What is eddy currents loss in transformer? How it is minimized in a transformer?
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How to minimize eddy currents?
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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William Stoertz, Consultant at Unification Thought Institute (2017-present)
Answered Jul 23, 2017
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.
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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William Stoertz, Consultant at Unification Thought Institute (2017-present)
Answered Jul 23, 2017
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.
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☆when there is a loss of energy in the form of heat in the core of a transformer then this loss of energy is termed as eddy current.
In order to reduce the eddy current following preventative measures are taken:
☆ The iron core is laminated by making it of a number of thin sheets of iron insulated from each other ,instead of making it from one solid piece of iron.
☆Higher the resistance of the iron core, lesser will be the eddy current loss .
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