Which design feature of transformer cores helps reduce energy losses due to eddy currents?

• A. Solid Steel
• B. Laminated Steel
• C. Copper
• D. Air Core

Answer: (B)

Eddy currents are circulating currents induced in a conductive material when magnetic flux changes. In transformer cores, these currents waste energy as heat. The way to minimize them is to break up the path those currents can take, which is exactly what laminating the core does. By using many thin steel sheets separated by an insulating layer, each sheet carries only small, localized loop currents and the insulating layers prevent currents from flowing through the entire thickness. This dramatically reduces the area of the loops and the overall eddy-current losses. Solid steel would let large loops form and waste more energy; copper isn’t used as the core material; an air core would avoid iron losses but isn’t practical for providing the needed magnetic path. Laminated steel is the design feature that best reduces eddy-current losses.