Jul 23, 2017 · Author has 1.6kanswers and 392.6k answer views

The eddy current loss is significant only in AC power applications; the higher the frequency the greater the eddy current loss can be. Especially in a transformer core, if the core is solid metal (usually iron), the eddy currents are expansive, in counter to the coil current. To reduce the eddy current loss, the first way is by laminating the core -- that's why you usually see transformers having many layers or stripes on the sides. An even better way is to design a ferrite core made of fine grains of iron oxide, manganese-zinc ferrite [MnaZn(1-a)Fe2O4], or nickel-zinc ferrite [NiaZn(1-a)Fe2O4)] embedded in ceramic or epoxy. Thus the eddy currents are restricted to a microscopic domain, and are more easily reversible with the high-frequency AC current.

Hope it Helps!!