The construction of the core can significantly impact which parameter of a transformer?

• A. Watt losses
• B. Output voltage
• C. Efficiency
• D. Size

Answer: (A)

Core losses, the heat produced in a transformer’s magnetic path, come mainly from hysteresis and eddy currents in the core material. The way the core is built—what material it’s made of, how the laminations are arranged, how thin the laminations are, the insulation between layers, and whether any air gap is present—directly controls how big those losses are. Thin, well-insulated laminations of a suitable material reduce eddy currents by breaking the path for circulating currents and increasing resistance to them. At the same time, choosing materials with favorable magnetic properties and operating at appropriate flux densities lowers hysteresis losses. Since watt losses are just these core losses expressed as heat, the core’s construction has a direct, significant impact on them.

Output voltage is determined mainly by the turns ratio, not the core construction. Efficiency and size are influenced by losses and power handling, but the most immediate effect of how the core is built is on the watt losses.